As in the METAR, winds greater than 99 knots are given in three digits. 

6. Forecast visibility—reported in statute miles, in whole numbers or fractions. If the forecast visibility is greater than 6 miles, it will be coded as “P6SM.” 

7. Forecast significant weather—weather phenomenon is coded in the TAF reports in the same format as the METAR. If no significant weather is expected during the forecast time period, the denotation “NSW” will be included in the “becoming” or “temporary” weather groups. 

8. Forecast sky condition—reported in the same manner 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), Becoming (BECMG), and Temporary (TEMPO). “From” is used when a rapid and significant change, usually within an hour, is expected. “Becoming” is used when a gradual change in the weather is expected over a period of no more than 2 hours. “Temporary” is used for temporary fluctuations of weather, expected to last for less than an hour. 

10. Probability forecast—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: 

TAF KPIR 111130Z 111212 15012KT P6SM BKN090 TEMPO 1214 5SM BR 

FM1500 16015G25KT P6SM SCT040 BKN250 

FM0000 14012KT P6SM BKN080 OVC150 PROB40 0004 3SM TSRA BKN030CB 

FM0400 1408KT P6SM SCT040 OVC080 TEMPO0408 3SM TSRA OVC030CB 

BECMG 0810 32007KT= 

## Explanation: 

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 statute miles, broken clouds at 9,000 feet, temporarily, between 1200Z and 1400Z, visibility 5 statute miles in mist. 

From 1500Z, winds from 160° at 15 knots, gusting to 25 knots, visibility greater than 6 statute miles, clouds scattered at 4,000 feet and broken at 25,000 feet. 

From 0000Z wind from 140° at 12 knots; visibility greater than 6 statute miles, clouds broken at 8,000 feet, overcast at 15,000 feet between 0000Z and 0400Z, there is 40 percent probability of visibility 3 statute miles 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. 

Becoming between 0800Z and 1000Z wind from 320° at 7 knots end of report (=). 

## Area Forecasts (FA) 

The aviation area forecast (FA) gives a picture of clouds, general weather conditions, and visual meteorological conditions (VMC) expected over a large area encompassing several states. There are six areas for which area forecasts are published in the contiguous 48 states. Area forecasts are issued three times a day and are valid for 18 hours. This type of forecast gives information vital to en route operations as well as forecast information for smaller airports that do not have terminal forecasts. 

## Inflight Weather Advisories 

Inflight weather advisories are forecasts provided to en route aircraft, and detail potentially hazardous weather. These advisories are also available to pilots prior to departure for flight planning purposes. 

## Airman’s Meteorological Information (AIRMET) 

AIRMETs (report type designator WA) are issued every 6 hours with intermediate updates issued as needed for a particular area forecast region. The information contained in an AIRMET is of operational interest to all aircraft, but the weather section concerns phenomena considered potentially hazardous to light aircraft and aircraft with limited operational capabilities. An AIRMET includes forecast of moderate icing, moderate turbulence, sustained surface winds of 30 knots or greater, widespread areas of ceilings less than 1,000 feet and/or visibilities less than 3 miles, and extensive mountain obscurities. Each AIRMET bulletin has a fixed alphanumeric designator, and is numbered sequentially for easy identification, beginning with the first issuance of the day. SIERRA is the AIRMET code used to denote IFR and 

