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July 2023 EZNews

Hello and thanks for reading the 27th edition of EZNews!

We really appreciate those that have recently joined, renewed their annual membership or signed up for auto-renewal. We want to especially thank Leif A. who renewed their membership for $100! We truly appreciate your generosity which helps support our continued innovation and growth moving forward. 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 which takes less than 10 seconds per device. Follow the link above or see the 140+ page Pilots Guide for more information on how to install EZWxBrief as a PWA on all of your devices. Also check out our playlist on YouTube for some helpful videos on how to use the various features found in EZWxBrief.


Weather Essentials for Pilots online class coming soon...


Yes, starting January 2024, a new twelve week aviation weather course called Weather Essentials for Pilots will be offered. This unique class will be taught exclusively by Dr. Scott Dennstaedt. The course will be designed to fill in the missing knowledge and piece together the various weather guidance pilots need to use to make more confident decisions to depart on a proposed flight. Please note that this is not meant to teach you how to use the EZWxBrief progressive web app. This course is specifically directed at certificated private/commercial pilots and flight instructors who feel their aviation weather knowledge is significantly lacking and is open to pilots with and without an instrument rating. Putting it succinctly, this is meant to be a slight notch above a beginner level. For most students attending, 20% of the class will be a review of basic aviation weather topics and the other 80% will be new or untaught material.

The class will be held at 8 pm eastern time during the week (exact day of the week is to be determined). Each session will last 1 hour with 15 minutes added to allow for questions (a total of ~75 minutes). The sessions will be held using Google Meet and each session will be recorded for those that cannot attend live. The recording will be made available the following day to those attending the class. The class size will be limited to allow for active Q&A during each session. A final syllabus will be provided to those registered in early January.


The cost of the class will be set at $395 for each attendee (no refunds will be given once the first class begins). Two books will be recommended, but are optional. These can be purchased prior to class. A coupon code will be provided to those attending to reduce the cost of each book.


If you are interested, please send an email to support@ezwxbrief.com. If there is enough interest in the program, it will likely start the second week in January. A waiting list will be started once the class has reached maximum capacity. The specifics on how to register will be sent out in a future blog post.


"Who's who in aviation & weather" YouTube series kicked off in June


In case you missed it, the first episode of "Who's Who in Aviation & Weather" aired on Saturday, June 17th and turned out really well. You can view this 30 minute interview with Captain Doug Morris who has the unique credentials of being both a meteorologist and the captain of a Boeing 787 for Air Canada.


This new program will bring you the latest news and insights from the top minds in the aviation and weather industries. Each month with a focus on weather, we'll feature interviews with leading experts on topics such as air traffic control, flight safety, forecasting, flight instruction and more. We'll also explore the latest trends and developments in these fields, and provide you with the information you need to stay ahead of the learning curve. So join every four to six weeks as we explore the latest news and trends in these two fascinating industries.


On the schedule for later this year we will be chatting with some industry experts to include Dave Hubner from SiriusXM, John Zimmerman of Sportys and Gary Reeves of PilotSafety.org.


> How to watch <


The program will be hosted live on EZWxBrief's YouTube channel. If you cannot attend live, the episodes are recorded and will become available on the same channel shortly after the live broadcast ends. You can also find them in the Who's Who in Aviation & Weather playlist. The exact date and time for future episodes will be announced through this blog and will appear on the EZWxBrief YouTube community page.


New gridded LAMP static imagery


For many years, the gridded localized aviation MOS program (GLMP) static weather imagery in EZWxBrief has been very unreliable. EZWxBrief scrapes these images off of the NWS file system each hour to be displayed in the static weather imagery view. However, these images reside on a NWS server that is old and often returns old imagery from previous runs of the model when queried. Moreover, their own interface is slow given that it is driven by the same outdated server.


So, in order to avoid continuing down this path of uncertainty, we decided to build these images from the raw binary files each hour like the image you see below. This includes the forecasts for ceiling height, surface visibility, surface wind speed and surface wind gust. One of the drawbacks to this change is that the forecasts will be available about 30 minutes later since the raw binary files don't become available until about 55 minutes past the hour and the imagery takes roughly 30 minutes process and build these images.


