That’s because both precipitation and smoke are a possibility during the airshow (July 22-28), according to Scott Dennstaedt, author of the EZWxBrief and a FLYING contributor.

• READ MORE: FLYING Unveils ‘Oshkosh Live’ Video Programming Lineup

For starters, the wildfires in Canada and to the west may result in some smoky skies, Dennstaedt said. This was a factor last year, resulting in thick haze, poor visibility, and blood-red sunrises and sunsets. Photographs taken in the early morning hours had a sepia-tone look to them—a bonus if you are taking pictures of vintage aircraft.

In a forecast released Thursday, Dennstaedt predicted AirVenture attendees may smell the smoke earlier in the day but by later afternoon could expect some convective activity that should clear away the smoke due to the unstable atmosphere and ground heating up.

Dennstaedt presents an entertaining and educational look at the factors impacting aviators who are trying to get to the event as well as what to expect when they get there. The data is derived from atmospheric tools used by the National Oceanic Atmospheric Administration (NOAA).

EZWxBrief AirVenture Weather Roundup

The post Flying to AirVenture? What You Can Expect of the Oshkosh Weather appeared first on FLYING Magazine.

Answer: It depends on your mission and how many Ben Franklins you have to spare. Your sferics (short for radio atmospherics) equipment may represent the only real-time weather you’ll ever see in your cockpit.

Sure, panel-mounted and portable weather systems deliver their product in a timely fashion, but it will never be as immediate as your sferics device. Once you understand how to interpret your real-time lightning guidance, it can become a valuable asset in your in-flight aviation toolkit. 

Choices in the Cockpit

You have two options if you want lightning data in the cockpit: You can choose from ground-based lightning sensors or onboard lightning detection from a sferics device such as a Stormscope.

A Stormscope provides real-time data but does require some basic interpretation. Ground-based lightning, on the other hand, is a bit delayed and is only available through a data link broadcast at this time. Ground-based lightning is normally coupled with other weather guidance, such as ground-based weather radar (NEXRAD), surface observations, pilot weather reports, and other forecasts.   

Ground-Based Lightning

The ground-based lightning that’s now available through the Flight Information System-Broadcast (FIS-B) comes from the National Lightning Detection Network (NLDN). This network of lightning detectors has a margin of error of 150 meters for locating a cloud-to-ground strike. The ground-based lightning sensors instantly detect the electromagnetic signals given off when lightning strikes the earth’s surface.    

With 150-meter accuracy, I’d choose ground-based lightning any day. Don’t get too excited, though. Ground-based lightning is expensive (the data is owned by private companies like Vaisala), and you’ll not likely see a high-resolution product in your cockpit anytime soon.

SiriusXM satellite weather pulls from a different lightning detection network and includes both cloud-to-ground and intracloud lightning. It produces a 0.5 nm horizontal resolution lightning product. This means that you will see a lightning bolt or other symbol arranged on your display in a 0.5 nm grid.

Even if 50 strikes were detected minutes apart near a grid point, only one symbol will be displayed for that grid point. Same is true for the FIS-B lightning.

Stormscope Advantages

A Stormscope must be viewed as a gross vectoring aid. You cannot expect to use it like onboard radar.

Nevertheless, it does alert you to thunderstorm activity and will provide you with the ability to see the truly ugly parts of a thunderstorm.  Where there’s lightning, you can also guarantee moderate or greater turbulence.   

No lightning detection equipment shows every strike, but the Stormscope will show most cloud-to-ground and intracloud strikes. This allows you to see the intensity and concentration of the strikes within a cell or line of cells with a refresh rate of two seconds. It also lets you see intracloud electrical activity that may be present in towering cumulus clouds even when no rain may be falling.

Even if no cloud-to-ground strikes are present, intracloud strikes may be present. The Stormscope can detect any strike that has some vertical component (most strikes do). This is important since there are typically more intracloud strikes than cloud-to-ground strikes.

To emphasize this point, most of the storms in the Central Plains have 10 times more intracloud strikes than cloud-to-ground strikes. Moreover, during the initial development of a thunderstorm, and in some severe storms, intracloud lightning may dominate the spectrum. 

Also keep in mind that a sferics device does not suffer from attenuation like onboard radar. That is, it can “see” the storm behind the storm to paint cells in the distance out to 200 nm, but it does not see precipitation or clouds.     

Stormscope Disadvantages

It doesn’t take a full-fledged storm, complete with lightning, to get your attention.

Intense precipitation alone is a good indicator of a strong updraft (or downdraft) and the potential for moderate to severe turbulence in the cloud. Consequently, the Stormscope does not tell you anything about the presence or intensity of precipitation or the absence of turbulence.

Never use the Stormscope as a tactical device to penetrate a line of thunderstorm cells. Visible gaps in the cells depicted on the Stormscope may fill in rapidly. Fly high and always stay visual and you will normally stay out of any serious turbulence.        

A Stormscope display is often difficult to interpret by a novice. Radial spread, splattering, buried cables, and seemingly random “clear air” strikes can create a challenge for the pilot. It may take a couple years of experience to be completely comfortable interpreting the Stormscope display. Often what you see out of your window will confirm what you see on your display.    

Radial Spread

As the name suggests, the biggest Stormscope error is the distance calculation along the radial from the aircraft.

The placement of the strike azimuthally is pretty accurate. However, how far to place the strike from the aircraft along the detected radial is a bit more complicated and prone to error.

Lightning strikes are not all made equally. When the sferics devices were invented back in the mid-1970s, they measured the distance of the cloud-to-ground strike based on the strength of the signal (amperage) generated by the strike. An average strike signature of 19,000 amperes is used to determine the approximate distance of the strike.

Statistically, 98 percent of the return strokes have a peak current between 7,000 and 28,000 amperes. That creates the potential for error in the distance calculation. This error is a useful approximation, however, in that strokes of stronger intensity appear closer and strokes of weaker intensity appear farther away. 

In strike mode on the Stormscope, strikes are displayed based on a specific strike signature, whereas cell mode on the newer Stormscope models uses a clustering algorithm that attempts to organize these strikes around a single location or cell.

Cell mode will even remove strikes that are not part of a mature cell. Most thunderstorm outbreaks are a result of a line of storms. Cell mode provides a more accurate representation to the extent of the line of thunderstorms.

Radial spread is not necessarily always a bad thing. You can use it to your advantage to distinguish between false or clear air strikes and a real thunderstorm. Most of the strikes of a real storm will be of the typical strike signature and be placed appropriately.

As mentioned above, stronger than average strikes will be painted closer to the airplane. Looking at this in strike mode, a line of these stronger strikes will protrude toward the aircraft.  The result is a stingray-looking appearance to the strikes.    

You can confirm this by clearing the display.  The same stingray pattern should reappear with the tail protruding once again toward the airplane.

Clear Frequently

Clearing the Stormscope display frequently is a must.  How quickly the display “snaps back” will provide you with an indication of the intensity of the storm or line of storms.

You should be sure to give these storms an extra-wide berth.  Clearing the Stormscope in “clear air” will also remove any false strikes that may be displayed allowing you to focus on real cells that may be building in the distance.

Aging

Both ground-based and onboard lightning use a specific symbol to indicate the age of the data.

For Stormscope data shown on the Garmin 430/530, a lightning symbol is displayed for the most recent strikes (first six seconds the symbol is bolded). The symbol changes to a large plus  sign after one minute followed by a small plus  sign for strikes that are at least two minutes old. Finally, it is removed from the display after the strike is three minutes old.

Cells with lots of recent strikes will often contain the most severe updrafts and may not have much of a ground-based radar signature. Cells with lots of older strikes signify steady-state rainfall reaching the surface that may include significant downdrafts. 

Flight Strategy

A nice feature of a Stormscope is that you can quickly assess the convective picture out to 200 nm while still safely on the ground. Same is true for lightning received from the SiriusXM datalink broadcast.

However, for those with lightning from FIS-B, you won’t receive a broadcast until you are well above traffic pattern altitude unless your departure airport has an ADS-B tower on the field.  

