Page 5.543 (6027)
Reading Terminal Area Forecasts (TAF)
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Contents
...Terminal Area Forecasts; ...About TAFs; ...What is a TAF?;...Type of TAF Report; ...ICAO Station Identifier; ...Date and Time of Origin; ...Valid Period Date and Time; ...Wind; ...Visibility; ...Qualifiers of Intensity or Proximity; ...Sky Condition; ...Optional Data; ...Probability Forecast; ...Forecast Change Indicators; FROM Group; BECOMING Group; TEMPORARY Group; ...TAF Coverage;...Amendment Criteria of TAFs; Prognostic TAF Qualifiers; Uncommon TAF Terms; ....TAF Samples; TAF Terms Revisited;

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 14008KT 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 21015KT 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. WWW.awc-KC.NOAA.gov/index.html or WWW.awc-C.NOAA.gov/awe/Aviation_Weather_Center.html

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 18007KT 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
VRB16G28KT - 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).

Qualifiers of Intensity or Proximity
- Light
Moderate (no qualifier)
+ Heavy or well-developed
VC in the Vicinity

Qualifier Descriptor
MI Shallow
BC Patches
DR Low Drifting
BL Blowing
SH Showers
TS Thunderstorm
FZ Freezing
PR Partial

Precipitation
DZ Drizzle
RA Rain
SN Snow
SG Snow Grains
IC Ice Crystals
PE Ice Pellets
GR Hail
GS Small Hail or Snow Pellets (less than 1/4 inch in diameter)
UP Unknown precipitation (automated stations only)

Obscuration
BR Mist (Foggy conditions with visibilities greater than 5/8 statute mile)
FG Fog (visibility 5/8 statute mile or less)
FU Smoke
DU Dust
SA Sand
HZ Haze
PY Spray
VA Volcanic Ash

Other
PO Well-Developed Dust/Sand Whirls
SQ Squalls
FC Funnel Cloud
+FC Well-Developed Funnel Cloud, Tornado or Waterspout
SS Sandstorm
DS Duststorm

Obscurations to vision will be forecast whenever the prevailing visibility is forecast to be 6 statute miles or less.

If no significant weather is expected to occur during a specific time period in the forecast, the weather group is omitted for that time period. If, after a time period in which significant weather has been forecast, a change to a forecast of no significant weather occurs, the contraction NSW (No Significant Weather) will appear as the weather group in the new time period. However, NSW is only included in the BECMG or TEMPO groups.

Sky Condition
TAF sky condition forecasts use the METAR format. Cumulonimbus clouds (CB) are the only cloud type forecast in TAFs.

When the sky is obscured due to a surface-based phenomenon, vertical visibility (VV) into the obscuration is forecast. The format for vertical visibility is VV followed by a three-digit height in hundreds of feet.

Note: Ceiling layers are not designated in the TAF code. For aviation purposes, the ceiling is the lowest broken or overcast layer or vertical visibility into a complete obscuration.

Examples:
SKC - Sky clear
SCT005 BKN025CB BKN250 - Five hundred scattered, ceiling two thousand five hundred broken cumulonimbus clouds, two five thousand broken.
VV008 - Indefinite ceiling eight hundred

Optional Data (Wind Shear)
Wind shear is the forecast of non-convective low level winds (up to 2000 feet) and is entered after the sky conditions when wind shear is expected. The forecast includes the height of the wind shear followed by the wind direction and wind speed at the indicated height. Height is given in hundreds of feet AGL up to and including 2,000 feet. Wind shear is encoded with the contraction WS followed by a three-digit height, slant character, and winds at the height indicated in the same format as surface winds. The wind shear element is omitted if not expected to occur.

Example:
WS010/18040KT - Low level wind shear at one thousand, wind one eight zero at four zero.

Probability Forecast
The probability or chance of thunderstorms or other precipitation events occurring, along with associated weather conditions (wind, visibility, and sky conditions).

The PROB40 group is used when the occurrence of thunderstorms or precipitation is in the 30% to less than 50% range, thus the probability value 40 is appended to the PROB contraction. This is followed by a four-digit group giving the beginning hour and ending hour of the time period during which the thunderstorms or precipitation is expected.

