Aviation Forecasts  Terminal Aerodrome Forecasts (TAF)  Observed weather condition reports are often used in the  creation of forecasts for the same area. A variety of different  forecast products are produced and designed to be used in the  preflight planning stage. The printed forecasts that pilots need  to be familiar with are the terminal aerodrome forecast (TAF),  aviation area forecast (FA), inflight weather advisories  (SIGMET, AIRMET), and the winds and temperatures aloft  forecast (FB).  A TAF is a report established for the five statute mile  radius around an airport. TAF reports are usually given for  larger airports. Each TAF is valid for a 24 or 30-hour time  period and is updated four times a day at 0000Z, 0600Z,  1200Z, and 1800Z. The TAF utilizes the same descriptors  and abbreviations as used in the METAR report. The TAF  includes the following information in sequential order:  TAF  KPIR 111130Z 1112/1212  TEMPO 1112/1114 5SM BR  FM1500 16015G25KT P6SM SCT040 BKN250  FM120000 14012KT P6SM BKN080 OVC150 PROB30  1200/1204 3SM TSRA BKN030CB  FM120400 1408KT P6SM SCT040 OVC080  TEMPO 1204/1208 3SM TSRA OVC030CB  Routine TAF for Pierre, South Dakota…on the 11th day of  the month, at 1130Z…valid for 24 hours from 1200Z on the  11th to 1200Z on the 12th…wind from 150° at 12 knots…  visibility greater than 6 SM…broken clouds at 9,000 feet…  temporarily, between 1200Z and 1400Z, visibility 5 SM in  mist…from 1500Z winds from 160° at 15 knots, gusting  to 25 knots visibility greater than 6 SM…clouds scattered  at 4,000 feet and broken at 25,000 feet…from 0000Z wind  from 140° at 12 knots…visibility greater than 6 SM…clouds  broken at 8,000 feet, overcast at 15,000 feet…between 0000Z  and 0400Z, there is 30 percent probability of visibility 3  SM…thunderstorm with moderate rain showers…clouds  broken at 3,000 feet with cumulonimbus clouds…from  0400Z…winds from 140° at 8 knots…visibility greater than  6 miles…clouds at 4,000 scattered and overcast at 8,000…  temporarily between 0400Z and 0800Z…visibility 3 miles…  thunderstorms with moderate rain showers…clouds overcast  at 3,000 feet with cumulonimbus clouds…end of report (=).  Explanation:  13-9  1. Type of report—a TAF can be either a routine forecast  (TAF) or an amended forecast (TAF AMD).  2. ICAO station identifier—the station identifier is the  same as that used in a METAR.  3. Date and time of origin—time and date (081125Z)  of TAF origination is given in the six-number code  with the first two being the date, the last four being  the time. Time is always given in UTC as denoted by  the Z following the time block.  4. Valid period dates and times—The TAF valid period  (0812/0912) follows the date/time of forecast origin  group. Scheduled 24 and 30 hour TAFs are issued  four times per day, at 0000, 0600, 1200, and 1800Z.  The first two digits (08) are the day of the month for  the start of the TAF. The next two digits (12) are the  starting hour (UTC). 09 is the day of the month for  the end of the TAF, and the last two digits (12) are  the ending hour (UTC) of the valid period. A forecast  period that begins at midnight UTC is annotated as 00.  If the end time of a valid period is at midnight UTC,  it is annotated as 24. For example, a 00Z TAF issued  on the 9th of the month and valid for 24 hours would  have a valid period of 0900/0924.  5. Forecast wind—the wind direction and speed forecast  are coded in a five-digit number group. An example  would be 15011KT. The first three digits indicate the  direction of the wind in reference to true north. The  last two digits state the windspeed in knots appended  with “KT.” Like the METAR, winds greater than 99  knots are given in three digits.  6. Forecast visibility—given in statute miles and may  be in whole numbers or fractions. If the forecast is  greater than six miles, it is coded as “P6SM.”  7. Forecast significant weather—weather phenomena  are coded in the TAF reports in the same format as  the METAR.  8. Forecast sky condition—given in the same format as  the METAR. Only cumulonimbus (CB) clouds are  forecast in this portion of the TAF report as opposed  to CBs and towering cumulus in the METAR.  9. Forecast change group—for any significant weather  change forecast to occur during the TAF time period,  the expected conditions and time period are included  in this group. This information may be shown as from  (FM), and temporary (TEMPO). “FM” is used when a  rapid and significant change, usually within an hour, is  expected. “TEMPO” is used for temporary fluctuations  of weather, expected to last less than 1 hour.  10. PROB30—a given percentage that describes the  probability of thunderstorms and precipitation  occurring in the coming hours. This forecast is not  used for the first 6 hours of the 24-hour forecast.  Example: 