September 2025 EZNews

Hello and thank you for taking a few minutes to read the 53rd edition of EZNews!

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Are you new to EZWxBrief?

For members new to EZWxBrief, you won't find EZWxBrief in the App Store or Google Play Store. For the best user experience, EZWxBrief is optimized to run as a progressive web app (PWA) and must be installed on your device. This is quick and painless and takes less than 10 seconds per device. Follow the instructions in this video or visit the 180+ page Pilots Guide for more information on how to install EZWxBrief as a PWA on all of your devices. For example, shown to the left, here's how to install EZWxBrief on your iPhone or iPad...it's that EZ!

In Flight Weather Essentials for Pilots eight-week class is nearly full

This is your last opportunity to register for this live class before registration closes on September 7, 2025.

There's no doubt that fair weather environments and severe clear conditions provide the best flying experience. However, pilots that use their aircraft to travel longer distances and those that fly more frequently will inevitably increase their exposure to some adverse weather. This class will enable you to recognize serious adverse weather environments both in how to avoid them and provide guidance on how to negotiate the best path out of them or around them. In the end, this class isn't about dealing with in-flight weather emergencies as they occur, but how to avoid them before they happen.

In a nutshell, this eight-week course is specifically directed at certificated private/commercial pilots, flight instructors and designated pilot examiners who feel their weather skillset is significantly lacking. It is open to pilots with and without an instrument rating. Putting it succinctly, this is designed to take the serious cross country pilot to the next level.

The live class, In Flight Weather Essentials for Pilots will begin on Monday, September 15, 2025. The class will meet each subsequent Monday night for eight total weeks. This announcement is a little bittersweet given it will be the last live class that Scott teaches as he eases into retirement over the next few years. So, if you are interested in enduring one more class with Scott, registration has begun so you can reserve your spot as there are just a couple seats remaining for this class. Tuition is $345.

Register now >>> 

Once your registration is complete, you should receive two emails. The first is a confirmation of the payment for your registration and a second is the Google Meet link to join each session. Please check your spam folder if they have not reached your inbox. Important: the same link will be used for each and every class.

Each class will start promptly at 8 pm eastern time on Mondays beginning on September 15, 2025. You can expect about 45-60 minutes of instruction with 15 minute s added to allow for questions and spillover. The sessions will be held using Google Meet and each class will be recorded and a personal link to the recording along with a PDF of the presentation and quiz will be provided to you within 36 hours. Therefore, it is not mandatory that you attend each live class to get the most from the eight-week course. Although you can join the class on a handheld device using the Google Meet app, it is recommended that you use a laptop or desktop computer (Google Chrome is recommended).

Using the personal mins map layer in EZWxBrief

Are you trying to determine airports that might suffice as a good alternate if you can't make it to your intended destination? If so, then you might want to spend some time looking at one of the Station Marker layers on the EZWxBrief map called Use Personal Mins.

You will notice that the first option under the Station Markers layer is called Use Personal Mins (red arrow above). This layer provides the capability to evaluate the current or forecast weather at a station (airport) against a subset of your personal weather minimums that you defined within the settings. Under this layer, four attributes are available (yellow arrow above) to include (1) Flight Category, (2) Ceiling Height, (3) Surface Visibility and (4) Crosswinds. Moreover, this can be applied to the personal minimum settings you've defined for the departure airport (Departure), en route (En route) or destination airport (Destination) accordingly (blue arrow above). The result on the Map will be a solid-filled marker using the EZWxBrief traffic light concept that is also the same concept used in the EZDeparture Advisor and corresponds to the table below.

Please note that the application of these personal minimums applies only for the time set on the EZDeparture Advisor and no active route is necessary for this feature to function.

Here's an example. Let's say you are headed to KILN (blue arrow below) and you have the Map layer set to render the Use Personal Mins Flight Category layer using the Destination personal minimums. The marker at the destination implies that the expected flight category meets your personal minimums given that is is yellow. Yellow suggests that the weather (flight category) is at the edge of your comfort level making this a moderate risk. In this case, you may want to look at airports close to your destination or along the route as possible alternates.

Any airports that show up as green in the example below would make an excellent alternate. Not only do they meet your personal minimums, but they do so conservatively. Red, on the other hand, would be airports to avoid as an alternate given that they do not meet your personal minimums.

