May 2025 EZNews

Hello and thank you for taking the time to read the 49th issue of EZNews!

This April marked the 4th anniversary of the initial release of the EZWxBrief progressive web app! Development of this ground breaking app started June 2019 and took nearly 2 years to complete EZWxBrief v1.0. Then an effort started in November 2022 to completely rebuild the app and EZWxBrief v2.0 emerged this time last year. Both of these efforts required a substantial financial investment and we need your help to spread the word!

We value those members who have chosen to enable automatic renewal of their EZWxBrief membership on a monthly basis. If you haven't done so, please sign in and visit the User Profile page (see right) and tap or click on the Renew button on this page. By doing this, you can establish your monthly renewal with a Visa, MasterCard, or Discover credit card. This ensures that you continue to enjoy the simplicity of EZWxBrief.

AirVenture savings start today - discounts apply through July 27th!

If you were not able to attend any of the three live aviation weather classes, you have the opportunity to get the lowest prices available on the recording for each of these three classes. This includes the Weather Essentials for Pilots, Advanced Weather Essentials for Pilots and the Skew-T Weather Essentials classes. These include -

• Weather Essentials for Pilots (12 classes)

• Advanced Weather Essentials for Pilots (10 classes)

• Skew-T Weather Essentials (12 classes) 

  
  

Check out this free video from the sixth Advanced Weather Essentials for Pilots 10-week class that discusses convective guidance and considerations. This free video is nearly an hour long and will give you a sample of the content found in each of the three programs mentioned above.

Each program contains hyperlinks to all of the recorded videos as well as hyperlinks to PDFs containing the slides presented in each class. In addition to purchasing each of these three classes individually, for a limited time we are offering a Combo pricing for the Weather Essentials and Advanced Weather Essentials classes and a Triple Combo pricing to purchase all three programs. 

Purchase now >>>

Upon purchase you will be provided a link to download a Summary Guide. This same link to the purchased program will also be provided within an email. The emailed link is valid for 30 days of purchase. This Summary Guide is a PDF that includes the following -

• Table of contents

• Hyperlinks to the unlisted video recordings of each class 

• Hyperlinks to a PDF containing the slides for each class

• Hyperlinks to each quiz and quiz answers for each class (no quizzes are included for the Advanced Weather Essentials for Pilots class)

This is provided for your personal use only. Please do not share this or post this content online. We appreciate your cooperation. This offer is available for a limited time and ends on July 27, 2025. Don't delay, purchase access to these programs today!

Free webinar, "Ask a Meteorologist"

Our good friends at SiriusXM Aviation are sponsoring a FREE 60-minute webinar on May 13th at 7 pm EDT. Dr. Scott Dennstaedt will be providing the answers to frequently asked questions about aviation weather. If you are interested in attending, please register here. Please spread the word!

Preliminary weather analysis for a TBM 700 accident near Minneapolis, Minnesota

Check out this recent blog post that documents the weather associated with a fatal TBM 700 accident that impacted terrain in Brooklyn Park, Minnesota on March 29, 2025.

Coming to AirVenture this year?

Hard to believe, but it's that time again! EZWxBrief will have a booth at EAA's AirVenture in Hangar C (Booth 3082) this year and we are looking forward to meeting many of you there. This year will be a little bittersweet. With rising costs of attending this event, this will be our final time attending AirVenture as a vendor. Stop by Hangar C during the event and say hello and get a demonstration of EZWxBrief v2.0 or attend one of Scott's many forum presentations planned throughout the week including presentations on the Skew-T log (p) diagram, turbulence, datalink weather, icing and more. So far, Scott is currently scheduled to give a presentation on datalink weather at the AOPA Pavilion on Friday, July 25 at 2:00-2:45 p.m. CDT. So mark your calendar. The remainder of the forum schedule is still being finalized with EAA and will be posted in the July edition of EZNews. Stay tuned and hope to see you there!

Two 1-on-1 training subscription plans with new lower annual prices!

Does weather perplex you? Are you interested in taking your aviation weather knowledge to a new level? Perhaps you want to review the weather before you depart on your next cross-country flight? Then you may want to do purchase a 12-month online training plan where an expert can help you can improve your weather briefing skills. You have two subscription plan options. You can purchase a plan for five 60-minute sessions or five 30-minute sessions at a cost of $349 and $199, respectively. And if you prefer not to purchase one of these two plans, you can always book a single 60-minute or 30-minute session instead.

Sessions can be booked with Dr. Scott Dennstaedt for appointments held Monday through Friday from 9 a.m. to 5 p.m. eastern time. As a seasoned flight instructor for the last 25 years and meteorologist for over 45 years, Scott has the unique qualifications to teach you how to minimize your exposure to adverse weather. At the present time there is no availability for evening sessions or on weekends/holidays. Blackout times will apply during some aviation events (e.g., AirVenture). See this post for more information on how to purchase and redeem your sessions for these two annual subscription plans.

The NWS is being stretched thin, very thin!

