Sections 10-19 | Appendixes

Table A-1. Definition of Common Terms Used in En route Forecasts and Advisories (FA, SIGMET, AIRMET, TCA, VAA, ROFOR)

Contraction

Translation

Definition

EMBD

Embedded thunderstorms or cumulonimbus

Thunderstorms or cumulonimbus (CB) clouds that are embedded in cloud layers or concealed by haze.

EXTREME TURB

Extreme Turbulence

Turbulence in which aircraft is violently tossed about and is practically impossible to control. It may cause structural damage.

FIR

Flight Information Region

An airspace of defined dimensions within which flight information service and alerting service are provided.

FL

Flight Level

A surface of constant atmospheric pressure which is related to a specific pressure datum, 1013.2 hectopascals (hPa), and is separated from other such surfaces by specific pressure intervals.

FRQ

Frequent thunderstorms or cumulonimbus

Consisting of elements with little or no separation between adjacent thunderstorms with a maximum spatial coverage greater than 75 percent of the area affected by the phenomena at a fixed time or during the period of validity.

IMC

Instrument Meteorological Conditions

Ceiling greater than or equal to 500 feet to less than 1,000 feet and/or visibility greater than or equal to 1 to less than 3 miles. LIMC is a sub-category of IMC, thus, IMC conditions are ceiling less than 1,000 feet and /or visibility less than 3 miles.

ISOL

Isolated thunderstorms or cumulonimbus

Consisting of individual features affecting an area with a maximum spatial coverage less than 50 percent of the area affected by the phenomena at a fixed time or during the period of validity.

LINE TS

Line (of thunderstorms)

A line of thunderstorms being at least 60 miles long with thunderstorms affecting at least 40 percent of its length

LIMC

Low Instrument Meteorological Conditions

Ceiling less than 500 feet and/or visibility less than 1 SM. LIMC is a sub-category of Instrument Meteorological Conditions.

MVMC

Marginal Visual Meteorological Conditions

Ceiling greater than or equal to 1,000 feet to less than or equal to 3,000 feet and/or visibility greater than or equal to 3 to less than or equal to 5 miles.

MOD ICE

Moderate Icing

The rate of accumulation is such that even short encounters become potentially hazardous and use of deicing/anti-icing equipment or diversion is necessary.

MOD TURB

Moderate Turbulence

Turbulence that causes changes in attitude (pitch, roll, yaw) and/or altitude, but the aircraft remains in positive control at all times. It usually causes variations in indicated airspeed.

Contraction

Translation

Definition

MT OBSC

Mountain Obscuration

Conditions over significant portions of mountainous geographical areas are such that pilots in flight should not expect to maintain visual meteorological conditions or visual contact with mountains or mountain ridges near their route of flight.

OBSC

Obscured thunderstorm or cumulonimbus

Obscured by haze, smoke or cloud or cannot be readily seen due to darkness.

OCNL

Occasional thunderstorms or cumulonimbus

An area with a maximum spatial coverage between 50 and 75 percent of the area affected by the phenomena at a fixed time of during the period of validity.

SCT

Scattered

25 to 50 percent of area affected.

SEV ICE

Severe Icing

The rate of accumulation is such that normal deicing/anti-icing equipment fails to reduce or control the hazard. Immediate diversion is necessary.

SEV TURB

Severe Turbulence

Turbulence that causes large, abrupt changes in altitude and/or attitude. It usually causes large variations in indicated airspeed. Aircraft may be momentarily out of control.

VMC

Visual Meteorological Conditions

Ceiling greater than 3,000 feet and visibility greater than 5 miles.

VOLCANIC ERUPTION

Volcanic Eruption

A volcano eruption has occurred when an eruption report is received from a volcano observatory. A volcanic eruption is also considered to have occurred regardless of volcano observatory notification if reported by PIREP, or ground observer, or if remote sensing data indicates that an eruption has occurred based on satellite imagery or WSR-88D radar data or any other reliable sources are identified.

VOLCANIC ASH

Volcanic Ash

Any ash that can be seen by any one or more of the following: satellite imagery (visible, IR, multi channel or TOMS), PIREPs, ground observations, radar and VAFTAD (In the event volcanic ash is entrained in clouds, the volcanic ash will be treated as visible using the VAFTAD as guidance).

WDLY SCT

Widely Scattered

Less than 25 percent of area affected

WDSPR

Widespread

50 percent or greater of the area affected

A

AAA

(or AAB, AAC…etc., in sequence) Amended meteorological message (message type designator)

AAWU

Alaskan Aviation Weather Unit

ABNDT

Abundant

ABNML

Abnormal

ABT

About

ABV

Above

AC

Altocumulus or Convective Outlook

ACARS

Aircraft communication and addressing system

ACC

Altocumulus Castellanus

ACCID

Notification of an aircraft accident

ACCUM

Accumulate

ACFT

Aircraft

ACPY

Accompany

ACRS

Across

ACSL

Altocumulus Standing Lenticular

ACT

Active or activated or activity

ACYC

Anticyclone

ADA

Advisory area

ADDN

Addition or additional

ADJ

Adjacent

ADQT

Adequate

ADQTLY

Adequately

ADRNDCK

Adirondack

ADVCT

Advect

ADVCTD

Advected

ADVCTG

Advecting

ADVCTN

Advection

ADVCTS

Advects

ADVN

Advance

ADVNG

Advancing

ADVY

Advisory

ADVYS

Advisories

AFCT

Affect

AFCTD

Affected

AFCTG

Affecting

AFT

After…(time or place)

