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Manual on METAR, TREND and TAF
METAR
METAR is aerodrome routine meteorological report (in meteorological code).
AERODROME
METAR LJLJ 280830Z 32008KT 9999 FEW030 BKN050 17/13 Q1024 NOSIG=
THE DATE AND TIME OF METAR REPORT
The consecutive day of the month
METAR LJLJ 280830Z 32008KT 9999 FEW030 BKN050 17/13 Q1024 NOSIG=
Hour
METAR LJLJ 280830Z 32008KT 9999 FEW030 BKN050 17/13 Q1024 NOSIG=
Minute
METAR LJLJ 280830Z 32008KT 9999 FEW030 BKN050 17/13 Q1024 NOSIG=
Letter Z indicates time in UTC
METAR LJLJ 280830Z 32008KT 9999 FEW030 BKN050 17/13 Q1024 NOSIG=
AUTO METAR
METAR LJLJ 280830Z AUTO 32008KT 9999 FEW030/// BKN050/// 17/13 Q1024 NOSIG=
The code word AUTO is inserted when the report contains fully automated observation without
human intervention.
WIND
Wind direction in degrees from true north.
METAR LJLJ 280830Z 32008KT 9999 FEW030 BKN050 17/13 Q1024 NOSIG=
The encode VRB is used when the variation of measured wind direction is 180° or more.
METAR LJLJ 280830Z VRB08KT 9999 FEW030 BKN050 17/13 Q1024 NOSIG=
Wind speed
METAR LJLJ 280830Z 12008KT 9999 FEW030 BKN050 17/13 Q1024 NOSIG=
Units used for wind speed are knots (KT) or meters per second (MPS)
METAR LJLJ 280830Z 12008KT 9999 FEW030 BKN050 17/13 Q1024 NOSIG=
Wind gusts are indicated when wind gusts exceed 10KT of mean wind speed. Gusts are
indicated by using the letter G directly after the mean speed, followed by the maximum
gust speed.
METAR LJLJ 280830Z 32012G25KT 9999 FEW030 BKN050 17/13 Q1024 NOSIG=
VISIBILITY
In METAR report prevailing visibility is reported. Values are reported in meters, 9999 indicates a
prevailing visibility of 10 km or greater.
Prevailing visibility
METAR LJLJ 280830Z VRB02KT 7000 FEW030 BKN050 17/13 Q1024 NOSIG=
Minimum visibility is significantly different from the prevailing visibility
METAR LJLJ 280830Z VRB02KT 7000 0300SE FEW030 BKN050 17/13 Q1024 NOSIG=
RUNWAY VISUAL RANGE - RVR
Runway designator
METAR LJLJ 280830Z VRB02KT 0300 R30/0600 FG VV001 05/05 Q1002 NOSIG=
RVR visibility in meters
METAR LJLJ 280830Z VRB02KT 0300 R30/0600 FG VV001 05/05 Q1002 NOSIG=
RVR visibility greater than 2000m
METAR LJLJ 280830Z VRB02KT 0700 R31/P2000 FG VV001 05/05 Q1002 NOSIG=
RVR visibility less than 150m
METAR LJLJ 280830Z VRB02KT 0100 R31/M0150 FG VV001 05/05 Q1002 NOSIG=
Tendency – RVR has increased during the observation period
METAR LJLJ 280830Z VRB02KT 0400 R31/0800U FG VV001 05/05 Q1002 NOSIG=
Tendency – RVR has decreased
METAR LJLJ 280830Z VRB02KT 0400 R31/0800D FG VV001 05/05 Q1002 NOSIG=
Tendency – indicates no distinct change in RVR
METAR LJLJ 280830Z VRB02KT 0400 R31/0800N FG VV001 05/05 Q1002 NOSIG=
PRESENT WEATHER
Weather phenomena reported in METAR report are:
DZ
RA
SN
Precipitation
Drizzle
Rain
Snow
SG
Snow grains
PL
GR
GS
Ice pellets
Hail
Small hail and/or snow
pellets
BR
FG
FU
Obscuration
Mist
Fog
Smoke
VA