With the recent federal government staffing cuts and retirements throughout the National Oceanic and Atmospheric Administration (NOAA) that includes the National Weather Service (NWS), the former meteorologist-in-charge at the NWS weather forecast office in Jackson, Mississippi commented, "You can only stretch things so much. Eventually things start to break."

It is expected that 300 or more NWS employees will take the latest federal buyout and more are expected to retire in the coming months. Among many other duties, the 122 NWS forecast offices around the country are responsible for issuing 700+ terminal aerodrome forecasts (TAFs) in addition to launching weather balloons twice a day and issuing severe thunderstorm and tornado warnings. Under normal operation, most of these local offices employ 12 to 15 people that require 24/7 coverage, but it is estimated by NWS Director Ken Graham, that many of these offices could be operating with seven or fewer meteorologists in the coming months. Given three shifts every day (including holidays), this puts many local offices at a dangerous deficit.

Staffing shortages such as this create tremendous pressure for meteorologists especially especially during severe weather outbreaks, including last month's Midwest convective outbreak that killed at least 29 people. Offices need at least two or three meteorologists available to safely conduct radiosonde launches while also maintaining normal forecast operations. For reference, it takes 90 minutes to an hour to fill a weather balloon with hydrogen (or helium), get it fitted with a sensor using the proper length of cord, then ready it for launch making sure the radiosonde doesn't drag on the ground. Meteorologists then track the data for about two hours before the balloon bursts at 100,000 feet and falls back to Earth for a total of about four to five hours work for one person. When active weather is expected, these offices normally require double the staff to support radar operations as well as sending out warnings and putting out social media posts. Weather balloons are not considered a priority for these situations.

One April 17, 2025, the NWS sent out the following notice -

Effective April 17, 2025 until further notice, the National Weather Service (NWS) may temporarily reduce or suspend scheduled radiosonde launches at selected NWS upper air sites due to staffing limitations or operational priorities. Office(s) will continue to conduct special observations as resources allow and in response to emerging weather events. To mitigate potential impacts, the NWS is actively pursuing alternative sources of upper-air data and adjusting internal staffing and procedures to maintain continuity of service. Additional updates will be provided as needed.

Discussed in the April EZNews, the partial or full reduction in radiosonde launches has affected 14 upper air stations. Under normal operations, the NWS conducts and/or supports radiosonde launches twice a day from 100 upper air sites throughout the United States, Caribbean, and the Pacific Basin. The notice above suggests that any or all of the remaining sites may be affected depending on the current workload at each office. Among regularly reporting weather stations, the NWS had averaged about only one outage of balloon launches a day from 2021 to 2024, according to an Associated Press (AP) analysis of launch data.

On April 17th, six tornadoes tracked across eastern Nebraska from just before 7 p.m. until just after 9 p.m. Chris Vagasky, is a meteorologist and radiosonde expert said with respect to this severe weather outbreak, "The National Weather Service issued the proper tornado warnings at the right time but that additional data available only from balloons could have helped identify the tornado threat sooner." Vagasky also added, “The forecasters in the weather service know what to look for on radar and other data to issue the right warnings at the right time, but having additional data that gives an indication of low-level wind shear or moisture helps give you confidence when issuing those warnings.”

Nevertheless, this reduction in staffing will both directly and indirectly affect the aviation sector. Given the additional reduction in scheduled radiosonde launches, this data is ingested into forecast models and is used to calibrate other data used by these models. Forecast accuracy will decrease without this valuable data. Moreover, several airports with TAF service issued four times a day have been eliminated with many more on the chopping block in the coming months. TAFs must be monitored throughout the day and amended as necessary. Amendments may not occur as frequent as they do now. Moreover, area forecast discussions are a luxury and will likely contain less detail moving forward. The lack of coordination between neighboring offices will likely contribute to conflicting forecasts where their county warning areas (CWAs) touch. While forecasters are currently keeping up with the load and forecasts and warnings have not yet suffered, morale has been sinking.

Weather is the single biggest physical factor affecting our flying activity. If any of this is concerning to you as a pilot, you are encouraged to write or call your federal representatives and voice that concern. We all need the NWS working at its best.

Double rainbow and why they form

Did you know that every rainbow is a double rainbow? It's true. The secondary rainbow forms when sunlight is reflected twice within a drop of water, but it's typically fainter than the primary rainbow, which is formed by a single reflection. Therefore, most of the time that second rainbow is just not bright enough to be visible. The photo above was captured on April 10th as a line of low-topped convection with no lightning move through the Charlotte area.

Roy G Biv is a memory aid that you might have learned as a child. It's a reminder of the colors and their order within the rainbow, namely, Red, Orange, Yellow, Green, Blue, Indigo and Violet.

Rainbows visible from the ground are not rare, but can only occur during certain times of the day. They are usually visible shortly after sunrise or shortly before sunset. This is because the sun needs to be at a relatively low angle above the horizon, ideally less than 42 degrees, for a rainbow to be formed. At midday, when the sun is high in the sky, the rainbow's arc would be entirely below the horizon, making it invisible. 