As soon as your Stormscope is turned on, within a few minutes you’ll get a pretty good picture of the challenging weather ahead. If you are flying IFR, you may want to negotiate your clearance or initial headings with ATC to steer clear of the areas you are painting on your display. I’ve canceled or delayed a few flights based strictly on the initial Stormscope picture while I was still on the ramp. 

Another goal is to fly as high as allowable. You will benefit from being able to get above the haze layer, and the higher altitude will allow you to see the larger buildups and towering cumulus from a greater distance.

If you are flying IFR and you are continually asking for more than 30 degrees of heading change to get around small cells or significant buildups, then you should call it quits. You are too close, or you are making decisions too late.

Visual or not, the goal is to keep the strikes (in cell mode) out of the 25-mile-range ring on your Stormscope. If one or two strikes pop into this area, don’t worry. Just keep most of the strikes outside of this 25-mile ring.      

Don’t discount the value of a sferics device.  Add one of the data link cockpit weather solutions as a compliment, and you will have a great set of tools to steer clear of convective weather all year long.

The post Is Sferics Equipment Still Needed in the Cockpit? appeared first on FLYING Magazine.

The Atlantic hurricane season officially began June 1 and runs through November 30. While the National Oceanic and Atmospheric Administration (NOAA) has not released its official forecast for 2024 as of this writing, in an average Atlantic hurricane season the U.S. experiences 14 named storms, seven of which are hurricanes and three are major hurricanes.

Buckle up. Given the likely return of La Niña (one of three phases of the El Niño-Southern Oscillation) and record warm sea surface temperatures in February as heated as we see in mid-July, this is not good news if you were hoping for just a mediocre season. If you live and fly anywhere along the Atlantic coastal plain or the Gulf of Mexico, here’s how you can prepare for what may be a wild hurricane season.

Even though hurricane season peaks on September 10, the tropics will begin to see increased activity during the months of June, July, and August as sea surface temperatures increase and the jet stream migrates north into Canada, creating a more favorable breeding ground in the tropics. During this time, what are called tropical waves will develop in the Atlantic Ocean, Gulf of Mexico, and Caribbean Sea, forming in the tropical easterlies (winds moving from east to west). A weak area of low pressure with a closed circulation called a tropical depression may develop along one of these waves.

• READ MORE: The Ins and Outs of Pilot Weather Reports

If conditions are favorable, such as the presence of weak atmospheric wind shear over relatively warm waters, then convection can organize and strengthen into a tropical storm. Once it reaches tropical storm criteria, the National Hurricane Center (NHC) will give the storm a name. The first named storms of 2024 were Alberto and Beryl, with Chris, and Debby to follow. If you recognize a few of these names, be aware that the list is recycled every six years. The NHC points out that a name is removed from the list only “if a storm is so deadly or costly that the future use of its name for a different storm would be inappropriate for reasons of sensitivity.”

Saffir-Simpson Scale

Let’s become familiar with the Saffir-Simpson Hurricane Wind Scale. This scale from 1 to 5 was introduced in the early 1970s by the NHC, using estimates of peak wind, storm surge, and minimum central pressure to describe the destruction from both water and wind for tropical cyclones making landfall.

The Saffir-Simpson scale was simplified in 2010 to be solely determined by a one-minute-average maximum sustained wind at a height of 10 meters (33 feet) above ground level. Once a tropical cyclone reaches hurricane strength (sustained wind speed of 64 knots or greater), it is assigned a category, with a Category 1 hurricane being the weakest and a Category 5 hurricane being the strongest (sustained wind speed of 137 knots or greater). There has been some interesting discussion lately to expand this open-ended scale from 5 to 6 categories given that some of the strongest Category 5 hurricanes are well above that minimum threshold and may not truly capture the potential destruction. This change, however, is unlikely to occur any time soon.

• READ MORE: How to Wrap Your Head Around Weather

Next, you should become familiar with the NHC website, where you will find all of the official guidance published by NOAA. Each named storm, tropical depression, and tropical disturbance will be tracked along with public advisories, such as watches and warnings (e.g., hurricane watch) based on the threat to people and property. You’ll also find a public discussion for the tropics when there are no named storms and a discussion for each system being tracked.

Hurricane Graphics

One product that is ubiquitous during hurricane season is the tropical cyclone forecast cone graphic. This is designed to depict the expected track, location, and strength of the tropical cyclone over the next five days. It also shows the cone of uncertainty.

According to the NHC, “the cone represents the probable track of the center of a tropical cyclone where the entire track can be expected to remain within the cone roughly 60-70 percent of the time.” Of course, the cone tends to get wider with forecast lead time. In other words, there’s more certainty with a forecast that is valid in 48 hours (smaller cone) versus one that is valid in 120 hours (larger cone).

Currently, the graphic only includes those watches and warnings along coastal regions. Starting in 2024, the NHC will be issuing an experimental tropical cyclone forecast cone graphic that also includes inland tropical storm and hurricane watches and warnings in effect for the contiguous U.S. Recommendations from social science research suggest that the addition of inland watches and warnings to the cone graphic will help communicate inland wind risk during tropical cyclone events while not overcomplicating the current version of the graphic with too many data layers.

Electrification of Hurricanes

It’s probably not a surprise to hear that a healthy squall line moving through the Midwest can generate lightning at a rate of more than one strike per second for an extended period of time. But what about in a tropical storm or hurricane? You might be astonished to learn that, on average, a hurricane rarely produces more than a single lightning strike every 10 minutes. While there are some hurricanes and tropical storms that are highly electrified (especially when making landfall), don’t let your guard down—many are not.

No GA pilot is going to fly through the center of a tropical storm or hurricane on purpose. There’s typically plenty of advance warning from the NHC on the location and track of these powerful weather systems. However, once the tropical system makes landfall and weakens, how safe is it to fly through some of the precipitation remnants of the storm? A dissipating tropical system over land can contain some nasty convective turbulence and even small EF0 and EF1 tornadoes. Consequently, it is not unusual for the Storm Prediction Center (SPC) to issue a tornado watch for most tropical systems making landfall.

• READ MORE: Flying Through the Center of a Trough Should Have Been Uneventful

The precipitation signature as depicted on a ground-based radar mosaic associated with tropical cyclone remnants may not look too threatening to the average pilot.

First, it is often void of lightning, unlike what you might see with other convective outbreaks. Also, the automated surface observations in the area may only include +RA for heavy rainfall. In other words, you may not see +TSRA implying lightning exists as well as rain. Second, the ground-based radar mosaic may not have much of a true cellular structure with high reflectivity gradients that we often see with other deep, moist convection.

Despite the lack of lightning and a relatively benign-looking radar image, tropical system remnants should be treated as if they were that intense squall line in the Midwest. After such a tropical system makes landfall and begins to rapidly dissipate into a tropical depression or extra-tropical cyclone, it will move inland carrying similar risks.

This is evidenced by the remnants of Hurricane Katrina in 2005. This was a powerful storm that made landfall as a strong Category 3 hurricane at the end of August near New Orleans and moved north into the Tennessee and Ohio valleys as it dissipated.

Even after the storm was declared as extra-tropical, tornado watches were issued just to the east of Katrina’s track along the central and southern Appalachian Mountains and into the Mid-Atlantic. It is important to understand that the lack of lightning does not imply the lack of dangerous convective turbulence.

In order for lightning to form within deep, moist convection, three ingredients must be present in the right location of the cloud. This includes ice crystals, supercooled liquid water, and a “soft hail” particle called graupel.

Updrafts in tropical systems are actually quite limited, usually no more than 1,500 feet per minute. These updrafts are far from upright, owing to the strong horizontal wind shear present. According to hurricane researcher Dr. Robert Black, “while there is some presence of electrical fields, the graupel-liquid water-ice combination turns out to be at the wrong place at the wrong temperature and in insufficient volume to give the spatial charge distribution to produce a lightning discharge.”

In layman’s terms, little supercooled liquid water gets carried high enough to the level necessary to electrify the cloud. This continues to be true even after the tropical system makes landfall and dissipates inland.

