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Aeronautical Information Manual (AIM), page 510

Index   509 -- Page 510 -- 511

7110.65R
AIM CHG 2



A3012 . . . . . . . . altimeter three zero one two
RMK . . . . . . . . remarks
AO2 . . . . . . . . . this automated station has a
weather discriminator (for
precipitation)

SPECI KCVG 152224Z 28024G36KT 3/4SM
+TSRA BKN008 OVC020CB 28/23 A3000 RMK
TSRAB24 TS W MOV E

SPECI . . . . . . . (nonroutine) aviation special
weather report
KCVG . . . . . . . Cincinnati, OH
152228Z . . . . . . date 15th, time 2228 UTC
(no modifier) . . This is a manually generated
report due to the absence of
"AUTO" and "AO1 or AO2"
in remarks
28024G36KT . . wind two eight zero at
two four gusts three six
3/4SM . . . . . . . . visibility three fourths
+TSRA . . . . . . . thunderstorms, heavy rain
BKN008 ceiling eight hundred broken
OVC020CB . . . two thousand overcast
cumulonimbus clouds
28/23 . . . . . . . . . temperature two eight,

dew point two three
A3000 . . . . . . . . altimeter three zero zero zero
RMK . . . . . . . . remarks
TSRAB24 . . . . . thunderstorm and rain began
at two four
TS W MOV E thunderstorm west moving
east

c. Aerodrome Forecast (TAF). A concise state-
ment of the expected meteorological conditions at an
airport during a specified period. At most locations,
TAFs have a 24 hour forecast period. However, TAFs
for some locations have a 30 hour forecast period.
These forecast periods may be shorter in the case of
an amended TAF. TAFs use the same codes as
METAR weather reports. They are scheduled four
times daily for 24-hour periods beginning at 0000Z,
0600Z, 1200Z, and 1800Z.

Forecast times in the TAF are depicted in two ways.
The first is a 6-digit number to indicate a specific
point in time, consisting of a two-digit date,
two-digit hour, and two-digit minute (such as
issuance time or FM). The second is a pair of
four-digit numbers separated by a "/" to indicate a
3/15/07
5/26/16
12/10/15

beginning and end for a period of time. In this case,
each four-digit pair consists of a two-digit date and
a two-digit hour.
TAFs are issued in the following format:

TYPE OF REPORT/ICAO STATION IDENTIFIER/
DATE AND TIME OF ORIGIN/VALID PERIOD
DATE AND TIME/FORECAST METEOROLOG-
ICAL CONDITIONS
NOTE-
The "/" above and in the following descriptions are for
separation purposes in this publication and do not appear
in the actual TAFs.
TAF KORD 051130Z 0512/0618 14008KT 5SM BR
BKN030
TEMPO 0513/0516 1 1/2SM BR
FM051600 16010KT P6SM SKC
FM052300 20013G20KT 4SM SHRA OVC020
PROB40 0600/0606 2SM TSRA OVC008CB
BECMG 0606/0608 21015KT P6SM NSW
SCT040
TAF format observed in the above example:

TAF = type of report
KORD = ICAO station identifier

051130Z = date and time of origin (issuance time)

0512/0618 = valid period date and times
14008KT 5SM BR BKN030 = forecast meteorolo-
gical conditions

Explanation of TAF elements:
1. Type of Report. There are two types of TAF
issuances, a routine forecast issuance (TAF) and an
amended forecast (TAF AMD). An amended TAF is
issued when the current TAF no longer adequately
describes the on-going 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 communica-
tions header which precedes the actual forecasts.
2. ICAO Station Identifier. The TAF code
uses ICAO 4-letter location identifiers as described
in the METAR section.

3. Date and Time of Origin. This element is
the 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."
4. Valid Period Date and Time. The UTC
valid period of the forecast consists of two four-digit

7-1-66 Meteorology

Page 510 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

Index   509 -- Page 510 -- 511