How to Decode METAR, TAF, and pilot reports

 

How to Decode METAR, TAF, and pilot reports.

A METAR is a codified observation message indicating an airfield weather conditions observed at a given time. Such a message is established every hour.

 

A SPECI message is identical to a METAR but is established punctually instead of regularly. It is a special observation message highlighting any significant change since the last METAR or SPECI was issued.

 

A TAF is a terminal forecast.  It is issued every few hours, and is updated if necessary sooner.

Raw METAR  (Meteorological Terminal Air Report) 

KBOS 040954Z 04011KT 7SM RA OVC008 09/07 A2978 RMK AO2 SLP083 P0008 T00890067 $

KBOS 040854Z 05008KT 6SM RA BR BKN007 OVC019 09/08 A2977 RMK AO2 SLP080 P0009 60031 T00940078 56014 $

KBOS 040754Z 04011KT 10SM -RA BKN008 BKN013 OVC055 09/07 A2978 RMK AO2 SLP084 P0010 T00940072 $

 

Raw TAF (Terminal Air Forecast)

KBOS 040907Z 0409/0512 05008KT 6SM RA BR BKN007 OVC019

  FM041200 04011G20KT 3SM -RADZ BR OVC008

  FM041700 02012G21KT P6SM VCSH OVC008

  FM042200 03008KT P6SM OVC010

  FM050500 08004KT P6SM OVC020

  FM050800 09005KT P6SM -RA OVC015

KBOS       Boston

040954Z   Date 04th Time 0954zulu  (5:54AM)

04011KT  Winds 040 at 11knots

7SM          Visibility 7statue Miles

RA            Conditions - Raining

OVC008   Cloud cover overcast at 800'

09/07        Temperature 09deg C; Dewpoint 07

A2978       Altimeter 2978

RMK        Remarks

AO2         Automated Weather Station - A02 site is automated and HAS a precipitation sensor. 

SLP083    Sea Level Pressure 

P0008  

T00890067  Expanded Temperature & Dewpoint  0 + 08.9   + 06.7   

A02 means that the site is automated and HAS a precipitation sensor. If it were AO1, there would be no precip sensor

Aviation Routine Weather Report (METAR)

 

Example:

METAR	KRNO	210056Z	05012KT	10SM	-SN	BKN050	02/M08	A3016	RMK AO2 SLP228	T00221083
1	2	3	4	5	6	7	8	9	10	11

 

1.     Message Type

·         METAR: routine weather report

·         SPECI: special weather report, triggered by a weather change

·         AUTO will be first item for ASOS/AWOS generated reports

2.     ICAO Identifier (4-letter)

3.     Issuance Time DDHHMMz (UTC)

·         COR (CCD in Canada) if correction to observation

4.     Wind

·         First 3 digits: True Wind direction or average if variable (VRB).

Note: If the wind direction varies 60° or more, the direction will be indicated with a V (e.g. 180V250)

·         Next 2 digits: Mean speed and units

-        KT=knots, KMH=kilometers/hour, MPS=meters/second

·         G (gust) as needed – 2 or 3 digit maximum speed

·         Calm will be indicated by 00000KT

·         Example: 18012G22KT 150V240

5.     Horizontal Visibility

·         Prevailing Visibility (PV)

-        Statue miles (SM) and fractions (US & Canada only) or,

-        4 digit minimum visibility in meters, and,

-        Lowest value and direction, as required (shown as a remark)

 

 

·         Runway Visual Range (RVR)

-        R: Runway Designator, L/R/C as needed, “/”

-        P/M: Plus/Minus (US only)

-        4 digit value (feet/meters)

-        V (variability) with tendency U/D/N (up/down/no change)

-        Example: R18R/1200FTV/U

6.     Present Weather (Constructed sequentially):

·         Intensity

·         Descriptor

·         Precipitation (Dominant type is listed first if more than one type reported)

·         Obscuration

·         Other

 

 