The most serious electrification occurs in the outer rain bands as they spiral outward from the center of the storm. These can often look a lot like that Midwest frontal convection. Most convective cells along that squall line in the Great Plains or Midwest often move in a northeasterly direction based on the shift of the air mass and the winds aloft.

However, this may not be the case for these tropical cyclone bands. You may find these cells moving in a northerly or even westerly motion depending on the track of the tropical system.

Remain Outside of the Northeast Quadrant

If you split the storm into four quadrants based on its forward movement, the most intense atmospheric shear occurs in the northeast quadrant. This is typically where you will find the highest storm surge at landfall and where tornado watches are usually issued. As the system makes landfall, moves inland, dissipates, and becomes extra-tropical, you will find the northeast quadrant should be strictly avoided.

As we make our way through hurricane season this year, keep a close eye on the tropics and heed the guidance from the NHC. Even weak storms making landfall can add significant hazards for most aircraft. The convection associated with these storms is not the normal kind we experience during the warm season. Therefore, you can’t assume that the same ground-based signatures you might steer away from with normal convection will be present with this tropical convection.

Last, but not least, don’t use the lack of lightning to be your guide to determine what precipitation is safe to fly through. Assume there is ample wind shear in the atmosphere regardless of how it appears on radar. It may prove not to be a fair match for your aircraft or skill set.

This feature first appeared in the May 2024/Issue 948 of FLYING’s print edition.

The post Keeping an Eye on the Storm appeared first on FLYING Magazine.

Answer: In general aviation, one of the most cumbersome things to do while in flight is to file a pilot weather report, more commonly known as a PIREP. This has created the unfortunate situation that on any given day 98 percent of the PIREPs in the system are typically describing weather conditions at or above 18,000 feet.

It wasn’t all that long ago that the Enroute Flight Advisory Service (EFAS) was available primarily for pilots to receive weather updates while they were flying to their destination. More importantly, EFAS was the main outlet to file a PIREP such that it was guaranteed to be input into the system and become available for other pilots to see. This service was also called Flight Watch.

Given that EFAS was organized by Air Route Traffic Control Centers (ARTCC), you simply put 122.0 MHz into your radio, keyed the mic, and referenced them by a particular center’s airspace you were located within. For example, if you were in the Jacksonville Center’s airspace in Florida, your initial call might have been, “Jacksonville Flight Watch, Skyhawk One Two Three Whiskey X-ray, 30 miles southwest of the Brunswick V-O-R at five thousand five hundred.” Then as long as you were more than 5,000 feet above the ground, someone from Flight Watch came on the frequency, and you engaged in a two-way conversation to file your PIREP.

• READ MORE: The Ins and Outs of Pilot Weather Reports

However, EFAS was terminated on October 1, 2015. This now leaves the arduous task of finding the right Flight Service Station (FSS) frequency, making contact, and hoping someone on the other end responds to your call. The frequency you use to transmit and receive is dependent on your location. Pull out your VFR sectional (paper or electronic version), find the nearest VOR to your location, and look for the frequency located on the top of the VOR information box.

Of course, the correct frequency to use may also be available through your avionics or one of the many heavyweight electronic flight bag apps.

This is the frequency you will use to transmit and receive. Below the box is the name of the particular FSS to use in your initial call. For example, if you are near the Brunswick VORTAC in Georgia, your initial call may be, “Macon Radio, Skyhawk One Two Three Whiskey X-ray, transmitting and receiving on 122.2, over.” This is the easy case.

• READ MORE: How to Wrap Your Head Around Weather

If there’s an “R” shown at the end of the frequency (e.g., 122.1R), then that means FSS will receive on this frequency and you will transmit on this frequency. And you’ll need to be sure you listen for its response over the VOR frequency. Make sure your volume is turned up and not muted on your VOR radio.

This column first appeared in the May 2024/Issue 948 of FLYING’s print edition.

The post How Do I File a Pilot Weather Report Online? appeared first on FLYING Magazine.

Northrop Grumman, I needed something that would challenge my mind, body, and spirit. There were two options on the table. I had just graduated with my master’s degree and was seriously thinking of taking the next leap of faith and earning a doctorate.

But that was quickly overshadowed by my second option—my childhood dream of learning to fly. And I wasn’t disappointed. It did challenge my mind, body, and spirit every step of the way.

What intrigued me the most about learning to fly was that it required mastering many disciplines. In other words, it’s more than just jumping into an airplane and learning stick-and-rudder skills. You have to become entrenched in subjects such as aerodynamics, radio navigation, geography, radio communications, airspace, map reading, legal, medical, and my favorite discipline, meteorology.

Despite my background as a research meteorologist, my aviation weather background was limited when I was a student pilot. So, I was very excited to discover what more I might learn about weather in addition to all of these other disciplines. If you are a student pilot, here are some tips that will help you achieve a good foundation with respect to weather.

It Isn’t Easy

First and foremost, weather is inherently difficult. It’s likely the most difficult discipline to master because of the uncertainty and complexity it brings to the table. Therefore, strive to understand what basic weather reports and forecasts the FAA effectively requires that you examine before every flight. It certainly doesn’t hide it. It’s a fairly short and succinct list that’s all documented in the new Aviation Weather Handbook (FAA-H-8083-28) and the Aeronautical Information Manual (AIM). Ultimately, knowing the nuts and bolts of this official weather guidance will help with your knowledge and practical tests and give you a head start once the ink is dry on your private pilot certificate.

Second, as a student pilot, plan to get your weather guidance from a single and reliable source. Try not to bounce around using multiple sites or apps. There are literally hundreds, if not thousands, of websites and apps that will deliver weather guidance to your fingertips such that you can become overwhelmed with all of the choices, and entropy quickly takes over. Besides, flight instructors love to show off their unique collection of weather apps on their iPhone. Sticking with the official subset of weather guidance will allow you to focus on what matters the most.

• READ MORE: Aviation Weather Center Website Upgrade—the Good, Bad, and Ugly

Once you receive your private certificate, then you can expand the weather guidance you use to include other websites and apps.

The two internet sources that should be at the top of your list include the Aviation Weather Center (aviationweather.gov) and Leidos (1800wxbrief.com). Both of these sites provide the essential weather guidance needed to make a preflight weather decision. Using one or both of these sites will help focus you on the official weather guidance the FAA demands you use.

Categorize Your Data

Third, when you look at the latest weather guidance, take a minute and characterize each product. It should fall into one of three categories: observational data, advisories, or forecasts. Knowing its category will tell you how to properly utilize that guidance. For example, if you come across a visible satellite image, that’s an example of observational data.

Observational data is always valid in the past and typically comes from sensors. What about a ground-based radar mosaic (e.g., NEXRAD)? That’s also an observation. Pilot weather reports (PIREPs) and routine surface observations (METARs) are also considered observational data. While not a pure observation, the latest surface analysis chart that is valid in the recent past will identify the major players driving the current weather systems.

• READ MORE: What Is the Criteria for Issuing a Convective SIGMET?

Observations are like the foundation when building a house. All other weather guidance you use will build on that foundation. A sturdy and well-built foundation is the key to a good preflight weather briefing. You can’t know where the weather is going until you know where it has been. Identifying the latest trends in the weather through the use of these observations is the cornerstone of this foundation. When possible, looping the guidance over time will expose these trends. Is the weather moving or stagnant? Is it strengthening or weakening over time?

Advisories such as the initial graphical AIRMETs (G-AIRMETs) snapshot, SIGMETs, and center weather advisories (CWAs) are the front lines of aviation weather. They are designed to highlight the current location of the truly ugly weather. Advisories build the structure that sits atop of this foundation. Essentially, these advisories summarize the observational data by organizing it into distinct hazards and areas of adverse weather to be avoided.

Forecasts are the springboard for how these observations and advisories will evolve over time. You can think of forecasts as the elements that protect the finished house, such as paint, shingles, and waterproofing. This also includes the alarm and surveillance system to alert you to the possible adverse weather scenarios that may occur during your flight. While forecasts are imperfect, they are still incredibly useful. Forecasts include terminal aerodrome forecasts (TAFs), convective outlooks, prog charts, and the remaining four snapshots for G-AIRMETs.

