Terminal Area Forecasts
Using the area of a particular airport TAF predicts the next 24-hour weather beginning with where and when. The 24 hours Zulu time is divided into periods of weather change. The first time-group gives forecast wind, visibility, sky condition, and weather important to aviation. A change in any one area will trigger a new time period directed only to those areas of change. All other elements in the first time period not changing remain the same and though not mentioned are carried forward but not written as unchanged into the second time period. A K as KOAK for Oakland will precede all three-letter station identifiers. Day of the month and time-group is followed by valid time-group. TAF format has been changed so that each time change now begins on a new line.
First break the TAF down into specific time periods. Sequence of wind, visibility, significant weather, cloud cover and cloud height follows for each time block. Basically the same forecast for a definite time period. The initial weather group and the FM (FROM) group always include the wind, visibility and sky condition. Cloud conditions are divided into eighths.
If no visibility or weather is mentioned it is assumed to be unrestricted or non-existent. WS in a TAF is wind shear not part of convective activity. Qualifiers such as TEMPO is used with two digit beginning hour and two digit ending hour.
Get copy of NWS Federal Meteorological Handbook (FMH1A) from government printing office. It has TAF Decoding Chart but takes some time to learn.
About TAFs
1. Six TAFs cover U.S. SFO, (West coast), SLC, DFW, CHI, BOS and MIA.
2. Contains written flight precautions with broad brush (crying wolf) with nothing left to chance.
3. Times forecast for weather changes included in the text.
4. Most likely errors to be in time rather than occurrence
5. An inaccurate forecast tells you about actual as compared to expected.
6. Serve as an alert to seek other weather information.
7. Flight precautions in airmet category of TAF and amended by Airmets
What Is a Terminal Aerodrome Forecast?
A Terminal Aerodrome Forecast (TAF) is a concise statement of the expected meteorological conditions at an airport during a specified period (usually 24 hours).
The TAF code, as described here, is the one used in the
United States. TAFs use the same weather code found in METAR weather reports.
TAF Report Elements
TAF
KOKC 051130Z 051212 1400T 5SM BR BKN030 TEMPO 1316 1 1/2SM BR
FM1600 16010KT P6SM NSW SKC
BECMG 2224 20013G20KT 4SM SHRA OVC020 PROB40 0006 2SM TSRA OVC008CB
BECMG 0608 2101T P6SM NSW SCT040=
TAF Sequence of Elements in Order:
1. Type of Report
2. ICAO Station Identifier
3. Date and Time of Origin
4. Valid Period Date and Time
5. Forecast Meteorological
The U.S. has no requirement to forecast temperatures in an aerodrome forecast and the NWS will continue to forecast icing and turbulence in AIRMETs and SIGMETs.
The Center for this new icing forecast is located at Norman Oklahoma Weather forecasts have been perfected to the point of showing where icing is expected as well as its intensity. This development includes the ability to determine were "drizzle drop" icing is likely to occur when impacted by an aircraft. With is ability coming into use, there is all the more reason to check icing forecasts. All airline pilot training, commercial pilot training, air force pilot training, fighter pilot training, pilot training schools, flight training schools, flight attendant training, helicopter flight training, accelerated flight training, airline flight training, flight training florida, flight attendant training schools, instrument flight training, cpl flight flying school training training, flight training simulator, flight training academy, atp flight training, helicopter flight training schools, california flight training, professional flight training, data flight training, orlando flight training, corporate flight attendant training, flight nurse training, warrant officer flight training, flight training device, lufthansa flight training, flight training san diego, alien alien flight flight training, military pilot training, sport pilot training and private pilot training.
Type of TAF Report
The report type header will always appear as the first element in the TAF forecast. There are two types of TAF reports, a routine forecast, TAF, and an amended forecast, TAF AMD. An amended TAF is issued when the current TAF no longer adequately describes the ongoing weather or the forecaster feels the TAF is not representative of the current or expected weather.
Corrected (COR) or delayed (RTD) TAFs are identified only in the communications header which precedes the forecast text.