Qualifier				Weather Phenomena
Intensity or Proximity		Descriptor		Precipitation		Obscuration		Other
–	Light	BC	Patches	DZ	Drizzle	BR	Mist (1)	DS	Duststorm
		BL	Blowing (2)	GR	Hail (3)	DU	Widespread Dust
No qualifier	Moderate	DR	Low Drifting (4)	GS	Small Hail and/or snow pellets (5)	FG	Fog (6)	FC	Funnel Clouds
		FZ	Freezing	IC	Ice Crystals	FU	Smoke	PO	Dust/Sand Whirls
+	Heavy	MI	Shallow	PL	Ice Pellets	HZ	Haze	SQ	Squall(s)
		PR	Partial	RA	Rain	SA	Sand
VC	Vicinity (7)	SH	Shower(s)	SG	Snow Grains	VA	Volcanic Ash	SS	Sandstorm
		TS	Thunderstorm	SN	Snow
				UP	Unknown Precipitation
(1)    Visibility at least 1000m (5/8SM) but not more than 9600m (6SM) (2)    6 feet or more above the ground (3)    Hailstone diameter 5mm or greater (4)    Less than 6 feet above the ground (5)    Hailstone diameter less than 5mm (6)    Visibility less than 1000m (5/8SM) (7)    Within 8KM (5SM) of the aerodrome but not at the aerodrome

 

 

7.     Sky Cover

·         Cloud Description

-        Amount in eights (octas)

SKC=Sky Clear (clear below 12,000 for ASOS/AWOS)

NSC=No significant clouds

FEW=Few (1/8 to 2/8 sky cover)

SCT=Scattered (3/8 to 4/8 sky cover)

BKN=Broken (5/8 to 7/8 sky cover)

OVC=Overcast (8/8 sky cover)

8.     Terperature/Dewpoint (whole °C) (preceded by M=minus)

·         First 2 digits = temperature

·         Second 2 digits = dewpoint

9.     Altimeter setting (QNH) and indicator (A=InHg, Q=hPa)

10. Supplementary Information

·         RE = Recent weather followed by weather codes

·         WS = Windshear, followed by:

-        TKOF/LDG (takeoff/landing)

-        RWY (2 digits runway identifier and designator L/R/C)

·         RMK = Remark

-        SLP = Sea Level Pressure

-        T00221083 (Expanded temp/dewpoint)

1^st, 5^th digits: 0=plus, 1=minus

2^nd-4^th digits: temp (decimal missing) (02.2)

6^th-8^th digits: dewpoint (decimal missing) (-8.3)

11. Trend Forecast (2 hours from time of observation) (Not used in US)

·         PROB and 2 digits (30 or 40) = probability 30% or 40%

·         Used to indicate the probability of occurance of alternate element(s) or temporary fluctuations

·         Change Indicator

-        BECMG = Becoming (used where changes are expected to reach or pass through specified values

-        TEMPO = Temporary (fluctuations of less than one hour duration

-        NOSIG = No significant change

 

·         Forecast Wind (same as item 4)

·         Forecast Visibility (as item 5) (9999 indicates 10Kilometers vis or greater)

·         Forecast Weather (as item 6)

·         Forecast Cloud (as item 7)

 

EIGHT FIGURE GROUP

An eight digit telegraphic code on runway conditions for some European airports may be included at the end of hourly METAR messages:

Eight Figure Group
1st two digits	Runway designator
3rd digit	Runway deposits
4th digit	Extent of runway contamination
5th and 6th digits	Depth of deposit
7th and 8th digits	Friction coefficient or braking action

 

The first two digits correspond to the runway designator.  For parallel runways LEFT is indicated by the designator only (18L would be displayed as 18) and RIGHT has 50 added (18R would be displayed as 68).  When all runways are affected the figure group 88 will be used.  If 99 appears as the first two digits the information is a repetition of the last message because no new message has been received in time for transmission.