Dive into the Details…

Fourth, details matter quite a bit. Look at the guidance and identify what stands out. Don’t make a decision too early. Instead, carefully observe and gather facts. Is the precipitation occurring along the route limiting the ceiling and/or visibility? Is the precipitation expected to be showery? This is a clear indication of a convective process in place.

Are the surface observations reporting two or three mid- or low-level cloud layers? Again, this is another indication of a convective environment. This can be especially important to identify, especially when there’s a risk of thunderstorms that have yet to form.

…But Fall Back on the Big Picture

Fifth, get a sense of the big weather picture. This is likely the most difficult aspect of learning how to truly read the weather. Think about the big weather picture as the blueprint for building an entire community. It’s what brings everything together. When I do my own preflight briefings, my decisions are largely driven by what’s happening at that synoptic level.

Lastly, read, read, and read some more. Focus mostly on the weather guidance and less on weather theory. These are the specific weather products mentioned earlier. Weather theory is something you can tackle at a later time. The FAA’s Aviation Weather Handbook is a great start. You can download a PDF document for free from the agency website and add this to your online library. This was issued in 2022 to consolidate the weather information from six FAA advisory circulars (ACs) into one source document. My book, Pilot Weather: From Solo to the Airlines, was published in 2018 and is written for pilots at all experience levels in their journey to learn more about weather.

If you fly enough, you will eventually find yourself in challenging weather. The goal of any preflight weather briefing is to limit your exposure to adverse conditions, and that takes resources and time. Once you’ve mastered the weather guidance, then giving Flight Service a call at 1-800-WXBRIEF will allow you to sound like a true professional.

Yes, I eventually did earn that doctorate, but I am really happy that I took the step over 25 years ago to learn to fly. One guarantee with weather: You can never learn enough. I am still learning today.

This column first appeared in the March 2024/Issue 946 of FLYING’s print edition.

The post How to Wrap Your Head Around Weather appeared first on FLYING Magazine.

“No one enjoys flying through turbulence, whether you’re piloting a single-engine piston or riding in the back of a jet,” said Henrik Hansen, ForeFlight’s chief technology officer.

ForeFlight says the additional feature within the mobile app displays the measured intensity of turbulence at multiple altitudes, making it easy for pilots to find the smoothest altitude along their flight path. ForeFlight Mobile automatically uploads the reports once it establishes an internet connection after the flight or instantly if connectivity is maintained during flight, according to officials.

Turbulence reports are depicted as colored markers on the Maps tab: Gray signifies smooth air, while yellow, orange, and dark orange represent increasing levels of turbulence, ranging from light to severe.

While pilots traditionally rely on weather forecasts and PIREPs for route planning, ForeFlight says its Reported Turbulence method offers distinct advantages, including enhanced accuracy and objective reporting.

ForeFlight estimates its Reported Turbulence layer offers 50 times more turbulence reports than manual PIREPs, per Sporty’s IPAD Pilot News.

Reported Turbulence is available as two add-ons for Pro Plus subscribers. Reported Turbulence (Low) offers access to turbulence reports up to 14,000 feet, whereas Reported Turbulence (All) provides access to reports across all altitudes.

Editor’s Note: This article first appeared on AVweb.

The post ForeFlight Introduces Reported Turbulence Map appeared first on FLYING Magazine.

But wait, is vertical visibility even a legitimate visibility? Actually, it’s a bit of a misnomer and not a true measure of visibility in the traditional sense. Vertical visibility is a close cousin to ceiling. That is, it represents the distance in feet a person can see vertically from the surface of the Earth into an obscuring phenomenon, or what is called an indefinite ceiling. What isn’t obvious is how vertical visibility is determined, and how this is different from a definite ceiling.

It’s arguable that an indefinite ceiling is perhaps the most misunderstood phenomenon reported in a routine (METAR) or special surface (SPECI) observation. Forecasters will add vertical visibility in a terminal aerodrome forecast (TAF) as illustrated in the image below for Bradford Regional Airport (KBFD) in Pennsylvania. Whether this occurs in a METAR or TAF, vertical visibility is coded as “VV” followed by a three-digit height in hundreds of feet above the ground level. For example, you may see “VV002,” which is a vertical visibility of 200 feet. While a definite ceiling can be broken or overcast, a vertical visibility always implies the sky is completely covered. Let’s explore the difference between a definite and indefinite ceiling and the operational considerations.

Automated Observations

In the early days, human weather observers used to employ what were called “pilot balloons” to estimate the ceiling height. Essentially the balloon was launched by the observer and, given the balloon’s known rate of ascent, they watched the balloon enter the base of the clouds and measured the time it took using a stopwatch to determine the ceiling height. Then new technology emerged called a rotating beam ceilometer that measured the height of clouds. While it was more effective than launching a balloon, this method was phased out around 1990 and replaced with the laser beam ceilometer, the technology still widely used today.

The task of walking outside and assessing the height of clouds is generally a thing of the past given that this technology is incorporated into the automated surface observing system (ASOS) or automated weather observing system (AWOS) present at many airports throughout the U.S. The trained observer simply logs in to the ASOS (or AWOS) and makes their observation based on the data gathered and reported by the automated system. Then the observation is edited and augmented by the observer as necessary. Depending on the airport, this process may be completely automated.

In all honesty, making an estimate of the height of the cloud base isn’t the difficult part. What’s difficult is to provide a representative description of the amount of cloud coverage (e.g., few, scattered, broken, or overcast) in the airport’s terminal area. A laser beam that points straight up may easily miss a scattered or broken cloud deck. To alleviate this issue, the automated systems process the data over a given amount of time since clouds are generally moving through the sensor array area. It was found that a 30-minute time period provided a representative and responsive observation similar to that created by a trained observer. The most recent 10 minutes of sky cover and ceiling height are double weighted using a harmonic mean. (A harmonic mean is used in the visibility and sky cover algorithms rather than an arithmetic mean because it is more responsive to rapidly changing conditions such as decreasing visibility or increasing sky coverage/lower ceiling conditions.) In the end, the goal is to provide an observation representative of the airport’s terminal area, which is the area within 5 sm from the center of the airport’s runway complex. Visibility, wind, pressure, temperature, etc., all have their own harmonic means accordingly.

In our everyday experience, we know that many cloud decks observed from the ground have a very well-defined base. For an untrained observer, it might not be a simple task to determine their height. However, it’s easy to pick out where the base of the cloud starts. Even in these cases, the cloud decks may vary in height and multiple cloud layers may exist. Visually, that may be more difficult to discern for the untrained eye, but automated systems do a reasonable job making that observation. In a convective scenario, it is not unusual to see multiple scattered and broken cloud heights. For example, at the West Michigan Regional Airport (KBIV) the following was observed:

KBIV 122353Z AUTO 08011KT 4SM RA BR FEW011 SCT048 OVC065 19/18 A2972

This observation includes three definite cloud layers, which are a telltale sign that a convective environment is in place even before the first lightning strike.

Nuts and Bolts

An ASOS continuously scans the sky. To determine the height(s) of the clouds, the backscatter returns from the ceilometer are put into three different bins. When there’s a “cloud hit,” the system identifies a well-defined and sharp signature pattern that you’d expect with the sensor striking the cloud base. Essentially this means most of the hits are aggregated around a particular height above the ground. Such a sharp signature is then incorporated into the 30-minute sky cover and cloud height harmonic average, and a new observation is born.

On the other hand, a “no hit” is recorded when there isn’t an ample amount of backscatter received, usually because there are no clouds below 12,600 feet agl over the sensor. Note that the ASOS (and AWOS) is designed only to detect clouds below 12,600 feet above the ground, although a trained observer can and does report higher clouds. Lastly, if the backscatter does not provide that sharp signature around a particular height, an “unknown hit” is recorded. It is this unknown hit that leads us down the path to an indefinite ceiling or vertical visibility.

Haze, Mist, and Fog, Oh, My!