AFTN

Afternoon

AFSS

Automated Flight Service Station

AGL

Above ground level

AGN

Again

AGRD

Agreed

AGRS

Agrees

AGRMT

Agreement

AHD

Ahead

AIREP

Air-report

AIRMET

Airman’s Meteorological Information (Information concerning en-route weather phenomena which may affect the safety of low-level aircraft operations)

AK

Alaska

AL

Alabama

ALF

Aloft

ALG

Along

ALGHNY

Allegheny

ALQDS

All quadrants

ALSTG

Altimeter setting

ALT

Altitude

ALTA

Alberta

ALTHO

Although

ALTM

Altimeter

ALUTN

Aleutian

AMD

Amend or amended (used to indicate amended meteorological message; message type designator)

AMDG

Amending

AMDT

Amendment

AMP

Amplify

AMPG

Amplifying

AMPLTD

Amplitude

AMS

AMSL

Above mean sea level

AMT

Amount

ANLYS

Analysis

ANS

Answer

AOA

At or above

AOB

At or below

AP

Airport or anomalous propagation

APCH

Approach

APCHG

Approaching

APCHS

Approaches

APLCN

Appalachian

APLCNS

Appalachians

APPR

Appear

APPRG

Appearing

APPRS

Appears

APR

April

APRNT

Apparent

APRX

Approximate or approximately

AR

Arkansas

ARFOR

Area Forecast (in aeronautical meteorological code)

ARND

Around

AS

Altostratus

ASC

Ascend to or ascending to

ASSOCD

Associated

ASSOCN

Association

AT…

At (followed by time at which weather change is forecast to occur)

ATLC

Atlantic

ATP

At…(time or place)

ATTM

At this time

ATTN

Attention

AUG

August

AVBL

Available or availability

AVG

Average

AWC

Aviation Weather Center

AWT

Awaiting

AZ

Arizona

AZM

Azimuth

B

BACLIN

Baroclinic

BAJA

Baja, California

BASE

Cloud base

BATROP

Barotropic

BC

British Columbia

BCFG

Fog patches

BCH

Beach

BCKG

Backing

BDA

Bermuda

BDRY

Boundary

BECMG

Becoming

BFR

Before

BGN

Begin

BGNG

Beginning

BGN

Begins

BHND

Behind

BINOVC

Breaks in overcast

BKN

Broken

BL…

Blowing (followed by DU = dust, SA = sand or SN = snow)

BLD

Build

BLDG

Building

BLDUP

Buildup

BLKHLS

Black Hills

BLKT

Blanket

BLKTG

Blanketing

BLKTS

Blankets

BLO

Below clouds

BLW

Below…

BLZD

Blizzard

BND

Bound

BNTH

Beneath

BR

Mist

BRF

Brief

BRK

Break

BRKG

Breaking

BRKHIC

Breaks in higher clouds

BRKS

Breaks

BRKSHR

Berkshire

BRM

Barometer

BLDU

Blowing Dust

BLSA

Blowing Sand

BLSN

Blowing Snow

BTL

Between layers

BTN

Between

BYD

Beyond

C

C

Degrees Celsius (Centigrade) or centre (runway identification)

CA

California

CAA

Cold air advection

CAPE

Convective Available Potential Energy

CARIB

Caribbean

CASCDS

Cascades

CAT

Category or Clear air turbulence

CAVO

Visibility, cloud and present weather better than prescribed values or conditions

CB

Cumulonimbus

CC

Cirrocumulus

CCA

(or CCB, CCC…etc., in sequence) Corrected meteorological message

CCLDS

Clear of clouds

CC

Counterclockwise

CCSL

Cirrocumulus Standing Lenticular

CDFNT

Cold front

CDN

Coordination

CFP

Cold front passage

CHC

Chance

CHCS

Chances

CHG

Modification (message type designator)

CHGD

Changed

CHGG

Changing

CHGS

Changes

CHSPK

Chesapeake

CI

Cirrus

CIG

Ceiling

CIGS

Ceilings

CIT

Near or over large towns

CLA

Clear type of ice formation

CLD

Cloud

CLDNS

Cloudiness

CLDS

Clouds

CLKWS

Clockwise

CLR

Clear(s) or cleared to…or clearance

CLRG

Clearing

CLRS

Clears

CLSD

Close or closed or closing

CM

Centimeter

CMPLX

Complex

CNL

Cancel or cancelled

CNDN

Canadian

CNTR

Center

CNTRD

Centered

CNTRL

Central

CNTY

County

CNTYS

Counties

CNVG

Converge

CNVGG

Converging

CNVGNC

Convergence

CNVTN

Convection

CNVTV

Convective

CNVTVLY

Convectively

CONFDC

Confidence

CO

Colorado

COMPR

Compare

COMPRG

Comparing

COMPRD

Compared

COMPRS

Compares

COND

Condition

CONS

Continuous

CONT

Continue(s) or continued

CONTLY

Continually

CONTG

Continuing

CONTRAILS

Condensation trails

CONTDVD

Continental Divide

CONUS

Continental U.S.