This example above was set to evaluate the Flight Category attribute using the Destination personal minimums. If you are mostly concerned about ceiling, visibility or crosswind you could choose those individually as well. The Flight Category simply combines both the ceiling category and the visibility category so it makes for a better one-stop-shopping experience. Of course, you will want to check multiple times before and after your estimated time of arrival to be sure those alternate airports have a forecast that meets your personal minimums. Lastly, the Crosswind option is only available for the Departure or Destination personal minimums.

Icing Folklore

With a brief taste of the polar vortex coming down from Canada this week, it's time to start thinking about airframe ice once again. Icing is a terribly complex topic without many of the old wives’ tales and rules of thumb making it even more difficult and confusing. Rules of thumb generally plead ignorance. Ignorance often leads to bad decisions. When the Mother Nature is on her worst behavior, rules of thumb rarely apply and can actually be dangerous and replace real weather analysis. Here are a few of those rules when it comes to icing folklore.

Folklore: It is possible to accrete ice when the static air temperature is greater than 0 degrees Celsius.

It is quite common to hear pilots say that they’ve picked up ice at temperatures above freezing – even as warm as +5 degrees Celsius. Induction icing, sure, but airframe icing, it can’t happen. Typically this is attributed to a faulty or inaccurate immersion thermometer that is reading a few degrees too warm.

Assuming the outside air temperature (OAT) probe is accurate, the other possible explanation is that the pilot descended into a supercooled liquid cloud while the temperature just above the cloud was a degree or two above freezing. It is not uncommon to see a temperature inversion (an increase in temperature with altitude) immediately above a cloud deck. The pilot notices that the OAT is 2 or 3 degrees Celsius just before entering the cloud and jumps to the quick conclusion that the remainder of the descent has to be above freezing. They are astonished to witness ice form on the wings and were completely unaware that the temperature in the cloud was actually colder than above it. Moreover, when the probe accretes ice or gets wet, errors occur due to evaporative cooling.

Cold soaking is another possibility, but it would be a rare event. Imagine an aircraft quickly descending from very cold conditions into a cloud deck. The temperature in the clouds is slightly warmer than 0 degrees Celsius. There may be just enough thermal momentum to keep part of the aircraft’s surface below freezing causing ice to accrete briefly. This can occur even especially for aircraft that may have quickly descended from the flight levels. Even so, there has not been any accident or incident strictly attributed to cold-soaking scenarios.

Folklore: A layer of clouds a couple thousand feet thick is not a serious icing hazard.

This is definitely not the case for a stratocumulus cloud deck. These clouds are often found in the wake of strong cold fronts. Stratocumulus clouds can produce some nasty icing and are typically only a few thousand feet thick. They have characteristics of both stratus clouds and cumulus clouds. They can cover a large geographic area like stratus, but are associated with instability like cumulus. These clouds are “capped” by a strong temperature inversion which acts like a lid on their growth. Instead of the smooth appearance of the tops of most overcast stratus decks, stratocumulus clouds have a quilt-like appearance.

January 13, 2006, stratocumulus clouds like those shown above crippled a Cirrus SR22 southeast of Birmingham, Alabama. The pilot departed Birmingham along with three other passengers and attempted to climb on top of this rather “thin” deck of clouds. Just as he broke out on top, he had to activate the Cirrus Airframe Parachute System (CAPS) after losing control of the aircraft due to significant ice accumulation. This aircraft did not have any ice protection except for pitot heat.

According to the NTSB, “The airplane entered the clouds at 5,000 feet on autopilot climbing at 120 knots. Upon reaching 7,000 feet the airplane encountered icing conditions. The pilot informed the controller that he would like to climb to 9,000 feet which was approved. As the airplane reached the cloud tops in visual flight conditions at 8,000 feet the airplane began to buffet.”

It is common to have the highest liquid water content right at the very top of these clouds where the drops are normally the largest and the temperature is the coldest. In this case, the cloud top temperature was -10 degrees Celsius…perfect for a nasty icing event.

Folklore: Flying into a cloud that is producing snow is not an icing risk.

Snow falling from a cloud base is a good sign that ice crystals exist in the clouds producing them. So it is easy to draw the conclusion that supercooled liquid water doesn’t exist in them, and therefore, there isn’t an icing risk in these clouds.

