AvWxWorkshops.com Basic Workshops Table of Contents
The growing library of AvWxWorkshops.com contains dozens of "bite-sized" aviation weather workshops ranging from 5 to 20 minutes in length. Below you will find a brief description of every basic workshop available within the library. Each description contains a link to the details page of that workshop. Feel free to use this table of contents to locate a topic of interest by searching this table of contents. Regular and Elite members of AvWxWorkshops.com can login and freely view all of these basic workshops as many times as you'd like assuming your membership has not yet expired. If you are not a member, please feel free to register now. Note that this table of contents does not include a description for any premium workshops.
[Using a Skew-T to fill in the gaps - Many flight planners use very low resolution data in time and space to depict the winds and temperatures aloft. This can often provide a misleading picture, especially when temperature is a concern. Temperature is a continuous element in the atmosphere and is best depicted using a Skew-T log (p) diagram. This workshop will discuss the value of using a Skew-T diagram to provide a more accurate representation of the temperature aloft than you might get with some of the flight planning apps.
Cumulus cloud tops - A flight through a healthy cumulus cloud can inflict moderate or greater turbulence. Flight through them at an altitude that is below freezing can result in a nasty icing encounter, especially near the tops. So, knowing the vertical extent of these clouds can be quite useful. A ride above the clouds is often smooth and uneventful. While difficult at times, this workshop will explain how to determine the vertical extent of an area of building cumulus clouds.
The dryline - The dryline is an unfamiliar feature that is found on the mean sea level surface analysis chart. It is not a frontal system and does not separate air masses. Instead, it separates warm, moist air from warmer dry air. While it can be the focal point of deep, moist convection since it often marks the boundary of convectively unstable air, the dryline is usually relatively harmless. This workshop will offer an explanation of how the dryline forms and moves and when to be concerned that is may play a significant role in the development of thunderstorms.
Isolated convective turbulence - While the location of most convective turbulence is easily identified by looking at various weather weather products such as NEXRAD and convective SIGMETs, at times it may surprise even the most astute pilot. Convective turbulence can occur any time during the year including the northern tier of states. This workshop will show you how to identify trends in the infrared satellite image to identify the potential for isolated convective turbulence using a flight in northern Idaho in early January.
Matching online guidance to your flight plan - When planning any flight pilots often have an optimal departure time in mind. Any online preflight weather briefing requires that you must match your flight plan departure and arrival times to weather guidance that's available online. This requires understanding the various products and how to decipher the valid date-time stamps on those product within the context of your flight plan. This workshop will use a proposed IFR flight from Seattle, Washington to Crescent City, Oregon to demonstrate how to match up online weather guidance in association with a planned departure and arrival time as well as a planned cruise altitude.
Standing wave clouds - A flight over a mountain range is one of the most captivating experiences any pilot will enjoy. But as spectacular as this may appear pilots must also be aware that terrain such as this can induce mechanical turbulence and mountain waves. When the conditions are right, these mountain waves can also make such a trip challenging or potentially dangerous especially when standing lenticular clouds are evident. But what pilots don’t understand is that the presence of lenticular clouds do not always imply the presence of dangerous turbulence. This workshop provides some clues that may help determine when those lenticular clouds might be a signature for an uncomfortable ride.
QPF - Quantitative Precipitation Forecasts or QPF represent an accumulated precipitation forecast that's valid over a range of time. QPF is a forecast issued by the Weather Prediction Center (WPC) which is also responsible for issuing the prog charts. This workshop will describe how to use the QPF as a supplementary forecast for the prog charts.
Erroneous pilot weather reports - Most pilot weather reports are quite accurate. But it's important to verify the accuracy of any pilot report you may use - especially if it has been relayed through the Air Route Traffic Control Center (ARTCC). This workshop will discuss how to identify an erroneous icing pilot weather report.
Locating multiple cloud layers on the Skew-T - Flying in clear air between layers can be done safely, especially when flying under IFR. Determining the altitudes that are free of clouds can be easily done using a Skew-T log (p) diagram. This workshop discusses how to located clear air between two cloud layers.
Cumulus clouds - Cumulus clouds rarely cause you to cancel your flight. They are usually scattered to broken and tend to develop in the late morning and dissipate in the early evening. They are rooted in the planetary boundary layer. Flight under and through these clouds will almost always produce some form of turbulence. This workshop discusses how to minimize your exposure to uncomfortable convective turbulence.
The cutoff low - The cutoff low is not a rare event, but certainly doesn't happen very frequently. They are troughs that are cut off from the main flow aloft. They tend to move very slow and can hang around the area for days at a time keeping the forecast filled with adverse weather. This workshop emphasizes how a cutoff low can surprise pilots by lowering the freezing level.