DU
SA
HZ
Volcanic ash
Wide-spread dust
Sand
Haze
PO
SQ
FC
SS
DS
Other
Dust/sand whirls
Squalls
Funnel cloud(s)
(tornado or waterspout)
Sandstorm
Duststorm
Intensity and descriptors of weather phenomena are:
+
Intensity
Light
Moderate
Heavy
MI
BC
PR
DR
BL
SH
TS
FZ
Descriptor
Shallow
Patches
Partial
Low drifting
Blowing
Shower(s)
Thunderstorm
Freezing (supercooled)
Examples:
Fog at the airport:
METAR LJLJ 280830Z VRB02KT 0400 R31/0800D FG VV001 05/05 Q1002 NOSIG=
Light rain at the airport:
METAR LJLJ 280830Z VRB02KT 3000 -RA OVC033 07/05 Q1002 NOSIG=
Moderate shower rain at the airport:
METAR LJLJ 280830Z 14007KT 7000 SHRA SCT030TCU BKN050 17/12 Q1012 NOSIG=
CLOUD
Cloud information group usually consists of six characters: the first three indicate the expected
cloud amount (in octas of sky coverage) and the last three characters indicate the expected
height of the base in units of 100 feet.
1/8 to 2/8
3/8 to 4/8
5/8 to 7/8
8/8
Cloud amount
FEW few
SCT
scattered
BKN broken
OVC overcast
Convective cloud type
CB Cumulonimbus
TCU Towering cumulus
Cloud
METAR LJLJ 280830Z VRB02KT 9999 FEW030
BKN100 15/07 Q1007 NOSIG=
1/8 to 2/8 of cloud with base at 3000 ft and 5/8 to 7/8 of cloud with base at 4000 ft above ground
level.
Convective cloud
METAR LJLJ 280830Z VRB02KT 6000 SHRA FEW030
Q1011 NOSIG=
SCT040TCU BKN050 22/16
1/8 to 2/8 of cloud with base at 3000 ft above ground level and 3/8 to 4/8 of cumulus congestus
with base at 4000 ft above ground level and 5/8 to 7/8 of cloud with base at 5000 ft above ground
level.
NSC - NIL Significant Clouds
METAR LJLJ 280830Z VRB02KT 3000 BR NSC 15/07 Q1007 NOSIG=
NCD - No Clouds Detected (AUTO METAR)
METAR LJMB 280830Z AUTO VRB02KT 3000 BR NCD 15/07 Q1007 NOSIG=
VERTICAL VISIBILITY
When the sky is obscured and cloud details cannot be assessed but information on vertical
visibility is available, the cloud group is replaced by vertical visibility (VV) in units of 100 feet, as
cloud base.
METAR LJLJ 280830Z VRB02KT 0400 R31/0800D FG VV001 05/05 Q1002 NOSIG=
Vertical visibility at the airport is 100 feet above ground level.
CAVOK
The code word CAVOK is used when the following conditions occur at the same time:
• prevailing visibility is 10 km or more,
• no cloud below 5 000 ft or below the higher minimum sector altitude, whichever is
greater, and no CB and/or TCU,
• NIL significant weather phenomena.
TEMPERATURE
Air temperature in 0C
METAR LJLJ 280830Z VRB02KT 9999 FEW030 BKN100 15/07 Q1007 NOSIG=
0
Dew point temperature in C
METAR LJLJ 280830Z VRB02KT 9999 FEW030 BKN100 15/07 Q1007 NOSIG=
0
Negative temperature in C
METAR LJLJ 280830Z VRB02KT 9999 FEW030 BKN100 01/M03 Q1007 NOSIG=
PRESSURE
The last group of the main part of the report should indicate the QNH rounded down to the
nearest whole hectopascal.
Air pressure in hPa
METAR LJLJ 280830Z VRB02KT 9999 FEW030 BKN100 15/07 Q1007 NOSIG=
Air pressure is 1007 hPa.
