Aircrew Quick Reference to the METAR and TAF

Aircrew Quick Reference to the METAR and TAF
Air Force Pamphlet 11-238
17 March 2011
Flying Operations
Aircrew Quick Reference
to the
METAR and TAF Codes
ACCESSIBILITY: Pu
ublications and forms are av
vailable on the
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ordering.
RELEASABILITY: There are no releasability restrictions on this
publication.
OPR: AFFSA/A3OF
Supersedes AFPAM 11-238, 1 Nov 05
Certified by: HQ USAF/A3O-B
(Mr. Steven Pennington)
Pages: 36
Introduction
The Aircrew Quick Reference Guide to the METAR and TAF Codes helps
aircrews quickly and clearly translate METAR and TAF codes into plain
language. See Attachment 1 for a list of source documents.
METAR reports are observed weather conditions while the TAF indicates
forecast conditions. Both are lines of text made up of coded data groups
separated by spaces. Some groups are not discussed because they are only
intended for use by the weather community. Differences between military
and civilian renderings of the code are discussed.
Aircrews should always check METAR and TAF reports thoroughly for all
hazards to flight safety and other elements that may affect aircraft
performance or mission accomplishment. When users have weather-related
questions, they should contact a certified US military forecaster or
MAJCOM-approved weather source for clarification. Weather briefing
requirements for USAF Aircrews are spelled out in AFI 11-202, Volume
3, General Flight Rules.
Refer recommended changes and questions about this publication to the
Office of Primary Responsibility (OPR) using the AF Form 847,
Recommendation for Change of Publication; route AF Form 847s from the
field through the appropriate functional’s chain of command. This
publication may not be supplemented.
SUMMARY OF CHANGES
This document includes clarifications of METAR sector visibility and
vertical visibility and removes references to runway surface conditions
(now reported via NOTAMs). It also incorporates several changes to the
TAF format, specifically: repositioning the AMD and COR modifiers for
emphasis, adding a ―prepared/disseminated‖ time group to military TAFs
(already included in civilian TAFs), reformatting of the TAF valid time
groups, noting that some civilian TAFs are valid for up to 30 hours, and
adding a ―T‖ before both maximum and minimum temperature groups in
military TAFs.
2
Table of Contents
Section I, METAR decoding:
Report Type
Location and Date/Time
Auto/Cor
Wind
Wind Variability
Visibility
Runway Visual Range
Type of Weather
Clouds
Temperature/Dewpoint
Altimeter Setting
Remarks, US
Remarks, Overseas
Section II, TAF decoding:
Report Type
Location
Date/Time
Time and Type of Change Expected
Wind
Visibility
Type of Weather
Clouds
Wind Shear
Icing
Turbulence
Minimum Altimeter Setting
Temperatures
Page
4
5
6
7
8
9
10
11
13
14
15
16
17
Page
19
20
21
22
23
24
25
26
27
28
29
30
31
Figures
1. Weather/Obscuration Table - METAR/TAF
2. Remarks Decode Table - METAR
3. Icing Intensity Decode Table - TAF
4. Turbulence Intensity Decode Table - TAF
Attachments
1. Glossary of References and Supporting Information
2. Temperature Conversion, Fahrenheit to Celsius
3. Reportable Visibility Conversion, Statute Miles to Meters
4. Runway Visibility Conversion
5. Pressure Conversion, Millibars to Inches
Page
12
18
28
29
Page
32
33
34
35
36
3
METAR
Report Type
What kind of report is this?
KBLV 011657Z AUTO 25015G30KT 210V290
3/8SM R32L/1000FT FG BKN005 01/M01 A2984
RMK A02 SLP034
This report is a METAR (roughly translated from French as
Aviation Routine Weather Report)—a scheduled observation
normally taken between 50-59 minutes past the hour (also
referred to as a routine hourly observation). A METAR can be
distinguished from a TAF by its single date/time group.
SPECI KBLV 011715Z 25015G30KT 210V290 3SM
BR BKN015 01/M01 A2984 RMK SLP034
SPECI (Aviation Selected Special Weather Report) refers to
an unscheduled report taken when certain criteria have been
met (such as a change from VFR to IFR) and may be taken
anytime.
4
METAR
Location and Date/Time
How do I determine the location and the date and time of
issuance?
PAAQ 011657Z AUTO 25015G30KT 210V290
3/8SM BKN005 03/M01 A2984 RMK A02 SLP034
KCLK 291012Z AUTO 08009KT 2SM -RA SCT005
OVC009 M01/M01 A2999 RMK AO2
The 4-character ICAO identifier is the location; PAAQ
(Palmer Municipal) and KCLK (Clinton Regional) are the
locations/stations in these examples.
The 7-character group following the ICAO identifier is the
date and time of issuance. The first two digits are the date; the
last four digits are the coordinated universal time (UTC),
sometimes called ―zulu time.‖
In the first example, 01 is the 1st day of the month, and
1657Z is 1657 UTC. The second example takes place on the
29th day of the month at 1012 UTC.
When ICAO identifiers are not available or cannot be used, a
4-character identifier starting with KQ will be used. This
practice is normally found in a contingency environment,
where the location/identifier combination is often classified.
Consult the local weather flight for more details.
5
METAR
AUTO/COR
What does AUTO and/or COR mean, if included?
Let’s look at the meanings of AUTO and COR separately.
KBLV 011657Z AUTO 25015G30KT 210V290 3/8SM
R32L/1000FT FG BKN005 01/M01 A2984 RMK A02A
SLP034
AUTO refers to an automated observation with measurements taken
by equipment such as the domestic Automated Weather Observing
System (AWOS) or Automated Surface Observation System
(ASOS), or the Air Force’s Automated Meteorological Station
(AMS), also known as AN/FMQ-19. AO1 denotes an observation
taken by equipment lacking a precipitation type discriminator (rain
vs. snow). AO2 denotes an observation taken by standard equipment
with a full complement of sensors. A02A denotes an automated
observation augmented by a human observer. Absence of these
indicators denotes a manual report by a human observer.