So, isn’t an indefinite ceiling the same thing as a ground fog event? Not necessarily. Stratus is the most common cloud associated with low ceilings and reduced visibility. Stratus clouds are composed of extremely small water droplets or ice crystals (during the cold season) suspended in the air and may be touching the surface, so to speak. An observer along a coastal region or on the side of a mountain would likely just call this plain old fog. This is certainly understandable, since we grew up calling this kind of situation foggy.

Fog, however, is thought to be more of an obstruction to visibility from a surface observing standpoint. To understand the recording of obscurations, here’s how the ASOS automatically determines what to report. Once each minute, the obscuration algorithm checks the reported visibility. When the visibility drops below 7 sm, the current dew point depression (temperature-dew point spread) is checked to distinguish between fog (FG), mist (BR), and haze (HZ). If the dew point depression is less than or equal to 4 degrees Fahrenheit (~2 degrees Celsius), then FG or BR will be reported. Visibility will then be used to further differentiate between FG and BR.

Whenever the visibility is below five-eighth sm, FG is reported regardless of the “cloud” that produces it. So fog isn’t really about a cloud or ceiling as much as it is about visibility. Therefore, stratus and fog frequently exist together. In many cases, there is no real line of distinction between the fog and stratus; rather, one gradually merges into the other. Flight visibility may approach zero when flying in stratus clouds. Stratus over land tends to be lowest during night and early morning, dissipating by late morning or early afternoon. Low stratus clouds often occur when moist air mixes with a colder air mass or in any situation where temperature-dewpoint spread is small.

• READ MORE: Decoding the Weather

Moisture-Rich Environment

Essentially, an indefinite ceiling means there is something obscuring your view of the cloud base. When you look up, you won’t be able to see a well-defined cloud base like you would on a day where the sky isn’t obscured. According to the ASOS User’s Guide, “these ‘unknown hits’ are primarily caused by precipitation and fog that mask the base of the clouds.” The laser beam bounces off moisture at various heights, making it impossible to process this as a definite cloud hit. Instead, the ASOS identifies these unknown hits as a vertical visibility abbreviated as “VV” in the resulting routine or special observation.

Given the broad moisture field near the surface that scatters the laser beam signal, indefinite ceilings are guaranteed to be paired with low visibility situations. You are not going to see a surface visibility of 10 miles paired with a VV of 200 feet. Usually this means a low or very low IFR flight category anytime there’s an indefinite ceiling. Also keep in mind that an indefinite ceiling in a terminal forecast will result in a low visibility forecast.

In general, the higher the vertical visibility, the better the surface visibility. Therefore, a vertical visibility of 200 feet (VV002) is usually met with a visibility of one-half sm. Furthermore, a vertical visibility of 700 feet (VV007) will likely be associated with a visibility between 1 and 2 sm. While rare, you may even see a fairly high vertical visibility over 1,000 feet (e.g., VV012). In this case, the surface visibility may be over 3 sm. The really bad stuff, however, occurs with a visibility of one quarter sm (or even “M1/4 SM” denoting less than that) and a vertical visibility of zero feet (VV000) as illustrated in the image below for Bradford Regional Airport. This very low indefinite ceiling is not all that common unless you are stationed on the summit of Mount Washington in New Hampshire, where this low vertical visibility happens quite often throughout the year. It also occurs fairly often at airports along West Coast regions of the U.S., especially during their “May gray” or “June gloom” time frame.

As mentioned earlier, fog and precipitation are the two primary reasons the base of the cloud deck is obscured. Therefore, it’s common to see vertical visibility reported when light rain, drizzle, or even snow is falling from the cloud base.

Precipitation or not, it’s generally rare to see a single station reporting an indefinite ceiling. Most of the time, you will see indefinite ceiling reports embedded in a widespread area of low or very low IFR conditions, especially at coastal airports. Although airports such as Nantucket Memorial Airport (KACK) in Massachusetts can be reporting a low indefinite ceiling, at stations farther inland near Cape Cod the sky can be clear or nearly so.

It’s important to note that conditions producing an indefinite ceiling often take longer to improve. Normally there will be a transition from an indefinite to definite ceiling once the moisture begins to mix out with the help of the sun. However, the visibility may still be quite low for the next few hours. Keep this in mind when flight planning to an airport reporting an indefinite ceiling.

Operational Significance

From a practical standpoint, you should treat an observation or forecast for a vertical visibility the same as you’d treat a definite ceiling. Given the nature of conditions that produce an indefinite ceiling, you can expect a longer transition as you depart into such a ceiling under IFR. It’s easy to get spatial disorientation because of the gradual change.

An indefinite ceiling restricts the pilot’s flight (air-to-ground) visibility. Therefore, an instrument approach may be a bit more challenging even after you drop below the reported ceiling height because of the reduced visibility. Most importantly, a circle-to-land approach with an indefinite ceiling will make it quite difficult to keep the runway in sight, especially at night. And, as a final consideration, with an indefinite ceiling, don’t be surprised to see runway visual range also pop up in the observation for airports with such equipment.

This feature first appeared in the October 2023/Issue 942 of FLYING’s print edition.

The post Here’s the Lowdown on ‘Vertical Visibility’ appeared first on FLYING Magazine.

If you call Flight Service for a standard briefing or get an automated briefing through one of the many heavy-weight apps, you can bet the farm that any TAFs along your proposed route and at your departure and destination airports will be a part of this briefing. There are, however, some finer details about the forecast found in TAFs that instructors fail to pass along to their primary students possibly owing to their own lack of knowledge. The top one on the list includes a forecast for nonconvective low-level wind shear (LLWS).

What Your CFI Didn’t Teach

A forecast for nonconvective LLWS is probably the most misunderstood aviation forecast among pilots and instructors. In a TAF, this forecast appears in coded form with a WS code such as WS020/15055KT. Such a forecast can also appear in a graphical AIRMET (G-AIRMET) issued by forecasters at the Aviation Weather Center (AWC). In a preflight briefing, pilots hear the term “wind shear” and immediately equate this with thunderstorms and severe turbulence. It’s a common misconception, but nonconvective LLWS as it appears in a TAF is not a forecast for turbulence at all. In fact, in most cases when this is forecast, the air is glassy smooth.

With a large-scale weather system, this form of windshear is quite common on either side of a warm front for a developing or occluded area of low pressure. But it’s also quite prevalent in the overnight hours during fair weather conditions coupled with a clear sky and calm wind at or near the surface.

Even though wind seems to be the common denominator in this description, atmospheric stability is the catalyst behind most nonconvective LLWS occurrences. We know that wind naturally tends to increase in speed with increasing height, but it normally does so gradually, especially in the latter part of the afternoon when the boundary layer near the surface is well mixed. But what if the winds are light or nearly calm at the surface and increase to 55 knots just 1,500 or 2,000 feet above the ground? That’s an example of vertical speed shear and is known as nonconvective LLWS.

When the winds are expected to increase rapidly with height within 2,000 feet of the airport’s surface, it is common that a forecast for nonconvective LLWS will be issued in a TAF for that airport. Such a forecast tells the pilot about the potential for the wind speed to increase rapidly with increasing height above the ground within a shallow layer called the wind shear layer. That is, faster air at the top of the wind shear layer is moving over slower air near the base of that layer. There also may be an accompanying shift in wind direction with altitude in this layer, but it is the vertical speed shear that is the primary trigger for the forecast.