Note: PROB40 will not be shown during the first six hours of a forecast.
Examples:
PROB40 2102 1/2SM +TSRA - Chance between 2100Z and 0200Z of visibility one-half thunderstorm, heavy rain.
PROB40 1014 1SM RASN - Chance between 1000Z and 1400Z of visibility one rain and snow.
PROB40 2024 2SM FZRA - Chance between 2000Z and 0000Z of visibility two freezing rain.

Forecast Change Indicators
The following change indicators are used when either a rapid, gradual, or temporary change is expected in some or all of the forecast meteorological conditions. Each change indicator marks a time group within the TAF report.

FROM Group
The FM group is used when a rapid change, usually occurring in less than one hour, in prevailing conditions is expected. Typically, a rapid change of prevailing conditions to more or less a completely new set of prevailing conditions is associated with a synoptic feature passing through the terminal area (cold or warm frontal passage). Appended to the FM indicator is the four-digit hour and minute the change is expected to begin and continues until the next change group or until the end of the current forecast.

A FM group will mark the beginning of a new line in a TAF report. Each FM group contains all the required elements -- wind, visibility, weather, and sky condition. Weather will be omitted in FM groups when it is not significant to aviation. FM groups will not include the contraction NSW.

Examples:
FM0100 SKC - After 0100Z sky clear
FM1430 OVC020 - After 1430Z ceiling two thousand overcast

BECOMING Group
The BECMG group is used when a gradual change in conditions is expected over a longer time period, usually two hours. The time period when the change is expected is a four-digit group with the beginning hour and ending hour of the change period which follows the BECMG indicator. The gradual change will occur at an unspecified time within this time period. Only the conditions are carried over from the previous time group.

Example:
OVC012 BECMG 1416 BKN020 - Ceiling one thousand two hundred overcast. Then a gradual change to ceiling two thousand broken between 1400Z and 1600Z.

TEMPORARY Group
The TEMPO group is used for any conditions in wind, visibility, weather, or sky condition which are expected to last for generally less than an hour at a time (occasional), and are expected to occur during less than half the time period. The TEMPO indicator is followed by a four-digit group giving the beginning hour and ending hour of the time period during which the temporary conditions are expected. Only the changing forecast meteorological conditions are included in TEMPO groups. The omitted conditions are carried over from the previous time group.

Examples:
SCT030 TEMPO 1923 BKN030 - Three thousand scattered with occasional ceilings three thousand broken between 1900Z and 2300Z.
4SM HZ TEMPO 0006 2SM BR HZ - Visibility four in haze with occasional visibility two in mist and haze between 0000Z and 0600Z.

TAF Coverage:
--IFR conditions
--Mountain obscurations
--Moderate turbulence, icing, 30 kt winds
--Coincides with AIRMET information
--Three times a day. A 12 hour forecast with 6 hour outlook that is `printed 15 minutes before an hour to all stations
--Hazards/flight precautions
--IFR conditions/thunderstorms
--Icing, turbulence, obscurations
--Visibility when below 5 miles
--Winds over 30 kts.
--Synopsis is a Total overview that is good for six hours
--Clouds and Weather good for 12 hours referenced to mean sea level
--Ceilings referenced to ground level
--Outlook good for 18 hours
--TAF excludes temperature, turbulence and icing forecasts.
--Ceiling is not designated: defined as lowest broken or overcast layer or the vertical visibility.

Amendment Criteria of TAFs
Visibility

9000 meters = 56. miles
8000 meters = 5 miles (File IFR)
7000 meters = 4.3 miles
6000 meters = 3.7 miles
4800 meters = 3 miles
1600 meters = 1 mile Don't fly)
9999 means more than 6 miles visibility
Shortcut is to subtract 3 from the thousands place and call it miles.

Ceiling
If the forecast is Amend if...
No ceiling or ceiling above 3000' Forecast is not representative or ceiling is 3000' or less.
3000' to 2000' Ceiling = or < 3000' or below 2000'
Less than 2000' to 1000' = or < 2000' or below 1000'
Less than 1000' to 600' = or < 1000' or below 600'
Less than 600' to 200' = or < 600' or below 200'
Less than 200' = or < 200'

Visibility
Forecast Amend if:
< 5 miles Decreases to 5 miles or less
3 to 5 miles < than 5 or below 3 miles
2 to > 3 miles = or < 3 or below 2 miles
1 to > 2 miles = or < 2 or below 2 miles
1/2 to > 1 mile = or < 1 or below 1/2 mile
> 1/2 mile = or < 1/2 mile