ICAO Station Identifier
The TAF code uses the ICAO four-letter location identifiers. In the conterminous United States, the three-letter identifier is prefixed with a K. For example SEA (Seattle) becomes KSEA. Elsewhere, the first one or two letters of the ICAO identifier indicate in which region of the world and country (or state) the station is.
Date and Time of Origin
This element is the UTC date and time the forecast is actually prepared. The format is a two-digit date and four-digit time followed, without a space, by the letter Z. Routine TAFs are prepared and filed approximately one-half hour prior to scheduled issuance times. TAFs are scheduled for issuance foure times daily at 0000Z, 0600Z, 1200Z, and 1800Z.
Example:
091050Z - Forecast prepared on the ninth day of the month at 1050Z.
Valid Period Date and Time
The UTC valid period of the forecast is a two-digit date followed by the two-digit beginning hour and two-digit ending hour. Routine TAFs are valid for 24-hours. Valid periods beginning at 0000Z shall be indicated as 00. Valid periods ending at 0000Z shall be indicated as 24. The 24 indication applies to all time group ending
times.
In the case of an amended forecast, or a forecast which is corrected or delayed, the valid period may be for less than 24 hours. Where an airport or terminal operates on a part-time basis (less than 24 hours/day) the TAFs issued for those locations will have the abbreviated statement NIL AMD SKED AFT (closing time) Z, added to the end of the forecast. For the TAFS issued while these locations are closed, the word NIL will appear in place of the forecast text. A delayed (RTD) forecast will then be issued for these locations after two complete observations are received.
What does the A01 mean?
KAPF 122135Z 1800T 10SM CLR 22/12 A2999 RMK AO1
Automated Observation without precipitation discriminator
Examples:
091212 - Forecast valid from the ninth at 1200Z til the tenth at 1200Z.
110023 - Forecast valid from the eleventh at 0000Z till the twelfth at 0000Z.
010524 - Amended forecast valid from the first at 0500Z till the second at 0000Z.
Forecast Meteorological Conditions
This is the body of the TAF. The basic format is:
Wind - Visibility - Weather - Sky Condition - Optional Data (Wind Shear)
The wind, visibility, and sky condition elements are always included in the initial time group of the forecast. Weather is included in the initial time group only if significant to aviation. If a significant, lasting change in any of the elements is expected during the valid period, a new time period with changes is included. It should be noted that, with the exception of a FM group, the new time period will include only those elements which are expected to change; i.e., if a lowering of the visibility is expected but the wind is expected to remain the same, the new time period reflecting the lower visibility would not include a forecast wind. The forecast wind would remain the same as in the previous time period.
Any temporary conditions expected during a specific time period are included with that time period.
Wind
The wind group includes forecast surface winds. The surface wind is the expected wind direction (first three digits) and speed (last two or three digits if 100 knots or greater). The contraction KT follows to denote the units of wind speed in knots. Wind gusts are noted by the letter G appended to the wind speed followed by the highest expected gust (two or three digits if 100 knots or greater).
Calm winds (three knots or less) are encoded as 00000KT.
Variable winds are encoded when it is impossible to forecast a wind direction due to winds associated with convective activity or low wind speeds. A variable wind direction is noted by VRB where the three digit direction usually appears.
Examples:
18010KT - Wind one eight zero at one zero knots
35012G20KT - Wind three five zero at one two gust two zero knots
00000KT - Wind calm
VRB16G2T - Wind variable at one six gust two eight knots
Visibility
The expected prevailing visibility is forecast in statute miles and fractions of statute miles followed by SM to note the units of measure. Statute miles followed by fractions of statute miles are separated with a space, for example, 1 1/2SM. Forecast visibility greater than 6 statute miles is indicated by coding P6SM. Directional or variable visibility is not forecasted and the visibility group is omitted if missing.
Examples:
1/2SM - Visibility one-half statute mile
2 1/4SM - Visibility two and one-quarter statute miles
5SM - Visibility five statute miles
P6SM - Visibility more than six statute miles.
Weather
The expected weather phenomenon or phenomena is coded in TAF reports using the same format, qualifiers, and phenomena contractions as METAR reports (except UP).
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