Air pressure in inches of mercury
METAR LJLJ 280830Z VRB02KT 9999 FEW030 BKN100 15/07
Air pressure is 30.17 inches of mercury.
A3017 NOSIG=
SUPLEMENTARY INFORMATION
Recent weather
Using the indicator letters RE, information on recent weather is reported when weather
phenomena were observed since the last observation, but not at the time of observation.
METAR LJLJ 280830Z 14007KT 7000 -RA SCT030 BKN050 17/12 Q1012 RETSRA NOSIG=
Wind shear along the runway 31
METAR LJLJ 280830Z 14007KT 7000 -RA SCT030 BKN050 17/12 Q1012 WS RWY31 NOSIG=
Wind shear along all runways
METAR LJLJ 280830Z 14007KT 7000 SCT030 BKN050 17/12 Q1012 WS ALL
RWY NOSIG=
SNOWTAM
Report of the state of the runway.
METAR LJLJ 280830Z 14007KT 7000 SCT030 BKN050 17/12 Q1012 R31/451293 NOSIG=
Runway designator: R31/451293
Applies to all runways: R88/451293
A previous report is repeated: R99/451293
Type of deposit: R88/451293
Code
Meaning
0
clear and dry
1
damp
2
wet or water patches
3
rime or frost < 1mm
4
dry snow
5
wet snow
6
slush
7
ice
8
compacted or rolled snow
9
frozen ruts or ridges
/
not reported (e.g. due to runway clearance in
progress)
Extent of contamination: R88/451293
Code
Meaning
1
10% or less of runway covered
2
11% to 25% of runway covered
5
26% to 50% of runway covered
9
51% to 100% of runway covered
/
not reported (e.g. due to runway clearance in
progress)
Depth of deposition: R88/451293
Meaning
Code
00
depth of deposition is less than 1 mm
01
depth of deposition in mm
90
91
92
93
94
95
96
97
98
99
//
is not in use
depth of deposition is 100 mm
depth of deposition is 150 mm
depth of deposition is 200 mm
depth of deposition is 250 mm
depth of deposition is 300 mm
depth of deposition is 350 mm
depth of deposition is 450 mm or more
runway not operational due to contamination or due to
clearance in progress
depth not significant (e.g. ice or not measurable e.g. wet)
Friction coefficient or braking conditions: R88/451235
35 indicates friction coefficient 0.35.
friction coefficient
0,40 or more
0,39 - 0,36
0,35 - 0,30
0,29 - 0,26
0,25 or less
braking action
5
4
3
2
1
If the friction coefficient is not available following estimates are used:
braking action good
95
94
braking action medium good
93
braking action medium
92
braking action medium poor
91
braking action poor
99
braking action unreliable or not
measurable
Friction coefficient or braking conditions: R88/451293
93 indicates medium braking action.
Runway 31 is not in use due to cleaning: R31///99//
Report is not updated: R31///////
Airport closed due to snow: R/SNOCLO
Contamination has disappeared (runway has been cleared): R31/CLRD//
TREND
TREND forecasts are appended to METAR. Information contained in the TREND is a forecast
covering a period of 2 hours from the time of observation.TREND forecast indicates significant
changes in respect of one or more of the elements: surface wind, prevailing visibility weather and
cloud. When nil significant change is expected to occur, this is indicated by abbrevation NOSIG.
NOSIG – NIL Significant Changes.
METAR LJLJ 280830Z VRB02KT 9999 FEW030 BKN100 15/07 Q1007 NOSIG=
Change indicator - BECMG
The change indicator BECMG is used to describe expected changes which reach or pass
specified values at a regular or irregular rate. The period during which, or the time at which, the
change is forecast to occur is indicated by using the abbreviations FM (from), TL (till), AT, as
appropriate.
•
When the change is forecast to start at the beginning of the TREND forecast period and
to be completed by the end of that period, or when the change is forecast to occur within
the TREND period but the time is uncertain, the change indicator BECMG is used.