The 3000-foot rule - Most instrument rated pilots have heard of the 3000-foot rule with respect to icing. That is, if you encounter airframe ice while en route, simply climb or descend by 3000 feet and you will usually exit those conditions. This workshop discusses if this "rule of thumb" really has some validity.
Low topped convection and snow pellets - It's rare for pilots in Southern California to get convection that produces hail...but what about snow pellets? Snow pellets are common with low-topped convection. The environment that produces them is different than the environment that produces ice pellets. This workshop discusses the conditions that are conducive for producing low-topped convection and snow pellets.
Freezing fog - Freezing fog is a common obstruction to visibility found in a surface observation and TAF during the winter months especially in Canada and the northern tier of the U.S. What is freezing fog and is this a concern for structural icing? This workshop will discuss how FZFG is determined by the surface observing equipment and whether or not this is considered a known icing risk.
Identifying an erroneous surface observation - While automated surface observations can be incorrect, it's important to verify the integrity of all observations you may use for preflight planning. This workshop will discuss how to use a buddy check and the Skew-T log (p) diagram to identify an erroneous report of light snow.
Identifying low level severe turbulence potential in a sounding - Severe or extreme turbulence can be quite scary for even the most seasoned pilot. However, forecasts for this kind of event are at best difficult or fundamentally impossible. Pilot weather reports or PIREPs represent the best source of information to alert pilots to the potential for severe or extreme turbulence events. However, PIREPs are not always available so it's important to recognize those signatures that can lead to such an event. This workshop describes the how to use a Skew-T log (p) diagram to identify a low level severe turbulence event.
Identifying trends in forecast soundings - In many cases, forecasts are actually quite good, but may be off in the timing of the event by a couple of hours. This is especially true for long range forecasts. So, it's important to not only look at the forecast that best fits your proposed departure time, but forecasts that may be valid a few hours prior or after your departure. If the forecast is for the ceiling to build down, then that trend may very well be more important that the forecast itself. Seeing that the weather is trending to improve or deteriorate is valuable especially for forecasts at 12 hours or beyond. This workshop will demonstrate how a forecast sounding was quite good, but two hours early in predicting an overcast cloud layer.
Eliminating ground clutter - Most ground-based radar sites are not very clean and contain non-precipitation returns called ground clutter. This clutter can look remarkably like real precipitation and easily confuse the pilot. While normally filtered, ground clutter can also show up on your ground-based radar display that is broadcast to your satellite-based receiver. This workshop discusses some strategies on how to recognize and eliminate that annoying ground clutter.
Surprise convection in the Pacific Northwest - While thunderstorms do occur in the Pacific Northwest, it's actually a rare event even during the warm season. That is, the Aviation Weather Center (AWC) rarely issues convective SIGMETs in this region even during the month of August in the late afternoon when thunderstorms are normally expected in many other locations in the country. This workshop will discuss a case where convection developed in the Pacific Northwest in early August even though a standard weather briefing did not provide much help warning pilots of such an event.
Dissipating tropical systems - It's true that most pilots would not fly into an area with a land falling hurricane or tropical storm. However, what about after the system dissipates and moves inland? This workshop will discuss how dissipating tropical systems are not your ordinary deep, moist convection. They often have very benign-looking radar signatures and little or no lightning. But can contain significant convective turbulence including small tornadoes.
Altimeter settings and elevation - Absolute station pressure is rarely used by anyone. That's because pressure decreases as you gain elevation. So, pressures at airports at a high elevation would always have a lower pressure; not very useful for analyzing pressure patterns. So, the effects of elevation must be removed and that's done through a computation that reduces the pressure to sea level. This workshop will highlight how this reduction to produce an altimeter setting can be problematic for airports with high elevations.
Determining a clear sky during the warm season - Ever wonder how a forecaster can determine if the sky will be completely clear during a summer afternoon? Even on the best weather days, the sky often has some scattered to broken cumuliform clouds. This workshop provides an inside look on how to use a Skew-T log (p) diagram to determine when the sky will be perfectly clear.
The ugly side of virga - Most pilots are taught to avoid virga despite the fact that most virga is quite harmless. Virga is a product of precipitation falling into a very dry atmosphere causing it to evaporate and cool. While it is ordinarily very harmless, virga in the vicinity of deep, moist convection can be dangerous. This dense air makes its way to the ground in the form of downdrafts or weak microburst. At a minimum, it may cause moderate to severe turbulence. This workshop highlights a case of dangerous virga in the Dallas/Fort Worth area at the end of April.
