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A temperature inversion occurs when cold air is trapped beneath warmer air. The temperature of the air in the air mass near the ground is colder than the temperature in the air mass above. Inversions often occur when the cold air is trapped in a valley surrounded by high mountains. In the US, LA and [...]

Two hurricanes recently hit the Gulf Coast and it’s interesting to see the how the altimeter dropped and wind picked up over the course of a few hours. The code PRESFR means Pressure falling rapidly. I edited out the TNSO, A02, and AUTO so more of the information fits on one line. I have readings [...]

METARs and TAFs have been around since before the high-speed internet made data transmission instantaneous so they use a somewhat cryptic method for encoding weather data. However, once you learn how to decode them they aren’t many surprises. Occasionally you see something different. This post is my list of unusual reports. For help in decoding, [...]

The FAA knowledge tests have many questions on thunderstorms—the stages, hazards associated with them, and weather products related to them. Stages of a Thunderstorm The best explanation of the stages is found in Aviation Weather pp. 111-112. For a thunderstorm to form, the air must have (1) sufficient water vapor, (2) unstable lapse rate, and [...]

Most FBOs have a computer for checking the weather but I can never remember the addresses for METARs, NOTAMs, and TFRs. This is a list of sites I check before returning. Metar lookup and my home Metars NWS Local Forecast Fill in your city or zip. TFRs Active Special Use Airspace (SUAs) NOTAMs NOAA’s Aviation [...]

This post summarizes FAA Advisory Circular AC 00-54 PILOT WINDSHEAR GUIDE issued 11/25/88. I changed the punctuation a bit and left out a lot of the text. Additions are indicated by brackets [ ]. Bold indicates things I’d like to remember. This document uses windshear as a single word—other documents split it into two words—wind [...]

The Aviation Safety Network database contains 69 wind-shear accidents, most of which did not result in fatalities. Three accidents—New Orleans in 1975, New York in 1982, and Dallas-Fort Worth crash in 1985—prompted NASA to begin a program to understand and detect wind shear. As a result of the program, wind-shear alert systems have been installed [...]

[The Aviation Weather Services book includes a section on Supplementary Products. These are not likely to be of interest to general aviation pilots, but are included here for completness.] Collaborative Convective Forecast Product (CCFP) The Collaborative Convective Forecast Product (CCFP) is a graphical representation of forecast convective occurrence verifying at 2-, 4 -, and 6-hours [...]

Short-Range Surface Prognostic (Prog) Charts Short-Range Surface Prognostic (Prog) Charts (Figure 8-1) provide a forecast of surface pressure systems, fronts and precipitation for a 2-day period. The forecast area covers the 48- contiguous states, the coastal waters and portions of adjacent countries. The forecasted conditions are divided into four forecast periods, 12-, 24-, 36-, and [...]

Area Forecasts (FA) The NWS issues Area Forecasts (FA) to provide an overview of regional weather conditions that could impact aviation operations in the U.S. and adjacent coastal waters. Area forecasts are issued by the following offices for the following areas: • The Aviation Weather Center (AWC)   o Conterminous U.S. and adjacent coastal waters (CONUS) [...]