METAR LJLJ 280830Z VRB02KT 9999 FEW030 BKN100 15/07 Q1007 BECMG
32012KT=
•
When a change is forecasted to begin and and within the TREND forecast period, the
beginning and end of change are indicated by using the abbreviations FM and TL.
METAR LJLJ 280830Z VRB02KT 9999 FEW030 BKN100 15/07 Q1007 BECMG FM0900
TL1000 32012KT=
•
When the change is forecast to start at the beginning of the TREND period but is
expected to be completed before the end of that period, only the abbreviation TL and its
associated time group is used to indicate the end of the change.
METAR LJLJ 280830Z VRB02KT 9999 FEW030 BKN100 15/07 Q1007 BECMG TL1000
32012KT=
•
When the change is forecast to begin during the TREND forecast period and to be
completed at the end of that period, the abbreviation FM and associated time group is
used to indicate the beginning of the change.
METAR LJLJ 280830Z VRB02KT 9999 FEW030 BKN100 15/07 Q1007 BECMG FM0930
32012KT=
•
When the change is forecast to occur at a specific time during the TREND forecast
period, the abbreviation AT followed by the associated time group is used to indicate the
time of the change.
METAR LJLJ 280830Z VRB02KT 9999 FEW030 BKN100 15/07 Q1007 BECMG AT0930
32012KT=
Change indicator - TEMPO
The change group TEMPO is used to describe forecast temporary fluctuations in the
meteorological conditions which reach or pass specified values and last for a period of less than 1
hour in each instance and in total for less than half of the forecast period during which the
fluctuations are forecast to occur. The period during which the temporary fluctuations are
expected to occur is indicated by using the abbreviations FM and/or TL, as appropriate, followed
by a time group.
•
When the period of temporary fluctuations are forecast to start at the beginning of the
TREND period and to continue throughout the period, the change indicator TEMPO is
used.
METAR LJLJ 280830Z VRB02KT 9999 FEW030 BKN100 15/07 Q1007 TEMPO
32012KT=
•
When the period of temporary fluctuations are forecast to begin and end within the
TREND forecast period, the beginning and the end are indicated by using the
abbreviations FM and TL, respectively, with their associated time groups.
METAR LJLJ 280830Z VRB02KT 9999 FEW030 BKN100 15/07 Q1007 TEMPO FM0900
TL1000 32012KT=
•
When the period of temporary fluctuations are forecast to start at the beginning of the
TREND period but are expected to end before the end of the period, TL and its time
group is used to indicate the end of fluctuations.
METAR LJLJ 280830Z VRB02KT 9999 FEW030 BKN100 15/07 Q1007 TEMPO TL1000
32012KT=
•
When the period of temporary fluctuations are forecast to begin during the TREND period
and to continue throughout the period, the abbreviation FM and its associated time group
only is used to indicate the beginning of fluctuations.
METAR LJLJ 280830Z VRB02KT 9999 FEW030 BKN100 15/07 Q1007 TEMPO FM0930
32012KT=
TAF
Aerodrome forecast (TAF) describes expected meteorological conditions at aerodrome.
AERODROME
TAF LJLJ 100500Z 1006/1106 27004KT 2500 BR OVC003 TEMPO 1009/1017 6000 NSW
BKN007=
THE DATE AND TIME OF ISSUE OF THE FORECAST
TAF LJLJ 100500Z 1006/1106 27004KT 2500 BR OVC003 TEMPO 1009/1017 6000 NSW
BKN007=
th
Time of issue is 0500 UTC on the 10 day of the month.
PERIOD COVERED BY THE FORECAST
TAF LJLJ 100500Z 1006/1106 27004KT 2500 BR OVC003 TEMPO 1009/1017 6000 NSW
BKN007=
th
th
TAF forecast valid from the 10 day at 0600 UTC till 11 day of the month at 0600 UTC.
WIND
Wind direction from true north.
TAF LJLJ 100500Z 1006/1106 27004KT 2500 BR OVC003 TEMPO 1009/1017 6000 NSW
BKN007=
The encode VRB is used when the variation of wind direction is expected to be 180° or
more, or when it is not possible to forecast a single wind direction.