 

Runway Deposits		Extent of Runway Contamination		Depth of Deposit
0	Clear & Dry	1	<10% contaminated (covered)	00	Less than 1mm
1	Damp	2	11% to 25% contaminated (covered)	01-90	Measurement in mm
2	Wet or water particles			92	10cm
3	Rime or frost covered (normally > 1mm)	5	26%-50% contaminated (covered)	93	15cm
4	Dry Snow	9	51%-100% contaminated (covered)	94	20cm
5	Wet Snow			95	25cm
6	Slush	/	Not reported (runway clearance in progress)	96	30cm
7	Ice			97	35cm
8	Compacted or rolled snow			98	40cm or more
9	Frozen ruts or ridges			99	Runway not operational due to snow, slush, ice, large drifts or runway clearance, depth not reported
/	Not reported (runway clearance in progress)			//	Not operationally significant or not measurable

Note: the quoted depth is the mean of a number of reading or if operationally significant the greatest depth measured.

 

 

Friction Coefficient or Braking Action (7th and 8th digits)
28	Friction coefficient 0.28
35	Friction coefficient 0.35
91	Braking action poor
92	Braking action medium to poor
93	Braking action medium
94	Braking action medium to good
95	Braking action good
99	Figures unreliable
//	Braking action not reported or runway not operations or airport closed.

Note: Where braking action is assessed at a number of points along the runway the mean value will be transmitted or if operationally significant the lowest value.

If measuring equipment does not allow measurement of friction with satisfactory reliability (such as contaminated by wet snow, slush or loose snow) the figure 99 will be used.

 

Automated Surface/Weather Observation System (ASOS/AWOS)

 

The Automated Surface Observation System (ASOS) and Automated Weather Observation System (AWOS) observe and report altimeter setting, wind direction and speed, temperature, dewpoint, visibility and ceiling/cloud height.  Pilots may use automated weather observation from ASOS/AWOS, provided the observations from ASOS/AWOS, provided the observation includes all necessary weather parameters, and that the system is installed, operated and maintained according to applicable FAA standards.

Pilots may obtain the ASOS/AWOS reports through written, radio or telephone methods.  Refer to METAR section for ASOS/AWOS report format.

ASOS/AWOS observations may not be used as an authorized weather observation if either the visibility or the wind is reported as missing.

ASOS/AWOS observation are unusable for the purpose of initiating or conducting an instrument approach if the altimeter setting is reported as missing unless an approved alternate source is noted on the applicable approach chart.

 

 

TAF

Example:

TAF	KRNO	202320Z	210024	04010G20KT	P6SM	-SN	SCT060
1	2	3	4	5	6	7	8

 

FM0300	05008KT	P6SM	SCT060
9

1.     Type of report (TAF)

2.     ICAO Identifier (4 letter)

3.     Issuance time (DDHHMMZ) UTC.  May precede ICAO identifier at some airports.

4.     Day (DD).  Hour begins (1^st two digits XX) Hour ends (2^nd two digits).

5.     Wind. First 3 digits true wind direction or average if variable.  If the wind varies 60° or more, the direction will be indicated with a V (e.g. 120V190).  Next two digits Mean speed and units (KT=knots, KMH=kilometers per hour, or MPS=meters per second).  G=gust as needed (2 or 3 digits).  Calm will be indicated by 00000XXX (XXX will be replaced by the appropriate units).

