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Code 4680

FM 12-IX Ext. SYNOP code form

In reports from fully automatic stations (THAT ARE EQUIPPED WITH THE APPROPRIATE SENSORS), a separate 'present weather' code table is used (wawa): After the station number group (IIiii), comes a group which contains information on whether or not 'weather' groups are included, and which code table is used. The important figure is the second figure in the group [ iRiXhVV ] as under:

 iX  Type of station  7 ('weather')- group
 1  Manned  Included
 2  Manned  Not-included (no sig.Wx to report)
 3  Manned  Not-included (data not available)
 4  Automatic  Included using 'old' wwWW present weather coding
 5  Automatic  Not-included (no sig. Wx to report)
 6  Automatic  Not-included (data not available)
 7  Automatic  Included using 'new' wawa Code table (as below)

 

A scanned display of the the plotting convention for this code type will be found here.


 01-09  Description
 01  Clouds generally dissolving or becoming less developed (during past hour)
 02  State of sky generally unchanged
 03  Clouds forming or developing (during past hour)
 04  Haze, smoke or suspended dust (vis >=1.0km)
 05  [as 04 but vis < 1.0km ]
 06  -
 07  -
 08  -
 09  -

 10-19  Description
 10  Mist
 11  Diamond dust (not yet used)
 12  Distant lightning (not yet used)
 13  -
 14  -
 15  -
 16  -
 17  -
 18  Squalls
 19  -

Code 20-26: used to report precipitation, fog (or ice fog) or thunderstorm at the station in the past hour, but not at time of observation. 27-29 appear to be current weather!

 20-29  Description
 20  Fog
 21  Precipitation
 22  Drizzle (non-freezing) or snow grains
 23  Rain (non-freezing)
 24  Snow
 25  Freezing drizzle or rain
 26  Thunderstorm (with/without ppn) (not yet used)
 27  Blowing/Drifting snow/sand (not yet used)
 28  Blowing/Drifting snow/sand: vis >=1.0km (not yet used)
 29  Blowing/Drifting snow/sand: vis < 1.0km (not yet used)

 30-39  Description
 30  Fog
 31  Fog/Ice Fog in patches
 32  Fog/Ice Fog - thinning in past hour
 33  Fog/Ice Fog - no change
 34  Fog/Ice Fog - set in, or thickened in past hour
 35  Fog - depositing rime
 36  -
 37  -
 38  -
 39  -

 40-49  Description
 40  Precipitation (PPN)
 41  PPN - slight/moderate
 42  PPN - heavy
 43  Liquid PPN - slight/moderate
 44  Liquid PPN - heavy
 45  Solid PPN - slight/moderate
 46  Solid PPN - heavy
 47  Freezing PPN - slight/moderate
 48  Freezing PPN - heavy
 49  -

 50-59  Description
 50  Drizzle
 51  Drizzle, not freezing - slight
 52  Drizzle, not freezing - moderate
 53  Drizzle, not freezing - heavy
 54  Drizzle, freezing - slight
 55  Drizzle, freezing - moderate
 56  Drizzle, freezing - heavy
 57  Drizzle & rain mixed - slight
 58  Drizzle & rain mixed - moderate/heavy
 59  -

 60-69  Description
 60  Rain
 61  Rain, not freezing - slight
 62  Rain, not freezing - moderate
 63  Rain, not freezing - heavy
 64  Freezing rain - slight
 65  Freezing rain - moderate
 66  Freezing rain - heavy
 67  Rain/drizzle & snow mixed - slight
 68  Rain/drizzle & snow mixed - moderate/heavy
 69  -

 70-79  Description
 70  Snow
 71  Snow - slight
 72  Snow - moderate
 73  Snow - heavy
 74  Ice Pellets - slight
 75  Ice Pellets - moderate
 76  Ice Pellets - heavy
 77  Snow grains
 78  Ice crystals
 79  -

 80-89  Description
 80  Intermittent PPN
 81  Intermittent rain - slight
 82  Intermittent rain - moderate
 83  Intermittent rain - heavy
 84  Intermittent rain - violent
 85  Intermittent snow - slight
 86  Intermittent snow - moderate
 87  Intermittent snow - heavy
 88  -
 89  Hail (not yet used)

 90-99  Description
 90  Thunderstorm (TS)(not yet used)
 91  TS, slight/moderate - no PPN (not yet used)
 92  TS, slight/moderate - rain/snow showers (not yet used)
 93  TS, slight/moderate - hail (not yet used)
 94  TS, heavy - no PPN (not yet used)
 95  TS, heavy - rain/snow showers (not yet used)
 96  TS, heavy - hail (not yet used)
 97  -
 98  -
 99  Tornado !!! (not yet used)

 

NB: This is not an official publicising of the WMO code form. It is purely intended for interested amateurs who want to be aware of the relevant code forms. If you have a professional requirement to use these codes, you should refer to the appropriate WMO publications for the official listing, or contact your national meteorological service for more details. I will not be responsible for any omissions, errors etc.