TAF LJLJ 100500Z 1006/1106 VRB02KT 2500 BR OVC003 TEMPO 1009/1017 6000 NSW
BKN007=
Wind speed
TAF LJLJ 100500Z 1006/1106 27004KT 2500 BR OVC003 TEMPO 1009/1017 6000 NSW
BKN007=
Units used for wind speed are knots (KT) or meters per second (MPS).
TAF LJLJ 100500Z 1006/1106 27004KT 2500 BR OVC003 TEMPO 1009/1017 6000 NSW
BKN007=
Wind gusts are indicated using the letter G directly after the mean speed, followed by wind
gusts speed.
TAF LJLJ 100500Z 1006/1106 32008G20KT 9999 FEW030=
VISIBILITY
In TAF prevailing visibility is forecasted. Values are expected in meters, 9999 indicates a
prevailing visibility of 10 km or greater.
Prevailing visibility
TAF LJLJ 100500Z 1006/1106 27004KT 2500 BR OVC003 TEMPO 1009/1017 6000 NSW
BKN007=
WEATHER
Weather phenomena forecasted in TAF forecasts are:
Precipitation
Obscuration
DZ Drizzle
BR Mist
RA Rain
FG Fog
SN Snow
FU Smoke
SG
Snow grains
PL
GR
GS
Ice pellets
Hail
Small hail and/or snow
pellets
VA
DU
SA
HZ
Volcanic ash
Wide-spread dust
Sand
Haze
Intensity and descriptors of weather phenomena are:
+
Intensity
Light
Moderate
Heavy
MI
BC
PR
DR
BL
SH
TS
FZ
Descriptor
Shallow
Patches
Partial
Low drifting
Blowing
Shower(s)
Thunderstorm
Freezing (supercooled)
PO
SQ
FC
SS
DS
NSW
Other
Dust/sand whirls
Squalls
Funnel cloud(s)
(tornado or waterspout)
Sandstorm
Duststorm
Nil significant weather
Examples:
Mist at the airport is expected.
TAF LJLJ 100500Z 1006/1106 27004KT 1500 BR OVC003 TEMPO 1009/1017 4000 BKN007=
Light rain is expected at the airport.
TAF LJLJ 100500Z 1006/1106 27004KT 7000 -RA OVC030=
Moderate showers are expected at the airport.
TAF LJLJ 100500Z 1006/1106 27006KT 7000 SHRA SCT030TCU OVC040 BECMG 1015/1018
NSW SCT040=
CLOUD
Cloud information group usually consists of six characters: the first three indicate expected cloud
amount (in octas of sky coverage) and the last three characters indicate expected height of the
base of the cloud in units of 100 feet.
Cloud amount
FEW few
1/8 to 2/8
SCT
scattered
3/8 to 4/8
BKN broken
5/8 to 7/8
OVC overcast
8/8
Convective cloud type
CB Cumulonimbus
TCU Cumulus congestus
CLOUD
TAF LJLJ 100500Z 1006/1106 27006KT 7000 SCT030
SCT040=
OVC040 BECMG 1015/1018 NSW
3/8 to 4/8 of cloud coverage with base at 3000 ft and 8/8 cloud coverage with base at 4000 ft
above ground level (height).
Convective cloud
TAF LJLJ 100500Z 1006/1106 27006KT 7000 SHRA SCT030TCU
1015/1018 NSW SCT040=
OVC040 BECMG
3/8 to 4/8 cumulus congestus with base at 3000 ft and 8/8 cloud with base at 4000 ft above
ground level (height).
NSC – NIL Significant Clouds
TAF LJLJ 100500Z 1006/1106 27004KT 1500 BR NSC TEMPO 1009/1017 4000 BKN005=
VERTICAL VISIBILITY
When the sky is expected to be obscured, the cloud group is replaced by vertical visibility (VV)
forecast in units of 100 feet.
TAF LJLJ 100500Z 1006/1106 27004KT 0500 FG VV001 TEMPO 1009/1017 4000 BR
BKN005=
Forecasted vertical visibility at the airport is 100 feet.
