AIM

8/15/19

7

−

1

−

68

Meteorology

RAE42

rain ended at four two

. . . . . . .

SNB42

snow began at four two

. . . . . . .

METAR KSFO 041453Z AUTO VRB02KT 3SM
BR CLR 15/12 A3012 RMK AO2

METAR

aviation routine weather 

. . . . . .

report

KSFO

San Francisco, CA

. . . . . . . .

041453Z

date 4

th

, time 1453 UTC

. . . . . .

AUTO

fully automated; no human

. . . . . . .

intervention

VRB02KT

wind variable at two

. . . .

3SM

visibility three

. . . . . . . . .

BR

visibility obscured by mist

. . . . . . . . . .

CLR

no clouds below one two

. . . . . . . . .

thousand

15/12

temperature one five, dew

. . . . . . . . .

point one two

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 15

th

, 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

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 METEOROLOGI-
CAL 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 meteorologi-
cal conditions

Explanation of TAF elements: