US METAR RMK Section decoding

[eeetogo]

Good Day Everybody!

I could need some help in decoding the RMK section of the US/Canada METARs. For example METAR Calgary:

METAR: CYYC 190800Z 34018KT 1 1/4SM -SN DRSN BKN010 OVC021 M09/M10 A3005 RMK SN4SC3SC1 /S01/ RVR RWY28 4500 FT SLP238

Any idea what "...SN4SC3SC1 /S01/ ..." stands for?

In US METARs sometimes you find also in the RMK section something like this: 931023. 931 seems to be the group identifier, but what group?

I do very much appreciate any help. Anybody found any website with an extensive decoding of the RMK section for US/Canada METARs?

Thanks a lot.
eeetogo

[datafox]

METAR: CYYC 190800Z 34018KT 1 1/4SM -SN DRSN BKN010 OVC021 M09/M10 A3005 RMK SN4SC3SC1 /S01/ RVR RWY28 4500 FT SLP238

Snow is obscuring 4/8ths of the sky, the lowest stratocumulus layer is obscuring another 3/8ths, and the higher stratocumulus layer is obscuring 1/8th, making a total of 8/8ths of the sky being covered.

"931" groups indicate the total snowfall/frozen precipitation amount fallen in the past 6 hours. For example, 931023 would mean 2.3" of snow/sleet/etc. had fallen in the past 6 hours preceding the observation.

Here is the book observers use in U.S.:

http://www.faa.gov/airports_airtraffic/air_traffic/publications/at_orders/media/SWO.pdf

There have been some amendments (like the "931" group), which haven't been published, but the book should give you a good idea. Note the remarks in METARs are not in the order they are presented in the book, that is because the ASOS software does not, unfortunately, coincide with what is published in the book.

[eeetogo]

datafox, you deserve your name!

Thanks a lot, very helpful answer indeed.

eeetogo

[HeLIS aLL DaY]

Was wondering if anyone could help me decode this remark. I downloaded the Surface Weather Observations pdf that DataFox suggested but couldn't find anything except this stuff about wind groups:Wind (dddff(f)GfmfmfmKT)

As you can see its cold out, and I cant fly my little heli so i figure I'd see if anyone knew what this meant.

KBJC 150448Z 00000KT 12SM SCT013 SCT030 M21/M24 A2997 RMK GF S LAST

[Hold West]

The best source for info on decoding US METARs is the Federal Meteorological Handbook 1 (http://www.ofcm.gov/fmh-1/fmh1.htm) (FMH-1).

As to your question, I can't find anything for GF. S is South, LAST indicates it's the last observation of the day for a non-24h station.

Wasn't GF the indicator for ground fog in the old SA sode? Maybe the observer is trying to indicate Ground Fog South of the station.

[HeLIS aLL DaY]

That would probably make sense given the dew point spread at the time.

Thanks