COORD

Coordinates

COR

Correct or correction or corrected (used to indicate corrected meteorological message; message type designator

COT

At the coast

COV

Cover or covered or covering

CPBL

Capable

CPC

Climate Prediction Center

CRLC

Circulate

CRLN

Circulation

CRNR

Corner

CRNRS

Corners

CRS

Course

CS

Cirrostratus

CSDR

Consider

CSDRBL

Considerable

CST

Coast

CSTL

Coastal

CT

Connecticut

CTSKLS

Catskills

CU

Cumulus

CUFRA

Cumulus Fractus

COV

Cover or covered or covering

CWSU

Center Weather Service Unit

CYC

Cyclonic

CYCLGN

Cyclogenesis

D

D

Downward (tendency in RVR during previous 10 minutes)

DABRK

Daybreak

DALGT

Daylight

DBL

Double

DC

District of Columbia

DCR

Decrease

DCRD

Decreased

DCRG

Decreasing

DCRGLY

Decreasingly

DCRS

Decreases

DE

Delaware or from (used to precede the call sign of the calling station) (to be used in AFS as a procedure signal)

DEC

December

DEG

Degrees

DELMARVA

Delaware-Maryland-Virginia

DFCLT

Difficult

DFCLTY

Difficulty

DFNT

Definite

DFNTLY

Definitely

DFRS

Differs

DGNL

Diagonal

DGNLLY

Diagonally

DIF

Diffuse

DIGG

Digging

DIR

Direction

DISC

Discontinue

DISCD

Discontinued

DISCG

Discontinuing

DISRE

Disregard

DISRED

Disregarded

DISREG

Disregarding

DIST

Distance

DKTS

Dakotas

DLA

Delay or delayed or delay (message type designator)

DLT

Delete

DLTD

Deleted

DLTG

Deleting

DLY

Daily

DMG

Damage

DMGD

Damaged

DMGG

Damaging

DMNT

Dominant

DMSH

Diminish

DMSHD

Diminished

DMSHG

Diminishing

DMSHS

Diminishes

DNG

Danger or dangerous

DNS

Dense

DNSLP

Downslope

DNSTRM

Downstream

DNWND

Downwind

DOM

Domestic

DP

Dew point temperature

DPND

Deepened

DPNG

Deepening

DPNS

Deepens

DPR

Deeper

DPT

Depth

DR…

Low drifting (followed by DU =dust, SA = sand or SN = snow)

DRFT

Drift

DRFTD

Drifted

DRFTG

Drifting

DRFTS

Drift

DRG

During

DS

Duststorm

DSCNT

Descent

DSIPT

Dissipate

DSIPTD

Dissipated

DSIPTG

Dissipating

DSIPTN

Dissipation

DSIPTS

Dissipates

DSND

Descend

DSNDG

Descending

DSNDS

Descends

DSNT

Distant

DSTBLZ

Destabilize

DSTBLZD

Destabilized

DSTBLZG

Destabilizing

DSTBLZS

Destabilizes

DSTBLZN

Destabilization

DTG

Date-time group

DTRT

Deteriorate or deteriorating

DU

Dust

DUC

Dense upper cloud

DUR

Duration

DURC

During climb

DURD

During descent

DVLP

Develop

DVLPD

Developed

DVLPG

Developing

DVLPMT

Development

DVLPS

Develops

DVRG

Diverge

DVRGG

Diverging

DVRGNC

Divergence

DVRGS

Diverges

DVV

Downward vertical velocity

DWNDFTS

Downdrafts

DZ

Drizzle

E

E

East or eastern longitude

EB

Eastbound

EFCT

Effect

ELEV

Elevation

ELNGT

Elongate

ELNGTD

Elongated

ELSW

Elsewhere

EMBD

Embedded in a layer (to indicate cumulonimbus embedded in layers of clouds)

EMC

Environmental Modeling Center

EMERG

Emergency

ENCTR

Encounter

ENDG

Ending

ENE

East-northeast

ENELY

East-northeasterly

ENERN

East-northeastern

ENEWD

East-northeastward

ENHNC

Enhance

ENHNCD

Enhanced

ENHNCG

Enhancing

ENHNCS

Enhances

ENHNCMNT

Enhancement

ENR

En route

ENTR

Entire

EQPT

Equipment

ERN

Eastern

ERY

Early

ERYR

Earlier

ESE

East-southeast

ESELY

East-southeasterly

ESERN

East-southeastern

ESEWD

East-southeastward

ESNTL

Essential

ESTAB

Establish

EST

Estimate or estimated or estimate (message type designator)

ETA

Estimated time of arrival or estimating arrival

ETC

Et cetera

ETD

Estimated time of departure or estimating departure

ETIM

Elapsed time

EV

Every

EVE

Evening

EWD

Eastward

EXCLV

Exclusive

EXCLVLY

Exclusively

EXC

Except

EXP

Expect or expected or expecting

EXTD

Extend or extending

EXTRAP

Extrapolate

EXTRAPD

Extrapolated

EXTRM

Extreme

EXTRMLY

Extremely

EXTSV

Extensive

F

F

Degrees Fahrenheit or fixed

FA

Area Forecast (U.S. domestic)

FAA

Federal Aviation Administration

FAM

Familiar

FAX

Facsimile transmission

FBL

Light (used to indicate the intensity of weather phenomena, interference or static reports, e.g. FBL RA = light rains)

FC

Funnel cloud (tornado or waterspout)

FCST

Forecast

FEB

February

FEW

Few

FG

Fog

FIG

Figure

FILG

Filling

FIR

Flight information region

FIRAV

First available

FL

Florida or Flight Level

FLD

Field

FLRY

Flurry

FLRYS

Flurries

FLT

Flight

FLUC

Fluctuating or fluctuation or fluctuated

FLW

Follow(s) or following

FLY

Fly or flying

FM

From

FM…

From (followed by time weather change is forecast to begin)

FMT

Format

FNCTN

Function

FNTGNS

Frontogenesis

FNTLYS

Frontolysis

FORNN

Forenoon

FPM

Feet per minute

FQTLY

Frequently

FRI

Friday

FRM

Form

FRMG

Forming

FRMN

Formation

FRNG

Firing

FRONT

Front (relating to weather)

FROPA

Frontal passage

FROSFC

Frontal surface

FRQ

Frequent

FRST

Frost

FRWF

Forecast wind factor

FSS

Flight Service Station

FST

First

FT

Feet (dimensional unit)