KBLV 011657Z AUTO COR 25015G30KT 210V290
3/8SM R32L/1000FT FG FU BKN005 01/M01 A2984
RMK A02A SLP034 COR 1725
COR indicates a corrected observation. Disregard the previous
transmission. COR 1725 means that the correction was transmitted
at 1725Z.
6
METAR
Wind
How do I determine the wind speed and direction?
KBLV 011657Z AUTO 25015G30KT 210V290
3/8SM R32L/1000FT FG BKN005 01/M01 A2984
RMK A02 SLP034
The data group followed by KT (knots) is the wind.
The first three digits are the true direction to the nearest 10
degrees from which the wind is blowing. The next two digits
are the sustained speed. If gusts are present, the next two or
three digits following the ―G” are the ―gust,‖ the maximum
wind speed in the last ten minutes.
In this example, the 25015G30KT group is the wind
direction and speed. Here, the wind is blowing from 250
degrees (true) at a sustained speed of 15 knots, gusting up to
30 knots.
Calm wind is encoded as 000000KT.
7
METAR
Wind Variability
How do I determine if the wind is varying between
directions?
KBLV 011657Z AUTO 25015G30KT 210V290
3/8SM R32L/1000FT FG BKN005 01/M01 A2984
RMK A02 SLP034
A wind variability group will be reported if the wind is
variable by 60 degrees or more and the speed is greater than 6
knots. This remark will contain the extremes of the wind
directions, separated by ―V.‖
In the example above, 210V290 reads, ―wind direction
varying between 210 and 290.‖
KBLV 011657Z AUTO VRB03KT 3/8SM
R32L/1000FT FG BKN005 01/M01 A2984 RMK
A02 SLP034
VRB is used (without direction extremes) when the wind speed
is less than or equal to 6 knots. In the example above,
VRB03KT reads, ―wind direction is variable at 3 knots.‖
8
METAR
Visibility
How do I determine the prevailing visibility?
KBLV 011657Z 25015G30KT 210V290 3/8SM
R32L/1000FT FG BKN005 01/M01 A2984 RMK SLP034
Visibility is measured in statute miles. In this example, 3/8SM
(3/8 of a statute mile) is the prevailing visibility. Prevailing
visibility is the greatest horizontal visibility observed
throughout at least half the horizon circle, not necessarily
continuous. Surface visibility is measured at a point six feet
above ground level.
Sector visibility may be reported in the remarks section if it
differs from the prevailing visibility and is less than 3 miles,
or otherwise considered operationally significant. For sector
visibility format, see VIS remarks in Figure 2 on page 18.
EDDF 071320Z 22008KT 9999 SCT036 SCT090
BKN280 19/10 Q1011 NOSIG
Most overseas locations report visibility in meters and omit
the SM identifier. The largest reportable metric value is
9999. This value represents a visibility greater than 9000
meters (7 SM or more). The contraction CAVOK (ceiling and
visibility OK) may be used when there is no significant
weather, the visibility is 10 km or greater, and the ceilings are
greater than 5,000 ft. To convert visibility values from meters
to statute miles see Attachment 3 or the Flight Information
Handbook conversion tables.
9
METAR
Runway Visual Range, “R”
What if there is a group that begins with the letter “R?”
KBLV 011657Z AUTO 25015G30KT 210V290 3/8SM
R32L/1000FT FG BKN005 01/M01 A2984 RMK A02
SLP034
Runway Visual Range (RVR) follows the visibility and begins with
the letter ―R.‖ The runway heading will follow the ―R,‖ and in this
example, ―32L‖ represents runway 32-Left (C-Center, R-Right).
The last four digits report the visibility in feet.
In this example, R32L/1000FT reads, ―runway visual range for
runway 32 Left is 1,000 ft.‖
Most overseas locations report visibility in meters and omit the FT
identifier from the RVR group. The same RVR at an overseas
location would appear as R32L/0300 and read, ―runway visual
range for 32 Left is 300 meters.‖
How would I decode the formats M0600FT or P6000FT or
R06L2000V4000FT (not in example above)?
M0600FT
P6000FT
R06L2000V4000FT
Reads, ―RVR is less than 600 feet.‖ (M =
less than)
Reads, ―RVR is greater than 6,000 feet.‖
(P = greater than)
Reads, ―RVR for 6 Left is variable
between 2,000 and 4,000 feet.‖
―V‖ indicates that the RVR is variable
between two thresholds.
For RVR conversion charts, see Attachment 4 or the front section of
any Instrument Approach Procedures (IAP) booklet.
10
METAR
Type of Weather
How do I determine if there is any weather?
KBLV 011657Z AUTO 25015G30KT 210V290
3/8SM R32L/1000FT FG BKN005 01/M01 A2984
RMK A02 SLP034
If a weather element (precipitation or obstruction to visibility)
is observed, it will be found in the data group following the
visibility. The absence of a weather element group indicates
that no precipitation or obstruction to visibility is occurring at
the time of the observation. In this example, ―FG‖ represents
―Fog.‖
To methodically decode a weather group, look for six key
elements (depending on the phenomena, one or more may be
omitted). In order, these elements are: Intensity (symbol
preceding the code), Proximity, Descriptor, Precipitation
Description, Obscuration (other than precipitation), and
Other.
For a complete table of weather group elements and examples,
see Figure 1 on page 12, or reference Section C ―METAR and
TAF Code‖ of the Flight Information Handbook.