We hear your feedback!


We are grateful for the feedback we have received from EZWxBrief members and continue to strive to make the app more user friendly and easier to use. At this point we have been working to build EZWxBrief v2.0 that will have a more intuitive user interface and will have better overall performance. This effort is ongoing and will take a few more months to develop and test and we hope to have EZWxBrief v2.0 released this coming fall.


Here is a peek at the new EZDeparture Advisor. The EZDeparture Advisor in the legacy app took up a lot of space especially on small devices. So, to make it easier to use and consume less space, you'll see a timeline of color-coded blocks that provide a summary of the personal minimums as they are evaluated for the route. Each block represents a three hour period. A block labeled 15Z, for example, examines all 12 personal minimums for 14Z, 15Z and 16Z. If the block is yellow that means that one or more of the personal weather minimums has been flagged as a moderate risk, but no high risk concerns were found.

Additionally, to make better use of the screen, the columns in the legacy app that defined the personal minimums for each estimated time of departure are now grouped so that only three at a time are presented. As you move the time slider or hover over any of the three hour color-coded blocks, those three columns attributed to that time frame will appear momentarily so you can determine how each personal minimum was evaluated. After a few seconds, the columns will automatically disappear. Moreover, clicking or tapping on that block will move the time slider to that point and momentarily display the three columns for that block of time.


Lastly, we've gotten several requests from pilots who are color blind to change the depiction since it may be difficult for them to tell the difference between a red and green dot that is used in the legacy app. So, in EZWxBrief v2.0 you'll see red triangles, yellow squares and green dots.


Come visit EZWxBrief at AirVenture 2023


AirVenture is right around the corner! EZWxBrief will have a virtual booth and physical booth (3004) at EAA's AirVenture in Hangar C this year and we are looking forward to meeting many of you there. Stop by during the event and say hello and get a free EZWxBrief T-shirt (while supplies last!) and a personal demo of the EZWxBrief progressive web app including release version 2.0. We'll also have a couple of show specials if you'd like to purchase The Skew-T log (p) and Me: A Primer for Pilots and Pilot Weather: From Solo to the Airlines. Scott will be happy to sign your copy of the book.


Don't forget to catch one or more of Scott's six (maybe eight) forums this year that includes presentations at the NAFI Professional Development Center (PDC), EAA's Pilot Proficiency Center (PPC) and at the AOPA Pavilion. His full schedule is posted here. For those flying to the event, check out The Daily EZ Weather Brief, AirVenture Edition playlist, The AirVenture Daily Weather Roundup 2023. Recorded videos will be added to the playlist from Tuesday, July 18th through Friday, July 21st.


The dryline


During the spring and most of the summer in the Great Plains, it is common to find a feature called a dryline depicted on the mean sea level surface analysis chart and surface prog charts. Most of the time, the dryline is pretty quiescent and comes and goes without too much fuss. It is generally quite harmless and does not pose a significant hazard to aviation most of the time. However, when a dryline is coupled with a large-scale weather system, it can be the focal point of deep, moist convection or thunderstorms assuming a favorable environment exists. The dryline is a bit of an odd bird so it’s important understand how it evolves and why it propagates east and west across the southern and central Great Plains during an average summer day.

First and foremost, the dryline is not a frontal zone and does not separate air masses like you normally see with a cold, warm, stationary or occluded front. Instead, it represents a narrow boundary where there is a steep horizontal change in moisture. Unlike most frontal boundaries that have an upper-level support system (e.g., upper-level trough), drylines are strongly linked to the planetary boundary layer - that’s the layer of air that is directly influenced by its contact with the earth’s surface. Therefore, a dryline separates moist air from dry air and is sometimes referred to as a dewpoint front or Marfa front (after Marfa, Texas where it frequently occurs). The density discontinuity at the dryline is minor as compared to what you can achieve with most frontal zones that separate warm, moist air and cold, dry air. At times, a dryline can contribute to the development of thunderstorms since it usually marks the westernmost boundary of moist, convectively unstable air and can be an area of convergence near the surface.


