Significant Weather Phenomena Matrix

WX PHENOMENA QUALIFIER
Precipitation Intensity or Proximity Descriptor 1
Light

-
Moderate


Heavy

+
Vicinity

VC 2
Shallow

MI
Partial

PR
Patches

BC
Low
Drifting
DR 3
Blowing

BL
Shower(s)

SH
Thunder-
storm
TS 4
Freezing

FZ
Drizzle DZ -DZ DZ +DZ - - - - - - - - FZDZ
Rain RA -RA RA +RA - - - - - - SHRA TSRA FZRA
Snow SN -SN SN +SN - - - - DRSN BLSN SHSN TSSN -
Snow Grains SG -SG SG +SG - - - - - - - - -
Ice Crystals 5 IC - IC - - - - - - - - - -
Ice Pellets PE -PE PE +PE - - - - - - SHPE TSPE -
Hail 5,6 >= 1/4" GR - GR - - - - - - - SHGR TSGR -
Hail 5,7 < 1/4" GS - GS - - - - - - - SHGS TSGS -
Unknown Precipitation UP Automated Stations Only - No Intensity - - - - - - - -
Thunderstorms, Showers, Freezing, and their Intensity or Proximity Indicator - - - - - - -
TS - - TS - VCTS 8 - - - - - - - -
TSRA - -TSRA TSRA +TSRA - - - - - - - - -
TSSN - -TSSN TSSN +TSSN - - - - - - - - -
TSPE - -TSPE TSPE +TSPE - - - - - - - - -
TSGR - - TSGR - - - - - - - - - -
TSGS - - TSGS - - - - - - - - - -
SH - - - - VCSH 9 - - - - - - - -
SHRA - -SHRA SHRA +SHRA - - - - - - - - -
SHSN - -SHSN SHSN +SHSN - - - - - - - - -
SHPE - -SHPE SHPE +SHPE - - - - - - - - -
SHGR - - SHGR - - - - - - - - - -
SHGS - - SHGS - - - - - - - - - -
FZDZ - -FZDZ FZDZ +FZDZ - - - - - - - - -
FZRA - -FZRA FZRA +FZRA - - - - - - - - -
FZFG - - FZFG - - - - - - - - - -
Obscurations Intensity or Proximity Descriptor
Light

-
Moderate


Heavy

+
Vicinity

VC
Shallow

MI
Partial

PR
Patches

BC
Low
Drifting
DR
Blowing

BL
Shower(s)

SH
Thunder-
storm
TS
Freezing

FZ
Mist 10 BR - BR 10 - - - - - - - - - -
Fog 11 FG - FG 11 - VCFG 12 MIFG 13 PRFG 14 BCFG 15 - - - - FZFG 16
Smoke FU - FU - - - - - - - - - -
Volcanic Ash 17 VA - VA 17 - - - - - - - - - -
Widespread Dust DU - DU - - - - - DRDU BLDU - - -
Sand SA - SA - - - - - DRSA BLSA - - -
Haze HZ - HZ - - - - - - - - - -
Spray PY - - - - - - - - BLPY - - -
Blowing Phenomena - - - - - - - - - - - -
BLSN 18 - - BLSN - VCBLSN - - - - BLSN - - -
BLSA - - BLSA - VCBLSA - - - - BLSA - - -
BLDU - - BLDU - VCBLDU - - - - BLDU - - -
Other - - - - - - - - - - - -
Sand/Dust Whirls PO - PO - VCPO - - - - - - - -
Squalls 19 SQ - SQ - - - - - - - - - -
Funnel Cloud FC - FC - - - - - - - - - -
Tornado/Waterspout 20 +FC - - +FC - - - - - - - - -
Sandstorm 21 SS - SS +SS VCSS - - - - - - - -
Duststorm 22 DS - DS +DS VCDS - - - - - - - -

Footnotes for the Weather Phenomena Matrix

1 - Only one descriptor shall be included for each weather phenomena group, e.g., BCFG. Only two exceptions exist to this rule: VCSH and VCTS.
2 - Vicinity is defined as greater than 0 Statute Miles(SM) to 10SM of the point of observation for precipitation. Other than precipitation (VCFG, VCBLSN, VCBLSA, VCBLDU, VCPO, VCSS, VCDS), vicinity is 5SM to 10SM.
3 - Raised by wind to less than 6 feet above the ground.
4 - TS may be reported by itself if no precipitation is associated with the thunderstorm.
5 - No intensity is ever given to hail (GR/GS [snow pellets]) or ice crystals (IC).
6 - Largest hailstone observed has a diameter of 1/4 inch or more.
7 - Hailstone diameter is less than 1/4 inch. No remark is entered for hailstone size.
8 - VCTS shall only be used by automated stations. If thunder is heard, TS shall be reported.
9 - Showers (SH), when associated with the indicator VC, the type and intensity of the showery precipitation shall not be specified, i.e., +VCSHRA is not allowed; only VCSH would be reported. VCSH shall be used to report any type of precipitation not at point of observation, but > 0 to 10SM.
10 - BR (mist) shall only be used when the visibility is at least 5/8SM, but not more than 6SM.
11 - For FG (fog) to be reported without the qualifiers VC11,MI 12,PR13,or BC14 the visibility shall be less than 5/8SM.
12 - VC is used to report any type of fog observed in the vicinity (5 to 10SM) of the station.
13 - MIFG (shallow fog) to be reported, the visibility at 6 feet above ground level shall be 5/8SM or more and the apparent visibility in the fog layer shall be less than 5/8SM.
14 - PRFG (partial fog) indicates that a substantial part of the station is covered by fog while the remainder is clear of fog.
15 - BCFG (patches of fog) indicates that patches of fog randomly cover the station.
16 - FZFG is any fog consisting predominately of water droplets at temperatures below 0 degrees C, whether it is depositing rime or not.
17 - Volcanic Ash is always reported in the body of the METAR/SPECI when present. Visibility is not a factor.
18 - SN BLSN indicates snow falling from clouds with blowing snow occurring. If the observer cannot determine whether or not snow is also falling from clouds, then only BLSN shall be reported.
19 - SQ (squall) is a sudden increase in wind speed of at least 16 knots, the speed rising to 22 knots or more and lasting for at least one minute.
20 - Tornadoes and Waterspouts shall be reported using the indicator "+", i.e., +FC.
21 - SS (sandstorm) reported if the visibility is greater than or equal to 5/16SM and less than or equal to 5/8SM. Report +SS if the visibility is less than 5/16SM.
22 - DS (sandstorm) reported if the visibility is greater than or equal to 5/16SM and less than or equal to 5/8SM. Report +DS if the visibility is less than 5/16SM.



In the METAR code, No more than three weather groups shall be used to report weather phenomena at or near the station. If more than one significant weather phenomena is observed, separate weather phenomena groups shall be included in the report. If more than one form of precipitation is observed, the appropriate abbreviations shall be combined in a single group with the predominant type of precipitation being reported first. In such a single group, the intensity shall refer to the total precipitation and be reported with one or no indicator as appropriate, e.g., -RASN FG HZ.



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