• READ MORE: The Points Forecast Sheds New Light on TAFs

Not Like a Thunderstorm

Keep in mind that this is not the same horizontal and vertical wind shear that may be experienced in the vicinity of deep, moist convection or thunderstorms, hence the name nonconvective LLWS. In fact, forecasts for convective and nonconvective LLWS have very distinct differences. In a TAF, convective LLWS will typically contain a reference to showers or thunderstorms (e.g., SHRA, TS, VCTS) and will contain CB—which stands for cumulonimbus—in the cloud group. Also, the surface winds are typically forecast to be strong and gusty. While convective LLWS can occur at any time of the day or night, most occur in the afternoon and early evening when convection is the most prevalent, especially west of the Continental Divide. Here are three examples of forecasts for convective LLWS that can be found in a TAF:

• FM132200 33010G20KT P6SM VCTS SCT015 BKN040CB

• FM131600 22013G35KT 3SM TSRA BR BKN035CB

• FM140000 VRB20G55KT 1/2SM +TSRA FG BKN015CB

Nonconvective LLWS can occur in the cool or warm sector of an area of low pressure, but it can frequently take place in the presence of a strong nocturnal surface-based temperature inversion. Frontal nonconvective LLWS can happen any time of the day or night and normally possesses the characteristics of light wind sat the surface and cloudy skies but can be strong and gusty when the weather system is associated with an intense occluded area of low pressure. Here are three examples of TAFs for nonconvective LLWS associated with a frontal system:

• FM111600 13010KT 5SM -RA OVC015 WS020/27055KT

• FM120100 VRB03KT 4SM BR OVC008 WS015/25045KT

• FM120900 19018G30KT 3SM +SHRA BR OVC005WS020/17075KT

However, nocturnal nonconvective LLWS occurs in the overnight or early morning hours often with a light wind and clear sky. This is a manifestation of radiation cooling and likely occurs in the region under an area of high pressure. Here are three examples of the nocturnal version of nonconvective LLWS in a TAF:

• FM221100 19004KT P6SM SKC WS015/17040KT

• FM230800 VRB03KT P6SM SCT010 WS010/22035KT

• FM230400 00000KT P6SM SKC WS020/23055KT

Where to Find It

In both cases of nonconvective LLWS, the LLWS code—WS—will be included in the TAF immediately after the cloud group. Let’s take a closer look at this misunderstood forecast group. Assume the following from a TAF:

• FM252300 15014G25KT P6SM SKC WS020/16055KT

The first element to the immediate right of the WS code is a height above the airport—in this case 020 or 2,000 feet. This represents the maximum depth of the wind shear layer.

This altitude is “typically” one of four values—005 for 500 feet agl, 010 for 1,000 feet agl, 015 for 1,500 feet agl, or 020 for 2,000 feet agl. Even if the wind shear layer extends higher, the maximum height that is forecast is 2,000 feet.

Following the forward slash, the next group contains the true wind direction followed by the wind speed in knots at the indicated height, or 160 degrees at 55 knots in this example. This implies indirectly that the wind is rapidly increasing from the surface through the indicated height, although this says nothing about the wind direction throughout this shear layer. Effectively this forecast translates into “the wind at 2,000 feet agl is 160 degrees at 55 knots.” But it does not imply there will be turbulence at 2,000 feet agl or below. In most cases, you’ll find smooth conditions in this wind shear layer, especially for the nocturnal instance of nonconvective LLWS.

A Question Of Stability

The catalyst for the development of nonconvective LLWS is atmospheric stability. We also know that temperature normally decreases with increasing altitude. This is generically referred to as a lapse rate—simply a change of temperature over a change of increasing altitude. Anytime the temperature decreases with increasing altitude, it’s referred to as a positive lapse rate. If the temperature increases with altitude, that’s referred to as a negative lapse rate or more commonly called a temperature inversion. The larger the lapse rate, the greater the atmospheric instability. An unstable environment (large lapse rate) promotes vertical mixing and provides for a more turbulent air flow potential. On the other hand, a stable atmosphere (small or negative lapse rate) inhibits vertical mixing and provides for a laminar and nonturbulent flow.

One might suspect that vertical speed shear (faster air flowing over slower air) could cause the air to overturn and produce turbulent eddies within this windshear layer. Think about a tumbleweed rolling across the ground somewhere in the southern Plains. However, just about all nonconvective LLWS occurrences feature a surface-based, low-level temperature inversion. Any kind of overturning or vertical mixing introduces the potential for turbulence, however, an extremely stable layer such as this tends to dampen or resist vertical mixing.

So why does the air accelerate rapidly with height? The extreme stability courtesy of the inversion eliminates upward and downward motion or vertical mixing (neutral buoyancy). This promotes a laminar flow, and the effects of surface friction are no longer “felt” at heights a few hundred feet above the surface. This allows the flow of air just above the treetops to accelerate uninhibited and insulated from surface friction below through the depth of the wind shear layer.

You can think of this as a faster flowing river of air (called a low-level jet) located just above the surface. The stronger and deeper the inversion, the less likely there will be any kind of turbulence.

Why It’s Forecast

So, if nonconvective LLWS isn’t a forecast for turbulence, why is it forecast at all? When the sky is clear and surface winds are light, the nocturnal version of this phenomenon is just as common as low-level thermal turbulence in the afternoon during the warm season. Unless you were fixated on your groundspeed approaching an airport late at night or in the early morning hours, you probably flew right through it without even noticing that it existed. In most cases, nocturnal nonconvective LLWS isn’t typically forecast.

Nevertheless, there are several situations where you should pay close attention. First, if you are departing out of an airport with a high density altitude, nonconvective LLWS can make for a difficult climb if the low-level jet is off your tail. It’s not uncommon for the winds to be light or calm at the surface although they may be 30 knots or more just above the tree tops. With light or calm winds at the surface, you may not realize that during the initial climb to pattern altitude, the prevailing wind is at your back. If you pilot a balloon, you should pay close attention to these forecasts. A hot air balloon is not a rigid body and can deform easily in the presence of these conditions.

The most important one to watch out for is when nonconvective LLWS of 50 knots or greater is coupled with the potential for moderate to heavy rain showers (SHRA or +SHRA) or even thunderstorms (TSRA or +TSRA). Yes, both convective and nonconvective LLWS can be forecast at the same time.

As the moderate to heavy rain falls through the low-level jet, some of the momentum of the jet gets transferred or directed toward the surface of the earth. This is like taking a fire hose and deflecting it downward toward the ground. The downward momentum of that low-level jet creates the potential for wet microbursts or downbursts.

In this case, the magnitude of the nonconvective LLWS event and convective outflow can make for a real interesting approach to land. If nonconvective LLWS is forecast and the atmosphere in the windshear layer is not as stable, then you might experience a rough ride.

What if There Isn’t a TAF?

TAFs are one way to identify the likelihood of nonconvective LLWS for your departure or destination airport. However, not all airports are served by a TAF. Meteorologists at the AWC also issue a forecast for nonconvective LLWS. These are issued for areas that cover at least 3,000 square miles, or roughly two-thirds the size of Connecticut. You’ll see this as part of the routine issuance of a graphical AIRMET (G-AIRMET). While the forecast depth of the wind shear layer may vary in a TAF, the wind shear layer in a G-AIRMET is fixed at a depth of 2,000 feet agl.

Wind shear in a preflight briefing is often equated with thunderstorms and severe turbulence. Understandably, it’s common for many pilots to become anxious when they see such a forecast. But some forms of wind shear might not always be dangerous or even problematic to light aircraft. When nonconvective low-level wind shear (LLWS) exists, for example, the air maybe glassy smooth. This is especially true when you see a forecast for nonconvective LLWS in the overnight hours that’s not associated with a large-scale weather system.

It’s not a forecast that should instill fear in a pilot like it often does. In most cases, it will be a nonevent that you may not even notice if you missed it in your preflight briefing. Even so, always keep a close watch on pilot weather reports for turbulence.

This column first appeared in the July 2023/Issue 933 print edition of FLYING.

The post The Down-Low on Wind Shear appeared first on FLYING Magazine.

• READ MORE: NOAA Changing Weather Site

Overview

A majority of the weather data will appear on the graphical forecasts for aviation (GFA) webpage. This is the heart and soul of the new site. Here’s a brief description of the purpose of this page as posted in the GFA help on aviationweather.gov.  

“The GFA webpage is intended to provide the necessary aviation weather information to give users a complete picture of the weather that may impact flight in the United States (including Alaska & Hawaii), Gulf of Mexico, the Caribbean, and portions of the Atlantic and Pacific Oceans. The webpage includes observational data, forecasts, and warnings that can be viewed from 18 hours in the past to 18 hours in the future. Hourly model data and forecasts, including information on clouds, flight category, precipitation, icing, turbulence, wind, and graphical output from the National Weather Service’s National Digital Forecast Data (NDFD), are available.”