Qualifying Terms of TAFs
LIFR (Low IFR)
Ceiling below 500' visibility below 1 mile
IFR
Ceiling 1000 to 500, visibility 1 to 3 miles
MVFR (Marginal VFR)
Ceiling 1000 to 3000, visibility 3-5 miles
VFR
Ceiling over 3,000, visibility over 5 miles

Intensity/proximity
- light, +heavy, no sign = moderate
VC: Vicinity 5-10 sm from runway center

Description
MI shallow, BC patches, DR drifting, TS Thunderstorm, PR Partial
BL blowing, SH showers, FZ freezing PO dust devil

Weather
DZ drizzle, RA rain, SN snow, SG snow grains
IC diamond dust, PE ice pellets, GR hail (French), GS small hail

Obscuration
BR mist (French), FG fog, FU smoke (French), VA volcanic ash
SA sand, HZ haze, SY blowing spray, DU dust PY spray

Other
SK sky clear CLR clear TCU towering cumulus
SQ squall, SS sand storm, DS dust storm, PO dust whirls
FC funnel cloud MI shallow SA sand
CAVOK = CAVU = WX NIL or SKC
CIG010 = ceiling 1000
SKY-X = sky partially obscured
9//005 Sky obscured(9), clouds not visible (//) 500' vertical visibility Octas (eights)
2CU030 = 2/8 scattered cumulus at 3000'

Prognostic TAF Qualifiers
Permanent shifts
GRADU = gradual change over 1/2 hour as with fog burning off
RAPID = with time a quick (less than 1/2 hour) turnabout
FRONT = rarely used
Short term variations
TEMPO = CHC less than 1 hour of variation
INTER = OCNL quick changes in ceilings/visibility
PROB = VRBL less certain of changes.
Others:
00000 = calm winds
VRB means variable direction of winds
1920 from 1900Z to 2000Z
OCNL, OCNLY = Occasional, occasionally means greater than 50% chance for less than half of the forecast period.
OTLK = outlook covers six hours following forecast period.
CHC = chance means 30 to 50% probability during forecast period.
SLGT CHC = 10 to 20% chance
ISOLD = isolated is lowest thunderstorm/precipitation alert level
WDLY SCT = widely scattered is less than 25% chance
SCT = scattered 25 to 54%
CHC means that there is a 30 to 50% likelihood of an event. Chance tests your appraisal of what is believable compared to what you would rather believe. Any flight into a chance of icing or thunderstorms is considered by the NTSB as an FAR violation.
NMRS = numerous is more than 54% chance
VCNTY = vicinity between 5 and 25 miles
VC-SHRA = rain showers in vicinity
NSW = no significant weather
9999 = visibility over 6 miles
BR = mist (baby rain)
T16/11 = temperature 16&deg;C at 1100Z
6CU030 = 6/8th cumulus at 3000'
FEW = 1/8 to 2/8 sky coverage
COR = correction
SPECI = special or Special Report)
KPIT U.S. station identifiers begin with K followed by three letters.
201955Z 20th day 1955Z time of issue. It is always 6 digits and "Z"
COR for correction to observation) ...follows the time field (when present)?
RMK SLP013 remarks, sea level pressure 30.13
FM1930 FroM and 2-digit hour and 2-digit minutes indicates significant change in weather. Each FM group has a separate line which is indented five spaces.
PROB40 2022 PROBability and 2-digit percent; probable condition during 2-digit beginning and 2-digit ending time period.

Intensity or proximity
 - = light no sign = moderate + = heavy
 VC = vicinity This covers only weather in vicinity of airport up to ten miles.
 TAFs tend to be more accurate than FAs.
 Three FTs a day, valid for 24 hours
 18 hour forecast with additional 6 a categorical outlook
 Expected ceilings, clouds/coverage, visibility, weather, vision, surface winds
 Outlook of last 6 hours is VFR, MVFR, IFR, and low IFR
 Ceilings as C in 100s of feet above ground
 Clouds in ascending order
 Visibility in miles and fractions up to 2 miles. Over 6 not reported.
 Winds reported to neared 10 degrees from true north in knots.
 Extends only 5 miles from airport center
 VCTNY in forecast means within 25 miles
 Never use an FT after the station has closed for the day.
 If the surface report and FT are not available at destination have alternate.
 2/10 of weather coverage (rain) means that 80% of area is rain free.