FTHR

Further

FU

Smoke

FVRBL

Favorable

FWD

Forward

FYI

For your information

FZ

Freezing

FZ LVL

Freezing level

FZDZ

Freezing drizzle

FZFG

Freezing fog

FZRA

Freezing rain

G

G

Gust or green

GA

Georgia

GAMET

Area forecast for low level flights

GEN

General

GENLY

Generally

GEO

Geographic or true

GEOREF

Geographical reference

GFS

Global Forecast System (model)

GLFALSK

Gulf of Alaska

GLFCAL

Gulf of California

GLFMEX

Gulf of Mexico

GLFSTLAWR

Gulf of St. Lawrence

GND

Ground

GR

Hail

GRAD

Gradient

GRDL

Gradual

GRDLY

Gradually

GRIB

Processed meteorological data in the form of grid point values expressed in binary form (aeronautical meteorological code)

GRT

Great

GRTLY

Greatly

GRTLKS

Great Lakes

GS

Small hail and/or snow pellets

GSTS

Gusts

GSTY

Gusty

GTS

Global Telecommunication System

H

HAZ

Hazard

HDFRZ

Hard freeze

HDSVLY

Hudson Valley

HDWND

Head wind

HGT

Height

HI

Hawaii or high

HIFOR

High level forecast

HJ

Sunrise to sunset

HLDG

Holding

HLF

Half

HLTP

Hilltop

HN

Sunset to sunrise

HND

Hundred

HOL

Holiday

HPA

Hectopascal

HPC

Hydrometeorological Prediction Center

HR

Hours

HRZN

Horizon

HTG

Heating

HURCN

Hurricane

HUREP

Hurricane report

HVY

Heavy or heavy (used to indicate the intensity of weather phenomena, e.g. heavy rain = HVY RA)

HVYR

Heavier

HVYST

Heaviest

HWVR

However

HWY

Highway

HYR

Higher

HZ

Haze

I

IA

Iowa

IAO

In and out of clouds

IC

Icing (PIREPs only) or ice crystals (very small ice crystals in suspension, also known as diamond dust)

ICAO

International Civil Aviation Organization

ICE

Icing

ICGIC

Icing in clouds

ICGICIP

Icing in clouds and in precipitation

ICGIP

Icing in precipitation

ID

Idaho or identifier or identity

IDENT

Identification

IFR

Instrument flight rules

IGA

International general aviation

IL

Illinois

ILS

Instrument landing system

IMC

Instrument meteorological conditions

IMD

Immediate or immediately

IMPL

Impulse

IMPLS

Impulses

IMPR

Improve or improving

IMT

Immediate or immediately

IMPT

Important

INC

In cloud

INCL

Include

INCLD

Included

INCLG

Including

INCLS

Includes

INCR

Increase

INCRD

Increased

INCRG

Increasing

INCRGLY

Increasingly

INCRS

Increases

INDC

Indicate

INDCD

Indicated

INDCG

Indicating

INDCS

Indicates

INDEF

Indefinite

INFO

Information

INOP

Inoperative

INPR

In progress

INSTR

Instrument

INSTBY

Instability

INTCNTL

Intercontinental

INTL

International

INTMD

Intermediate

INTMT

Intermittent

INTMTLY

Intermittently

INTR

Interior

INTRP

Interrupt or interruption or interrupted

INTRMTRGN

Intermountain region

INT

Intersection

INTS

Intense

INTSFCN

Intensification

INTSF

Intensify or intensifying

INTST

Intensity

INTVL

Interval

INVRN

Inversion

IOVC

In overcast

INVOF

In vicinity of

IPV

Improve

IPVG

Improving

ISA

International standard atmosphere

ISOL

Isolated

J

JAN

January

JCTN

Junction

JTST

Jet stream

JUL

July

JUN

June

K

KFRST

Killing frost

KG

Kilograms

KLYR

Smoke layer aloft

KM

Kilometers

KMH

Kilometers per hour

KOCTY

Smoke over city

KPA

Kilopascals

KS

Kansas

KT

Knots

KY

Kentucky

L

L

Left (runway identification)

LA

Louisiana

LABRDR

Labrador

LAN

Inland

LAT

Latitude

LAWRS

Limited aviation weather reporting station

LCTMP

Little change in temperature

LFTG

Lifting

LGT

Light or lighting

LGWV

Long wave

LI

Lifted Index

LIS

Lifted indices

LK

Lake

LKS

Lakes

LKLY

Likely

LLJ

Low level jet

LLWAS

Low-level wind shear alert system

LLWS

Low-level wind shear

LN

Line

LOC

Local or locally or location or located

LONG

Longitude

LONGL

Longitudinal

LRG

Long range

LRGLY

Largely

LRGR

Larger

LRGST

Largest

LST

Local standard time

LTD

Limited

LTG

Lightning

LTGCC

Lightning cloud-to-cloud

LTGCG

Lightning cloud-to-ground

LTGCCCG

Lightning cloud-to-cloud, cloud-to-ground

LTGCW

Lightning cloud-to-water

LTGIC

Lightning in cloud

LTL

Little

LTLCG

Little change

LTR

Later

LTST

Latest

LV

Light and variable (relating to wind)

LVE

Leave or Leaving

LVL

Level

LWR

Lower

LWRD

Lowered

LWRG

Lowering

LRY

Layer or layered

M

M

Meters (preceded by figures) or Mach number (followed by figures)

MA

Massachusetts

MAG

Magnetic

MAINT

Maintenance

MAN

Manitoba

MAR

March

MAX

Maximum

MAY

May

MB

Millibar

MBST

Microburst

MCD

Mesoscale discussion

MD

Maryland

MDFY

Modify

MDFYD

Modified

MDFYG

Modifying

MDL

Model

MDLS

Models

MDTLY

Moderately

ME

Maine

MED

Medium

MEGG

Merging

MESO

Mesoscale

MET

Meteorological or meteorology

METAR

Aviation routine weather report (in aeronautical meteorological code)

