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Definition METAR/SPECI und TAF

METAR: The routine weather message is an internationally standardised weather observation message at aerodromes. It is issued in coded form.

SPECI: Indicates whether it is a planned sighting METAR or an intermediate sighting (SPECI). The SPECI is rarely used today as most weather stations publish a new observation every half hour.

TAF: The Terminal Aerodrome Forecast (TAF) is an aviation weather forecast for larger aerodromes. The form, content and meaning of the TAF are internationally standardised via ICAO guidelines.

METAR – Meteorological Aerodrome Report

SPECI – Special Weather Report

Example:

METAR LSZH 111320Z VRB02KT 8000 FEW007 BKN009 03/00 Q1035 BECMG BKN010

1.ICAO Abbreviation Airport

LSZH = Zurich

2.Publication Time

YYGGggZ

YY = day of current month

GG = hours

gg = minutes

Z = code letter UTC

Publication time METAR:

Full hour +20/50 minutes

/ = missing data marked with slashes

3.Auto

AUTO = Code Letter for automatic weather observation (optional)

4.Wind

dddffGfmfmKT

ddd = wind direction (geographical)

ff = wind velocity (kt)

G = code letter for blasts

fmfm = strong blasts (only mentioned if 10kt over medium wind)

VRBffKT

VRB = variable wind direction

Variation 060° - 180° (< 3kt)

or variation >= 180°

00000KT = windless (<1kt)

dndndnVdxdxdx

If the direction of the wind varied the last 10minutes around 60° to 180° with a wind velocity of 3kt or more, the two maximum wind directions are mentioned in here

(V = code letter for variation)

Wind velocity and blast with 99kt and more are mentioned with <P99>

5.Visibility

Visibility Range

VVVV VmVmVmVmDv

VVVV = prevailing visibility (minimum on the half radius)

VmVmVmVm = minimum visibility range in meters

Dv = direction in which the smallest visibility was measured (SW, W, NW etc.)

The minimum visibility range is only measured if

1.) smaller than 1500m or

2.) less than 50% of the prevailing visibility range and smaller than 5000m. It should be reported additional to prevailing visibility range with the direction.

9999 = visibility 10km or more

Runway Visual Range (RVR)

RDRDR/VRVRVRVRi

R = code letter for runway visual range

DRDR = runway indicator (parallel runways additional C for center, R for right, L for left)

VRVRVRVR = runway visual range in meters (average in the last 10 minutes)

I = change trend (last 10 minutes) of the runway visual range (U=ascend, D=descend, N=constant)

With significant changes during the last 10 minutes, the highest and the lowest 1minute average are mentioned, e.g. R16/0125V0550U (V = code letter for variation)

Requirements for RVR:

RVR < 1500m, visual range <1500m

Special cases; M0050 = RVR <50m, P2000 = RVR > 2000m

6.Weather

Intensity or Proximity

- weak

moderate (no sign)

+ strong (distinctive)

VC in the vicinity (between 8 to 16km around the airport)

Descriptor

MI shallow

BC patches

PR partial

DR low drifting

BL blowing

SH shower(s)

TS thunderstorm

FZ freezing

Precipitation

DZ drizzle

RA rain

SN snow

SG snow grains

PL ice pellets

GR hail

GS small hail and/or snow pellets

UP unidentified precipitation

Obscuration

Hydrometeore

FG fog

visibility < 1000m

BR mist

Relative humidity >= 75%

Visibility >= 1000m and <= 5000m

Lithometeore

FU smoke

VA volcanic ash

DU widespread dust

SA sand

HZ haze

Relative humidity < 75%

Visibility >= 1000m and <= 5000m

OTHER

PO dust or sand whirls

SQ squalls

FC funnel cloud(s)

SS sand storm

DS dust storm

7.Clouds

NsNsNshshshs

NsNsNs = amount of clouds

hshshs = cloud basement in hundred feeds

VVhshshs =Vertical view (in hundred feeds) example: VV002

Cloud coverage

FEW = few 1 – 2 eighth

SCT = scattered 3 – 4 eighth

BKN = broken 5 – 7 eighth

OVC = overcast 8 eighth

The types of clouds is only mentioned for CB and TCU (Towering Cumulus) (example: SCT030CB or BKN025TCU)