Using the K Index to assess convective potential - The K Index is a parameter that all pilots learn how to use during their primary training. However, despite its apparent usefulness, the K Index has a few limitations that need to be understood. The K Index is not a result of lifting a parcel of air like many other convective indices such as CAPE and the lifted index. It is best used to identify non-severe convection or heavy convective rain fall events. This workshop will show how the K Index is derived and identify its key limitations.
Using loops to assess trends in weather reports and forecasts - The charts and diagrams used by pilots for preflight analysis are all presented in two dimensions. However, adding the dimension of time will enhanced the effectiveness of your preflight weather briefings. This can be done by using looping constructs. This workshop shows how to leverage common weather products to identify trends in the weather.
Deciphering those date-time stamps - With all of the choices of preflight weather products available, pilots can have a difficult time identifying how to read those date-time stamps to determine when the product is valid. There are often multiple dates on the product and some products are valid over a period of time or at a specific time. This workshop surveys many common weather products to get an edge up on learning how to determine when they are valid.
Cold stratocumulus clouds - Stratocumulus clouds are ordinarily a few thousand feet thick. Pilots tend to think they can easily climb or descend through this cloud deck during the cold season especially if they are producing snow. Well, think again. There may be a huge risk descending or climbing through a layer of cold stratocumulus clouds. This workshop presents a case of two Boeing 767s reporting severe rime ice as they descended down through such a cloud deck over Louisville during the overnight hours.
Surface analysis tips - The surface analysis chart should be where all pilots start their preflight briefing. The surface analysis chart can tell us a lot about the surface wind direction and wind speed at our departure and destination airports. This workshop discusses the nuts and bolts of how to use the surface analysis chart issued by the Hydrometeorological Prediction Center (HPC). This includes how to leverage the surface analysis chart to assess the wind direction and wind speeds at the surface.
ASOS precipitation - The purpose of this workshop is to describe a few important limitations of an unattended (AUTO) Automated Surface Observing System (ASOS). Specifically, an ASOS is incapable of reporting drizzle (DZ) or freezing drizzle (FZDZ) at this time. At some locations, however, a trained observer can augment the report to include drizzle or freezing drizzle.
Using AIRMET Zulu during the cold season - This workshop uses a flight planning scenario to illustrate how to properly utilize AIRMET Zulu during the winter months. AIRMETs have important limitations. They are time-smeared forecasts valid over a range of 6 hours. As a result, if the AIRMET area is large, it may be that only a small portion of the total AIRMET area may be affected at any one time.
Precipitation forecasts: Accumulated versus instantaneous - There are two kinds of precipitation forecasts you will typically use. One is an accumulated precipitation forecast valid over a range of time and the other is associated with precipitation coverage valid at a specific time. This workshop explains how to properly use these two types of precipitation forecasts.
Common errors in the FBWinds forecast - While the FBWinds may be the "official" NWS/FAA products for temperatures and winds aloft, it does have some inherent limitations that all pilots should know about. Using a flight planning scenario associated with the passing of a cold front, this workshop illustrates how using the official FBWinds forecast can result in a 3,000 ft. error in the freezing level.
Forecasting a low IFR event several days in advance - Whether flying VFR or IFR pilots often have sufficient guidance for determining the threat of IFR conditions on the outbound leg of a round-robin flight. But what if you are returning in two or three days? Do you want to make this trip at all if the weather is likely to be below your minimums on the return leg? Using a flight planning scenario, this workshop demonstrates how to use the graphical Model Output Statistics (MOS) to determine the potential for a low IFR event two or three days in the future.
Using LAMP guidance - If you live and fly on the west coast of the U.S., morning fog, known as the marine layer, is very normal part of your preflight planning. However, if you fly in and out of an airport without a scheduled terminal aerodrome forecast (TAF), how do you know when the fog will dissipate? Using a proposed departure from the Bay Area in California, this workshop explains how to use the GFS LAMP guidance to identify when the marine layer is likely to retreat.
Using historical data - Often what has occurred in the recent past can be extremely valuable to a pilot to understand the current weather. This is expecially true with convective precipitation. Most websites including the Aviation Digital Data Service (ADDS) do not provide a historical perspective. Using a flight planning scenario in the Midwest, this workshop provides guidance on how to use historical data to identify that area of precipitation is a convective debris leftover from previous thunderstorms and is safe to fly through.