METRO

Metropolitan

MEX

Mexico

MHKVLY

Mohawk Valley

MI

Michigan

MID

Mid-point (related to RVR)

MIDN

Midnight

MIFG

Shallow fog

MIL

Military

MIN

Minutes

MISG

Missing

MLTLVL

Melting level

MN

Minnesota

MNLD

Mainland

MNM

Minimum

MNLY

Mainly

MNT

Monitor or monitoring or monitored

MNTN

Maintain

MO

Missouri

MOD

Moderate (used to indicate the intensity of weather phenomena, interference or static reports, e.g. moderate rain = MOD RA)

MOGR

Moderate or greater

MON

Monday or above mountains

MOPS

Minimum operational performance standards

MOV

Move or moving or movement

MPH

Miles per hour

MPS

Meters per second

MRG

Medium range

MRGL

Marginal

MRGLLY

Marginally

MRNG

Morning

MRTM

Maritime

MS

Mississippi or minus

MSG

Message

MSL

Mean sea level

MST

Most

MSTLY

Mostly

MSTR

Moisture

MT

Montana or mountain

MTW

Mountain waves

MULT

Multiple

MULTILVL

Multilevel

MWO

Meteorological watch office

MX

Mixed type of ice formation (white and clear)

N

N

North or northern latitude or no distinct tendency (in RVR during previous 10 minutes)

NAB

Not above

NAM

North American Mesoscale (model)

NAT

North Atlantic

NAV

Navigation

NB

New Brunswick or northbound

NBFR

Not before

NBRHD

Neighborhood

NC

North Carolina or no change

NCEP

National Center of Environmental Prediction

NCO

NCEP Central Operations

NCWX

No change in weather

ND

North Dakota

NE

Nebraska or northeast

NEB

Northeast bound

NEC

Necessary

NEG

No or negative or permission not granted or that is not correct

NEGLY

Negatively

NELY

Northeasterly

NERN

Northeastern

NEWD

Northeastward

NEW ENG

New England

NFLD

Newfoundland

NGT

Night

NH

New Hampshire

NHC

National Hurricane Center

NIL

None or I have nothing to send to you

NJ

New Jersey

NL

No layers

NLT

Not later than

NLY

Northerly

NM

New Mexico or nautical miles

NMBRS

Numbers

NML

Normal

NMRS

Numerous

NNE

North-northeast

NNELY

North-northeasterly

NNERN

North-northeastern

NNEWD

North-northeastward

NNW

North-northwest

NNWLY

North-northwesterly

NNWRN

North-northwestern

NNWWD

North-northwestward

NNNN

End of message

NOAA

National Oceanic and Atmospheric Administration

NOPAC

Northern Pacific

NOSIG

No significant change (used in trend-type landing forecasts)

NOV

November

NPRS

Non-persistent

NR

Number

NRLY

Nearly

NRN

Northern

NRW

Narrow

NS

Nova Scotia or nimbostratus

NSC

Nil significant cloud

NSW

Nil significant weather

NTFY

Notify

NTFYD

Notified

NTL

National

NV

Nevada

NVA

Negative vorticity advection

NW

Northwest

NWB

Northwest bound

NWD

Northward

NWLY

Northwesterly

NWRN

Northwestern

NWS

National Weather Service

NY

New York

NXT

Next

O

OAT

Outside air temperature

OBS

Observe or observed or

observation

OBSC

Obscure or obscured or obscuring

OCFNT

Occluded front

OCLD

Occlude

OCLDS

Occludes

OCLDD

Occluded

OCLDG

Occluding

OCLN

Occlusion

OCNL

Occasional or occasionally

OCR

Occur

OCRD

Occurred

OCRG

Occurring

OCRS

Occurs

OCT

October

OFC

Office

OFP

Occluded frontal passage

OFSHR

Offshore

OH

Ohio

OHD

Overhead

OK

Oklahoma or we agree or it is correct

OMTNS

Over mountains

ONSHR

On shore

OPA

Opaque, white type of ice formation

OPC

Ocean Prediction Center

OPN

Open or opening or opened

OPR

Operator or operate or operative or operating or operational

OR

Oregon

ORGPHC

Orographic

ORIG

Original

OSV

Ocean station vessel

OTLK

Outlook (used in SIGMET messages for volcanic ash and tropical cyclones)

OTP

On top

OTR

Other

OTRW

Otherwise

OUBD

Outbound

OUTFLO

Outflow

OVC

Overcast

OVNGT

Overnight

OVR

Over

OVRN

Overrun

OVRNG

Overrunning

OVTK

Overtake

OVTKG

Overtaking

OVTKS

Overtakes

P

PA

Pennsylvania

PAC

Pacific

PATWAS

Pilot’s automatic telephone weather answering service

PBL

Planetary boundary layer

PCPN

Precipitation

PD

Period

PDMT

Predominant

PEN

Peninsula

PERM

Permanent

PGTSND

Puget Sound

PHYS

Physical

PIBAL

Pilot balloon observation

PIREP

Pilot weather report

PL

Ice pellets

PLNS

Plains

PLS

Please

PLTO

Plateau

PLVL

Present level

PM

Postmeridian

PNHDL

Panhandle

PO

Dust/sand whirls (dust devils)

POS

Positive

POSLY

Positively

POSS

Possible

PPI

Plan position indicator

PPINA

Plan position indicator not available (U.S. Weather Radar Report)

PPINE

Plan position indicator no echoes (U.S. Weather Radar Report)

