A Guide to Aviation Weather Contractions

Abbreviations

The following is a list of abbreviations and acronyms used in aviation operations:

A/FD Airport/Facility Directory
AC Advisory Circular
AGL Above Ground Level
ASOS Automated Surface Observing System
ATIS Automatic Terminal Information Service
AWOS Automated Weather Observing System
AWW Alert Weather Watch
CWA Center Weather Advisory
CWSU Center Weather Service Unit
DVFR Defense VFR (Flight Plan)
EFAS Enroute Flight Advisory Service
FA Area Forecast
FAA Federal Aviation Administration
FD Wind and Temperature Aloft Forecast
FSS Flight Service Station
FT Terminal Forecast
HIWAS Hazardous In-flight Weather Advisory Service
IFR Instrument Flight Rules
LIFR Low IFR Weather Conditions
MSL Mean Sea Level
MVFR Marginal VFR Weather Conditions
NOAA National Oceanic Atmospheric Administration
NOTAM Notice to Airmen
NWS National Weather Service
PATWAS Pilot's Automatic Telephone Weather Answering Service
PBS Public Broadcasting Service
TIBS Telephone Information Briefing Service
TWEB Transcribed Weather Enroute Broadcast
VFR Visual Flight Rules

Pilot Briefing Guide

Preparation for your weather briefing:

A.M. WEATHER is a 15-minute television weather program designed for pilots and can be seen on more than 300 PBS stations Monday through Friday mornings. Check your local TV listings for exact time and station.

Pilots may obtain Federal pre-flight weather briefings tailored to your individual needs. Any one of three types of briefings may be requested: standard, abbreviated or outlook.

A standard briefing should normally be requested even when you have received prerecorded or mass media weather information (e.g., TWEB, A.M. WEATHER, etc.). After giving the briefer the necessary background information, you will automatically receive the following:

* Not provided by NWS briefers

An abbreviated briefing should be requested if you have used prerecorded or mass media weather information to make a go/no-go decision and only selected additional information is required. You should provide the pertinent background information, tell the briefer what previous information source you have used, and ask for an abbreviated briefing with specified observation or forecast products.

An outlook briefing should be requested for long-range flight planning. This briefing contains forecasts for a flight beginning more than 6 hours in the future. An abbreviated or standard briefing should then be obtained when closer to the time of departure.

Contractions

Used in National Weather Service Aviation Products and in Area Forecast Discussions

ALF aloft NM nautical mile(s)
AMS air mass NMRS numerous
ACFT aircraft MRTM maritime
ACTV active MSL mean sea level
AGL above ground level MXD mixed
ARND around NOTAM notice to airmen
ASL above sea level OBSC obscure
BKN broken OCLN occlusion
BLZD blizzard OCNL occasional, occasionally
BRF brief OCR occur
BTWN between OTLK outlook
BTR better OTRW otherwise
BYD beyond OVC overcast
CAT clear air turbulence PCPN precipitation
CAVOK ceiling and visibility OK PIREP pilot report
CHG change PRST persist
CIG ceiling PBL probable
CONT continue PSBL possible
CSDRBL considerable PSG passing/passage
CVR cover PTLY partly
DCR decrease PVL prevail
DMSH diminish RA rain
DNS dense RAREP radar weather report
DRZL drizzle RESTR restrict
DSIPT dissipate RDG ridge
DVLP develop RGD ragged
EMBDD embedded RMN remain
EXTRM extreme RPD rapid
EXTSV extensive RTE route
FCST forecast RUF rough
FLRY flurry SCT scattered
FQT frequent SCTR sector
FROPA frontal passage SHFT shift
FROSFC frontal surface SHWR shower
GNDFG ground fog SKC sky clear
GRDL gradual SLGT slight
HGT height SMK smoke
HLSTO hailstones SNW snow
HND hundred SQLN squall line
HURCN hurricane STBL stable
HVY heavy STG strong
ICGIC icing in clouds SVR severe
ICGIP icing in preparation THN thin
IMDT immediate TSHWR thundershower
INCR increase TSTM thunderstorm
INDEF indefinite TURBC turbulence
INTSFY intensify TWD toward
ISOLD isolated UPSLP up slope
JTSTR jet stream VRBL variable
KT knot(s) VSBY visibility
LGT light WDLY widely
LMT limit WEA weather
LVL level WK weak
LWR lower WV wave
LYR layer WX weather



Aviation Hourly Weather Observations (Preceded METARS)

