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METAR interpretation - direction in visibility?

Hey,

The following METAR was just released for ESMS.

ESMS 031550Z 34004KT 9999 3000W NSC 04/02 Q1021 R17/19//95

I’ve never seen this before, I read it as >10km visibility but 3km to the west (from where the fog is rolling in, I can see it happening out my window :) )

This is certainly new to me, but is it common in Europe?

martin-esmi wrote:

This is certainly new to me, but is it common in Europe?

Are you asking whether the report is common or wether the occurrence itself is common? Because those are different question :)

I guess it’s as common as the probability of occurrence of said weather phenomenon.

I find that the Pareto rule applies with METARs very well. 80% of the time you only get 20% of the reported stuff which is always the same. But the other 20% of the time you get all the other 80% of codes/occurrences.

EDDW, Germany

I would say this is commonly reported and not uncommonly occurring in the UK. It is also sometimes total nonsense, as with other elements of METARs.

United Kingdom

Fair enough :) I was surprised to the format/code of the METAR and whether using that format was common practice.

I got curious enough so I called FPC in Sweden earlier today, and the person who responded mentioned that those codes in METAR was introduced a few years ago, which would explain why I hadn’t seen it before or remembered learning about it.

martin-esmi wrote:

I’ve never seen this before, I read it as >10km visibility but 3km to the west (from where the fog is rolling in, I can see it happening out my window :) )

This is certainly new to me, but is it common in Europe?

I’ve seen it a couple of times before (in Sweden), but is not a common phenomenon.

ESKC (Uppsala/Sundbro), Sweden

Very common in Scottish metars – and I’m surprised it’s said to be a recently added format.

Maoraigh
EGPE, United Kingdom

Never seen that in the US and it would be a daily occurrence at my home base and most coastal airports in California.

From UK Metoffice site:
“3 Visibility
Prevailing visibility 3200 ‘three thousand two hundred metres’
NOTES: 0000 = ‘less than 50 metres’ 9999 = ‘ten kilometres or more’. No direction is required.
Minimum visibility (in addition to the prevailing visibility if required) 1200SW ‘Twelve hundred metres to the south-west’
NOTES: The minimum visibility is also included alongside the prevailing visibility when the visibility in one direction, which is not the prevailing visibility, is less than 1500 metres or less than 50% of the prevailing visibility. A direction is also added as one of the the eight points of the compass. NDV = no directional variation (AUTO METARS only)”

Maoraigh
EGPE, United Kingdom

This is absolutely standard code vor sector visibility.

The sector visibility must be smaller than 50% of the prevailing visibility and the sector should be defined according to the direction.

Not everywhere are sector visibilities above 1500 m given but I think it makes perfect sense to give them when you can. In LSZH we always give it if conditions warrant it.

LSZH(work) LSZF (GA base), Switzerland
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