Terminal aerodrome forecasts, better known as TAFs are issued four (4) times daily and represent a forecast for the expected meteorological conditions at an airport that are significant to aviation for a specified period of time. Normally this period is 24 hours. While 24 hours will still be the norm for most airports in the U.S., 32 high-impact airports have been extended from 24 hours to 30 hours starting 0000 UTC on November 5, 2008. This change has triggered...

Deep 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 convection is either incredibly difficult or fundamentally impossible. Forecasters can look at ALL the available data, with ALL the available scientific understanding, and still be WAY off in their forecast. Thunderstorms develop at a particular time and place for a reason, even though it is often difficult to the point of being impossible to diagnose those reasons with enough accuracy to be able to forecast the initiation of thunderstorms...

On October 1, 2008, the Aviation Weather Center in Kansas City began issuing a new forecast called a Graphical-AIRMET. This new forecast product, dubbed the G-AIRMET, won't make it into a standard briefing with an Automated Flight Service Station (AFSS) specialist and it won't likely be included in a DUATS textual briefing either. That's because it is not a text-based product like the traditional AIRMET; instead, it is designed to be displayed graphically...

Terminal aerodrome forecasts, simply known to pilots as “TAFs” are the most detailed forecasts made available to pilots. Scheduled TAFs are issued by the NWS every six hours for 625 airports throughout the United States and its territories and represents the expected meteorological conditions ...

Whether you are on the ground or in the air, the phase "wind shear" should get the immediate attention of every pilot. How about when it appears in a terminal aerodrome forecast (TAF)? A pilot hears the term “wind shear” and immediately equates this with thunderstorms or turbulence. It’s a common misconception, but non-convective low level wind shear as it appears in a TAF is not usually a forecast for turbulence...

Before any cross country flight, the FAA requires every pilot to become familiar with all aspects of that flight including “weather reports and forecasts.” The regulations don’t specify, however, which weather reports and forecasts are important for any particular flight. How pilots get their preflight weather information has changed drastically since the mid-90s. Even though a simple call to speak with a Flight Service specialist satisfies this weather briefing requirement, it may not always be the best source...

As a new weather system approaches, one thing is for certain...you can usually count on a change in the weather. This includes a change in temperature, dewpoint, pressure and wind. As a frontal system approaches a high overcast begins to move in first which then builds down or lowers with time. Terminal aerodrome forecasts (TAFs) can be a reliable source to identify an overcast that is expected to build down. But if your destination airport isn't served by a TAF...

According to the October 2007 update to FAA advisory circular, Aviation Weather Services (00-45F), "The K Index is a measure of thunderstorm potential based on vertical temperature lapse rate, moisture content of the lower atmosphere and vertical extent of the moist layer." The K Index is a derived weather parameter that is best used to assess the potential for non-severe convection and heavy rainfall. In order to use the K Index successfully, understanding its limitations is paramount...

Pilot reports, known simply as "PIREPs" are like the finest gold to many pilots looking to find altitudes free of adverse weather on those long cross country flights. But PIREPs are also just as important to many other stakeholders in aviation safety including air traffic controllers, dispatchers and forecasters...