While a dryline can occur at any time of the year, they are the most common during the spring and summer. During this time, it is a semi-permanent fixture in the southern and central Plains especially in Texas, Oklahoma and Kansas although they can occur at times in the Midwest. This is due, in part, to the arid-to-semiarid air that is located in the Mexican Plateau, western Texas and New Mexico and juxtaposed to the warm, moist Gulf of Mexico-based air further east. This may seem like it is a separation of two air masses like you see with a front, but in reality, the temperature differences across the dryline are not as significant as the change in moisture content on either side of this boundary. In other words, the moisture

boundary represents a density discontinuity like you see with frontal zones.


Sometimes drylines are associated major weather systems, and sometimes they are not. The biggest difference is that they do not necessarily clip along west to east driven by a large-scale weather pattern like you may see with a cold front, for example. Instead, it’s location and motion are generally driven by the diurnal heating and cooling of the day wherever there’s a sharp contrast in moisture in the planetary boundary layer mentioned earlier.

On the surface analysis or surface prog chart issued by the Weather Prediction Center (WPC), you will see the dryline depicted as a line of brown, unfilled semicircles that resembles a warm front that is made up of a line of orange semicircles as shown above. The semicircles point in the direction of the moist air mass. As mentioned earlier, a dryline is also called a dewpoint front separating moist air from dry air which is best realized by examining the observed or forecast surface dewpoint temperature. The dewpoint temperature is a good measure of how much moisture (water vapor) is in the air near the surface. A higher dewpoint temperature means that there’s more moisture. On any given day, it is not usual to see a difference of 50 degrees Fahrenheit or more across one of these dewpoint fronts.


The green numbers on the station models in this surface analysis chart below depict the dewpoint temperature in degrees Fahrenheit. So, on the east or moist side of the dryline notice that the dewpoint temperatures are relatively high in the 60s and upper 50s in eastern Texas. Also notice on the east side of the dryline the surface wind direction is from the south and southeast. That’s a moist flow from the Gulf of Mexico which drives up the dewpoint temperatures at the surface.

On the west side of the dryline the wind is from the west and southwest bringing in very dry continental air from the Southwest U.S. and northern Mexico. This is also reflected well in the station model dewpoint temperatures that range from the low 40s to the upper teens as shown below. Even though the dryline represents a moisture boundary, its actual position on a weather map is plotted according to the shift in the surface winds, not the dewpoint temperature. The direction of the brown semicircles always point in the direction of the moist air.

As the sun was rising on this day in late March, the dryline was located in the western portion of the southern Plains as depicted on this surface analysis chart valid at 1200Z below. It is associated with an area of low pressure in north-central Kansas. As is usually the case, the cold front is trailing behind. This creates three distinct sectors of warm, moist air ahead of the dryline, warm, dry air between the dryline and cold front and cool, dry air to the north of the cold front. Throughout the day the dryline moves east and eventually stalls in central Texas in the late afternoon and early evening.

The typical synoptic set up for such a dryline is to have a surface anticyclone or area of high pressure to the east. This allows moist air originating from the Gulf of Mexico to flow into the Great Plains near the surface. There’s normally westerly flow aloft causing a lee trough, and providing a confluence zone for the concentration of the moisture gradient. Such a confluence zone can be seen on this streamline analysis depicting the winds speed and direction at the surface shown below. As surface air flows clockwise around the high centered in eastern North Carolina (green arrows), it merges together with the dry surface air from western Texas (yellow arrows). This creates a confluence line as air increases speed and moves north into the central Plains. This narrow zone of confluence is the dryline (dotted tan line) with the cold front trailing behind (blue solid line).

Ordinarily to the west of the dryline, the winds are westerly and are often strong. The skies tend to be clear with warm temperatures and low moisture. On the other hand, on the east side of the dryline, the winds are light from the south or southeast with hazy or cloudy skies and warm temperatures and high moisture.