6.     Horizontal visibility.

a.      Prevailing visibility (PV)

-        Statute Miles (SM) and fractions (US only), or

-        4 digit minimum visibility in meters, and

-        Lowest value and direction, as required

b.     Runway Visual Range (RVR)

-        R=Runway Designator, L/R/C as needed, “/”

-        P/M=Plus/Minus (US Only)

-        4 digit value (feet/meters)

-        V(variability) with tendency U/D/N (up/down/no change)

7.     Present Weather (constructed sequentially):

·         Intensity

·         Descriptor

·         Precipitation (Dominant type is listed first if more than one type reported)

·         Obscuration

·         Other

 

 

Qualifier				Weather Phenomena
Intensity or Proximity		Descriptor		Precipitation		Obscuration		Other
–	Light	BC	Patches	DZ	Drizzle	BR	Mist (1)	DS	Duststorm
		BL	Blowing (2)	GR	Hail (3)	DU	Widespread Dust
No qualifier	Moderate	DR	Low Drifting (4)	GS	Small Hail and/or snow pellets (5)	FG	Fog (6)	FC	Funnel Clouds
		FZ	Freezing	IC	Ice Crystals	FU	Smoke	PO	Dust/Sand Whirls
+	Heavy	MI	Shallow	PL	Ice Pellets	HZ	Haze	SQ	Squall(s)
		PR	Partial	RA	Rain	SA	Sand
VC	Vicinity (7)	SH	Shower(s)	SG	Snow Grains	VA	Volcanic Ash	SS	Sandstorm
		TS	Thunderstorm	SN	Snow
				UP	Unknown Precipitation
(8)    Visibility at least 1000m (5/8SM) but not more than 9600m (6SM) (9)    6 feet or more above the ground (10)Hailstone diameter 5mm or greater (11)Less than 6 feet above the ground (12)Hailstone diameter less than 5mm (13)Visibility less than 1000m (5/8SM) (14)Within 8KM (5SM) of the aerodrome but not at the aerodrome

 

8.     Sky Cover

·         Cloud Description

-        Amount in eights (octas)

SKC=Sky Clear (clear below 12,000 for ASOS/AWOS)

NSC=No significant clouds

FEW=Few (1/8 to 2/8 sky cover)

SCT=Scattered (3/8 to 4/8 sky cover)

BKN=Broken (5/8 to 7/8 sky cover)

OVC=Overcast (8/8 sky cover)

-        Height: 100s of feet (30m)

-        Type CB (Cumulonimbus) or TCU (Towering cumulus) only.

·         CAVOK – Ceiling and visibility OK (not used in US).  Replaces visibility/RVR, present weather, and clouds if:

-        Visibility is 10KM or greater

-        No CB and no cloud below 1500M (5000ft) or below highest minimum sector altitude whichever is greater, and

-        No precipitation, thunderstorm, sandstorm, duststorm, shallow fog, or low drifting dust/sand/snow.

·         Vertical visibility (when sky obscured) – VV100’s of feet (30m) (VV /// means vertical visibility unavailable)

Optional groups (Forecast icing, Turbulence, & Temperature)

T= Temperature group indicator

Temperature: two digits (if below 0°, will be preceded by “M”),”/”

Expected time temperature will be reached: 2 digits, Z.

Icing Layer(s): 6 digits for each icing group (6WXXXY). 

6: first digit of the icing group is always a 6.

Icing type: Second digit:

	Icing Intensity	Location
0	None	None
1	Light Icing
2	Light Icing	In cloud
3	Light Icing	In precipitation
4	Moderate
5	Moderate	In cloud
6	Moderate	In precipitation
7	Severe
8	Severe	In cloud
9	Severe	In precipitation

Icing layer’s base: next 3 digits.  (direct reading in 100s of ft/30s meters)

Thickness of icing layer: last digit:

	Thickness of Layer
0	Up to top of cloud
1	300m/1000’
2	600m/2000’
3	900m/2000’
4	1200m/4000’
5	1500m/5000’
6	1800m/6000’
7	2100m/7000’
8	2400m/8000’
9	2700m/9000’

 

Turbulence Layer(s): 6 Digits (5WXXXY)

5: first digit of the turbulence group is always a 6.