LOCATION IDENTIFIER, TYPE AND TIME OF REPORT SKY CONDITION AND CEILING VISIBILITY, WEATHER, AND OBSTRUCTIONS TO VISION SEA-LEVEL PRESSURE TEMPERATURE AND DEW POINT WIND DIRECTION, SPEED AND CHARACTER ALTIMETER SETTING REMARKS AND CODED DATA
MCI SA 0758 15 SCT M15 OVC 1R-F 132 /58/56 /1807 /993/ R01VR20V40
LOCATION IDENTIFIER:
3 or 4 alphanumeric characters (airport identifier).
TYPE OF REPORT:
SA = Scheduled record (hourly) observation.
SP = Special observation indicating a significant change in one or more of the observed elements.
RS = SA that also qualifies as an SP.
USP = Urgent special observation (tornado).
TIME OF REPORT:
Coordinated Universal Time (UTC or Z) using 24-hour clock. Example: 2255 = 10:55 PM.
SKY CONDITION AND CEILING:
Sky condition contractions are for each layer in ascending order. Numbers preceding contractions are base height in hundreds of feet above ground level (AGL). Sky condition contractions are: (-- = Thin).
CLR = Clear: Less than 0.1 sky cover.
SCT = Scattered: 0.1 to 0.5 sky cover.
BKN= Broken: 0.6 to 0.9 sky cover.
OVC = Overcast: More than 0.9 sky cover.
__ X = Partially obscured. 0.9 or less of sky hidden by precipitation or obstruction to vision (cloud bases at the surface).
X = Obscured: entire sky hidden.
A letter preceding height of a layer identifies a ceiling and indicates how ceiling was obtained.
E = Estimated. M = Measured.
W = Vertical visibility into obscured sky.
V following height = variable ceiling.
VISIBILITY:
Reported in statute miles and fractions.
V = Variable.
WEATHER & OBSTRUCTIONS TO VISION:
A Hail GF Ground fog
D Dust ZR Freezing rain
R Rain BD Blowing dust
F Fog SP Snow pellets
S Snow BN Blowing sand
H Haze SW Snow showers
K Smoke BS Blowing snow
IF Ice Fog T Thunderstorm
L Drizzle T+ Severe thunderstorm
IP Ice Pellets RW Rain showers
IC Ice Crystals IPW Ice pellet showers
SG Snow grains ZL Freezing drizzle
__ = Light. (no sign) = Moderate. + = Heavy.
SEA-LEVEL PRESSURE:
Pressure in hectopascals millibars): Shown as 3 digits. Leading or 10 and decimal point is omitted. Examples: 150 = 1015.0 950 = 995.0
TEMPERATURE AND DEW POINT:
Reported in Degrees Fahrenheit (F).
WIND DIRECTION SPEED & CHARACTER:
Direction in tens of degrees from true north, speed in knots. 0000 = calm. G = gusty. Q = squall. Peak speed of gusts in the past ten minutes follows G or Q. WSHFT in Remarks = windshift occurred at time indicated. Example: 3627G40 = 360 at 27 peak gusts 40 knots.
ALTIMETER SETTING:
Actual altimeter setting with first digit omitted.
Examples: 005 = 30.05" 992 = 29.92"
RUNWAY VISUAL RANGE (RVR):
RVR is reported for some stations. Values) during 10 minutes prior to observation are given in hundreds of feet. Runway number precedes RVR report. V = Variable.
DECODED REPORT:
Kansas City Int'l Airport: Record observation completed at 0758Z. 1500 feet scattered clouds, measured ceiling 2500 feet overcast, visibility 1 mile, light rain, fog, sea level pressure 1013.2 hectopascals, temperature 58F, dewpoint 56F, wind 180, 7 knots, altimeter setting 29.93". Runway 01 visual range varying from 2000 to 4000 feet in the past 10 minutes.
PILOT REPORTS (PIREPS):
A PIREP describes actual in-flight conditions. Pilots are encouraged to provide PIREPS to an FAA facility. Example: UA/OV FRR 275045/TM 1745 /FL330 /TP B727 /SK 185 BKN 220 280 BKN 310 /TA-53 /WV 290120 /TB LGT-MDT CAT ABAV 310. Decoded: Pilot report, Front Royal VORTAC, 275 radial 45nm, at 1745Z, flight level 330; Boeing 727; cloud base 18500 broken, tops 22000, second layer 28000 broken, tops 31000; air temperature minus 53 degrees Celsius; wind 290 degrees 120 knots; light to moderate clear air turbulence above 31000.