11
METAR
Weather/Obscuration Table
Figure 1. Weather/Obscuration Table
Phenomenon Qualifiers
Element 1: Intensity
-
Element 2: Proximity
none
Light
VC
none Moderate
DSNT
+
Element 3: Description
On station
BC
Patches
In the vicinity
(5-10 miles)
> 10 miles
BL
Blowing
DR
FZ
MI
PR
Low Drifting
Heavy
Note: + can also mean
a well-developed dust storm,
sandstorm, whirl, dust devil,
tornado, or waterspout
SH
TS
Freezing
Shallow
Partial (covering
part of the sky)
Shower(s)
Thunderstorm
Types of Weather Phenomenon
Element 4: Precipitation
DZ Drizzle
GR Hail, diam. ≥ 5mm (.25")
GS Small Hail / Snow Pellets,
diam. < 5mm (.25")
Ice Crystals
Ice Pellets
Rain
Snow Grains
IC
PL
RA
SG
SN Snow
UP Unknown Precipitation
Element 5: Obscuration
Mist, vis. ≥ 5/8SM
BR
DU
FG
FU
HZ
PY
SA
VA
(or ≥ 1000m)
Widespread Dust
Fog, vis. < 5/8SM
(or ≥ 1000m)
Smoke
Haze
Spray
Element 6: Other
DS Dust Storm
FC Funnel cloud(s)
e.g., tornado
or waterspout
PO Well-developed
dust/sand whirls
SQ Squalls
SS Sandstorm
Sand
Volcanic Ash
(Automated only)
Examples:
+SHRASNPL
TSRAGS
BR HZ
BCFG
PRFG
heavy rain showers, snow, ice pellets
thunderstorm, moderate rain, small hail
mist (vis. >= 5/8SM), haze
patchy fog (vis. < 5/8SM)
partial fog (sector vis. < 5/8SM)
+DRSN
VCSH
FZDZ
BLPY
+DS
heavy snow, drifting
showers in vicinity
freezing drizzle
blowing spray
heavy dust storm
A similar table can be found in Section C of the Flight Information Handbook.
12
METAR
Clouds
How do I determine the layers of clouds?
KBLV 011657Z AUTO 25015G30KT 210V290 3/8SM
R32L/1000FT FG BKN005 01/M01 A2984 RMK A02
SLP034
Each observed cloud layer is encoded in a cloud group with sky
coverage, altitude of the cloud base above ground level (AGL), and
sometimes cloud type. The first three letters of each cloud group
denote sky coverage as in the table below. In this example, BKN
indicates broken cloud coverage. To interpret the reported cloud
base, append two zeros to the value given. In this example, 005
represents the value 500 feet AGL. Finally, in augmented or manual
observations, codes for convective cloud types may be appended.
CB stands for cumulonimbus; TCU stands for towering cumulus.
If surface-based obscurations (e.g., clouds, smoke, haze) are
reported, and the lowest broken or overcast cloud base cannot be
determined, then vertical visibility in hundreds of feet determines
the ceiling. For example, VV002 represents a vertical visibility of
200 feet.
Sky coverage in eighths:
SKC or CLR
Sky clear
FEW
Few (Trace – 2/8)
SCT
Scattered (3/8 – 4/8)
BKN
* Broken (5/8 – 7/8)
OVC
* Overcast (8/8)
* The lowest layer reported as broken or overcast constitutes a ―ceiling‖
A similar table can be found in Section C, ―METAR and TAF
Code‖, of the Flight Information Handbook.
13
METAR
Temperature/Dewpoint
How do I determine the current temperature and
dewpoint?
KBLV 011657Z AUTO 25015G30KT 210V290
3/8SM R32L/1000FT FG BKN005 01/M01 A2984
RMK A02 SLP034
The group following the sky condition is the temperature and
dewpoint information in degrees Celsius. To convert
temperatures from Celsius to Fahrenheit see Attachment 2 or
the Flight Information Handbook conversion tables.
In this example, 01 is the temperature in degrees Celsius
(1ºC), and M01 is the dewpoint in degrees Celsius (-1ºC). An
―M‖ in the temperature or dewpoint field means ―minus‖
(below zero).
14
METAR
Altimeter Setting
How do I determine the current altimeter setting?
KBLV 011657Z AUTO 25015G30KT 210V290
3/8SM R32L/1000FT FG BKN005 01/M01 A2984
RMK A02 SLP034
The 5-character group beginning with A, following the
temperature/dewpoint group is the altimeter setting in inches
and hundredths of an inch of mercury (inches Hg), used in the
United States and at US airfields overseas. In this example,
A2984 represents a current altimeter setting of 29.84 inches
Hg.
EDDF 071320Z 22008KT 9999 SCT036 SCT090
BKN280 19/10 Q1011 NOSIG
The 5-character group beginning with Q, following the
temperature/dewpoint group is the altimeter setting in
hectopascals (hPa), used at most overseas locations. A
hectopascal is equivalent to a millibar (mb). In this example,
Q1011 represents a current altimeter setting of 1011 hPa or
1011 mb.
To convert altimeter settings from mb (or hPa) to inches Hg,
see Attachment 5 or the Flight Information Handbook
conversion tables.
15
METAR
Remarks, US
What is RMK?
KBLV 011657Z AUTO 25015G30KT 210V290 3/8SM
R32L/1000FT FG BKN005 01/M01 A2984 RMK A02
SLP034
In METAR reports from the United States and from overseas US
military airfields, RMK indicates the start of the Remarks section.
Remarks contain any pertinent information beyond the standard
fields provided and can be either encoded or spelled out in plain
language. For a partial listing of possible METAR remarks, see
Figure 2 on page 18. Additional abbreviations are constructed in
accordance with FAA Order 7340.1, Contractions.
In this example, the remark, SLP034, is the sea level pressure in
millibars (or hectopascals) to the nearest tenth. To decode, place a
―10‖ or ―9‖ before the first digit (use a 9 if the 3-digit value is 500
or more), and place a decimal point before the last digit. The sea
level pressure remark in the above example would read ―current sea
level pressure of 1003.4 millibars.‖
Caution: Do not confuse the METAR remarks ―5####‖ group or
―6####‖ group with the TAF ―5######‖ (turbulence) group or the
TAF ―6######‖ (icing) group. Unlike TAF code usage, METAR
―5‖ and ―6‖ group codes indicate pressure tendency and cumulative
precipitation amounts--if you need these values, contact your
weather provider for decoding instructions. See pages 28 and 29 for
more info on decoding TAF icing and turbulence forecasts.