Turbulence type: Second digit:

	Intensity	Weather Condition	Frequency
0	None
1	Light
2	Moderate	Clear	Occasional
3	Moderate	Clear	Frequent
4	Moderate	Cloud	Occasional
5	Moderate	Cloud	Frequent
6	Severe	Clear	Occasional
7	Severe	Clear	Frequent
8	Severe	Cloud	Occasional
9	Severe	Cloud	Frequent

Turbulence layer’s base: next 3 digits.  (direct reading in 100s of ft/30s meters)

Thickness of turbulence layer: last digit:

	Thickness of Layer
0	Up to top of cloud
1	300m/1000’
2	600m/2000’
3	900m/2000’
4	1200m/4000’
5	1500m/5000’
6	1800m/6000’
7	2100m/7000’
8	2400m/8000’
9	2700m/9000’

 

 

 

SIGNIFICANT CHANGES IN FORECAST

1.     Probability groups(s)

-        PROB and 2 digits (30 or 40).

-        Probability 30% or 40% used to indicate the probability of occurrence of alternate element(s) or temporary fluctuations.  (US will only use 40%).  May also be listed as TEMPO by some non US weather services.

-        TIME (beginning 2 digits, ending 2 digits)

-        Forecast weather phenomena.

2.     Forecast Change

o       Indicators

§         BCMG=Becoming (used when changes are expected to reach or pass through specified values)

§         FM = From and 2 digit time

§         TO = To and 2 digit time

§         TEMPO = Temporary fluctuation

o       Forecast weather phenomena.

 

 

METAR /TAF Abbreviations / Cloud Types

 

A	Hail		AMOS	Automatic Meteorological observing system
ABM	Abeam
ABV	Above		AMS	Air mass
AC	Altocumulus		ANLYS	Analysis
ACCAS	Altocumulus castellanus		AO1	Automated observation with no precip discriminator (rain/snow)
ACCUM	Altocumulate
ACLD	Above clouds		AO2	Automated observation with precip discriminator (rain/snow)
ACSL	Standing lenticular altocumulus
ACTV	Active		AOA	At or above
ACYC	Anticyclonic		AOB	At or below
ADDN	Addition		AP	Anomalous propagation
ADRNDCK	Adirondack		APCH	Approach
ADVCTN	Advection		APRNT	Apparent
ADVY	Advisory		AS	Altostratus
AFDK	After Dark		ASOS	Automated surface observing system
AFT	After		ATLC	Atlantic
AFTN	Afternoon		ATTM	At this time
AGL	Above Ground Level		AURBO	Aurora Borealis
AGN	Again		AUTOB	Automatic weather reporting system
AHD	Ahead		AWOS	Automatic weather observing system
AIREP	Air Report		B	Beginning of precipitation (time in minutes (wx reports only)
AIRMET	Airmen’s Meteorological Info
ALF	Aloft		BACLIN	Baroclinic prognosis
ALG	Along		BATROP	Barotropic or barotropic prognosis
ALGHNY	Allegheny		BC	British Columbia
ALQDS	All quadrants		BCFG	Fog patches
ALSTG	Altimeter setting		BCKG	Backing
ALTA	Alberta		BCM(G)	Become (becoming)
ALUTN	Alleutian		BD	Blowing dust (wx reports only)
AMD	Amended forecast		BFDK	Before dark
AMDT	Amendment		BINOVC	Breaks in overcast

 