While there are important exceptions, precipitation falling from a cloud can lessen the icing threat within that cloud. Moreover, if the precipitation is snow, the threat of icing is even less – but not zero. Snowfall can scour out the supercooled liquid water in the cloud, but a snow-producing cloud still may be a mixed-phase cloud. That is, it will contain both ice crystals and supercooled liquid water.

This is especially true when the snow falling is “showery” as shown by the cellular pattern in the NEXRAD image above. Aircraft flying into weather that is producing snow showers will often report rime ice accretion. Normally the most significant accretion isn’t from the clouds that are actually producing the snow, but those around the snow-producing clouds. Those normally contain the highest liquid water content.

Folklore: Climbing is usually the best option when encountering freezing rain or freezing drizzle.

If you are accreting ice and you are below the cloud base or are between layers, you are likely flying in freezing rain or freezing drizzle. Pilots are taught to climb to a higher altitude if this happens. That’s making a dangerous assumption that there’s an altitude above you that contains air that is warmer than 0 degrees Celsius.

In the case of freezing rain, there might actually be a warm layer above. Freezing rain is produced when snowfall from a rather deep cloud enters a layer of air that is above freezing. The warmer air in this layer completely melts the snow into rain drops which then fall into a subfreezing layer below and deposits on your aircraft. In this particular case, a warmer layer aloft does exist. Even so, freezing rain is a ground-hugging event that you will usually experience on departure or arrival and not while enroute at your cruise altitude.

For freezing drizzle, this is often not the case. There will likely be warmer air above you, but often the temperature aloft doesn’t rise above the freezing mark. Freezing drizzle is normally the result of an all liquid process as small drops in the more shallow-depth cloud collide and coalesce into drizzle-sized drops large enough to fall out of the cloud as freezing drizzle.

The best strategy in this case is to turn around and go back to where you were not accreting ice. If you don’t know the temperature profile above you, it may not be wise to attempt a climb unless you can clearly climb into clear air.

Folklore: Using the standard lapse rate is a good way to estimate the freezing level.

For example, if the temperature at the surface is 4 degrees Celsius, the freezing level is 2,000 feet above ground level by applying the standard lapse rate of 2 degrees Celsius per 1,000 feet. This means that the temperature decreases 2 degrees Celsius for every 1,000 feet gain in altitude. Therefore, with a temperature of 4 degrees Celsius at the surface, flying in the clouds at, say, 4,000 feet AGL would be a bad idea. Correct?

Actually, that’s rarely the case, especially when Mother Nature is at her worst. In an unstable situation as discussed with stratocumulus clouds, the lapse rate near the surface is often greater than standard – often reaching 3 degrees Celsius per 1,000 feet. This is called the dry adiabatic lapse rate. This means that the freezing level will be lower than what you might calculate using the standard lapse rate. At the other extreme in a stable environment, there is often a temperature inversion that may put the freezing level as high as 10,000 feet AGL making a flight at 4,000 feet very manageable.

Estimating the freezing level using the standard lapse rate is like dividing 19 by 95 and getting 1/5th by crossing out the 9s. The method worked well for this particular example, but it’s likely not to work when applied to other similar situations like crossing out the sixes in 16 divided by 65 to get 1/6th...which is incorrect.

The best advice with respect to icing is to put aside old wives’ tales and avoid using rules of thumb. If you want to know the freezing level, for example, look at a temperature profile of the atmosphere using a forecast temperature sounding instead of guessing with a formula that only works when the atmosphere fits the formula. Alternately, as shown below, use the route profile in EZWxBrief that clearly depicts the expected freezing level along the entire route of flight using forecast model guidance.

If you want to know if a snow-producing cloud is an icing threat, look for the presence of icing G-AIRMETs or examine the EZWxBrief route profile that depicts icing severity as shown above. In other words, attack the problem directly by utilizing weather guidance that depicts the current icing environment instead of relying on icing folklore.

Was it clear air turbulence?

