Understanding weather information is crucial for students and pilots to ensure safe and efficient flights. Two key components of aviation weather reports are Terminal Aerodrome Forecast (TAF) and Winds Aloft. In this blog post, we'll delve into the intricacies of interpreting TAFs and Winds Aloft.
Decoding TAFs (Terminal Aerodrome Forecast):
KPSM 211131Z 2112/2212 33010KT P6SM FEW250
FM211300 34012G21KT P6SM FEW250
FM212200 32009KT P6SM FEW250
Time Frame: TAFs are typically issued four times a day and cover a 24 or 30-hour period. "211131Z" means the TAF came out on the 21st day of the month at 1131Z. "2112/2212" means the data is valid between the 21st day of the month at 1200Z to the 22nd of the month at 1200Z.
Wind: The first element in a TAF is the wind forecast. It includes the wind direction and speed in knots. For example, "27015KT" means the wind is coming from 270 degrees at 15 knots.
Visibility: Visibility is expressed in statute miles (SM) and indicates the horizontal distance a pilot can see. "6SM" means visibility is 6 statute miles. The "P" indicates the visibility is greater than 6SM.
Weather Phenomena: TAFs include codes for various weather phenomena, such as rain (RA), snow (SN), fog (FG), and thunderstorms (TS). Reference the legend below for more phenomena codes found in TAFs.
Sky Conditions: The cloud cover is specified in terms of sky conditions, represented by cloud cover in eighths. For instance, "BKN020" means broken clouds at 2000 feet.
Tempo and PROB: Temporary (TEMPO) and probability (PROB) sections indicate forecasted changes in weather conditions that are expected to be temporary or have a certain probability of occurring.
Interpreting Winds Aloft:
FT 3000 6000 9000 12000 18000 24000 30000 34000 39000
BOS 3626 3530-04 3437-04 3343-08 3244-22 3145-35 304550 304255 791052
Altitude Levels: Winds Aloft reports typically cover various altitudes, commonly at 3,000 feet increments starting from 6,000 feet.
Wind Direction and Speed: Similar to TAFs, Winds Aloft reports provide information on wind direction and speed. For example, "3626" means the wind is coming from 360 degrees at 26 knots. At 39,000ft, the winds for BOS read 7910. When the wind direction reads over 360, this is a sign that the wind speed is over 100 knots. You would subtract 50 from the wind directions to get 29, or 290 degrees, and adad 100 to the velocity to get 110 knots.
Temperature: The temperature at each altitude level is also included. This is crucial for calculating true airspeed. -04 is -4 degrees C. Above 24,000ft the temperature is assumed to always be negative, despite no negative sign.
Conclusion:
Reading TAFs and Winds Aloft reports is a skill every pilot should master to ensure a safe and smooth flight. Regularly checking and understanding these weather forecasts will enable pilots to make informed decisions, adjust flight plans accordingly, and enhance overall flight safety. Stay weather-aware and keep the skies friendly for your journey!