PPSN

Present position

PRBL

Probable

PRBLY

Probably

PRBLTY

Probability

PRECD

Precede

PRECDD

Preceded

PRECDG

Preceding

PRECDS

Precedes

PRES

Pressure

PRESFR

Pressure falling rapidly

PRESRR

Pressure rising rapidly

PRFG

Aerodrome partially

covered by fog

PRI

Primary

PRIN

Principal

PRIND

Present indications are

PRJMP

Pressure jump

PROB

Probability

PROC

Procedure

PROD

Produce

PRODG

Producing

PROG

Forecast

PROGD

Forecasted

PROGS

Forecasts

PRSNT

Present

PRSNTLY

Presently

PRST

Persist

PRSTS

Persists

PRSTNC

Persistence

PRSTNT

Persistent

PRVD

Provide

PRVDD

Provided

PRVDG

Providing

PRVDS

Provides

PS

Plus

PSG

Passing

PSN

Position

PSND

Positioned

PSR

Primary surveillance radar

PTCHY

Patchy

PTLY

Partly

PTNL

Potential

PTNLY

Potentially

PTNS

Portions

PUGET

Puget Sound

PVA

Positive vorticity advection

PVL

Prevail

PVLD

Prevailed

PVLG

Prevailing

PVLS

Prevails

PVLT

Prevalent

PWB

Pilot weather briefing

PWR

Power

Q

QFE

Atmospheric pressure at aerodrome elevation

QN

Question

QNH

Altimeter sub-scale setting to obtain elevation when on the ground

QSTNRY

Quasistationary

QTR

Quarter

QUAD

Quadrant

QUE

Quebec

R

R

Right (runway identification) or rain (U.S. Weather Radar Reports)

RA

Rain

RADAT

Radiosonde additional data

RAFC

Regional area forecast centre

RAG

Ragged

RAOB

Radiosonde observation

RCH

Reach or reaching

RCKY

Rocky

RCKYS

Rockies

RCMD

Recommend

RCMDD

Recommended

RCMDG

Recommending

RCMDS

Recommends

RCRD

Record

RCRDS

Records

RDC

Reduce

RDGG

Ridging

RDL

Radial

RDVLP

Redevelop

RDVLPG

Redeveloping

RDVLPMT

Redevelopment

RE…

Recent (used to qualify weather phenomena, e.g. RERA = recent rain)

REC

Receive or receiver

RECON

Reconnaissance

REF

Reference to…or refer to…

REP

Report or reporting or reporting point

RES

Reserve

REQ

Request or requested

RESP

Response

RESTR

Restrict

RGLR

Regular

RGN

Region

RGNS

Regions

RH

Relative humidity

RI

Rhode Island

RITE

Right (direction of turn)

RIOGD

Rio Grande

RLBL

Reliable

RLTV

Relative

RLTVLY

Relatively

RMK

Remark

RMN

Remain

RMND

Remained

RMNDR

Remainder

RMNG

Remaining

RMNS

Remains

RNFL

Rainfall

ROFOR

Route forecast (in aeronautical meteorological code)

ROT

Rotate

ROTD

Rotated

ROTG

Rotating

ROTS

Rotates

RPD

Rapid

RPDLY

Rapidly

RPLC

Replace or replaced

RPT

Repeat or I repeat (to be used in AFS as a procedure signal)

RPTG

Repeating

RPTS

Repeats

RQMNTS

Requirements

RQR

Require

RQRD

Required

RQRG

Requiring

RQRS

Requires

RRA

(or RRB, RRC…etc., in sequence) Delayed meteorological message (message type designator)

RSG

Rising

RSN

Reason

RSNG

Reasoning

RSNS

Reasons

RSTR

Restrict

RSTRD

Restricted

RSTRG

Restricting

RSTRS

Restricts

RTD

Delayed (used to indicate delayed meteorological message; message type designator)

RTE

Route

RTN

Return or returned or returning

RTS

Return to service

RUC

Rapid Update Cycle (model)

RUF

Rough

RUFLY

Roughly

RVR

Runway visual range

RVS

Revise

RVSD

Revised

RVSG

Revising

RVSS

Revises

RWY

Runway

S

S

South or southern latitude

SA

Sand

SAP

As soon as possible

SARPS

Standards and Recommended Practices (ICAO)

SASK

Saskatchewan

SAT

Saturday

SATFY

Satisfactory

SB

Southbound

SBSD

Subside

SBSDD

Subsided

SBSDNC

Subsidence

SBSDS

Subsides

SC

South Carolina or stratocumulus

SCND

Second

SCSL

Stratocumulus Standing Lenticular

SCT

Scattered

SD

South Dakota

SE

Southeast

SEB

Southeast bound

SEC

Seconds

SECT

Sector

SELY

Southeasterly

SEP

September

SEPN

Separation

SEQ

Sequence

SER

Service or servicing or served

SERN

Southeastern

SEV

Severe (used to qualify icing and turbulence reports)

SEWD

Southeastward

SFC

Surface

SG

Snow grains

SGFNT

Significant

SGFNTLY

Significantly

SH…

Showers (followed by RA = rain, SN = snow, PL = ice pellets, GR = hail, GS = small hail and/or snow pellets or combinations thereof, e.g. SHRASN = showers of rain and snow)

SHFT

Shift

SHFTD

Shifted

SHFTG

Shifting

SHFTS

Shifts

SHLD

Shield

SHLW

Shallow

SHRT

Short

SHRTLY

Shortly

SHRTWV

Shortwave

SHUD

Should

SIERNEV

Sierra Nevada

SIG

Signature

SIGMET

Significant Meteorological Information (Information concerning en-route weather phenomena which may affect the safety of aircraft operations)