When METAR data is missing from the body of the report (e.g. dew point), it is simply omitted and the user must know the sequence to recognize this. Some exceptions apply in remarks such as RVRNO, or SLPNO when RVR or SLP are normally reported but not currently available. METARs exclude trend forecast.

Uncommon TAF Terms
9M04/// means temperature -4 degC, dew point not available.
FM1930 = FroM gives a two digit hour and two digit minute as time of
significant change. Each FM begins a new line indented five spaces.
PROB = PROBability
PROB40 2022 Has a two digit percent during time between two digit beginning and end.
TEMPO = TEMPOrary
TEMPO0407 Changes less than an hour duration and less than half of time between two digit beginning and two digit end.
BECOMING = BECoMinG
BECMG 1315 Change expected from beginning two digit and ending two digit time period.
BINOVC breaks in overcast
BRKS N breaks in layer below 1000' covers 6/10+ of sky
ACCAS ALQDS Altocumulus castellanus all quadrants
CUFRA W cumulus factus clouds west
IC4 ice crystals 4/10 of sky
PRESSRR pressure rising rapidly
RADAT 87120 87 is relative humidity of freezing level, 120(00) is altitude
RADAT ZERO freezing level at ground
F5 fog covering 5/10 of sky
RWU E Rain showers of unknown intensity east
OCNL LTGIC occasional lightning in clouds
FQT LTGCCCA Frequent lightning cloud to cloud and cloud to atmosphere
SB50 PRESSFR Snow began 50 minutes after the hour pressure falling rapidly
KOCTY smoke over the city
CLDS APCHG STN clouds approaching station
PRJMP 8/1012/18 pressure jump .8inch at 10:12 stopped at 18 after 10:00
TWRINUN control tower in unknown
AB13E20 HLSTO1/2 Hail began 13 after and ended 20 after 1/2" hailstones
SU N snow of unknown intensity north
SHLW GFDEP 4 Shallow ground fog 4 feet deep
SNOINCR 1/4/8 snow depth increase 1inch per hour/4 inches last six 8" deep
PCPN 103 1.03 precipitation in past hour
ACSL altocumulus standing lenticular clouds
CCSL Cirrocumulus standing lenticular
CBMAMcumulonimbus mama
P (Plus)as a letter imposed before visibility means 'greater than' otherwise means +. (Plus)
NSC means no significant clouds apparently differs from SKC (sky clear).
NSW means no significant weather
VC means vicinity...at or within five miles
DSNT means distant...at or beyond ten miles
SKC means sky clear
FEW means cloud coverage 1 to 2 eights sky coverage
TEMPO (Means "conditions temporary about half of time) Weather and visibility from another time period carries forward through TEMPO unless mentioned.
PROB40 (40% chance of...),
BECMG (becoming...) After qualifiers components omitted are expected to remain the same. Weather not expected to continue into BECMG or TEMPO time periods is written as NSW (no significant weather)

TAF Samples
KRNO
141624Z 1818 28010KT P6SM SCT035 SCT100 BKN250 BECMG 1920 25012KT
SCT075 BKN100 TEMPO 1901 VRB12G40KT 11/2SM +TSRA OVC015CB BECMG
OOO1 26006KT SCT730 SCT100 BKN250 BECMG 0909 00000KT 5SM BR SCT250
BECMG 1213 25007KT NSW SCT025=
Interpretation
First six digits give (14th) day of month, (1624Z)time of issue. Four digits (1818) give valid time of forecast from 1800Z the 14th to 1800Z the 15th.
Forecast wind (28010KT) is from 280 at 10 kts.
Visibility expected is (P)over (6SM) six statute miles.
(SCT055) Scattered clouds at 5,500'. Next layer is scattered at 10,000' (Only CU or CB cloud types are ever mentioned.) Broken clouds are at 25,000'.
Becoming a change (BECMG) between (1920) 1900Z and 2000Z wind (2512KT) from 250 at 12 kts a layer of (SCT075) scattered clouds at 7,500' and a layer (BKN100) of broken clouds at 10,000'.
Visibility when not given is unlimited.
(TEMPO) Temporarily (up to half of the time) between 1900Z and 0100Z a variable (VBL12G40) direction wind with velocities between 12 and 40 knots.
Visibility is one and one-half (11/2SM) statute miles with heavy (+TSRA) thunder showers with temporary ceiling (OVC015CB) at 1,500 and cumulus buildups.
Between midnight and 0100Z (BECMG 0001)wind becoming from 260 degrees at six knots with cloud layers of Scattered at 7,300, another scattered layer at 10,000', and broken clouds at 25,000'.
Becoming (BECMG) between 0900Z and 0900 calm wind conditions (000000KT) with five ((5SM) statute mile visibility in mist (BR) was a scattered layer at 25,000'.
By the period between (1213)1200Z and 1300Z becoming a wind from 250 at seven knots, (NSW) no significant weather other than scattered clouds a 25,000'.