VFR convective flight planning - Flying IFR in a convective environment may be challenging for the average instrument pilot. Often it is beneficial to fly under VFR to provide the greatest flexibility for route and altitude. Using a flight planning scenario in the Deep South, this workshop demonstrates how to use various NWS convective guidance to plan a flight under VFR when thunderstorms are a flight risk. This also includes how to select the best altitude for such a flight.
Conditions inhibiting a radiation fog event - Pilots are taught that radiation fog (ground fog) can form when the sky is clear, winds are light or calm and the relative humidity is high. Unfortunately, even when all of these conditions exist, radiation fog may still be inhibited from forming. That's because the conditions above focus only on what is happening at the surface and do not take into account what is happening just above the surface in the potential fog layer. This workshop discusses what can keep that radiation fog from forming even though all the "right" ingredients are present.
Understanding the saturation mixing ratio - The saturation mixing ratio is perhaps the most mysterious of all the lines on a thermodynamic chart called a Skew-T log (p) diagram. This workshop discusses how to use the saturation mixing ratio to calculate the lifted condensation level (LCL) to determine the bases of most cumuliform clouds.
High instability with no chance of thunder - Pilots are taught when the lifted index is highly negative that thunderstorms, should be anticipated. However, that isn't always the case especially when the area of instability is under a ridge of high pressure. Using a flight scenario in the Midwest, this workshop will illustrate how a ridge such as this will limit afternoon convection keeping the skies clear.
Non-convective low level wind shear - When a forecast for WS (wind shear) appears in the TAF or is issued by the Aviation Weather Center as part of AIRMET Tango, pilots immediately equate this to a nasty turbulence event. This is perhaps the most misunderstood forecast provided to pilots. This workshop explains why a forecast for non-convective low level wind shear is not a forecast for turbulence and why conditions are often glassy smooth.
Recognizing thin layer turbulence - Most moderate turbulence is often widespread. Some severe turbulence events, however, occur in rather thin layers. In fact, it is not unusual for there to be a severe turbulence report just 2,000 feet below a report smooth conditions. A thermodynamic chart called a Skew-T log (p) diagram is one of the best ways to diagnose thin layer turbulence events. This workshop provides specific guidance on how to determine the potential for severe thin layer turbulence.
Thunderstorm symbology - The present weather symbols used by graphical METARs Java Tool found on the Aviation Digital Data Service (ADDS) website do not always tell the complete story. In fact, when thunderstorms are being reported in the airport's vicinity while rain is being reported within the terminal area, don't count on seeing a thunderstorm symbol. This workshop discusses why it's important to always look at the textual METAR instead of relying strictly on the graphical representation.
Using the standard lapse rate to estimate the freezing level - The standard lapse rate is one of the aviation rules of thumb that gets drilled into most pilots. In fact, it is very common for pilots to use this lapse rate for preflight planning purposes such as calculating the freezing level based solely on the surface temperature. The standard lapse rate should never be used for this purpose. This workshop will demonstrate a more accurate and consistent approach on how to determine the freezing level.
Estimating wind gusts - Airports served by a terminal aerodrome forecast (TAF) have a detailed forecast for wind direction, wind speed and wind gust potential. However, if you are not flying into an airport served by a TAF, you will not have a site-specific forecast for wind. This workshop identifies how to use a thermodynamic chart called a Skew-T log (p) diagram to estimate the wind gust potential at the surface.
Multiple freezing levels - During the cold season it is not uncommon for there to be multiple freezing levels. While multiple freezing levels are not always a sign of adverse weather, it is typically a common requirement for the development of freezing rain (FZRA). This workshop illustrates several ways to accurately identify the potential for multiple freezing levels on your preflight analysis.
Convective SIGMETs - It may not always be obvious, but not all thunderstorms will meet convective SIGMET criteria. Once the criteria is met, a forecaster at the Aviation Weather Center (AWC) will issue a convective SIGMET. Most importantly, convective SIGMETs are not a forecast for thunderstorms; instead they represent more of a nowcast placing a fence around thunderstorms that are significant to aviation. In this workshop we will review the criteria used by this forecaster before a convective SIGMET is issued.
Collaborative convective forecast product - The CCFP is a seasonal forecast product available on the Aviation Digital Data Service website. It is produced in collaboration with several commercial entities and government organizations including the Aviation Weather Center, Center Weather Service Units and the airlines. The criteria used is not the same as convective SIGMETs, so it is not a thunderstorm forecast as most pilots believe. In fact, this forecast is not well-suited for most general aviation pilots. This workshop will show why general aviation pilots must be careful in using this forecast for their preflight weather briefing.