SIGWX

Significant weather

SIMUL

Simultaneous or simultaneously

SKC

Sky clear

SKED

Schedule or scheduled

SLD

Solid

SLGT

Slight

SLGTLY

Slightly

SLP

Slope

SLPG

Sloping

SLW

Slow

SLY

Southerly

SM

Statute mile

SML

Small

SMLR

Smaller

SMRY

Summary

SMTH

Smooth

SMTHR

Smoother

SMTHST

Smoothest

SMTM

Sometime

SMWHT

Somewhat

SN

Snow

SNBNK

Snow bank

SNFLK

Snowflake

SNGL

Single

SNOINCR

Snow increase

SNOINCRG

Snow increasing

SOP

Standard operating procedure

SPC

Storm Prediction Center

SPCLY

Especially

SPD

Speed

SPECI

Aviation selected special weather Report (in aeronautical meteorological code)

SPECIAL

Special meteorological report (in abbreviated plain language)

SPKL

Sprinkle

SPLNS

Southern Plains

SPRD

Spread

SPRDG

Spreading

SPRDS

Spreads

SPRL

Spiral

SQ

Squall

SQL

Squall line

SR

Sunrise

SRG

Short range

SRN

Southern

SRND

Surround

SRNDD

Surrounded

SRNDG

Surrounding

SRNDS

Surrounds

SRY

Secondary

SS

Sunset or sandstorm

SSE

South-southeast

SSELY

South-southeasterly

SSERN

South-southeastern

SSEWD

South-southeastward

SSW

South-southwest

SSWLY

South-southwesterly

SSWRN

South-southwestern

SSWWD

South-southwestward

ST

Stratus

STAGN

Stagnation

STBL

Stable

STBLTY

Stability

STD

Standard

STDY

Steady

STFR

Stratus Fractus

STF

Stratiform

STG

Strong

STGLY

Strongly

STGR

Stronger

STGST

Strongest

STM

Storm

STMS

Storms

STN

Station

STNR

Stationary

STS

Status

SUB

Substitute

SUBTRPCL

Subtropical

SUF

Sufficient

SUFLY

Sufficiently

SUG

Suggest

SUGG

Suggesting

SUGS

Suggests

SUN

Sunday

SUPG

Supplying

SUPR

Superior

SUPSD

Supersede

SUPSDG

Superseding

SUPSDS

Supersedes

SVC

Service message

SVRL

Several

SW

Southwest

SWB

Southwest bound

SWD

Southward

SWWD

Southwestward

SWLY

Southwesterly

SWRN

Southwestern

SX

Stability index

SXN

Section

SYNOP

Synoptic

SYNS

Synopsis

SYS

System

T

T

Temperature

TAF

Terminal aerodrome forecast

TAIL

Tail wind

TB

Turbulence (PIREPs only)

TC

Tropical Cyclone

TCNTL

Transcontinental

TCU

Towering cumulus

TDA

Today

TDO

Tornado

TEMPO

Temporary or temporarily

TEND

Trend forecast

THK

Thick

THKNG

Thickening

THKNS

Thickness

THKR

Thicker

THKST

Thickest

THN

Thin

THNG

Thinning

THNR

Thinner

THNST

Thinnest

THR

Threshold

THRFTR

Thereafter

THRU

Through

THRUT

Throughout

THSD

Thousand

THTN

Threaten

THTND

Threatened

THTNG

Threatening

THTNS

Threatens

THU

Thursday

TIL

Until

TL…

Till (followed by time by which weather change is forecast to end)

TMW

Tomorrow

TN

Tennessee

TNDCY

Tendency

TNDCYS

Tendencies

TNGT

Tonight

TNTV

Tentative

TNTVLY

Tentatively

TO

To…(place)

TOC

Top of climb

TOP

Cloud top

TOPS

Tops

TOVC

Top of overcast

TPC

Tropical Prediction Center

TPG

Topping

TR

Track

TRBL

Trouble

TRIB

Tributary

TRKG

Tracking

TRML

Terminal

TRMT

Terminate

TRMTD

Terminated

TRMTG

Terminating

TRMTS

Terminates

TRNSP

Transport

TRNSPG

Transporting

TROF

Trough

TROFS

Troughs

TROP

Tropopause

TRPCD

Tropical continental air mass

TRPCL

Tropical

TRRN

Terrain

TRSN

Transition

TS

Thunderstorm (in aerodrome reports and forecasts, TS used alone means thunder heard but no precipitation at the aerodrome)

TS…

Thunderstorm (followed by RA = rain, SN = snow, PL = ice pellets, GR = hail, GS = small hail and/or snow pellets or combinations thereof, e.g. TSRASN = thunderstorm with rain and snow)

TSFR

Transfer

TSFRD

Transferred

TSFRG

Transferring

TSFRS

Transfers

TSNT

Transient

TUE

Tuesday

TURB

Turbulence

TURBT

Turbulent

TWD

Toward

TWDS

Towards

TWI

Twilight

TWR

Aerodrome control tower or aerodrome control

TWRG

Towering

TX

Texas

TYP

Type of aircraft

TYPH

Typhoon

U

U

Upward (tendency in RVR during previous 10 minutes)

UA

Pilot weather report (U.S.)