TAF
TAF KIAD 271725Z 271818 21006KT P6SM VCSH SCT050 BKN090 TEMPO
1802 BKN050 BECMG 0002 23006KT KP6SM SCT060 TEMPO
0413 4SM BR SCDT010 BKN060
FM1300 28012G20KT P6SM BKN045 OVC080 PROB30 1318 5SM
-SHRA=
Interpretation
KIAD Location: Dulles International airport (K is the USA)
271725 Issued on the 27th day at 1725 Zulu
271818 Forecast 24-hour period from 1800Z the 27th to 1800Z the 28th
21006KT Wind forecast from 210 (TAF uses 3-digit wind) degrees at 6 knots
P6SM Visibility P stands for 'plus' greater than six statute miles.
Where weather is not given none relates to aviation.
SCT050 Sky conditions have scattered clouds at 5000' AGL (U.S. uses feet)
Scattered means 3 to 4 eights cloud coverage.
BKN090 Broken clouds at 9000' covering 5 to 7 octas of the sky. This is a
ceiling but must be a factor known to the pilot.
TEMPO 1802 Says a temporary change is forecast between 1800 Zulu and 0200 Zulu.
BKN050 Says the temporary change is a ceiling of 5000' over a period of eight hours only.
BECMG Means a gradual permanent change between 0002 and 0000 Zulu and 0200
Zulu there will be...
23006kt a Wind shift to 230 at 6 knots
P6SM visibility will be better than 6 statude miles along with
SCT060 Scattered clouds at 6000'
TEMPO 0413 Between 0400 Zulu and 1300 Zulu a temporary change will occur in which (4SM BR)
visibility will decrease to four statute miles in misty conditions.
BR means that you can see more than 5/8th of a mile. Fog has visibility less than 5/8th of a mile.
SCT010 a scattered layer of clouds will be at 1000'
BKN060 forecasts a broken layer of 5 to 7 octa at 6000'
FM begins a new line and indicates a change will take less than an hour.
1300 is the time the change begins
28012G20 knots winds will be from 280 at 12 knots gusting to 20 knots.
P6SM visibility over six statute miles
BKN045 cloud layer at 4500' AGL
OVC080 overcast layer at 8000' AGL
PROB30 is a 30% chance of a significant change between ...
1300 Z and 1800Z to
5SM visibility of five statute miles
-SHRA The weather visibility is reduced due to rain showers.

TAF KCRP 2371730z 271818 14020G29KT P6SM VCSH BKN020
OVC030 TEMPO 1822 5SM-SHRA BKN017
FM0100 15015G21KT P6SM SCT015 BKN025 WS020/17035KT
Interpretation
Issued on the 27th at 1730 and valid from 1800Z to 1800Z the 28th.
Wind will be from 140 at 20 knots gusting to 29 knots.
Visibility will be greater than 6 miles
Weather will consist of showers in the (VCSH) vicinity (within five miles)of the airport.
Broken clouds (ceiling) will be at 2000' and overcast at 3000'
There will be a temporary change from 1800Z to 2200Z with visibility of five statute miles due to light rain showers with broken (ceiling) at 1700'
From 0100Z winds will be 150 at 15 knots gusting to21 knots.
Visibility will be more than six statute miles. with scattered clouds (3 to 5 eights) at1500' and a broken cloud (ceiling) covering six to eight octas at 2500'.
Winds at 2000' will cause wind shear while blowing from 170 at 35 knots.