What’s a Progressive Web App?

Let’s begin with the good news. Like my website, EZWxBrief, the Aviation Weather Center (AWC) decided to build its website  as a progressive web app (PWA). The aviationweather.gov legacy site was very clumsy and nearly impossible to use on a mobile device such as an iPhone. Developing this as a PWA offers a very responsive design, and that means it works reasonably well on those smaller hand-held devices in both portrait and landscape orientations. 

No, you won’t find this “app” in the App Store or Google Play Store. Instead, you should install the PWA on your device to have the best user experience. Not to worry, it literally takes just a few seconds and applies to any device, not just handhelds. 

Here’s the installation process. Simply open a browser that supports a PWA such as Chrome, Safari, or Brave and enter “https://aviationweather.gov” into the browser’s address bar. On your hand-held device, locate the “Share” icon (sometimes called a “Bookmark” or “Send to” icon). This is an icon that’s shaped like a square with an upward pointing arrow in the center. Please note that not all browsers support progressive web apps. A tap on that icon and you have finished step one of three to install the app. 

Next, you’ll be shown the “Share” menu. Scan down that menu using Chrome or Safari and tap on the “Add to Home Screen” selection.

During the third and final step, you’ll be able to name your PWA icon. You are free to change the long default name from “AviationWeather.gov” to AWC or whatever you like. When you’ve chosen the name, tap on the “Add” button in the upper-right corner. This will add an Aviation Weather Center icon to your home screen with the name you chose. Even better, when the Aviation Weather Center makes future updates, they will be available the next time you restart the app. It’s actually easier than installing and updating native apps.

Just like any native app, tap on that home screen icon and the aviationweather.gov site will open up. You’ll notice that it doesn’t have any browser bar or other browser controls, which frees up valuable screen real estate on smaller devices. Essentially, it will have the same look and feel as a native app without the overhead of Apple or Google. 

You can do the same installation on your desktop or laptop computer, but the process is a bit different. Once again, open up your browser and type “https://aviationweather.gov” into the address bar, and you will see an Install button appear at the end of the address bar for any website (and browser) that supports a PWA.

Clicking on the “Install” button will provide the prompt below to install the app.  Once done, you’ll see an Aviation Weather Center icon on your desktop. By the way, you can also always uninstall the app at any time for any of your devices.

One of the issues that is apparent with the site on some hand-held devices is that the app will crash or reset when using a rapid, pinch-and-zoom gesture on the interactive GFA map. This is evidently an issue with Leaflet (the software it uses to render the maps), and the workaround is to avoid any rapid, pinch-and-zoom gestures. Just slow your roll and you’ll be fine.  

Cross Section Tool

To replace the Java Flight Path Tool that required you to download Java onto your computer (Java isn’t permitted on iOS devices), the AWC added a cross-section tool that now runs on any platform. You will see an icon on the right to start this tool. It’s the icon just under the settings icon (cog wheel).

You simply define a route, such as KMCI.KMEM.KAVL (note the periods in between the identifiers), and you can plot this path on the GFA map as a great circle route or view it as a cross section. Currently, the only variables you can plot on the vertical cross section are temperature, wind speed, turbulence, and icing.

Reduction in Static Imagery

The overall new design of the website is radically different from its legacy counterpart. Perhaps the most significant long-term effect is that the AWC decided to terminate the generation of dozens of static images that were available on the legacy site. Many flight planning websites, and even some of the heavyweight EFB apps referenced, scraped many of these images off of the AWC site. Consequently, you may have noticed back in the middle of October that these apps had to scramble to delete those from their own static imagery collections. The imagery collections that were depreciated included: 

• Lowest freezing level forecast from the Rapid Refresh (RAP) model
• TCF, eTCF, ECFP convective forecasts
• RAP/NAM Wind/Temperature graphics
• PIREP plots
• Satellite regional plots

Although you can still find access to prog charts, G-AIRMETs, as well as icing and turbulence static imagery within the decision support imagery page (https://aviationweather.gov/graphics), the AWC has a goal to eventually eliminate all static imagery.

Missed Opportunities

Your opinion  may differ, but I find the user interface for the decision support imagery to be very antiquated and clumsy. Even on large screens, you have to constantly scroll up and down, and it requires an immense amount of button clicks or taps to get what you want. It’s very exhausting and tedious to use. In fairness, that page suggests it was “designed for Center Weather Service Unit meteorologists who build information packages on desktop computers.” Instead, AWC suggests that pilots utilize the interactive map page (https://aviationweather.gov/gfa).

The issue here is that the DSS page gives you a vertical resolution of 2,000 feet for icing and turbulence forecasts. If you use its interactive map, you only get a 3,000-foot or even 6,000-foot vertical resolution despite the fact that the native vertical resolution of the icing and turbulence products is 1,000 feet. It is understandable that browsers have hard limitations, and this was likely a tradeoff to providing something that has a reasonable performance. 

While the Aviation Weather Center removed the regional satellite imagery from the site, it has been incorporated as a separate layer into the graphical forecasts for aviation (GFA) tool. Currently there isn’t a replacement for the color infrared satellite imagery. That is something it will be adding in the future.

Another deficiency is that the site doesn’t acknowledge when the layer you are viewing is void of data. For example, if you pull up the center weather advisories (CWAs) on the GFA tool, you may get a blank map. Is the map blank because there are no CWAs active, which happens more often than not? Or perhaps it’s because your browser or internet connection is being finicky? The lack of any data or advisories is just as critical as the presence of them. AWC doesn’t provide any acknowledgement or banner to alert you when this occurs.  

If you are looking to travel outside of the U.S., some of the weather guidance on the GFA tool, such as icing and turbulence, stops at the border. While this was also true with the legacy GFA tool, it still represents a shortcoming given that much of this guidance is available over a good portion of Canada and northern Mexico. The National Weather Service (NWS) has a directive that it can’t show forecasts outside of the U.S., especially over Canada and Mexico. Pilots are supposed to go to the respective website/services for those countries to receive that forecast information.

This is inconsistent since some decision support graphics (i.e., static imagery) clearly show forecasts for icing and turbulence in Canada and Mexico. Moreover, if you plot a route from International Falls, Minnesota, to Caribou, Maine (through southern Ontario and Quebec, Canada), the cross-section view shows this guidance.

Finding HEMS

If you are looking for the helicopter emergency medical services (HEMS) tool, it has been integrated into the interactive GFA and rebranded as the GFA-LA tool (with “LA” for “low altitude”). When viewing the GFA, click on the helicopter button in the upper-right part of the map to switch the GFA from general aviation mode into low-altitude mode, which offers expanded capability from the HEMS tool.

Final Thoughts

There’s no doubt that there are winners and losers with this update. I’ve read hundreds of comments on social media posts and other aviation forums that despise the new site and those that simply love it. The biggest advantage is that the site is very responsive on hand-held devices with the occasional glitch that I’m sure will be resolved in time. The dismantling of nearly half of the static imagery is truly a loss and will likely be felt for months, if not years, to come. As a matter of fact, I am in the process of finding replacements of these image collections for my own website, EZWxBrief. 

Lastly, if you are still hanging onto a glimmer of hope that AWC will bring back the legacy site, don’t hold your breath. While there are still some growing pains with this new version, the Aviation Weather Center is fully committed to this new release—so just get used to it. 

The post Aviation Weather Center Website Upgrade—the Good, Bad, and Ugly appeared first on FLYING Magazine.

A terminal aerodrome forecast, simply known as a TAF, is perhaps the most difficult forecast any meteorologist will ever make. Think about the challenge these forecasters face. A TAF is essentially an hour-by-hour forecast for conditions significant to aviation at an airport over the next 24 or 30 hours. This includes a forecast for details such as wind speed and direction, cloud coverage, ceiling height, prevailing visibility, and precipitation type.