KEY TO ASOS (AUTOMATED SURFACE OBSERVING SYSTEM) WEATHER OBSERVATIONS

LOCATION IDENTIFIER, TYPE OF REPORT TIME OF REPORT STATION TYPE

SKY CONDITION AND CEILING BELOW 12,000'

VISIBILITY, WEATHER, AND OBSTRUCTIONS TO VISION

SEA-LEVEL PRESSURE/ TEMPERATURE/DEW POINT/WIND DIRECTION, SPEED AND CHARACTER/ALTIMETER SETTING/

REMARKS

AUTOMATED REMARKS GENERATED AUTOMATICALLY IF CONDITIONS EXIST. AUGMENTED REMARKS ADDED IF CONDITIONS EXIST AND CERTIFIED WEATHER OBSERVER IS ATTENDING THE SYSTEM

STATUS REMARKS

SYSTEM GENERATED

HTM RS 1755 A02A

M19V OVC

1R--F

125/36/34/2116G24/990

R29LVR10V50 CIG 16V22 TWR VSBY 2 PK WI\ND 2032/1732 PRESFR

ZRNO $

LOCATION IDENTIFIER:
3 or 4 alphanumeric characters (usually airport identifier).
TYPE OF REPORT:
SA = Scheduled record (hourly) observation.
SP = Special observation indicating a significant change in one or more of the observed elements.
RS = SA that also qualifies as an SP.
USP = Urgent special observation to report tornado.
TIME OF REPORT:
Coordinated Universal Time (UTC or Z) using 24-hr. clock.
STATION TYPE:
AO2 = Unattended (no observer) ASOS.
AO2A = Attended (observer present) ASOS.
SKY CONDITION AND CEILING BELOW 12,000' AGL:
Sky condition contractions are for each layer in ascending order. Numbers preceding contractions are base height in hundreds of feet above ground level (AGL).
CLR BLO 120 = Less than 0.1 sky cover below 12,000'.
SCT = Scattered: 0.1 to 0.5 sky cover.
BKN = Broken: 0.6 to 0.9 sky cover.
OVC = Overcast: More than 0.9 sky cover.
A letter preceding the height of a base identifies a ceiling layer and indicates how ceiling height was determined.
M = Measured W = Indefinite
E = Estimated X = Obscured sky
The letter V is added immediately following the height of a base to indicate a variable ceiling: see Remarks.
VISIBILITY:
Reported in statute miles and fractions from 1/4 through 10+. V = variable; see Remarks.

PRESENT WEATHER:

TORNADO (when augmented).

T = Thunder (when augmented): see Status Remarks.
R = Liquid precipitation that does not freeze (e.g. rain).
P -- = Light precipitation in unknown form.
ZR = Liquid precipitation that freezes on impact (e.g., freezing rain): see Status Remarks.
A = Hail (when augmented).
S = Frozen precipitation other than hail (e.g., snow).
+ = Heavy. No sign = Moderate. -- = Light.
OBSTRUCTIONS TO VISION:
Reported only when visibility is less than 7 statute miles.
F = Fog H = Haze
VOLCANIC ASH (when augmented).
SEA-LEVEL PRESSURE:
Tenths of Hectopascals (millibars). Shown as last 3 digits only without decimal point (e.g., 950 - 995.0).
TEMPERATURE AND DEW POINT:
Degrees Fahrenheit.
WIND DIRECTION SPEED AND CHARACTER:
Direction in tens of degrees from true north. Voice broadcast in degrees from magnetic. Speed in knots.
0000 = calm. E = estimated. G = gusts Q = squalls. Variable wind, peak wind, wind shift: see Remarks.
ALTIMETER SETTING:
Hundredths of inches of mercury. Shown as last 3 digits only without decimal point (e.g., 005 = 30.05 inches).
MISSING DATA: Reported as M.
DENSITY ALTITUDE: Included on voice broadcast only when 1000 more feet above airport elevation.
REMARKS: Can Include:
RVR (Runway Visual Range), VOLCANIC ASH, VIRGA, TWR VSBY (Tower visibility), SFC VSBY (surface visibility), VSBY V (Variable visibility), CIG V (Variable ceiling), WSHFT (Windshift), PK WND (Peak wind), WND V (Variable wind direction), PCPN (Precipitation amount), PRESRR (Pressure rising rapidly), PRESFR (Pressure falling rapidly), PRJMP (Pressure jump), B (Time weather began), E (Time weather ended).
STATUS REMARKS:
PWINO = Present weather information not available.
ZRNO = Freezing rain information not available.
TNO - Thunderstorm information not available.
$ = Maintenance check indicator.
DECODED REPORT: Hometown Municipal Airport, record special observation at 1755 UTC. ASOS with observer. Measured ceiling 1900 feet variable, overcast. Visibility 1 mile, light rain, fog. Sea-level pressure 1012.5 hectopascals, temperature 36F, dew point 34F, wind from 210 true at 16 knots gusting to 24 knots, altimeter 29.90 inches. Runway 29L visual range 1000 variable to 5000 feet. Ceiling 1600 variable to 2200 feet, tower visibility 2 miles, peak wind 200 true at 32 knots at 1732 UTC< pressure falling rapidly. Freezing rain information not available, maintenance check indicator.
NOTE: Refer to ASOS Guide for Pilots and the Airman's Information Manual for more information. Refer to the Airport/Facility Directory, aeronautical charts, and related publications for broadcast, telephone and location data. Check Notices to Airmen for ASOS system status.