Snow covered ground and the visible satellite image - Most of the time, the visible satellite image is easy to use. Clouds are generally located wherever you see a shade of white. It helps the pilot show the extent of the cloud cover and the satellite loop shows their movement. But, in the winter what looks like clouds may actually be snow on the ground. This workshop provides some tips to help a pilot to differentiate between clouds and a snow-covered surface.
Lightning-free convection - Most pilots believe that you can only be struck by lightning when there are thunderstorms in close proximity. What pilots don't realize is that most aircraft fall victim to a lightning strike in regions where no natural lightning is occurring or expected to occur. The aircraft itself induces the lightning strike. In fact, it is thought that most airliners average about one lightning strike per year. This workshop will discuss how to avoid being the victim of an aircraft-induced lightning strike.
Turbulence in the wake of a cold front - In the wake of a cold front it can get quite windy including some stronger gusts. Strong winds and gusts normally equate to some moderate turbulence. However, even though it may be windy at the surface, it is often possible to find an altitude that is nearly smooth without the need for oxygen. This workshop will demonstrate how to use a Skew-T log (p) diagram to find the altitude with the smoothest ride in the region behind a cold front causing gusty winds at the surface.
Surface pressure troughs - When looking at the mean sea level surface analysis chart there are many familiar features. This includes high and low pressure centers, isobars and frontal systems. But, there are other elements depicted on this chart such as outflow boundaries and surface pressure troughs that may be unfamiliar. Surface pressure troughs are quite common, but many pilots don't understand what they may mean from an adverse weather perspective. This workshop will help to identify what kind of adverse weather you might expect if your proposed flight takes you through a surface trough.
Graphical TAFs - Terminal Aerodrome Forecasts (TAFs) are a textual forecast. Consequently, when examining the TAFs along their proposed route most pilots will simply view the text for each TAF. However, the Aviation Digital Data Service (ADDS) allows you to view the TAFs in a graphical format similar to the way METARs can be displayed graphically using a station model. This workshop will explain how to get the most from the ADDS graphical TAF display.
Freezing rain & thunderstorms - Pilots are taught to always avoid thunderstorms and never to fly into areas of freezing rain. But what about when they occur together? When freezing rain occurs there is generally a very stable layer (temperature inversion) near the surface. This kind of stability typically will squash any chance of thunderstorms. But, there are times where warm air can ride up and over the cold, dense air at the surface producing elevated convection. This workshop will discuss the conditions that can produce both freezing rain and thunderstorms.
Echo top heights - Echo top heights are produce by the same NWS NEXRAD Doppler radars that produce the familiar base reflectivity product. The echo top product is also available in the satellite weather broadcast. Echo tops are primarily used by meteorologists to determine the heights of thunderstorms. Higher tops are indicative of convective turbulence. While they do generally define the top of the echo region in a precipitating cloud, they are not the same as cloud tops and should never be used as such. This workshop explains why they can provide misleading information when determining if it is safe to fly through an area of precipitation.
Convective outflow boundaries - Cold, dense air is the exhaust of deep, moist convection. As this cold air exits the thunderstorm from below and hits the ground to spread out like pancake batter poured on a griddle. The edge of this outflow is a gust front that moves quickly away from the thunderstorm. Most outflow boundaries are benign, but there are some important aspects to consider. This workshop discusses a convective outflow boundary and provides some guidance on when pilots should be concerned flying through one of these outflow boundaries.
Anomalous propagation - We can't look at a NEXRAD image and take the image too seriously. Not everything presented on this image is real precipitation reaching the surface. In some cases, the radar beam is bent or ducted in a way that causes it to strike the ground far from the radar site producing what appears as precipitation returns that can resemble the appearance of thunderstorms. The phenomenon is referred to as anomalous propagation or AP. In some situations this can be successfully filtered by the radar, but not always. This workshop explains the reasons for anomalous propagation and how to recognize it on a NEXRAD image.
Satellite weather gone bad - Pilots are becoming more and more comfortable making flights since they've had the ability to see near real time weather while en route all courtesy of the satellite weather broadcast from XM Radio. The composite NEXRAD image is probably one of the most valuable products that gets broadcast. Every 5 minutes a new update is received allowing the pilot to see the location of areas of precipitation. But is that image something you can trust? Not always. This workshop will demonstrate how some returns presented on your satellite weather display may not be real precipitation. Also, discussed is how an over zealous filter may remove real areas of precipitation including severe thunderstorms.