Moreover, in order to see one of these beauties, you need the sun at your back and the rain in front of you as you look at the rainbow. This way, as the sun hits the falling raindrops, it refracts the sunlight on the inside wall of the raindrop. This allows the light to be reflected back out of the drop, bending the light once again. That first initial reflection of light outside the raindrop will produce a brilliant array of colors across the visible light spectrum, producing the sight we all know as a rainbow. Of course, if you see a rainbow, it's hard to stop and admire its beauty.

But in order to see a double rainbow, you need a secondary reflection inside the raindrop. That's why this is often called a secondary rainbow. As light reflects out of the backside of the raindrop, it too spreads out the light into an array of colors with one key difference - this time the rainbow will be seen in reverse order. In this case the violet and indigo colors will be first and the orange and reds will be seen last. Pretty cool.

And yes, you may have also seen a rainbow when flying above or next to a cloud. It will be a circular rainbow like the one shown above with a shadow of your aircraft in the middle. That's why it is called a glory. This rainbow doesn't require rainfall, but does require the cloud top to have liquid drops. So, don't discount that it might be a good indication that supercooled liquid water exists in the tops when the cloud top temperature is below 0°C. So if you are descending into this cold cloud, be prepared; you will likely accrete some ice depending on the liquid water content that exists.

G-AIRMETs get bougie!

With the retirement of the legacy AIRMET at the end of January, you may have noticed that some G-AIRMETs have gone full bougie. From the time the Traditional Alphanumeric Code (TAC) AIRMETs were conceived back in the late 1950s they were issued strictly as a textual product. That is, forecasters used a keyboard to type the alphanumeric text one character at a time. And, during those days when a pilot received a route briefing, the pilot pulled out a blank advisory plotting map to draw the various AIRMETs as polygons that the briefer provided. This information came from the geographical points provided in the AIRMET header. So it made sense to limit the maximum number of points of the polygon to 3 or 4 if at all possible. Five points was a rarity. Now with TAC AIRMETs gone forever as was announced in this post, forecasters are no longer limited by those rules (although SIGMETs still have those rules into the foreseeable future). Given that the number or points are essentially unlimited you might see some really fancy G-AIRMETs, especially for IFR conditions like the one shown above.

Where have all of the EF5 tornadoes gone?

If you pay attention to these things, you may have noticed that there have been no EF5-rated tornadoes recorded in a little over 11 years. Ratings start out at EF0 with the highest level as EF5. In fact, it's the longest drought without a tornado of this scale since official records began in 1950. First, a little history lesson. The Fujita (F) Scale was originally developed in 1971 by Dr. Tetsuya Theodore (Ted) Fujita to estimate tornado wind speeds based on damage left behind by a tornado. After reports of significant wind damage, NWS employees go out to survey the damage once the threat has passed. Based on the level and pattern of the damage, they can determine if it was caused by straight-line winds, a microburst or a tornado. If it is determined that the pattern of damage was caused by a tornado, then the next step is to give it an F rating. So, it is somewhat subjective.

The original F scale had limitations, such as a lack of damage indicators, no account for construction quality and variability, and no definitive correlation between damage and wind speed. These limitations may have led to some tornadoes being rated in an inconsistent manner and, in some cases, an overestimate of tornado wind speeds. Therefore, an Enhanced Fujita (EF) Scale was developed by a forum of nationally renowned meteorologists and wind engineers and made improvements to the original F scale. This EF Scale has replaced the original F scale in February 2007.

Researchers wondered if this lack of an EF5 tornado was due to Mother Nature or something else. So a study was done. In that study their findings suggested the lack of EF5 tornadoes is highly unlikely to be rooted in natural causes. This study mentions,

"A key breakpoint exists between how the legacy Fujita (F) scale and the EF scale handle the complete destruction and sweeping away of single-family homes, with standard “well-constructed” homes being swept away constituting F5 damage on the F scale but only EF4 damage on the EF scale."

This is likely the fundamental cause of the lack of EF5 tornadoes in recent years. These findings have been shared with a group within the American Society of Civil Engineers and American Meteorological Society, which is working on revisions to the current EF scale. 

EZWxBrief v2 News

EZWxBrief v2.0.3 is the current version. There have been no new releases at this point in time. We are diligently working to replace some of the weather data provided by NOAA that has discontinued recently due to the efforts by DOGE. Much of this data provided freely though tax dollars is extremely expensive to outsource and we are uncertain as to how much it will cost to replace. As a result, we have paused work to get a new version of the Skew-T diagram into the app until it is clear that the data will continue to be freely available. We are hoping to resume this development effort once it is clear the data will be available and we hope to complete this by early August.

Check out our Social Media

We have permanently deleted our Facebook and Instagram business pages. You can follow EZWxBrief on YouTube (https://youtube.com@ezwxbrief) and Bluesky (https://bsky.app/profile/ezwxbrief.bsky.social).

Most pilots are weatherwise, but some are otherwise™

Dr. Scott Dennstaedt

Weather Systems Engineer

Founder, EZWxBrief™

CFI & former NWS meteorologist