UDDF

Up- and downdrafts

UFN

Until further notice

UNA

Unable

UNAVBL

Unavailable

UNEC

Unnecessary

UNKN

Unknown

UNL

Unlimited

UNREL

Unreliable

UNRSTD

Unrestricted

UNSATFY

Unsatisfactory

UNSBL

Unseasonable

UNSTBL

Unstable

UNSTDY

Unsteady

UNSTL

Unsettle

UNSTLD

Unsettled

UNUSBL

Unusable

UPDFTS

Updrafts

UPR

Upper

UPSLP

Upslope

UPSTRM

Upstream

URG

Urgent

USBL

Usable

UT

Utah

UTC

Coordinated Universal Time

UVV

Upward vertical velocity

UWNDS

Upper winds

V

VA

Virginia or volcanic ash

VAAC

Volcanic Ash Advisory Center

VAAS

Volcanic Ash Advisory Statement

VAL

In valleys

VARN

Variation

VC

Vicinity of the aerodrome (followed by FG = fog, FC = funnel cloud, SH = showers, PO = dust/sand whirls, BLDU = blowing dust, BLSA = blowing sand or BLSN = blowing snow, e.g. VC FG = vicinity fog)

VCOT

VFR conditions on top

VCTR

Vector

VCY

Vicinity

VER

Vertical

VFR

Visual flight rules

VFY

Verify

VFYD

Verified

VFYG

Verifying

VFYS

Verifies

VIS

Visibility

VLCTY

Velocity

VLCTYS

Velocities

VLNT

Violent

VLNTLY

Violently

VLY

Valley

VMC

Visual meteorological conditions

VOL

Volume

VOLMT

Meteorological information for aircraft in flight

VORT

Vorticity

VR

Veer

VRB

Variable

VRG

Veering

VRISL

Vancouver Island, BC

VRS

Veers

VRT

Vertical motion

VRY

Very

VT

Vermont

VV

Vertical velocity

W

W

West or western longitude

WA

Washington

WAA

Warm air advection

WAFC

World area forecast centre

WAFS

Word area forecast system

WB

Westbound

WDI

Wind direction indicator

WDLY

Widely

WDSPR

Widespread

WED

Wednesday

WEF

With effect from or effective from

WFO

Weather Forecast Office

WFP

Warm front passage

WI

Wisconsin or within

WIBIS

Will be issued

WID

Width

WIE

With immediate effect or effective immediately

WINT

Winter

WINTEM

Forecast upper wind and temperature for aviation

WK

Weak

WKDAY

Weekday

WKEND

Weekend

WKN

Weaken or weakening

WL

Will

WLY

Westerly

WND

Wind

WNDS

Winds

WNW

West-northwest

WNWLY

West-northwesterly

WNWRN

West-northwestern

WNWWD

West-northwestward

WO

Without

WPLTO

Western Plateau

WRM

Warm

WRMG

Warming

WRN

Western

WRMR

Warmer

WRMST

Warmest

WRMFNT

Warm front

WRMFNTL

Warm frontal

WRNG

Warning

WRS

Worse

WS

Wind shear

WSPD

Wind speed

WSHFT

Wind shift

WSTCH

Wasatch Range

WSW

West-southwest

WSWLY

West-southwesterly

WSWRN

West-southwestern

WSWWD

West-southwestward

WTR

Water

WTSPT

Waterspout

WUD

Would

WV

West Virginia

WVS

Waves

WW

Watch notification message

WWD

Westward

WWW

World wide web

WX

Weather

WY

Wyoming

X

X

Cross

XCP

Except

XNG

Crossing

XPC

Expect

XPCD

Expected

XPCG

Expecting

XPCS

Expects

XPLOS

Explosive

XS

Atmospherics

XTND

Extend

XTNDD

Extended

XTNDG

Extending

XTRM

Extreme

XTRMLY

Extremely

Y

YDA

Yesterday

YKN

Yukon

YLSTN

Yellowstone

Z

Z

Coordinated Universal Time (in meteorological messages)

ZN

Zone

ZNS

Zones

Table E-1. Selected National Weather Service (NWS) Links

SITE

WEB ADDRESS

National Weather Service (NWS)

http://weather.gov/

Aviation Digital Data Service (ADDS)

http://adds.aviationweather.noaa.gov/

Aviation Weather Center (AWC)

http://aviationweather.gov

Hydrometeorological Prediction Center (HPC)

http://www.hpc.ncep.noaa.gov/

Storm Prediction Center (SPC)

http://www.spc.noaa.gov/

Tropical Prediction Center (TPC)

http://www.nhc.noaa.gov/

Alaska Aviation Weather Unit (AAWU)

http://aawu.arh.noaa.gov/

Center Weather Service Units (CWSU)

http://aviationweather.gov/products/cwsu/

Weather Forecast Offices (WFO)

http://www.srh.noaa.gov/

Weather Forecast Office (WFO) Honolulu, HI – Aviation Products

http://www.prh.noaa.gov/hnl/pages/aviation.php

Telecommunication Operations Center - NWS Fax Charts

http://weather.noaa.gov/fax/nwsfax.html

NWS Office at the FAA Academy

http://www.srh.noaa.gov/faa/

Table E-2. Selected Federal Aviation Administration (FAA) Links

SITE

WEB ADDRESS

Federal Aviation Administration (FAA)

http://www.faa.gov/

Air Traffic Control System Command Center (ATCSCC)

http://www.fly.faa.gov/flyfaa/usmap.jsp

Automated Flight Service Station (AFSS)

http://fsfeedback.gosysops.info

Table E-3. Selected Links to Aviation Weather Products

PRODUCT

WEB ADDRESS

Average Surface to 500 MB Relative Humidity Chart

http://weather.noaa.gov/pub/fax/QRUA00.TIF

Collaborative Convective Weather Forecast (CFP)

http://aviationweather.gov/products/ccfp/

Constant Pressure Charts

http://weather.noaa.gov/fax/barotrop.shtml

Convective Outlooks

http://www.spc.noaa.gov/products/outlook/

Current Icing Product (CIP)

http://adds.aviationweather.noaa.gov/icing/icing_nav.php

Center Weather Advisory (CWA)

http://aviationweather.gov/products/cwsu/

Area Forecast (FA)