NCD (no clouds detected) automatic sensors measures no clouds

NSW (nil significant weather) describes the end of an expected weather event

NSC (nil significant clouds) replaces the clouds group if there are no CB or other clouds beneath 5000ft or beneath the highest MSA (if this is higher than 5000ft). Only if CAVOK is not applicable

8.CAVOK (Ceiling and visibility ok)

The code word <CAVOK> replaces visibility, weather and clouds if following conditions are fulfilled during the time of observation:

- meteorological visibility: 10km or more

- no clouds beneath 5000ft or beneath the highest MSA (Minimum Sector Altitude), if this is higher than 5000ft

- no Cumulonimbus (CB) or Towering Cumulus (TCU) on all altitudes

- no significant weather (according table on top)

9.Temperature / Dew Point

T'T'/T'dT'd

T'T' = Temperature in °C

T'dT'd = Dew point in °C

Values beneath 0°C put in front <M>

(Example: 03/M02)

10.QNH

QPHPHPHPH

Q = Code letter for QNH in hPa

PHPHPHPH = QNH in hPa

11.Additional Information

REw'w'

Significant weather event before observation time

RE = abbreviation for «recent»

w'w' = weather event

WS RWYDRDR or WS ALL RWY

Wind shears atmospheric layers close to ground(up to 1600ft over runway height)

WS = wind shears

RWY = runway

DRDR = code letters runway

12.State of Runway

Runway designator

By parallel runways 50 is added to the right runway (R)

(Example: runway 25R = 75)

88 = all runways

99 = repetiotion of previous information

Condition of Runway / deposits

0 = clear and dry

1 = damp

2 = wet or water particles

3 = rime of frost covered (normally < 1 mm)

4 = dry snow

5 = wet snow

6 = slush

7 = ice

8 = compacted or rolled snow

9 = frozen ruts or ridges

/ = not reported, runway clearance in progress

Extend of Runway Contamination

1 = 10% or less

2 = 11% to 25%

5 = 26% to 50%

9 = over 50%

/ = not reported, runway clearance in progress

Depth of Deposit

00 = less than 1 mm

01 – 90 = measurement in mm

92 = 10cm

93 = 15cm

94 = 20cm

95 = 25cm

96 = 30cm

97 = 35cm

98 = 40cm

99 = runway not operation due to snow, slush, ice, large drifts, or runway clearance, depth not reported

// = not operational significant or not measurable

Braking Action or Friction Coefficient

Braking action estimated:

91 poor

92 medium to poor

93 medium

94 medium to good

95 good

99 figures unreliable

// not reported, runway closes

Friction Coefficient:

00 – 25 = poor

26 – 29 = medium to poor

30 – 35 = medium

36 – 39 = medium to good

40 – 90 = good

(Example: 35 friction coefficient 0,35)

Special Cases

If clearing of runway in progress: AA//99// (i.e. 16//99//)

Report nod updated due missing measurements (i.e. during night):

AA////// (i.e. 16//////)

88////// = all runways

If runway again normally operational:

AACLRD// (i.e. 16CLRD//)

88CLRD// = all runways

Airport closed due to snow: SNOCLO

13.Trend

Short-term forecast (expected significant changes within the next 2 hours after observation time). The changes refer to wind, visibility, weather and clouds.

BECMG = becoming

TEMPO = temporary

NOSIG = nil significant change

FM = from

TL = until

AT = at

Time group: GGgg hours and minutes in UTC

14.Automatic generated METAR

AUTO = indicates the automatic production of the METAR

NDV = no directional variation, optical range no variation of direction

NCD = no clouds detected

UP = unidentified precipitation, not clearly identified

REUP = recent UP, refer to last message with UP

/// = missing data. Example: System can't recognize the different types of clouds (CB; TCU)

15.Remarks

Information based on national agreements