16
METAR
Remarks, Overseas
What is supplemental information?
Overseas (except at US military installations), METAR remarks are called
―supplemental information.‖ Supplemental information follows the
altimeter setting and uses remark codes like US remarks, as in Figure 2 on
page 18, but is not preceded by RMK.
Supplemental information can also include:
- Recent weather elements, coded with a leading RE
- Sea surface temperature in ºC and sea state 0-9, coded W##/S#
- Runway state, coded as an 8-digit numerical group
- A 2-hour forecast trend as described below
EDDF 071320Z 22008KT 9999 SCT036 SCT090 BKN280
19/10 Q1011 NOSIG
Overseas METAR forecast trend groups either start with BECMG or
TEMPO, consistent with TAF coding conventions, or they consist entirely
of NOSIG, which indicates that no significant changes in reportable
weather elements are expected during the 2 hours following the reported
observation.
METARs issued by North Atlantic Treaty Organization (NATO) observers
have, as the last data group, a color code for ceiling and visibility data:
NATO Airfield Weather Color Code.
source: AFMAN 15-111 USAFESUP1
Color Code
Color
* Ceiling at or above: Visibility at or above:
BLU
blue
2500 feet
8000 meters
WHT
white
1500 feet
5000 meters
GRN
green
700 feet
3700 meters
YLO
yellow
300 feet
1600 meters
AMB
amber
200 feet
0800 meters
RED
red
< 200 feet
< 0800 meters
Airfield not useable for reasons other than
BLACK
black
ceiling or visibility
* Belgium, France, Netherlands, and United Kingdom use scattered clouds instead of ceiling
17
METAR
Remarks Decode Table
Figure 2. Remarks Decode Table
A01 – Reported by automated
observation equipment that
CANNOT distinguish between rain
and snow
A02 – Reported by automated
observation equipment that CAN
distinguish between rain and snow
ACC W – AltoCumulus Castellanus
clouds West
ACSL SW-S – AltoCumulus Standing
Lenticular clouds SouthWest through
South
ALSTG/SLP ESTMD– Estimated
Pressure. Primary airfield sensors
are suspect or inoperative; backup
equipment is being used.
CB W MOV E – CumulonimBus clouds
West MOVing East
CBMAM DSNT S – CumulonimBus
MAMmatus clouds to the DiStaNT
South
CCSL OVR MT E – CirroCumulus
Standing Lenticular clouds OVeR
MounTain(s) to the East
PK WND 34050/38 – PeaK WiND 340 at 50 knots
occurred at 38 minutes past the hour
PRESRR / PRESFR – PRESsure Rising Rapidly /
PRESsure Falling Rapidly
RAB20SNB20E55 – RAin and SNow Began at 20
minutes past the hour, Ended at 55 min past
RVRNO – RVR-equipped, but NO report
SFC VIS 2 1/2 – SurFaCe VISibility is 2 ½ statute
miles; remarked when (lower) tower visibility is
reported in METAR body
SLP015 – Sea Level Pressure is 1001.5 millibars
TCU OHD – Towering CUmulus clouds OverHeaD
TCU W – Towering CUmulus clouds to the West
TSB05E30 – ThunderStorm Began at 05 minutes
past the hour and Ended at 30 min past
TWR VIS 1 – ToWeR VISibility is 1 statute mile;
remarked when (lower) surface visibility is
reported in METAR body
VIRGA – VIRGA at the station; precipitation
observed but not reaching the ground
VIRGA DSNT NE – VIRGA to the DiStaNT
NorthEast
VIRGA SW – VIRGA to the SouthWest
CONS LTGCA – CONtinuouS (more
than 6 flashes per minute)
LighTninG, Cloud to Air
VIS 1V2 – VISibility is Variable between 1 and 2
miles
FROPA – … due to FROntal Passage
VIS 2 RWY 11 – VISibility is 2 statute miles at
RunWaY 11
FRQ – FReQuent (1-6 flashes per
minute for lightning)
LTGCA – LighTninG, Cloud to Air
LTGCC – LighTninG, Cloud to Cloud
LTGCG – LighTninG, Cloud to Ground
LTGIC – LighTninG, In-Cloud
OCNL – OCcassioNaL (less than 1
flash per minute for lightning)
VIS N 2 – VISibility in the Northern sector is 2
statute miles
WND DATA ESTMD – Estimated Wind. Primary
airfield sensors are suspect or inoperative;
backup equipment is being used.
WSHFT45 – Wind SHiFT at 45 minutes past the
hour
PK WND 28045/1955 – PeaK WiND
280 at 45 knots occurred at 1955Z
18
TAF
Report Type
What type of report is this?
KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030
WS010/18040KT QNH2960INS
BECMG 0513/0514 16010KT 3200 -SHRA OVC020 QNH2959INS
TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020
BECMG 0518/0519 31012G22KT 9999 NSW SCT040 WSCONDS
520004 QNH2952INS
BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/0518Z
TM01/0611Z
This report is a TAF (Terminal Aerodrome Forecast)—a weather forecast
at an airport or military base for a specific period. A TAF is distinguished
from a METAR by its multiple date/time groups.
AMD KBLV 051820Z 0518/0612 21015KT 0800 TSRA BKN008CB
QNH2958INS
BECMG 0518/0519 29008KT 1600 -RA OVC030 QNH2958INS
BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/18Z
TM01/11Z AMD 1820
AMD (Amended Aerodrome Forecast) is issued because the previous
version is no longer representative of the current or expected weather. The
amended TAF supersedes the previous TAF. In the above example, AMD
1820 indicates that the forecast was amended at 1820Z. Always refer to
the date/time group at the end of the TAF to determine the most current
forecast.
AMD KBLV 051925Z 0518/0612 21015KT 0800 TSRA BKN008CB
QNH2958INS
BECMG 0518/0519 29008KT 1600 -RA OVC030 QNH2958INS
BECMG 0520/0521 18015KT CAVOK QNH2950INS T08/18Z
TM01/11Z COR 1925
AMD is also used with COR (Corrected Aerodrome Forecast) to indicate
that a TAF has been corrected. When a corrected TAF is issued, disregard
previous TAFs. In the above example, COR 1925 indicates that the
amended forecast was corrected at 1925Z. Always refer to the date/time
group at the end of the TAF for the most current forecast.