CAVOK
The code word CAVOK is used when the following conditions are expected to occur at the same
time:
• prevailing visibility is 10 km or more,
• no cloud below 5 000 ft or below the higher minimum sector altitude, whichever is
greater, and no CB and/or TCU,
• NIL significant weather phenomena.
EXPECTED SIGNIFICANT CHANGES
Indication of significant changes
BECMG (becoming)- indicates a regular or irregular change to the forecast meteorological
conditions expected over a period.
TAF LJLJ 100500Z 1006/1106 27004KT 0500 FG VV001 BECMG 1009/1012 4000 BR
BKN005=
Meaning: The forecast conditions are expected to change between 0900 UTC and 1200 UTC on
th day
th
of the month. Prevailing conditions for the period between 1200 UTC on the 10 day of
the 10
th
the month and 0600 UTC on the 11 day of the month are expected to be: surface wind 270° at 4
kt, visibility 4000m, mist, 5/8 to 7/8 of cloud with base at 500ft.
TEMPO (temporary)- indicate temporary fluctuations in the forecast meteorological
conditions which may occur at any time during the period.
TAF LJLJ 100500Z 1006/1106 27004KT 0500 FG VV001 TEMPO 1018/1103 0900=
th
Meaning: Temporarily between 1800 UTC on the 10 day of the month and 0300 UTC on the 11t
day of the month the visibility is expected to be 900m.
h
The change indicators TEMPO and BECMG are followed by groups describing only the
meteorological elements which are forecast to change significantly. The change indicator
FM is used to indicate the beginning of a self-contained part of the forecast. All conditions
given before this group are superseded by conditions indicated after the group.
FM (from) is used when one set of prevailing weather conditions is expected to change
significantly and more or less completely to a different set of conditions.
TAF LJLJ 100500Z 1006/1106 27004KT 0500 FG VV001 FM101800 32010KT 9999 NSW
SCT030 BKN090=
Meaning: Expected meteorological conditions from 1800 UTC on the 10th day of the month: surface wind
direction 320°, wind speed 10 kt, prevailing visibility 10 km or more, nil significant weather, 3/8 to 4/8
cloud with base at 3000 ft and 5/8 to 7/8 cloud with base at 9000 ft.
PROB (probability)- indicates the probability percentage of occurrence.
TAF LJLJ 100500Z 1006/1106 27004KT 0500 FG VV001 PROB40 1018/1103 0800=
Meaning: 40% probability for improvement of visibility to 800m, between 1800 UTC on the 10
th
day of the month and 0300 UTC on the 11 day of the month.
th
PROB40 indicates 40% and PROB30 indicates 30% probability of occurrence.
TAF LJLJ 100500Z 1006/1106 27004KT 0500 FG VV001 PROB30
0800=
TEMPO 1018/1103
Meaning: 30% probability for temporarily improvement of visibility to 800m between 1800 UTC on
th
th
the 10 day of the month and 0300UTC on the 11 day of the month.
TAF AMENDMENTS
TAF AMD LJLJ 100700Z 1007/1106 27002KT 2500 BR OVC003 TEMPO 1009/1017 6000 NSW
BKN007=
TAF amendment is issued when the weather forecast does not match with the predicted
development of weather parameters.
TAF example:
TAF LJLJ 100500Z 1006/1106 27004KT 2500 BR OVC003 TEMPO 1009/1017 6000 NSW
BKN007=
th
Aerodrome forecast for LJLJ airport, time of issue is 0500 UTC on the 10 day of the month,
th
th
validity period from 0600 UTC on the 10 day of the month till 0600 UTC on the 11 day of the
month. Surface wind direction 270°, wind speed 4 kt, visibility 2500 m, mist, cloud 8/8 with base
th
at 300 ft above ground level. Temporarily between 0900 UTC and 1700 UTC on the 10 day of
the month, visibility 6000m, nil significant weather, cloud 5/8 to 7/8 with base at 700ft above
ground level is expected.