Clear air turbulence - Turbulence is largely a function of vertical mixing in the atmosphere. If air is moving up and/or down, the chances of turbulence is increased. Turbulence can occur within clouds, but it also frequently occurs in cloud-free areas. As a result, this is referred to as clear air turbulence. While most clear air turbulence is moderate or less, occasionally, it can get severe or extreme. Even so, it remains difficult to forecast. Nevertheless, knowing the patterns to look for is critical to assessing the potential for clear air turbulence. This workshop will discuss what to look for on a constant pressure chart and Skew-T log (p) diagram to identify signatures for significant clear air turbulence.
Using the infrared satellite image to determine cloud tops - There are very few sources to determine the altitude of the tops of a cloud deck. The area forecast and pilot reports are two great resources. However, pilot reports of tops are not always available and the area forecast is a textual product and doesn't have the best temporal and spatial resolution. The color-enhanced infrared satellite image provides cloud tops temperatures which can be used to determine the actual cloud tops. This workshop will show how to use the color-enhanced infrared satellite image along with other resources to accurately depict the height of most cloud tops.
Forecast soundings over water - When using the RUC soundings Java tool to show the future vertical profile of temperature and dewpoint, it's important to understand that the sounding isn't always valid right over the airport you entered. In fact, if you are using an airport near a body of water such as a lake, bay or ocean, you may find that the point that is shown in the diagram is over the water. This can produce a substantially different sounding than if over land. This workshop will identify the differences that can occur between a sounding over the water and one that is over land.
Graphical AIRMETs - Graphical AIRMETs or G-AIRMETs are a relatively new product issued by the Aviation Weather Center (AWC). It is issued by the same forecasters that issue the traditional text-based en route advisories known as AIRMETs. AIRMETs have limitations that are not completely understood by many pilots. They are time-smeared forecasts that are valid over a six hour period which provides a poor spatial and temporal resolution. G-AIRMETs, on the other hand, are snapshots defining the expected coverage of the adverse weather element valid at a specific time. This workshop will introduce the G-AIRMET product and identify how it is different from the traditional AIRMET text.
Using GFS and NAM model output statistics - Terminal forecasts (TAFs) are the only site-specific forecast available to pilots. However, thousands of airports are not served by a TAF. Model output statistics or MOS from the North American Mesoscale (NAM) and Global Forecast System (GFS) models provide site specific forecasts for over 1700 airports throughout the U.S. This workshop will demonstrate how to leverage these forecasts and read the tabular MOS bulletin.
Freezing rain depth - Freezing rain is one adverse weather element that should get every pilots attention...even those flying large turbojet aircraft. Many pilots are taught when encountering freezing rain, climbing is the best choice. It is explained that initiating a climb will put them into the warmer air aloft that is melting the falling snow into rain. What pilots don't appreciate is that freezing rain is truly a "ground-hugging" phenomenon. This workshop will explain how a freezing rain event occurs and how to determine its depth on a Skew-T log (p) diagram.
TAF amendments - Terminal aerodrome forecasts, better known to pilots as TAFs are one of the most detailed aviation forecasts available to pilots. They are constructed by forecasters located at the local Weather Forecast Offices (WFOs). Even after a particular TAF is issued, the forecaster must continue to monitor the weather to determine if the TAF is still representative of the current and forecast weather within the terminal area. Once the weather reaches amendment criteria, the forecaster will ordinarily amend the TAF. This workshop will provide the background on the criteria that is used by forecasters to determine when a TAF should be amended.
Too cold for structural icing - During the cold season when clouds are present, it is likely that the northern third of the U.S. will be blanketed by AIRMET Zulu warning pilots of the potential for widespread areas of structural icing. But, just because clouds are present, doesn't imply the presence of supercooled liquid water. When temperatures are very cold, even in areas of moderate snowfall, structural icing may not be likely as the clouds may be glaciated. As a result, AIRMET Zulu may not be issued for these areas. This workshop will explain how cold is "too cold" for the presence of supercooled liquid water.
Calculating the relative humidity using a Skew-T log (p) diagram - The RUC soundings java tool automatically calculates the relative humidity at any altitude where there is temperature and dewpoint data. The relative humidity is shown as a function of the cursor feature in this tool. However, you can calculate the relative humidity at locations other than those at specific data points. This workshop will provide instruction on how to use the saturation mixing ratio to calculate the relative humidity on a Skew-T log (p) diagram.
A case of bad CIP - Most of the time the Current Icing Product or CIP that is available on the Aviation Digital Data Service (ADDS) will provide a fairly accurate icing analysis at the top of each and every hour. One advantage that CIP brings to the table is that it uses several observational sources to build the analysis. This includes surface observations (METARs), pilot reports (PIREPs) NEXRAD radar, lightning data, two hour model forecast parameters and infrared and visible satellite data. But, CIP can have some issues distinguishing clouds from snow on the ground especially right at sunrise or sunset. This workshop will examine a case right after sunrise where CIP showed no chance of structural icing in Upstate New York despite reports of moderate icing from pilots in the area.