19
TAF
Location
How do I determine the location?
PAAQ 041419Z 0414/0512 VRB03KT 6SM BR OVC003
TEMPO 0414/0418 5SM BR
FM042000 34005KT P6SM FEW008 SCT070
KCLK 081126Z 0812/0912 07009KT 3SM -SN BR OVC003
FM082100 05008KT 1SM -SN BR OVC001
The 4-character ICAO identifier is the location. PAAQ (Palmer
Municipal) and KCLK (Clinton Regional) are the locations/stations
in these examples.
When ICAO identifiers are not available or cannot be used, a 4character identifier starting with KQ will be used. This is usually
in a contingency environment, and the location/identifier
combination is often classified. Consult the local weather flight for
more details.
20
TAF
Date/Time
How do I determine the date and valid times of the forecast?
KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030
WS010/18040KT QNH2960INS
BECMG 0513/0514 16010KT 3200 -SHRA OVC020 QNH2959INS
TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020
BECMG 0516/0517 29008KT 3200 -RA OVC030 620304
QNH2958INS
BECMG 0518/0519 31012G22KT 9999 NSW SCT040 WSCONDS
520004 QNH2952INS
BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/0518Z
TM01/0611Z
KPVU 081123Z 0812/0906 32009KT P6SM OVC050
TEMPO 0812/0816 SCT050
FM081600 VRB04KT P6SM SCT200
KSLC 081123Z 0812/0918 35007KT P6SM BKN120
FM090400 15005KT P6SM SCT200
FM090900 14004KT P6SM SCT120 BKN200
The next two groups that follow the ICAO identifier show the
preparation/dissemination time of the TAF and the valid time of the
forecast. In the KBLV (Scott AFB) example, 051151Z shows that
the TAF was prepared/disseminated on the 5th day of the month at
1151Z. The valid time of the forecast follows as 0512/0612 and
indicates that the forecast valid time is from 1200Z on the 5th day of
the month to 1200Z on the 6th day.
Although most TAFs are forecasted for a 24-hour period, the valid
times may vary, up to a maximum of 30 hours. For example, the
TAF at KPVU (Provo Municipal) is only valid from 1200Z on the
8th day until 0600Z on the 9th day, while the TAF at KSLC (Salt
Lake City International) is valid from 1200Z on the 8th day until
1800Z on the 9th day.
21
TAF
Time and Type of Change Expected
How do I determine the time and type of changes that will occur?
KSTL 051130Z 0512/0612 14008KT 5SM BR BKN030
WS010/18025KT
TEMPO 0513/0516 1 1/2SM BR
FM051600 16010KT P6SM NSW SKC
BECMG 0522/0524 20013G20KT 4SM SHRA OVC020
PROB40 0600/0606 2SM TSRA OVC008CB
BECMG 0606/0608 21015KT P6SM NSW SCT040
Civilian and military forecasters alike encode the time and type of change
expected with TEMPO, FM, and BECMG groups.
TEMPO represents a temporary condition. In this example, TEMPO
0513/0516 1 1/2SM BR reads, ―Temporary condition between
1300Z and 1600Z on the 5th day of 1 1/2 statute mile visibility in mist.‖
Only the temporary changing conditions are included in TEMPO groups.
FM means ―from‖ and indicates a rapid weather change where all data
groups in the previous line are superseded. In this example, FM051600
reads, ―From 1600Z on the 5th day…‖.
BECMG means ―becoming‖ or a ―gradual change‖ in meteorological
conditions and becomes the predominant group by the end time listed.
In this example, BECMG 0522/0524 reads ―Becoming from 2200Z to
2400Z on the 5th day.‖
PROB40 (civilian use only) represents a 40% probability or chance of
conditions occurring along with associated weather conditions (wind,
visibility, sky conditions).
In this example, PROB40 0600/0606 2SM TSRA 0VCOO8CB reads,
―40% chance between 0000Z and 0600Z on the 6th day of visibility 2
statute miles in moderate thunderstorms, 800 overcast cumulonimbus
clouds.‖
22
TAF
Wind
How do I determine the wind speed and direction?
KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030
WS010/18040KT QNH2960INS
BECMG 0513/0514 16010KT 3200 -SHRA OVC020 QNH2959INS
TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020
BECMG 0516/0517 29008KT 3200 -RA OVC030 620304
QNH2958INS
BECMG 0518/0519 31012G22KT 9999 NSW SCT040 WSCONDS
520004 QNH2952INS
BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/0518Z
TM01/0611Z
The data group after the valid time and followed by KT (knots) is
the forecast wind speed.
The first three digits within a wind group are the true direction to
the nearest 10 degrees from which the wind will blow. The next two
digits are the sustained speed. If gusts are forecasted, the next two
or three digits following the ―G‖ are the ―gust,‖ the maximum wind
speed in a ten-minute window.
In this example, 14005KT, 16010KT, 21015G30KT, 29008KT,
31012G22KT, and 30008KT are the wind direction and speed
groups.
In the first wind group, the wind is forecasted to blow from 140
degrees (true) at a sustained speed of 05 knots. No gust is
forecasted.
In the third wind group, the wind is forecasted to blow from 210
degrees (true) at a sustained speed of 15 knots, gusting up to 30
knots.
23
TAF
Visibility
How do I determine the forecast visibility?
KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030
WS010/18040KT QNH2960INS
BECMG 0513/0514 16010KT 3200 -SHRA OVC020 QNH2959INS
TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020
BECMG 0516/0517 29008KT 3200 -RA OVC030 620304
QNH2958INS
BECMG 0518/0519 31012G22KT 9999 NSW SCT040 WSCONDS
520004 QNH2952INS
BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/0518Z
TM01/0611Z
In the military and at most overseas locations, visibility is forecasted in
meters. The 4-character group following the wind is the forecast visibility.
