METAR decode query

[Kolibear]

I've just been looking at the S.E England Metars and if noticed that on the end of some of them, there is a string of digits :-

LONDON/HEATHROW EGLL 081050Z 05005KT 1200 09R/1300 09L/P1500 SN VV/// M00/M02 Q1017 TEMPO 4000 -SN BKN014 09520095 59510295

and

SOUTHEND EGMC 081050Z 36003KT 8000 FEW006 SCT007 BKN012 00/M01 Q1017 06499792

What do they mean? Is it anything to do with the condition of the runway braking/friction?

Current MET in SE Essex - 2-3 inches of snow after three hours, then it stopped for an hour but its just started snowing again.

[FlyingForFun]

Kolibear,

It is the runway contamination.

The first two digits of the eight-digit group is the runway number. Add 50 for a right runway (so the group beginning 59 in the LHR METAR is for 09R). 88 means all runways. 99 means this is a repeat of the last message, no new information.

The third digit is the type of contamination:


0 - clear and dry
1 - damp
2 - wet, or water patches
3 - rime or frost covered
4 - dry snow
5 - wet snow
6 - slush
7 - ice
8 - compacted snow
9 - frozen ruts or ridges
/ - type of contamination not reported


The fourth digit is the extent of the contamination:


1 - 10% contaminated
2 - 11% to 25% contaminated
3 - 26% to 50% contaminated
9 - 51% to 100% contaminated
/ - extent of contamination not reported


The fifth and sixth digits are the depth of the deposit:


00 - less than 1mm
01 to 90 - whole mms depth
91 - not used
92 - 10cm
93 - 15cm
94 - 20cm
95 - 25cm
96 - 30cm
97 - 35cm
98 - 40cm or more
99 - runway(s) non-operational but depth not reported
// - depth not significant, or not reported


The final two digits are the braking action:


91 - braking action poor
92 - medium to poor
93 - medium
94 - medium to good
95 - good
99 - figures unreliable, but braking action suspect
// - not reported, or runway closed


No, I didn't know all this, I had to look it up! ;)

FFF
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[Kolibear]

Thanks FFF - I'll have to print that off for future reference.

I wonder if Southend really have had 35 cm (about 16 ins ) or 35 mm (about 1.5 ins) :)

[FlyingForFun]

Well, if they'd had 35mm, I suspect they'd have put a "35" in their METAR, not a "97" - would be pretty tricky to confuse the two, I'd have thought?

35cm isn't quite 16in, more like 14in, but it's still a hell of a lot of snow!

FFF
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[FlyingForFun]

According to The Sun today:Two inches of snow fell across central London and up to 4ins in the suburbs. Southend, Essex, had 6insMust have been pretty bad over there to be singled out for a mention, but 6ins is still well short of 35cm, unless they were shovelling snow onto the runway instead of off of it? :eek: Anyone know what happened?

FFF
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