SPC convective outlooks - Part 2 - The Storm Prediction Center (SPC) is primarily concerned with severe weather such as severe thunderstorms. However, they do provide products that forecast the likelihood of general organized convection that is not severe. When initially issued the Day 1 convective outlook provides a categorical forecast for convection (including severe convection) for a period of 24 hours. A temporal resolution such as this is not as useful to pilots. This workshop will introduce an experimental product called the enhanced resolution thunderstorm outlook that provides a probabilistic forecast for thunderstorms that includes a temporal resolution as low as four hours.
Using the VAD wind profile (VWP) for cloud tops - The VAD Wind Profile provides a depiction of the winds with altitude. It is generated by the NWS WSR-88D NEXRAD Doppler radars. It is used by some pilots to determine the tops or height of a cloud deck. While it may paint a fairly reasonable depiction of the location of the cloud tops, the VWP is a volumetric sample around the radar site and may not always be representative of the tops, especially the further you are from the radar site. This workshop will demonstrate how to properly use this product and illustrate some of its inherent limitations.
Gust fronts on radar - Gust fronts can be highly dangerous to pilots. They often proceed a line of convection producing strong straight line winds and severe or extreme turbulence. In some cases, the gust front may appear as a thin line moving ahead of the convection on the NWS NEXRAD Doppler radar image. These gust fronts can move outward a considerable distance from the primary radar returns associated with the convection. However, they are seen as lower intensity returns and are ordinarily filtered by satellite weather providers such as XM Radio. This workshop will show how to identify a gust front on a NEXRAD radar image.
How moisture affect surface-based CAPE - When using a Skew-T log (p) diagram to determine the potential for deep, moist convection, pilots need to understand that a small change in the surface dewpoint temperature can adversely affect the resulting surface-based CAPE value. If the actual dewpoint temperature is greater than forecast, this may change the entire convective situation in the late afternoon. This workshop will illustrate just how to change the surface dewpoint on the Skew-T log (p) diagram to see the resulting lifted parcel lapse rate and new CAPE value.
Using the satellite image on XM-delivered satellite weather - An infrared satellite image is one of the many products available from the XM-delivered satellite weather broadcast. While it does a fairly good job showing the extent of cloud cover day or night, the broadcast satellite image may not show all clouds. This is especially true for cloud decks that have tops below 5,000 feet AGL. This workshop will explain the limitations of this satellite image product and how to recognize the when an overcast cloud deck might not be displayed.
Non-convective LLWS - Part 2 - While a forecast for non-convective low level wind shear (LLWS) is ordinarily not a threat for severe or greater turbulence, there are times where it can produce some dangerous conditions for pilots. This is especially true when it is associated with a strong and developing synoptic weather system. Non-convective LLWS is a form of vertical speed shear in the atmosphere. In other words, the wind is forecast to increase rapidly with height. This workshop will highlight the key elements to look for to determine when non-convective LLWS should be strictly avoided.
How to get the most from the RUC soundings Java tool - The RUC soundings Java tool allows the pilot to examine the vertical profile of atmospheric temperature and moisture by generating a forecast sounding or analysis on a thermodynamic chart called a Skew-T log (p) diagram. This diagram can be generated from that data captured during a weather balloon launch known as a rawinsonde observation or a diagram can be generated from the output of a forecast model such as the Rapid Update Cycle (RUC). The tool itself has many features a few of which are not well documented. This workshop will expose a few of those features in order to get the most utility out of the tool.
Upslope stratus - When pilots think of "upslope" stratus, they normally picture air flowing up the side of a mountain range. However, upslope stratus can be created even by the gentle slope from the middle Mississippi Valley to the central high Plains producing a very widespread IFR event. This workshop will explain the conditions that may lead to such an event in the Midwest U.S.
Shallow convective icing - During the early spring it is not uncommon to have a shallow convective icing event unfold just south of the Great Lakes region. As cold, dense air filters in aloft, early daytime heating can create rather unstable conditions to fuel such an event. While this is not a deep, moist convective event producing thunderstorms, it can produce some very juicy clouds containing copious amounts of supercooled liquid water. This workshop will explain how to use the simulated reflectivity product to help identify such an event.