In the KBLV example, 8000, 3200, 1600, 3200, and 9999 are the forecast
visibilities in meters. 9999 is the greatest value forecasted. A value of 9999
indicates a forecast visibility of greater than 9000 meters (7 statute miles or
greater). To convert visibility values from meters to statute miles, see
Attachment 3 or the Flight Information Handbook conversion tables.
Overseas locations may use the contraction ―CAVOK‖ (ceiling and visibility
OK) when there is no significant weather, the visibility is 10 km or greater,
and the ceilings are greater than 5,000 ft.
KSTL 051130Z 0512/0612 14008KT 5SM BR BKN030
WS010/18025KT
TEMPO 0513/0516 1 1/2SM BR
FM051600 16010KT P6SM NSW SKC
BECMG 0522/0524 20013G20KT 4SM SHRA OVC020
PROB40 0600/0606 2SM TSRA OVC008CB
BECOMG 0606/0608 21015KT P6SM NSW SCT040
In the CONUS, civilian TAFS forecast visibility in statute miles up to
6 statute miles, beyond which P6SM is used to indicate forecast visibility
greater than 6 statute miles.
24
TAF
Type of Weather
How do I determine if there is any forecast weather?
KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030
WS010/18040KT QNH2960INS
BECMG 0513/0514 16010KT 3200 -SHRA OVC020 QNH2959INS
TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020
BECMG 0516/0517 29008KT 3200 -RA OVC030 620304
QNH2958INS
BECMG 0518/0519 31012G22KT 9999 NSW SCT040 WSCONDS
520004 QNH2952INS
BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/0518Z
TM01/0611Z
The weather data group (forecast precipitation or obstruction to
visibility) follows the visibility data group.
In this example, BR means ―mist,‖ -SHRA means ―light rain
showers,‖ TSRA means a ―thunderstorm with moderate rain,‖ and
-RA means ―light rain.‖ NSW (no significant weather) is used to
indicate that the weather or obscuration listed in the previous group
is no longer expected to occur. Absence of a weather or obscuration
group means that no weather or obscuration is expected during the
forecast period.
To methodically decode a weather group, look for six key elements
(depending on the phenomena, one or more may be omitted). In
order, these elements are: Intensity (symbol preceding the code),
Proximity, Descriptor, Precipitation Description, Obscuration
(other than precipitation) and Other.
For a complete table of weather group elements and examples, see
Figure 1 on page 12, or reference Section C, ―METAR and TAF
Code‖, of the Flight Information Handbook.
25
TAF
Clouds
How do I determine the layers of forecast clouds?
KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030
WS010/18040KT QNH2960INS
TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020
BECMG 0520/0521 30008KT 9999 SKC QNH2950INS T08/0518Z
TM01/0611Z
Cloud height is forecasted in hundreds of feet. Add two zeros to the end of
the value given. In this example, FEW030, BKN008CB, OVC020, and
SKC represent the values 3,000 few, 800 broken cumulonimbus, 2,000
overcast, and sky clear. Overseas locations may use the contraction
CAVOK (ceiling and visibility OK) when there is no significant weather,
the visibility is 10 km or greater, and the ceilings are greater than 5,000 ft.
In place of cloud layers, vertical visibility in hundreds of feet will appear
in a TAF cloud group when the sky is forecast to be totally obscured. For
example, VV002 represents a vertical visibility of 200 feet. Vertical
visibility in a TAF represents the forecast ceiling.
When a surface-based partial obscuration is forecasted, it will be encoded
as FEW000, SCT000, or BKN000 in the cloud layer area. A remark will
appear after the altimeter that will describe the phenomena responsible.
For example, FG SCT000 would indicate the weather element causing the
obscuration is caused by fog and the layer amount is SCT. Surface-based
partial obscurations will not be considered a ceiling.
Sky coverage (eighths):
SKC or CLR
FEW
SCT
BKN
OVC
Sky clear
Few (Trace – 2/8)
Scattered (3/8 – 4/8)
* Broken (5/8 – 7/8)
* Overcast (8/8)
* The lowest layer reported as broken or overcast constitutes a ―ceiling‖
A similar table can be found in Section C, ―METAR and TAF Code‖, of
the Flight Information Handbook.
26
TAF
Wind Shear
How do I determine if wind shear is in the forecast?
KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030
WS010/18040KT QNH2960INS
BECMG 0513/0514 16010KT 3200 -SHRA OVC020 QNH2959INS
TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020
BECMG 0516/0517 29008KT 3200 -RA OVC030 620304
QNH2958INS
BECMG 0518/0519 31012G22KT 9999 NSW SCT040 WSCONDS
520004 QNH2952INS
BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/0518Z
TM01/0611Z
A wind shear group is included if non-convective low-level winds
(up to 2,000 feet) will change in speed and/or direction and result in
a shearing action. WS indicates forecast wind shear and is followed
by a 3-digit height in hundreds of feet AGL, a slant character, ‖/,‖
and forecast wind at the height indicated. WS010/18040KT reads,
―forecast wind shear at 1,000 feet above the station; wind at 1,000
feet is from 180 degrees (true) at 40 knots.‖
The remark WSCONDS is used to indicate the potential for wind
shear when there is not enough information available to reliably
predict the height, direction and speed of the wind shear. WSCONDS
is normally used beyond the first 6 hours of the TAF.
For some locations, the wind shear group will follow the minimum
altimeter setting group (in the TAF remarks) instead of following
the cloud group.
27
TAF
Icing
How do I determine forecast icing conditions?
KBLV 051153Z 0512/0612 14005KT 8000 BR FEW030
WS010/18040KT QNH2960INS
BECMG 0516/0517 29008KT 3200 -RA OVC030 620304
QNH2958INS T08/0518Z TM01/0611Z
If forecasted, the icing group will be prefixed by the number 6, and follows
the cloud group. To decode, follow these instructions:
1. Find the icing designator ―6‖ following the cloud group (620304).
2. The next digit gives icing type and intensity (620304). See Figure 3.
3. The next three digits give the base of the icing layer in hundreds of feet
(620304).
