Code in US Metar needs deciphering

[Jhieminga]

Hello all,

Recently found the code 'SNEMM' in the Remarks section of a US Metar. My guess is that it has to do with recent snowfall, but can somebody more knowledgable than me give the correct meaning?

[Teroc]

Jhieminga,

The only reference i can find for that is it means "Snow Ended"

Try putting a couple of these metars into a decoder which ive linked to below and you'll see what I mean.

METAR KAVL 191554Z 01005KT 1SM BKN009 OVC036 M01/M01 A3014 RMK AO2 SNEMM PRESFR SLP217 P0002 T10061006

KAUG 200553Z AUTO 34007KT 1 1/4SM BR FEW001 OVC006 M12/M14 A2979 RMK AO2 SNEMM SLP097 P0001 60005 T11221139 11111 21128 58041


http://www.wx-now.com/Weather/MetarDecode.aspx

[Jhieminga]

Teroc, thanks for that. It confirms my suspicion that the code is linked to a start or end of precipitation, but I'm still hoping that someone can confirm that it is just an incomplete section, instead of something special.

I've found this about it (from this page (http://www.met.tamu.edu/class/METAR/metar-pg13-rmk.html)):
Beginning and Ending of Precipitation (w'w'B(hh)mmE(hh)mm). At designated stations, the beginning and ending of precipitation shall be coded in the format, w'w'B(hh)mmE(hh)mm, where:

w'w' is the type of precipitation,

B denotes the beginning,

E denotes the ending, and

(hh)mm is the time of occurrence (only the minutes are required if the hour can be inferred from the report time).
There shall be no spaces between the elements. The coded remarks are not required in SPECI and should be reported in the next METAR. Intensity qualifiers shall not be coded. For example, if rain began at 0005, ended at 0030, and snow began at 0020, and ended at 0055, the remarks would be coded "RAB05E30SNB20E55". If the precipitation were showery, the remark would be coded "SHRABO5E30SHSNB20E55".

So you could have SNE05, meaning that snowing ended at 05 past the hour. I'm pretty sure that the SNEMM group is a variation on this, but did someone just forget to add the time, or is there a special meaning associated with this variation?

[TheOddOne]

Thanks for digging out that info. I looked at it and right on page 1 in bold type it says:

Note: The United States does not report remarks in the same manner as the WMO standard.

Why on earth not?

I thought the idea of ICAO was to work towards common standards worldwide so that we can maintain high levels of safety everywhere. If the United States think that their way is safer, why aren't they pressing ICAO to adopt their standards, or am I missing the point, somewhere?

Cheers,
TOO

[Teroc]

I agree, however remember that ICAO make recommendations only.

Any country can have their own standards once they inform ICAO of the differences.....and have published these in their AIP or similar, where it can be viewed.

To borrow from another site....

Contracting states will endeavour to conform with the recommended practices and are invited to notify any differences when considered important for the safety of aviation.


"If it is impossible for a state to comply with a standard, it is compulsory for that state to notify ICAO of this fact, and provide details of the difference(s) between the national regulation and the corresponding SARPS. Each annex contains a supplement listing all such differences.

All contracting states are invited to regulate their domestic aviation activities and align their regulations as closely as possible in accordance with ICAO SARPS. Naturally, national laws, not ICAO, control aviation within any given country. This is why air operator’s certificates usually specify what an operator must require of its pilots in the course of operating in that country."

[bookworm]

Thanks for digging out that info. I looked at it and right on page 1 in bold type it says:
--------------------------------------------------------------------------------
Note: The United States does not report remarks in the same manner as the WMO standard.
--------------------------------------------------------------------------------
Why on earth not?

The page in question is misleading. There is no "WMO standard" for remarks, and in fact there's no obligation to transmit remarks internationally. The idea of a RMK is that it can be plain language -- some groups may have particular ways of structuring remarks, in the same way that there are conventions for how to structure comments in computer programs. But that doesn't make it incorrect, or even unhelpful, to use different conventions.