BKN	Broken		CLD	Cloud
BLDUP	Build up		CLR	Clear
BLKHLS	Black Hills		CAS	Clear and smooth
BLO	Below		CNL	Cancel
BN	Blowing sand (wx reports only)		CNDN	Canadian
BNDRY	Boundary		CNTRL	Central
BOVC	Base of overcast		CNVG	Converge
BRAF	Braking action fair		CNVTV	Convective
BRAG	Braking action good		CONT-DVD	Continental Divide
BRAN	Braking action nil		CONTRAILS	Condensation trails
BRAP	Braking action poor		CS	Cirrostratus
BRF	Brief		CST	Coast
BRKSHR	Berkshire		CTGY	Category
BS	Blowing snow (wx reports only)		CTSKLS	Catskills
BTWN	Between		CU	Cumulus
BY	Blowing spray (wx reports only)		CUF	Cumuliform
CA	Clear above (PIREP only)		CUFRA	Cumulus fractus
CAN	Canada		CYC	Cyclonic
CARIB	Caribbean		CYCLGN	Cyclogenesis
CASCDS	Cascades		D	Dust (wx reports only)
CAVOK	Ceiling and visibility OK		DABRK	Daybreak
CAVU	Ceiling and visibility unlimited		DALGT	Daylight
CB	Cumulonimbus		DCAVU	Clear or scattered cloud and vis greater than 10, remainder or report missing (wx reports only)
CBMAM	Cumulonimbus mammatus
CC	Cirrocumulus
CCSL	Standing lenticular cirrocumulus		DCR	Decreased
CDFNT	Cold Front		DIAM	Diameter
CFP	Cold front passage		DKTS	Dakotas
CHC	Chance		DMSH	Diminish
CHSPK	Chesapeake		DNS	Dense
CIG	Ceiling		DNSLP	Downslope

 

DNSTRM	Downstream		FLG	Falling
DP	Deep		FLRY	Flurry
DPNG	Deepening		FNT	Front
DPTH	Depth		FNTGNS	Frontogenesis
DRFT	Drift		FNTLYS	Frontolysis
DRZL	Drizzle		FORNN	Forenoon
DSIPT	Dissipate		FRMG	Forming
DSNT	Distant		FROPA	Frontal passage
DTRT	Deteriorate		FRST	Frost
DRG	During		FRZ	Freeze
DWNDFTS	Downdrafts		FRZLVL	Freezing level
DWPNT	Dew point		FRZN	Frozen
E	Ending of precipitation (time in minutes)(wx reports only)		FZRANO	Freezing rain sensor not operating
			FT	Terminal Forecast
E	Equatorial (air mass)		G	Gusts reaching (knots)(wx reports only)
E	Estimated (wx reports only)		GF	Ground fog (wx reports only)
ELNGT	Elongate		GFDEP	Ground fog estimated (feet) deep
EMBDD	Embedded		GICG	Glaze icing
ENRT	Enroute		GLFALSK	Gulf of Alaska
ENTR	Entire		GLFCAL	Gulf of California
ERY	Early		CLFMEX	Gulf of Mexico
EVE	Evening		GLFSTLAWR	Gulf of St. Lawrence
EXCP	Except		GNDFG	Ground Fog
EXPC	Expect		GRAD	Gradient
EXTRM	Extreme		GRTLKS	Great Lakes
F	Fog (wx reports only)		GSTS	Gusts
FA	Area Forecast		GSTY	Gusty
FAH	Farenheit		H	Haze (wx reports only)
FAX	Facsimile		HCVIS	High clouds visible
FIBI	Filed but impracticable to transmit		HDEP	Haze layer estimated (feet) deep
FINO	Wx report will not be filed for transmission		HDSVLY	Hudson Valley

 

