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 6ins

Must 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? Anyone know what happened?

FFF
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