KEY TO AWOS (AUTOMATED WEATHER OBSERVING SYSTEM) OBSERVATIONS

LOCATION IDENTIFIER TYPE OF REPORT
TIME OF REPORT
STATION TYPE

SKY CONDITION AND CEILING BELOW 12,000'

VISIBILITY

TEMPERATURE/DEW POINT/ WIND DIRECTION, SPEED AND CHARACTER/ ALTIMETER SETTING

REMARKS: AUTOMATED REMARKS GENERATED AUTOMATICALLY IF CONDITIONS EXIST, AUGMENTED REMARKS ADDED IF CONDITIONS EXIST AND CERTIFIED WEATHER OBSERVER IS ATTENDING THE SYSTEM
HTM SA 1755 AWOS M20 OVC 1V 36/34/2015G25/990/ P010/VSBY 1/2V2 WND 17V23/WEA: R--F

LOCATION IDENTIFIER: 3 or 4 alphanumeric characters (usually the airport identifier).
TYPE OF REPORT: SA = Scheduled record (routine) observation. All observations identified as SA. Most are transmitted at 20-minute intervals (approximately 15, 35 and 55 minutes past each hour).
TIME OF REPORT: Coordinated Universal Time (UTC or Z) using 24-hour clock.
STATION TYPE: AWOS = Automated Weather Observing System site. Note: In the future, some systems will use "AO" designators.
SKY CONDITION AND CEILING: Sky condition contractions are for each layer in ascending order. Numbers preceding contractions are base heights in hundreds of fee above ground level (AGL).
CLR BLO 120 = No clouds below 12,000 ft.
SCT = Scattered: 0.1 to 0.5 sky cover.
BKN = Broken: 0.6 to 0.9 sky cover.
OVC = Overcast: More than 0.9 sky cover.
X = Obscured sky --X = Partially obscured
A letter preceding the height of a base identifies a ceiling layer and indicates how ceiling height was determined.
M = Measured W = Indefinite
VISIBILITY: Reported in statute miles and fractions. Visibility greater than 10 not reported. V = variable: see Automated Remarks
TEMPERATURE AND DEW POINT: Reported in degrees Fahrenheit.
WIND DIRECTION, SPEED & CHARACTER: Direction in tens of degrees from true north, except voice broadcast is in degrees magnetic. Speed in knots. 0000 = calm. G = gusts. See Automated Remarks for variable direction.
ALTIMETER SETTING: Hundredths of inches of mercury. Shown as last 3 digits only without decimal point (e.g., 30.05 inches = 005).
PRESENT WEATHER/OBSTRUCTIONS TO VISION: Reported only when observer is available. See Augmented Remarks. In the future, some systems will report precipitation, fog, and haze in the body of the observation.
AUTOMATED REMARKS: Precipitation accumulation reported in hundredth of inches (e.g., P110 - 1.10 inches; P010 - 0.10 inch). WND V = variable wind direction. VSBY V = variable visibility. DENSITY ALTITUDE is included in the voice broadcast when more than 1000 feet above airport elevation.
MISSING DATA: Reported as "M."
AUGMENTED REMARKS: "WEA: "Indicates manual observer data. Remarks include operationally significant weather conditions within a five mile radius of the airport (e.g., thunderstorms, precipitation, obstructions to vision when visibility is 3 miles or less, fog banks). Standard weather observation contractions are used.
DECODED REPORT: Hometown Municipal Airport, observation at 1755 UTC, AWOS report. Measured ceiling 2000 feet overcast. Visibility 1 mile variable. Temperature 36 degrees (F), dew point 34 degrees (F), wind from 200 degrees true at 15 knots gusting to 25 knots, altimeter setting 29.90 inches. Precipitation accumulation during past hour 0.10 inch. Visibility a\variable between and 2 miles. Wind direction variable from 170 degrees to 230 degrees true. Observer reports light rain (R--) and fog (F).
NOTE: Refer to the Airman's Information Manual for more information. Refer to the Airport/Facility Directory, aeronautical charts, and related publications for broadcast, telephone and location data. Check for AWOS system status.