HI	High		LABRDR	Labrador
HLSTO	Hailstones		LFT	Lift
HLYR	Haze layer aloft		LGT	Light
HURCN	Hurricane		LIFR	Low IFR (wx reports only)
HVY	Heavy		LK	Lake
IC	Ice crystal		LSR	Loose snow on runway
ICG	Icing		LST	Local Standard Time
ICGIC	Icing in clouds		LTGCA	Lightning cloud to air
ICGICIP	Icing in clouds and precipitation		LTGCC	Lightning cloud to cloud
ICGIP	Icing in precipitation		LTGCCCG	Lightning cloud to cloud, cloud to ground
IF	Ice fog		LTGCG	Lightning cloud to ground
IFR	Instrument flight rules		LTGCW	Lightning cloud to water
INCR	Increase		LTGIC	Lightning in clouds
INDC	Indicate		LTLCG	Little change
INDEF	Indefinite		LTNG	Lightning
INLD	Inland		LYR	Layer or layered or layers
INSTBY	Instability		M	Measured ceiling (wx reports only)
INTR	Interior		M	Missing (wx reports only)
INTR-MTRGN	Inter-mountain region		MAN	Manitoba
INTS	Intense		MDT	Moderate
INTST	Intensity		METAR	Scheduled aviation observation
INVRN	Inversion		MEX	Mexico
IOVC	In overcast		MHKVLY	Mohawk Valley
IP	Ice pellets (wx reports only)		MIDN	Midnight
IR	Ice on runway		MIFG	Patches of shallow fog not deeper than 2 meters
JTSTR	Jetstream		MLTLVL	Melting level
K	Smoke		MNLD	Mainland
KDEP	Smoke layer estimated (feet) deep		MOGR	Moderate or greater
KLYR	Smoke layer aloft		MOV	Move
KOCTY	Smoke over city		MRGL	Marginal
L	Drizzle (wx reports only)		MRNG	Morning

 

 

 

MRTM	Maritime		PGTSND	Puget Sound
MSTLY	Mostly		PIBAL	Pilot balloon observation
MTN	Mountain		PK WND	Peak wind (wx report only)
MVFR	Marginal VFR		PNHDL	Panhandle
NB	New Brunswick		PNO	Rain gauge not operating
NEW ENG	New England		PPINA	Radar weather report not available or omitted
NFLD	Newfoundland
NGT	Night		PPINE	Radar weather report no echoes observed
NOSPL	No special observations taken (wx reports only)		PPINO	Radar weather report equipment inoperative due to breakdown
NS	Nimbostratus		PPIOK	Radar weather report equipment operation resumed
NS	Nova Scotia
NVA	Negative vorticity advection		PPIOM	Radar weather report equipment inoperative due to maintenance
OBS	Observation
OBSC	Obscure		PRBLTY	Probability
OCFNT	Occluded front		PRESFR	Pressure falling rapidly
OCLD	Occlude		PRESRR	Pressure rising rapidly
OCLN	Occlusion		PRJMP	Pressure jump (wx reports only)
OFP	Occluded frontal passage		PROG	Prognosis or prognostic
OFSHR	Offshore		PSR	Packed snow on runway
OMTNS	Over mountains		PTCHY	Patchy
ONSHR	On shore		PTLY	Partly
ONT	Ontario		PVA	Positive vorticity advection
ORGPHC	Orographic		PWINO	Precipitaion identifier information not available (wx reports only)
OTAS	On top and smooth		Q	Squall (wx reports only)
OTLK	Outlook		QSTNRY	Quasistationary
OVC	Overcast		QUE	Quebec
OVR	Over		R	Rain (wx reports only)
PAC	Pacific		RADAT	Radiosonde observation data
PCPN	Precipitation		RAOB	Radiosonde observation
PDW	Priority Delayed Weather		RCKY	Rocky Mountains
PEN	Peninsula		RDG	Ridge

 

RGD	Ragged		TDWR	Terminal Doppler Weather Radar
RHINO	Radar echo height information not available		TEMP	Temperature
RHINO	Radar range height indicator not operating on scan		THDR	Thunder
RIOGD	Rio Grande		THRU	Through
RNFL	Rainfall		THRUT	Throughout
ROBEPS	Radar operating below prescribed standard		THSD	Thousand
RPD	Rapid		TIL	Until
RSG	Rising		TMW	Tomorrow
RUF	Rough		TNGT	Tonight
RVRNO	Runway visual range missing		TOP	Cloud top
RW	Rain shower (wx reports only)		TOVC	Top of overcast
S	Snow (wx reports only)		TPG	Topping
SASK	Saskatchewan		TROF	Trough
SAWRN	Supplementary Aviation Weather Reporting System		TROP	Tropopause
SC	Stratocumulus		TRPCL	Tropical
SCSL	Stratocumulus standing lenticular		TRRN	Terrain
SCT	Scattered		TSHWR	Thundershower
SELS	Severe local storms		TSNO	Lightning sensor not available
SFERICS	Atmospherics		TSTM	Thunderstorm
SG	Snow grains (wx reports only)		TURB	Turbulence
SHFT	Shift (wx reports only)		TURBC	Turbulence
SHLW	Shallow		TWD	Toward
SHWR	Shower		TWR	Tower
SIERNEV	Sierra Nevada		TWRG	Towering
SIR	Snow and ice on runway		TYPH	Typhoon
SPECI	Unscheduled aviation observation		U	Intensity unknown (wx reports only)
SLF	Sea level pressure		UA	Routine PIREP
SLPNO	Sea level pressure not available		UDDF	Up and down drafts
SNINCR	Snow increasing rapidly		UNSTBL	Unstable
TCU	Towering cumulus		UNSTDY	Unsteady
TDA	Today		UPR	Upper