To fully appreciate the evolution of the dryline, you have to look at the vertical structure of temperature and relative humidity. We know that the terrain rises gradually from east to west over the state of Texas as depicted below. This rise in terrain is quite important in how the dryline forms and moves throughout the day. The eastern part of the state has a fairly deep layer of warm, moist air owing to its lower elevation and the moisture being pumped in from the Gulf of Mexico. Because the terrain slopes upward to the west, the moist layer is shallow at the west edge of the moist air, and deeper to the east. The best way to picture this is to look at a vertical profile called a Skew-T log (p) diagram for each of these three locations.


Represented above are three basic Skew-T diagrams depicting the temperature and dewpoint changes with height cutting across Texas from the west to east. Temperature is shown by the red solid line and the dewpoint is the dashed blue line. One of the first things you will notice is a capping temperature inversion above the moist layer for Houston and Abilene. This cap or lid in the atmosphere traps the moist air and limits the growth of any clouds that may exist. Below the inversion is a saturated or near saturated layer. Notice the depth of the layer is greater in the east and shallows further west where conditions are very dry at the surface and aloft in the Texas panhandle.


Let’s go back to the dryline present at the end of March. Early in the morning at 1200 UTC, the dryline is at its morning location in western Texas. If we choose representative points at several locations from west to east, you’ll see below a similar temperature and moisture profile as shown earlier. The sounding analysis to the east has the deepest saturated layer below the inversion. The moist layer of air gets more shallow as elevation increases toward the west.

As the sun rises, the heating of the surface near the dryline in western Texas is greater than that of the surface to the east in the deeper moist air. Thus it takes less insolation or solar heating to mix out the shallow moist layer just to the east of the initial dryline position in western Texas. This mixing out brings dry air downward, and the position of the dry line effectively “moves” eastward. The Skew-T diagram loop from 12Z to 16Z shows how the moist shallow layer in the west eventually mixes out to clear skies.

As the heating continues throughout the morning, deeper and deeper moist layers are mixed out from west to east. This causes the apparent eastward “propagation” of the dry line. Further east, this Skew-T loop shows that the moist layer takes all of the morning and most of the afternoon to finally mix out. This propagation is not necessarily continuous or at a rate equal to the wind component perpendicular to the dry line like you will see with a frontal system. Eventually, the heating becomes insufficient to mix out the moist layer and the propagation stops.


Dryline bulges like the one shown above, are areas along the dryline whose movement relative to the rest of the dryline is altered. If a well-defined jet streak or faster flowing air exists aloft, we often see this bulge underneath the jet. Surface winds tend to deviate near the bulge to match those of the winds aloft. If you see such a bulge, it can lead to a greater focus for surface moisture convergence and the potential for severe thunderstorms in the area around the bulge.


The aviationweather.gov beta site goes live in September


For those that use aviationweather.gov, the National Weather Service will upgrade the Aviation Weather Center (AWC) website at on September 12, 2023. A preview of the upgraded site, which was provided for public comment/review in 2022, is available until the implementation date at: https://beta.aviationweather.gov. Upon implementation, the appearance and functionality of beta.aviationweather.gov will become operational at: www.aviationweather.gov.


The upgrade improves the website’s consistency, supportability, mobile friendliness, performance, and ease of use. The information on the upgraded website is similar to the current website, but the navigation and presentation is adaptable to permit use on mobile devices. All displays and tools available on the current aviationweather.gov are available on the updated website. The new website merges the legacy Helicopter Emergency Medical Services (HEMS) tool into the same framework as the Graphical Forecasts for Aviation while keeping its focus on low-altitude flight.


Even with this new upgrade, aviationweather.gov does not provide the capability to assess and quantify risk based on your own personal weather minimums. This is a capability that is baked into the EZWxBrief progressive web app fabric and simplifies a route-based weather briefing.


Most pilots are weatherwise, but some are otherwise™


Dr. Scott Dennstaedt

Weather Systems Engineer

Founder, EZWxBrief™

CFI & former NWS meteorologist






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