4. The last digit provides the icing layer depth in thousands of feet
(620304), so add this value to the base height to determine the top limit
of the icing conditions.
In the above example, the icing forecast will read, ―light rime icing (in
cloud) from 3,000 to 7,000 feet.‖
Figure 3. Icing Intensity Decode Table
CODE
DECODE
0
Trace Icing or None (see note)
1
Light Mixed Icing
2
Light Rime Icing In Cloud
3
Light Clear Icing In Precipitation
4
Moderate Mixed Icing
5
Moderate Rime Icing In Cloud
6
Moderate Clear Icing In Precipitation
7
Severe Mixed Icing
8
Severe Rime Icing In Cloud
9
Severe Clear Icing In Precipitation
Note: Air Force code ―0‖ means a trace of icing,
World Meteorological Organization code ―0‖ means no icing
28
TAF
Turbulence
How do I determine forecast turbulence conditions?
KBLV 051153Z 0512/0612 14005KT 8000 FEW030 QNH2960INS
BECMG 0518/0519 31012G22KT 9999 NSW SCT040 520004
QNH2952INS T08/0518Z TM01/0611Z
If forecasted, the turbulence code will be prefixed by the number 5, and
will follow the cloud or icing group. To decode, follow these instructions:
1. Look for the turbulence designator ―5‖ that follows the cloud or icing
group (520004).
2. The next digit will determine the intensity (520004). See Figure 4.
3. The next three digits will determine the base limit of the turbulence
layer in hundreds of feet AGL (520004).
4. The last digit will determine the turbulence layer depth in thousands of
feet (520004), so add this value to the base height to determine the top
limit of the turbulence conditions.
In the above example, the turbulence forecast will read, ―occasional
moderate turbulence in clear air from the surface to 4,000 feet.‖
Figure 4. Turbulence Intensity Decode Table
CODE
DECODE
0
1
2
3
4
5
6
7
8
9
X
None
Light turbulence
Moderate turbulence in clear air, occasional
Moderate turbulence in clear air, frequent
Moderate turbulence in cloud, occasional
Moderate turbulence in cloud, frequent
Severe turbulence in clear air, occasional
Severe turbulence in clear air, frequent
Severe turbulence in cloud, occasional
Severe turbulence in cloud, frequent
Extreme turbulence
Note:
Occasional is defined as occurring less than 1/3 of the time
29
TAF
Minimum Altimeter Setting
How do I determine the forecast lowest altimeter setting?
KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030
WS010/18040KT QNH2960INS
BECMG 0513/0514 16010KT 3200 -SHRA OVC020 QNH2959INS
TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020
BECMG 0516/0517 29008KT 3200 -RA OVC030 620304
QNH2958INS
BECMG 0518/0519 31012G22KT 9999 NSW SCT040 WSCONDS
520004 QNH2952INS
BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/0518Z
TM01/0611Z
Forecast minimum altimeter settings are only found in military
forecasts. These are near the end of the line, beginning with QNH
(minimum) and ending with INS (inches). To convert altimeter
settings from inches Hg to hectopascals (millibars), use Attachment
4 or the Flight Information Handbook conversion tables.
In the example shown above, QNH2960INS, QNH2959INS,
QNH2958INS, QNH2952INS, and QNH2950INS are read as
minimum altimeter settings of 29.60, 29.59, 29.58, 29.52, and 29.50
inches of mercury, respectively.
30
TAF
Temperatures
How do I determine the forecast temperatures?
KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030
WS010/18040KT QNH2960INS
BECMG 0513/0514 16010KT 3200 -SHRA OVC020 QNH2959INS
TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020
BECMG 0516/0517 29008KT 3200 -RA OVC030 620304
QNH2958INS
BECMG 0518/0519 31012G22KT 9999 NSW SCT040 WSCONDS
520004 QNH2952INS
BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/0518Z
TM01/0611Z
Forecast temperatures for the forecast period are routinely found
only in military TAFs. They are found on the last line, following the
minimum altimeter, beginning with the designator ―T,‖ maximum
temperature first. To convert temperature units from Celsius to
Fahrenheit, use Attachment 2 or the Flight Information Handbook
conversion tables.
In this example, T08/0518Z indicates a forecast maximum
temperature of 8°C on the 5th day at 1800Z, and TM01/0611Z
indicates a forecast minimum temperature of -1°C on the 6th day at
1100Z.