TAF (Terminal Aerodrome (Aviation) Forecast)
TAFKLIZ0606 31022/39 O700 71SN 9//008 QNH2990INSCIG008 INTER 0714 0000
39BLSN 9//000 620003 CIG000 GRADU 1415 33025 38 BLSN 8SC020 QNH 2993INS CIG 020 TEMP 1517 85SNSH ...GRADU 2021 32010 WXNIL 3S020 RAPID 22 VRB04 9999 SKC;
Interpretation
TAF = Terminal aerodrome forecast
KLIZ = K is the United States, LIX is station identifier
0606 TAS every six hours, 0000, 0500, 1200, 1800. = 0600 one day to 0600 the next.
31022/39 = Wind from 310 at 22 knots gusts to 39 knots.
0700 = meters of visibility, 3/8s of a mile
71SN = Uses code lattice 71 to indicate SN snow. No apparent reason for
the numbers since SN = snow.
9//008 = obscured sky with 800 feet vertical visibility
QNH2990INS = Altimeter MSL is 29.90 inches. May be lowest of forecast
period.
CIG008 = Ceiling of 800 feet
INTER0714 = Says from 0700 to 1400 conditions will occur frequently for less than an hour.
0000 = zero-zero visibility
39BLSN = Uses code lattice 39 to indicate blowing snow. No reason for numbers.
9//000 = Sky obscured with zero-zero visibility vertically
620003CIG000 = 6 = icing group symbol , 2 = light rime icing in cloud,
000 = lowest height AGL, 3 = 300 feet, CIG = ceiling, 000 = height above AGL (zero)
GRADU 1415 = A gradual change from 1400 to 1500
33025 = wind from 330 degrees at 25 knots
38 BLSN = 38 uses code lattice to indicate blowing snow, BLSN means blowing snow.
8SC020 = 8/10 stratocumulus sky cover. 0 temperature group symbol. 20 degrees Celsius.
QNH2993ins = Altimeter setting 29.93 inches of mercury
CIG 020 = Ceilings (?), 020 = 2000 feet (?)
TEMP 1517 = For less than 1/2 hour periods between 1500 and 1700
85SNSH = snow showers
...GRADU 2021 = gradual change from 2000 to 2100 zulu
32010 = wind at 320 degrees at 10 knots
WXNIL = no significant weather
3SC020 = 3/10 sky covered with stratocumulus, at 2000 feet
RAPID 22VRB04 = Rapid change of wind from 22 knots to 4 knots
9999 = Visibility greater than six miles
SKC = sky clear
WS015/30045KT wind shear field direction(s) and velocity

TAF KJKF 251720Z 1818 21007KT 5SM -SHRA BKN030 OVC 080
FM 22Z 33015G25KT P6SM 030BKN BKN080 PROB40 2301 1SM TSRA
FM05 32005 P6SM 050SCT 100SCT TEMPO 0709 00000KT 1SM FG
FM12 33010 4SM FGHZ BECMG 1416 30010 P6SM NSW SKC
Interpretation
This is the terminal forecast for John F. Kennedy airport for the 25th day of the month, prepared at 1720Z for
the period from 1800Z of the 25th until 1800Z on the 26th.

-The TAF calls for, from the beginning of the forecast period (1800Z) until 2200Z, winds out of the southwest (210&deg;) at 7 knots, with the visibility to be 5 statute miles in light rain showers, with a (broken) ceiling of 3000 feet and an overcast deck at 8000 feet. Note use of term deck instead of overcast)

After FM) 2200Z, it calls for winds out of the northwest (wind shift to 330&deg;) at 15 to 25 knots, with visibility improving to more than (P) 6 statute miles with just broken clouds, one deck (ceiling) at 3000 feet and an overcast deck at 8000 feet with a probability of (occasionally) Between 2300Z and 0100Z, visibility dropping to 1 statute mile in thunderstorms and rain showers.

-After 0500Z the winds are expected to be out of the Northwest (320&deg;)at only 5 knots, visibility more than (P)6 statute miles with just scattered clouds at 5000 and 10000 feet, but temporarily (chance of), Between 0700Z and 0900Z, the winds becoming calm and visibility dropping to 1 statute mile in fog.

-After 1200, the forecast calls for winds out of the northwest 330&deg; at 10 knots with visibility 4 statute miles in fog and haze becoming between (or by) 1400-1600Z winds out of the Northwest (300&deg;) at 10 knots, visibility more than 6 statute miles with no significant weather and clear skies.