Airports in the vicinity of higher terrain - The Skew-T log (p) diagram is one of the pilot’s most versatile aviation weather power tools. The Earth Systems Research Laboratory’s Global Systems Division (ESRL/GSD) developed a Java-based tool that will build Skew-T log (p) diagrams based on the output of several numerical weather prediction models including the Rapid Update Cycle or RUC model. It requires more than just interpreting a complex diagram, however. Before the first diagram appears in your browser, understanding how to choose the appropriate initial data source is critical especially when you are trying to assess the potential for fog or low ceilings at an airport in the vicinity of higher terrain. This workshop will examine a case where using the right initial data source makes a huge difference when determining the potential for low IFR conditions at an airport that has rising terrain to the north.
Stratocumulus clouds - Very few pilots are taught about the dangers of a thin stratocumulus deck. These clouds are typically produced in the wake of a cold front and are usually only a few thousand feet deep. Nevertheless, during the cold season they can contain a copious amount of supercooled liquid water especially near the cloud tops. This workshop will discuss what produces stratocumulus clouds and why they are so dangerous from an icing perspective.
Predicting an overcast to build down - As a major weather system approaches, it is common for a high overcast to blanket the sky. As it draws closer, the middle and lower clouds begin to fill in with time. Eventually, VFR conditions morph into marginal VFR and then eventually drop to IFR or low IFR. This workshop will demonstrate how to use a Skew-T log (p) diagram to predict the timing of an overcast building down to a low IFR event.
Air mass modification - Air masses are homogeneous bodies of air with the same temperature and moisture properties across a given line of latitude. They tend to originate in specific areas where they develop their characteristics. As air masses move from their source region, they can be modified by the characteristics of the terrain below. This workshop discusses how the Great Lakes can modify a cold and dry Canadian air mass.
30-hour TAFs - For years, TAFs have been only issued out to 24 hours. However, due to a recent change, the NWS will be issuing TAFs out to 30 hours for 34 high-impact airports throughout the U.S. and its territories. Adding 6 hours to the total forecast time was in support of long haul operators. This forecast forced a change in the format of TAFs. This workshop shows how to read the new coded format for TAFs.
How to identify a capped atmosphere - Pilots are taught that thunderstorms develop when there is sufficient moisture, instability and lift. Some convective indices such as the Lifted Index will only tell you whether or not there is ample moisture and instability. It says nothing about the presence of lift. Using a flight planning example in the Midwest, this workshop explains how thunderstorms are not likely even with a widespread region of very negative lifted indices.
Who cares about pilot reports? - Pilot reports or PIREPs are one of the most sought after pieces of weather information. Every pilot report helps other pilots to make good decisions in regard to preflight planning and en route operations. However, they are not just used by pilots. This workshop will show how forecasters can also leverage these pilot reports when making or amending forecasts.
Convective outlooks - Part 1 - Deep, moist convection also known as thunderstorms are one of the most difficult weather phenomenon to forecast. Depending on the circumstances, forecasting the time and location of the initiation of deep, moist convection is either incredibly difficult or fundamentally impossible. So the best forecasters can do at the moment is to provide general guidance through a probabilistic approach represented by convective outlooks. This workshop explains how use the convective outlook products issued by the Storm Prediction Center (SPC) and the Aviation Weather Center (AWC).
Convective flight planning - Even after you close the door on the airplane and are ready to depart, weather analysis never stops until you are safely back on the ground. This is especially important when deep, moist convection is in the forecast. In addition to all the fancy tools such as satellite-delivered weather, knowing what to look for outside cockpit can help with decisions of route and altitude. This workshop presents the clues to look for while you are en route to your destination to minimize your exposure to dangerous convective turbulence.
Using NEXRAD to identify the location of a front - Frontal systems are normally the focal point for deep, moist convection also known as thunderstorms. Using the NEXRAD radar image can be a great way to identify where the front may exist in real time. Fronts are boundaries in the atmosphere that separate two distinctly different air masses consisting of air of differing density defined by temperature and moisture. These density differences may show up readily on the NWS WSR-88D NEXRAD Doppler radar especially if the radar is in clear air mode. This workshop explores one such case where severe storms erupted along a boundary identified on NEXRAD radar.
Thunderstorms in the terminal area - Terminal aerodrome forecasts (TAFs) are a forecast for the meteorological conditions significant to aviation at an airport. The terminal area is defined as a radius of 5 statute miles from the center of the airport's runway complex. Given this small area, meteorologists at the local Weather Forecast Offices (WFOs) are reluctant to issue a forecast for thunderstorms unless there is an overwhelming feeling that thunderstorms will impact the small terminal area. This workshop will outline the criteria that must be met before meteorologists issue a forecast for thunder in the terminal area.
Edited 67 time(s). Last edit at 10/13/2014 08:40AM by Scott Dennstaedt.