 

 

 

UTC	Universal coordinated time		WND	Wind
UUA	Urgent PIREP		WRM	Warm
V	Variable (wx reports only)		WRMFNT	Warm front
VCSH	Showers in vicinity		WRNG	Warning
VCTY	Vicinity		WSHFT	Wind shift
VFR	Visual flight rules		WW	Severe weather forecast
VLY	Valley		WX	Weather
VRBL	Variable		X	Obscured sky condition
VSBY	Visibility		XCP	Except
WDLY	Widely		YDA	Yesterday
WEA	Weather		Z	UTC
WFP	Warm front passage		ZRNO	Freezing rain information not available (wx reports only)
WK	Weak
WKN	Weaken
WL	Will

 

 

 

AIRMETs

 

Hazardous weather advisories of moderate intensity will be issued as AIRMETs.  AIRMETs are issued when the following conditions are expected to cover an area of at least 3000 square miles:

Moderate icing.

Moderate turbulence.

Sustained surface winds of 30 knots or more.

Ceilings less than 1,000 ft. and/or visibility less than 3 miles affecting 50% of an area at one time.

Extensive mountain obscuration.

 

SIGMET's

 

Hazardous weather advisories of severe intensity will be issued as SIGMETs.  SIGMETs are reported as convective or nonconvective.

Convective SIGMETs report only thunderstorms and related phenomena (tornadoes, heavy precipitation, hail and high surface winds.

Nonconvective SIGMETs are issued when the following conditions occur or are expected to cover an area of at least 3,000 square miles:

Severe or extreme turbulence or clear air turbulence (CAT) not associated with thunderstorms.

Severe icing not associated with thunderstorms.

Widespread duststorms, sandstorms, or volcanic ash lowering surface or inflight visibilities to below three miles.

Volcanic eruption.

 

Volcanic eruption SIGMET's are identified by an alphanumeric designator which consists of an alphabetic identifier and issuance number. The first time an advisory is issued for a phenomenon associated with a particular weather system, it will be given the next alphabetic designator in the series and will be numbered as the first for that designator. Subsequent advisories will retain the same alphabetic designator until the phenomenon ends. In the conterminous U.S., this means that a phenomenon that is assigned an alphabetic designator in one area will retain that designator as it moves within the area or into one or more other areas. Issuance’s for the same phenomenon will be sequentially numbered, using the same alphabetic designator until the phenomenon no longer exists. Alphabetic designators NOVEMBER through YANKEE, except SIERRA and TANGO are only used for SIGMET's, while designators SIERRA, TANGO and ZULU are used for AIRMET's.

 

 

Pilot Weather Report (PIREP)

 

Pilots must report any significant weather or flight condition to ATC as soon as possible. Additionally, all significant weather or flight conditions that clearly differ from the forecast should be reported to Dispatch.  There is no specific format for this type of report.

NOTE: Report windshear encountered during departure or approach to the tower controller as soon as possible.Use the term PIREP to ensure that it is rebroadcast.