You may have heard about this event in the news that injured a couple dozen passengers and crew. On Wednesday, July 30, Delta Flight 56, an Airbus 330-900neo heavy aircraft was enroute from Salt Lake City, Utah with a planned international destination of Amsterdam. Shortly after departure while level at FL370, the flight hit extreme turbulence at 2323Z over Wyoming and later diverted to Minneapolis. But when you look at the initial report from NBC News (shown below), it blames this on "clear air turbulence." Was this really clear air turbulence or something else? In fact, this wasn't clear air turbulence but extreme convective turbulence. There's a huge difference. While some clear air turbulence encounters are hard to see and avoid until pilots begin to report the turbulence, convective turbulence like this is highly avoidable.

Instead, this flight encountered a thick band of vigorous convection over Wyoming. The aircraft flew into an active convective SIGMET (below) for an area of thunderstorms with tops above FL450.

CONVECTIVE SIGMET 84W

VALID UNTIL 0055Z

CO WY UT

FROM 40ESE DDY-20NE LAR-40WSW LAR-50WNW MTU-40SE MLD-40ESE DDY

AREA TS MOV FROM 20010KT. TOPS ABV FL450.

Below is the pilot weather report (PIREP) that was ultimately filed or relayed through the Denver Center (ZDV).

RWL UUA /OV CKW340010/TM 2342/FL370/TP A339/TB EXTREME TURB FL370/RM COULD NOT HOLD ALTITUDE +/- 900FT ZDVWC-34

Below is the altitude data from flightradar24. The first altitude deviation caused the aircraft to rapidly climb 1,000 feet reaching a maximum altitude of 38,075 feet in less than 30 seconds before a rapid descent to 36,250 feet over an additional 90 second period before recovering back to FL370. Whether this entire turbulence event occurred in "clear air" or within the cloud boundary is unknown and largely irrelevant to the conversation.

Below is a side-by-side close up comparison of the GOES-19 visible (left) and the Infrared (10.3 µm, right) satellite images. These images also include the ground-based location (cyan-colored asterisk) and the parallax-corrected cloud-top location (yellow +) of Delta Flight 56. It's easy to see that the aircraft flew into a region of overshooting tops (located in the red oval). Convective currents in and around overshooting tops can be quite hazardous given that they are a distinct sign of a vigorous local updraft. Click on the image to see a time-series loop.

Images courtesy of Scott Bachmeier, CIMSS

The coldest cloud top temperature for the overshooting tops was -63°C based on an infrared brightness temperature (not shown). Conveniently, a radiosonde (weather balloon) was launched at 2300Z in Riverton, Wyoming (RIW) just north and west of the region where Delta Flight 56 experienced the severe turbulence. This provides an excellent opportunity to compare the cloud top temperature of the data provided by the radiosonde observation.

According to a plot of radiosonde data from Riverton, Wyoming (below), that infrared brightness temperature represented a ~1 km overshoot of the surface-based (SB) air parcel’s equilibrium level (EL) — reaching an altitude around 11.5 km or 37,730 feet (above the 37,000 ft cruising altitude of Delta Flight 56). Of course, this radiosonde observation may not accurately depict the conditions at the location of the extreme turbulence event but is likely a fairly reasonable estimate.

Turbulence near thunderstorms, known appropriately as TNT, isn't a new concept. Even if you fly outside of the cloud boundary, the evolution of a thunderstorm can create gravity waves and other wind shear given that these massive cells act like obstructions to the prevailing wind flow similar to the wind flow over mountains. For convection, this is all trapped below the tropopause which creates that stable layer needed to develop gravity waves. Below is a time-lapse cross-section of the development and eventual collapse of a cell (note this is not the cell that Delta Flight 56 encountered). Red areas are regions where significant turbulence can exist outside of the cloud boundary that is shown in blue. This clearly demonstrates how violent the turbulence can be in regions above a thunderstorm as it is evolving over time.

EZWxBrief v2 News

EZWxBrief v2.0.3 is the current version. There have been no new releases at this point in time. A majority of the work over the last ten months has been to optimize the compute architecture to improve the app's overall performance and increase the security to minimize the potential for any cyber attacks.

The NWS has been planning to remove many of the model-based imagery over the next few months and to avoid interruption all of that static imagery had to be built from using the raw gridded-binary data. Doing this requires additional development and ongoing compute resources. Therefore, as of December 1, 2025, the EZWxBrief app subscription will be increased to $8.99 per month to help offset these costs and to help sustain EZWxBrief for another year.

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