ESOW 041820Z AUTO 28003KT 0250 R01/P2000N R19/P2000N BR NCD M17/M19 Q1022=
PS: There is no mist.
Meteorological visibility is 250m but RVR is way higher (possible if lights are really strong)
M17/M19, Temp 16.5, Dew 18.5
Runway 01, RVR2000
Runway 19, RVR2000
BR = “Brume” in French (visibility between 1km and 5km) and NCD no clouds detected (altough they better add vertical vsibility?)
Given it’s automatic and no moist, I imagine smoeone is burning woods to warm up the airport? or smoking weed with strong flames in front of those RVR devices?
AUTO is never good at dealing with fog.
I saw this online while ago for Mount Washington, visibility going from 130nm to 1/8nm in 1h
KMWN 210353Z 29030KT 130SM FEW/// SKC M25/M37 RMK TPS LWR FEW DSNT SW
KMWN 210255Z 29033KT 1/8SM FZFG SCT000 M27/M27 RMK FZFG SCT000 VRY LGT ICG
Still the 8th weather offender this year but all years winner 
My guess is there is some ice built-up on the sensors.
I can see the runway from here, and it’s one of the clearest nights, with no clouds, mist, or any humidity.
Here is direct access to the AUTO-sensors for the curious: http://wx.awos.se/?siteId=ESOW
Ibra wrote:
visibility going from 130nm to 1/8nm in 1h
I believe it is “statute mile”, that is about 1609 m instead of nmi (1852 m).
Yes SM sorry, does not make much difference neither for 1/8sm or 130sm
It’s the typical garbage Auto Metars produce.
One vis sensor recorded a vis of 250m. Transmissiometers obviously not. Present weather most likely did not record anything so it defaulted to BR, which at these temperatures is highly unlikely.
They got 3 vis sensors by the looks of it, unclear how many PW sensors, even though I’d expect 3 of them as well, likely colocated with the Transmissiometers. Unclear how many Ceilometers they have, I guess two.
It is great that they show their whole sensor page on the Internet. That way at least from the ground one has a possibility to check for obvious garbage. Nevertheless, it is rather frustrating to see how Autometars are being accepted all over the place without protests about the garbage they produce.
Looks to me as if the Autometar there also only works in off ops hours? If so, well… one can debate. Hopefully however it does not go into the weather modelling this way. Otherwise weather forecasts may go worse in the future if Autometars are actually fed into the base data for the wx models.
Ibra wrote:
KMWN 210353Z 29030KT 130SM FEW/// SKC M25/M37 RMK TPS LWR FEW DSNT SW
KMWN 210255Z 29033KT 1/8SM FZFG SCT000 M27/M27 RMK FZFG SCT000 VRY LGT ICG
This on the other hand I’ve seen happen many many times, even in a 30 minute message interval. The question rather is why they don’t have Special reports in between, or maybe they do but they are not listed. Apart, this is not an Autometar.
I’ve gone from Cavok to full soup outside in less than 10 minutes. By the looks of this one it would have been likely a fog bank which shoved itself onto the airport from outside, otherwise the rise of dew point is difficult to explain, but absolutely possible.
Mooney_Driver wrote:
Nevertheless, it is rather frustrating to see how Autometars are being accepted all over the place without protests about the garbage they produce.
What is interesting to me is that large UK airports release AUTO METARs all the time. For instance, EGLL Heathrow or EGCC Manchester, only one out of every five or so METARs is NOT an AUTO METAR.
In Spain, these METARs are only realised outside the hours of operation of the airfield. And most large commercial airports are H24, so never release any AUTOs.