HERBERT J. CARLISLE, Lt Gen, USAF
DCS, Operations, Plans, and Requirements
31
Attachment 1
GLOSSARY OF REFERENCES
AND SUPPORTING INFORMATION
References
AFMAN 15-111, Surface Weather Observations
AFMAN 15-124, Meteorological Codes
ICAO Document 8896AN/893/4, Manual of Aeronautical Meteorological Practice,
ISBN 92-9194-345-2
AFMAN 15-111 USAFESUP1, United States Air Forces in Europe Supplement to
Surface Weather Observations
FAA Order 7340.1, Contractions
Abbreviations and Acronyms
AGL—Above Ground Level
FAA—Federal Aviation Administration
ICAO—International Civil Aviation Organization
METAR—Aviation Routine Weather Report
NATO—North Atlantic Treaty Organization
RVR—Runway Visual Range
SPECI—Aviation Selected Special Weather Report
TAF—Terminal Aerodrome Forecast
UTC—Coordinated Universal Time, sometimes called ―zulu time‖
32
Attachment 2
TEMPERATURE CONVERSION
Degrees Fahrenheit to Degrees Celsius
ºF
ºF
ºF
ºF
ºC
From
To
ºC
From
To
ºC
From
To
ºC
128.3 130.0
54
83.3
85.0
29
38.3
40.0
04
-4.8
-3.1
M20
126.5 128.2
53
81.5
83.2
28
36.3
38.2
03
-6.6
-4.9
M21
124.7 126.4
52
79.7
81.4
27
34.7
36.2
02
-8.4
-6.7
M22
122.9 124.6
51
77.9
79.6
26
32.9
34.6
01
-10.2 -8.5
M23
121.1 122.8
50
76.1
77.8
25
32.0
32.8
00
-12.0 -10.3 M24
119.3 121.0
49
74.3
76.0
24
31.2
31.9 M00 -13.8 -12.1 M25
117.5 119.2
48
72.5
74.2
23
29.4
31.1 M01 -15.6 -13.9 M26
115.7 117.4
47
70.7
72.4
22
27.6
29.3 M02 -17.4 -15.7 M27
113.9 115.6
46
68.9
70.6
21
25.8
27.5 M03 -19.2 -17.5 M28
112.1 113.8
45
67.1
68.8
20
24.0
25.7 M04 -21.0 -19.3 M29
110.3 112.0
44
65.3
67.0
19
22.2
23.9 M05 -22.8 -21.1 M30
108.5 110.2
43
63.5
65.2
18
20.4
22.1 M06 -24.6 -22.9 M31
106.7 108.4
42
61.7
63.4
17
18.6
20.3 M07 -26.4 -24.7 M32
104.9 106.6
41
59.9
61.6
16
16.8
18.5 M08 -28.2 -26.5 M33
103.1 104.8
40
58.1
59.8
15
15.0
16.7 M09 -30.0 -28.3 M34
101.3 103.0
39
56.3
58.0
14
13.2
14.9 M10 -31.8 -30.1 M35
99.5 101.2
38
54.5
56.2
13
11.4
13.1 M11 -33.6 -31.9 M36
97.7
99.4
37
52.7
54.4
12
9.6
11.3 M12 -35.4 -33.7 M37
95.9
97.6
36
50.9
52.6
11
7.8
9.5
M13 -37.2 -35.5 M38
94.1
95.8
35
49.1
50.8
10
6.0
7.7
M14 -39.0 -37.3 M39
92.3
94.0
34
47.3
49.0
09
4.2
5.9
M15 -40.8 -39.1 M40
90.5
92.2
33
45.5
47.2
08
2.4
4.1
M16 -42.6 -40.9 M41
88.7
90.4
32
43.7
45.4
07
0.6
2.3
M17 -44.4 -42.7 M42
86.9
88.6
31
41.9
43.6
06
-1.2
+0.5 M18 -46.2 -44.5 M43
85.1
86.8
30
40.1
41.8
05
-3.0
-1.3
From
To
33
M19 -48.0 -46.5 M44
Attachment 3
REPORTABLE VISIBILITY CONVERSION
Statute Miles (SM) to Meters (m)
STATUTE
MILES
0
1/16
1/8
METERS
0000
0050
0100
0150
0200
STATUTE
MILES
1-1/8
1-1/4
1-3/8
METERS
1800
1900
2000
2100
2200
STATUTE
MILES
2-3/4
3
METERS
4400
4500
4600
4700
4800
3/16
0250
0300
1-1/2
2300
2400
-
4900
5000
¼
5/16
0350
0400
0450
0500
1-5/8
1-3/4
2500
2600
2700
2800
4
5
6
6000
7000
8000
9000
3/8
0550
0600
1-7/8
2900
3000
7
8
9999
9999
-
0650
0700
2
3100
3200
9
10
9999
9999
½
0750
0800
-
3300
3400
11
12
9999
9999
5/8
-
0900
1000
1100
2-1/4
-
3500
3600
3700
13
14
15
9999
9999
9999
¾
7/8
1
-
1200
1300
1400
1500
1600
1700
2-1/2
-
3800
3900
4000
4100
4200
4300
20
25
30
35
40
Etc.
9999
9999
9999
9999
9999
9999
Double underline marks a change in increment
34
Attachment 4
RUNWAY VISIBILITY CONVERSION
RVR IN
STATUTE NAUTICAL
HUNDREDS
METERS
MILES
MILES
OF FEET
12
1/4 *
2/10
370
16
1/4
2/10
490
3/10
20
3/8
610
4/10
24
1/2
730
6/10
32
5/8
970
7/10
40
3/4
1220
8/10
45
7/8
1370
9/10
50
1
1520
1-1/10
60
1-1/4
1830
* Helicopter Only
35
KILO
METERS
.4
.5
.6
.7
1.0
1.2
1.4
1.5
1.8
Attachment 5
PRESSURE CONVERSION
Millibars (mb)* to Inches of Mercury (inches Hg)
_ _ _0 _ _ _1 _ _ _2 _ _ _3 _ _ _4 _ _ _5 _ _ _6 _ _ _7 _ _ _8 _ _ _9
094_ 27.76 27.79 27.82 27.85 27.88 27.91 27.94 27.96 27.99 28.02
095_ 28.05 28.08 28.11 28.14 28.17 28.20 28.23 28.26 28.29 28.32
096_ 28.35 28.38 28.41 28.44 28.47 28.50 28.53 28.56 28.59 28.61
097_ 28.64 28.67 28.70 28.73 28.76 28.79 28.82 28.85 28.88 28.91
098_ 28.94 28.97 29.00 29.03 29.06 29.09 29.12 29.15 29.18 29.21
099_ 29.23 29.26 29.29 29.32 29.35 29.38 29.41 29.44 29.47 29.50
100_ 29.53 29.56 29.59 29.62 29.65 29.68 29.71 29.74 29.77 29.80
101_ 29.83 29.85 29.88 29.91 29.94 29.97 30.00 30.03 30.06 30.09
102_ 30.12 30.15 30.18 30.21 30.24 30.27 30.30 30.33 30.36 30.39
103_ 30.42 30.45 30.47 30.50 30.53 30.56 30.59 30.62 30.65 30.68
104_ 30.71 30.74 30.77 30.80 30.83 30.86 30.89 30.92 30.95 30.98
105_ 31.01 31.04 31.07 31.10 31.12 31.15 31.18 31.21 31.24 31.27
* A millibar (mb) is equal to a hectopascal (hPa)
36
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