TAF KMCI 011725Z 011818 24020KT 2SM FZRA OVC 010
MCI
Interpretaton
Eleventh day of the month at 1725 Zulu
Eleventh day of the month from 1800 zulu to 1800 zulu next day
wind 240 at 20 knots
2 statute miles visibility
freezing rain and overcast ceiling at 1000 feet.

TAF 131530Z KABC 0716 27015KT 10SCT015 TEMPO 1116 4000 +SHRA PROB30 TEMPO 1416 TSRA BKN010CB
Interpretation
131530z Thirteenth day of month at 1530 zulu
KABC K is U. S. code and three letter station identifier
0716 Date and time of forecast elements 0600 Z to 1600 Z
27015KT wind 270 at 15kts
10SCT015 sky 10,000' scattered visibility 15 miles
TEMPO temporary
1116 between 1100 and 1600 zulu always 4 digits separated.
4000 4000' ceiling with
+SHRA heavy rain showers
PROB30 30% chance
TEMPO 1416 Between 1400 and 1600Z
TSRA moderate chance of thunderstorm
BKN101CB Sky going to 1000' broken with cumulonimbus clouds

TAFs
ABC 1410 AMD VRB05KT 9000 BR SCT020 BKN050 OVCO80 QNH3020 CIG050 BCMG 1314 VRB05KT 1600 BR SCT020 BKN040 OVC100 QNH3018INS CIG040 VC-RA
Interpretation
Amended forecast 1400Z to tomorrows 1000Z"wind" variable to five knots 9000 meters visibility (5.6 miles) mist scattered clouds at 2000 feet broken at 5000 and overcast at 8000 feet altimeter 30.2 ceiling is 5000 feet becoming "between" 1300Z and 1400Z ind" variable at 5 knots 1600 meters visibility (1-mile) with misty (French word) 2000 scattered 4000 broken overcast at 10,000 altimeter 30.18 inches ceiling at 4000 rain in vicinity.

KJKF 251720Z 1818 21007KT 5SM-SHRA BKN030 OVC080
FM 22Z 33015G25KT P6SM BKN030 BKN080 PROB40 2301 1SM TSRA
FM05 32005 P6SM 050SCT 100SCT TEMPO 0709 00000KT 1SM FG
FM12 33010 4SM FGHZ BECMG 1416 300010 P6SM NSW SKC
Interpretation
This is the terminal forecast for John f. Kennedy airport for the 25th day of the month, prepared at 1720Z , for the period from 1800Z of the 25th day until 1800Z on the 26th. The TAF calls for, from the beginning of the forecast period (1800Z) until 2200Z, winds out of the southwest at 7 knots, with the visibility to be 5 statute miles in light rain showers, with a ceiling of 3000 feet and an overcast deck at 8000. After 2200Z, it calls for winds out of the northwest (note wind shift) at 15 to 25 knots, with visibility improving to more than 6 statute miles with just broken clouds, one deck at 3000 feet and the other at 8000 feet with a probability of (occasionally) between 2300Z and 0100Z, visibility dropping to 1 statute mile in thunderstorms and rain showers. After 0500Z, the winds are expected to be out of the northwest at only 5 knots, visibility more than 6 statute miles with just scattered clouds at 5000 and 10,000 feet, but temporally (chance of) between 0700Z and 0900Z, the winds becoming calm and visibility dropping to 1 statute mile in fog. After 1200Z, the forecast calls for winds out of the northwest at 10 knots with visibility 4 statute mines in fog and haze becoming between (or by) 1400-1600Z, winds out of the northwest at 10 knots, visibility more than 6 statute miles with no significant weather and clear skies.

TAF Terms Revisited
--TAF contains definitive forecast for specific time periods and replaces terminal forecast
--Where, When land Winds is nearly same as METAR except for time and date
--When gives two sets of times. First set of six digits is date and time of forecast posting with the letter Z
--Second set of six digits is in pairs of two. First pair is date of forecast, second pair is effective time of forecast, third is end of effective time next day. The two times are usually 24 hours apart.
--TAF is then further divided then into time segments of four digits following the key words
--Key words separating time periods are FM, PROB and BECMG
--FM is specific time usually on the hour or half-hour
--PROB, TEMPO and BECMG gives two pairs of time with the word "between" always understood.
--Each time period of TAF has same sequence as METAR
--PROB40 means probability of forecast being correct is 40 percent.

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