Hello and thank you for taking the time to read the 47th issue of EZNews!
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Two new 1-on-1 training subscription plans
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 so you can minimize your exposure to adverse weather? 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 $425 and $299, 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 Monday through Friday from 9 a.m. to 5 p.m. eastern time. He is has been an instrument flight instructor for over 25 years and as a meteorologist for the last 45 years, he is also an aviation weather expert. At the present time there is no availability in the evening or on weekends/holidays. Blackout times will apply during aviation events (e.g., AirVenture). See this post for more information on how to purchase one of these two plans.
Coming to SUN 'N FUN this year?
EZWxBrief won't have a vendor booth this year at SUN 'N FUN, but you can catch a couple of presentations by Dr. Scott Dennstaedt on Thursday, April 3rd if you are attending. He will have a presentation on Weather avoidance: Protecting the margins in the first floor cafeteria room (CFAA-01) at 10 am and 5 Things you must know about datalink weather at the AOPA Pavilion at 12 pm. Please stop by and say hello. Hope to see you there!
What are surface pressure troughs?
Before every flight, pilots should become familiar with the latest surface analysis and PROG charts to identify the major weather systems that are expected to affect the conterminous U.S. and southern Canada. These charts are made available in the EZWxBrief progressive web app static imagery and also on the aviationweawther.gov and wpc.ncep.noaa.gov websites. They depict an isobaric analysis or forecast of pressure (in millibars) adjusted to mean sea level that includes a few familiar features such as high and low pressure centers as well as the location and type of surface frontal zones. They also may include a few unfamiliar features such as drylines, squall lines, convective outflow boundaries, intermediate isobars and what are referred to as surface pressure troughs.
In general terms, a trough is simply an elongated area of low pressure with no distinct low-level pressure center. A trough is an axis (line) that defines both a wind shift and pressure change like a frontal zone. In fact, a front is an example of a surface pressure trough that separates air masses. From a surface pressure perspective, if a trough is headed your way, you will see the pressure begin to fall as the trough approaches and then as the center of the trough passes by you, the pressure will begin to increase. This is similar to what you see with a frontal passage.
As such, all surface pressure troughs represent an area of surface convergence. Outside of the influence of local terrain, surface winds usually shift or flow counter-clockwise or cyclonically through it like a front. Essentially, winds flow down into the trough and converge at the point of the lowest pressure within the trough. Think about digging a V-shaped trough in your backyard to route rainwater off your property. If you pour water on each side of the trough you just dug, it will flow down into the trough and the water converges in the center.
Unlike frontal systems, surface pressure troughs depicted as an orange dashed line on the surface analysis and PROG charts issued by the Weather Prediction Center do not separate air masses. Consequently, most surface troughs do not have "weather" associated with them in the form of clouds and precipitation. Most lee-side troughs found downwind of a major mountain range are often cloudless and thermal troughs forming over land during the day due to diurnal heating may only be found by a careful isobaric analysis. If the air is relatively dry and/or stable, little significant weather will be associated with a surface pressure trough. These are common to see in the Central Valleys of California, in the Desert Southwest and on the lee side of the Rocky and Appalachian Mountains.
There's an important distinction here. As just mentioned, a trough is an elongated area of low pressure with no distinct low-level center. So, a trough has no real center of circulation and will typically not have any upper-level support mechanism associated with it. In other words, it's a kink or wrinkle in the pressure field near the surface that could contribute to a non-frontal "change line" or wind shift line.
Don’t completely discount their potential to produce some adverse weather; if there's plenty of moisture and if there's available instability, these troughs can be the catalyst for convection, especially if the trough is moving out ahead of a frontal system. A good summary would be that a surface pressure trough is generally associated with a wind shift but one with little or no temperature or moisture differences across it like you might see with a front. Usually, there will not be any significant weather associated with these non-frontal troughs. Once you climb out of the planetary boundary layer to cruise altitude you probably won't see much of an influence from a surface pressure trough.
You may also see other features shown on the surface analysis or PROG chart that have a symbology like a trough. These include squall lines, convective outflow boundaries and intermediate isobars. On most surface analysis charts it is customary to draw lines of constant pressure, known as isobars, at four millibar intervals using a solid line. However, when the pressure gradient is weak a meteorologist will often include intermediate isobars every one or two millibars. These intermediate isobars are dashed and closely resemble the symbol used to denote a surface pressure trough. The intermediate isobars use a dashed line to allow a quick recognition so that the pressure gradient doesn’t artificially appear excessive. As a result, the usage of intermediate isobars is left to the meteorologist's discretion based on the pattern and value added to the surface analysis.
In addition to the surface pressure troughs, you may see those same orange dashed lines on the latest surface analysis chart that are used to depict convective outflow boundaries. Just to note that these outflow boundaries are not depicted on the surface PROG charts. Unfortunately, these look remarkably like the surface pressure troughs described above. To tell the difference meteorologists add a note OUTFLOW BNDRY in proximity to the outflow boundary. Convective outflow is the “exhaust” of deep, moist convection or thunderstorms as cold, dense air exits the base of the convection and moves outward in all directions like pouring pancake batter on a griddle. The edge of this outflow or gust front, is like a mesoscale cold front that can lay around long after the convection has subsided and may be the focal point of the next day’s round of convection.
Terminations in NOAA and NWS and other cuts
In addition to many websites in NOAA that have been shut down over the last few months, employees across NOAA and NWS, including those in mission-essential roles, have been terminated as a part of the widespread cuts implemented by the current administration's Department of Government Efficiency (DOGE). These are employees that work for various organizations such as the National Center for Environmental Prediction (NCEP), Aviation Weather Center (AWC), Storm Prediction Center (SPC), Climate Prediction Center (CPC), National Hurricane Center (NHC), Environmental Modeling Center (EMC) and the local weather forecast offices (WFOs) just to name a few. Some employees in these offices had already quit due to the buyout program, including many who took this opportunity to retire early. There's no doubt that many of these offices that have a strong aviation support are now sorely understaffed with the additional cuts and for decades have always been grossly underfunded. Many of these federal employees were the best and brightest in their industry and we've come to know many of these people personally.
We can all agree that the average American wants to reduce fraud, waste, and be more efficient and productive, but these wholesale cuts are not in the best interest of the flying public and to general aviation. This will undoubtedly cause many of the remaining employees in the NWS that care deeply about their job to be overworked and more will be driven to quit. Much of the work they do to support aviation is required 24/7, therefore, many of these federal employees work three different shifts regardless of their seniority. These current terminations and additional loss of highly trained meteorologists will result in reduced services, including aviation weather data that we all rely on to check the radar, satellite, and forecasts we use daily. Moreover, given that the Flight Information System-Broadcast (FIS-B) is not a mandated service for pilots and is expensive to operate, there has been recent discussion of eliminating the FIS-B datalink weather and eventually replacing ADS-B (In and Out) with a privatized space-based system (e.g., Starlink).
There's no easy answer but it is important for you to know what's happening in these organizations in case you see things not working like they have in the past. None of this should be political and this discussion is not meant to be. The NWS was and is the most popular Federal agency and one of the few things both sides of the political spectrum all support. We work closely with those talented people at NOAA/NWS and it is uncertain how this will play out without their help and continued support as further cuts in personnel and data are implemented.
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 been discontinued recently. Much of this data provided though tax dollars is extremely expensive to outsource and we are uncertain as to how much it will cost to replace. We are also working diligently to get a new version of the Skew-T diagram into the app assuming the data remains available from NOAA. This feature is expected to be released before the beginning of summer.
Lastly, we have 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
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