When you think of a TAF, size matters. This forecast is difficult because of the relatively small diameter of the area they are attempting to cover. The U.S. definition of a terminal area is the region within five statute miles of the center of the airport’s runway complex. Thus, meteorologists refer to a TAF as a “point forecast,” and it’s critical to understand its limitations and how they affect the forecasts general aviation pilots ultimately use every day.

The Terminal Area

A five statute mile area is a tiny region to get all forecast elements right over a given period. In fact, the terminal area is often smaller than the resolution of the forecast guidance they are using to issue the TAF. It’s like placing a coin on a sidewalk and asking someone at the top of a five-story building to identify if the coin is a nickel, dime, or quarter using their naked eyes.

Here’s a way to visualize why it’s so hard to issue these forecasts. Let’s pretend for a moment that you are the forecaster and someone asks, “What are the chances there will be a thunderstorm reported somewhere in the conterminous U.S. in the month of July?” Certainly, there are a lot of thunderstorms in July, and the conterminous U.S. encompasses a huge area. Your forecast would likely be that there’s a 100 percent chance. And you would be 100 percent correct.

That was an easy forecast, and you didn’t even need a meteorology degree to get it right. Now, how about a slightly different question? What is the chance of a thunderstorm reported sometime during the month of July in the state of Oklahoma? Given a month is a long period and Oklahoma is a state with lots of thunderstorms during the summer, again, I’d bet your answer would be that there’s a 100 percent chance. Now, how about the chance of a thunderstorm being reported on July 14 at the Oklahoma City airport at 8 a.m.? Well, once again, there’s a pretty easy answer; you’d likely say it’s a zero percent chance.

When you narrow down the time and the location, you can see the swing from a near guarantee at 100 percent to a near guarantee at zero percent. Forecasting for a small five statute mile area is incredibly difficult, if not fundamentally impossible at times, but meteorologists at the local weather forecast offices are asked to carry out the impossible every day. They need to determine if that coin is a nickel, dime, or quarter.

There’s no doubt that TAFs are used by all pilots because of the significant detail they provide. Everyone from general aviation pilots to commercial air carriers utilize TAFs to anticipate weather conditions in the airport terminal area. Without question, TAF content can have a strong impact on fuel loads, the need for alternates, and other operational aspects because of their stringent regulatory nature.

Scheduling TAFs

Each weather forecast office in the conterminous U.S. is typically responsible for issuing a TAF for up to ten airports within its region of coverage called a county warning area or CWA. For example, the Greenville-Spartanburg forecast office in Greer, South Carolina, is responsible for preparing TAFs for six local terminal areas, including the Charlotte Douglas International Airport (KCLT).

It’s important that the TAFs are prepared and issued by local forecasters instead of forecasters sitting in some Washington, D.C., office. They often consider sub-synoptic local effects, and they are tuned into the local weather patterns since they deal with them every day. The difference between a low IFR ceiling and a clear sky can be just a matter of 10 miles at times.

Therefore, the size of the terminal area is a point (pun intended) that should not be overlooked. The TAF may or may not always be representative of an area or zone forecast. Additionally, locally derived forecast rules and outside pressure from the FAA or even the airlines can cause the TAF to be quite different than an area forecast.

Scheduled TAFs are issued four times daily (every six hours) at 00Z, 06Z, 12Z, and 18Z. In most circumstances, the TAF is transmitted between 20 minutes and 40 minutes prior to these times. Moreover, for high-impact airports such as Atlanta, Chicago and New York, TAFs may be routinely issued every three or even two hours. For now, those off-schedule issuances will still be released as amendments. So, if you see an amended forecast in these regions, it may not be because of a poorly aligned forecast with respect to the weather—it may be a new and improved forecast.

Precipitation events, especially thunderstorms, give meteorologists the most trouble. Forecasting convection in the terminal area is all about quantifying the uncertainty of the event. Even in reasonably dynamic situations with traveling weather systems, meteorologists can find it challenging to predict when convection will impact the terminal area over the forecast period.

Dealing with Uncertainty

Unfortunately, forecasters do not have a convenient way in a TAF to quantify their uncertainty. In the public forecast, you’ll see something like “a 30 percent chance of thunderstorms.”

Sure, forecasters can throw in a PROB30 forecast group into a TAF, but by NWS directives, PROB30 groups are not allowed to exist in the first nine hours of the forecast period. By the way, the NWS only uses PROB30, although you may see PROB40 in international TAFs or TAFs issued by the military. So, what can a forecaster do when there’s a chance of thunderstorms in the public forecast, but the uncertainty is high? In most cases, the forecaster will leave out any mention of thunderstorms given that it is just too uncertain and the likelihood is small that a thunderstorm will roll through that tiny forecast region. Forecasters are also pressured by the airlines to avoid placing thunderstorms in a TAF in these situations. A forecast for thunder may require filing an alternate, and the need to take on more fuel.

Perhaps in this uncertain situation, these are just the scattered variety of afternoon pulse-type thunderstorms. In this case, the forecaster has two possible solutions, neither of which will appear in your aviation textbook or ground school. First, they can add rain showers (SHRA) or showers in the vicinity (VCSH)

instead of thunderstorms. Showery precipitation is inherently a convective process. It’s not unusual to see forecasters include one of these two precipitation forecasts into the TAF when the uncertainty of thunderstorms is high. Essentially it becomes a placeholder for thunderstorms. When conditions eventually begin to evolve and it becomes clear thunderstorms will impact the terminal area, the forecaster will likely amend the TAF to replace SHRA or VCSH with TSRA (rain and thunderstorms within the terminal area).

Area Forecast Discussions

Second, forecasters may often explain their reasoning in the area forecast discussion or AFD. No, it’s not a discussion about the aviation area forecast that was retired in 2018. Instead, it’s a discussion about the weather expected in the local county warning area (CWA) for that weather forecast office. Every AFD contains an aviation section that discusses the TAFs for airports within that CWA. It is in the AFD that a forecaster can explain, contemplate, brood over, or even complain about why they didn’t include a forecast for thunderstorms, fog, or freezing rain.

In fact, most forecasters will do a pretty good job trying to quantify their uncertainty. In the case of thunderstorms, you may see words in the AFD like “including light rain showers to cover the unlikely threat of thunderstorms.” The AFD isn’t something you’d get in a standard briefing, but it certainly should be part of your preflight brief. I’ve always said that if you are not reading the AFDs, you are missing half the forecast.

You can find the full AFD for each county warning area by visiting the weather.gov website. If you visit weather.gov, in the upper-left corner, type in a location such as an airport, city and state, or Zip code, and you will be presented with a forecast that includes a link on that page labeled “Forecast Discussion” that is valid for that town or airport. That link will contain the entire discussion that includes the aviation section. The AFD is also included in some of the heavyweight aviation apps or using my EZWxBrief progressive web app.

Local Knowledge

So, the next time you pore over the TAFs along your route, remember these two points. First, never assume the weather forecast at one airport applies to a nearby airport. On some occasions when the weather is homogeneous across a region, it very well may be that a TAF is representative of the weather at airports close by. Forecasters have local knowledge and often make forecasts that take into consideration how terrain or the previous day’s weather can impact the weather at any particular airport.

Second, TAFs are not an area or zone forecast and should never be used as such. It’s often easy to look at all of the TAFs along your route and make a hasty decision. Just because the three or four TAFs along your proposed route do not mention thunderstorms doesn’t mean you won’t encounter them during cruise. Use TAFs for what they are intended to show. Therefore, if you have an emergency and need to land, knowing the potential weather at those airports along your route is important. TAFs can tell you if they are likely to be good alternates if you need one.

Lastly, keep in mind that a precipitation forecast in a TAF defines the type of precipitation expected to reach the surface. For example, a forecast for –RA (light rain) or –DZ (light drizzle) doesn’t imply there’s no chance of running into FZRA (freezing rain) or FZDZ (freezing drizzle). The precipitation forecast is based on what’s expected at the surface. If the temperature is forecast to be a degree or two above freezing at the surface, you will see a forecast for rain (or drizzle), but you may find that just 500 feet above the surface, there’s a nasty freezing rain (or freezing drizzle) event waiting for you.

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