Model Output Discussions 18z 31/01/2016

[Summer Sun]

2 minutes ago, Ripeberry said:

Isn't it supposed to be very mild on Sunday?  If it can't manage to snow today, there's not a snowball in Hell's chance that it will snow at the weekend, lol!

Quite a difference between the 00z and 06z for the maximum temps on Sunday the 06z is certainly a colder run but how this sits within the ensembles remains to be seen

[warmintim]

I think it depends on when and where for this. If you check out the run there is a clear signal for much colder air to spread south during Sunday. SO at 6 am there is 11 deg C in the extreme south and -2 in Scotland. Later in the day the cold air has flooded across all areas so by 6 pm it is 2 dec C in the far south, with a dewpoint of -3. Will be an interesting change to observe (if it happens as this run predicts - which it won't...)

[feb1991blizzard]

3 minutes ago, Summer Sun said:

Quite a difference between the 00z and 06z for the maximum temps on Sunday the 06z is certainly a colder run but how this sits within the ensembles remains to be seen

Not any longer - here they are - right in the middle!

[winterof79]

14 minutes ago, bobbydog said:

currently a strong signal for snow virtually everywhere on sunday. (much stronger than todays feeble effort anyway) just 4 days away-

Currently. I do believe there were various strong signals for todays rain fest across much of England.

ECM says no to snow

[Eskimo]

Arpege ramps up the snow risk a tad and shows falling snow for the extreme east including East Riding and Lincolnshire down through to Cambridgeshire and Suffolk as the run goes on.

 

[nick sussex]

I'd be a bit dubious of the GFS snow predictions at that range. It has a known bias for overdoing the signal for snow so its better to wait till nearer the time.

The positive is the unstable air mass which means you might get some colder downfrafts in heavier showers lowering the freezing level.

 

 

 

[Mildcarlisle]

Sunday snow for Scotland.

Edited February 17, 2016 by Mildcarlisle

[feb1991blizzard]

Just now, Mildcarlisle said:

Sunday snow for Scotland.

Yes, looking at the models, It would actually be very surprising to me if PARTS of Scotland DONT receive a few decent dumpings in the next month and a half.

[Nouska]

39 minutes ago, PerfectStorm said:

Arpege ramps up the snow risk a tad and shows falling snow for the extreme east including East Riding and Lincolnshire down through to Cambridgeshire and Suffolk as the run goes on.

 

The AROME higher-res version of that.

[Nick F]

Is quite a potent PM blast on Sunday on GFS, quite unusual to have such low partial (850-1000mb) thicknesses and dew points from a Wly/NWly over a long sea fetch across southern UK. Thickness of 129 dm the absolute limit for snow but dew points well below 0C Sun evening.

As Nick Sussex mentions, the GFS tends to have a colder bias at that range and usually tones down potency nearer the time. Though the N Atlantic SSTs reach their coldest point late Feb into March and the current SST anomalies show a -ve anomaly to the west of the U.K. too which may help the potency of PM flows as they cross the long sea crossing before arriving over the UK.

06z GFS still going for the trough disruption into Western Europe end of medium range and we get an easterly, but uppers not cold.

Edited February 17, 2016 by Nick F

[Man With Beard]

On the face of it, these charts should be worth raising an eyebrow at - could be at 24 hour window for snow in places if this develops favourably. But I would expect more chance of northerly corrections rather than southerly corrections, based on past experience.

For the end of the month, very strong agreement (looking through the ens) on troughing dropping from N Atlantic through into Europe - but by now we're approaching the time of year when only a proper northerly block will bring significant cold - starting in the south around this time and gradually further and further north as March continues

Whilst that High is strong to our south-west, always the chance of it ridging in between systems to bring an early taste of spring - something like this which would bring mid-teens to England.

 

[nick sussex]

15 minutes ago, Nouska said:

The AROME higher-res version of that.

The AROME did very well with the January snow so lets hope its on the right trend here. I still laugh at the name of this model. Its like AROME by Givenchy! It sounds like a perfume! lol

[Nouska]

4 minutes ago, nick sussex said:

The AROME did very well with the January snow so lets hope its on the right trend here. I still laugh at the name of this model. Its like AROME by Givenchy! It sounds like a perfume! lol

I used to be very fond of a little dab of Lanvin's Arpege.

 

[Bullseye]

Some good news, Fergie tweeted, after this weekend evidence there for period of cold spell rest of Feb and into March.

[terrier]

59 minutes ago, Bullseye said:

Some good news, Fergie tweeted, after this weekend evidence there for period of cold spell rest of Feb and into March.

Yes but goes onto say this doesn't mean pronounced cold or servere cold just a broad picture of the ukmo update. 

[syncmaster]

23 minutes ago, terrier said:

Yes but goes onto say this doesn't mean pronounced cold or servere cold just a broad picture of the ukmo update. 

Well i just had a look on is twitter page, and it dosnt say that at all last post 2hrs ago !!!

Ian Fergusson ‏@fergieweather  2 hrs2 hours ago

W COUNTRY After a milder phase this weekend, there's evidence for an extended period of below-normal temps rest of Feb into early-mid March

[terrier]

19 minutes ago, syncmaster said:

Well i just had a look on is twitter page, and it dosnt say that at all last post 2hrs ago !!!

Ian Fergusson ‏@fergieweather  2 hrs2 hours ago

W COUNTRY After a milder phase this weekend, there's evidence for an extended period of below-normal temps rest of Feb into early-mid March

Click on his Twitter feed and u will see that he has replied to Matt and someone else specifying what I've put above. 

[mushymanrob]

27 minutes ago, syncmaster said:

Well i just had a look on is twitter page, and it dosnt say that at all last post 2hrs ago !!!

Ian Fergusson ‏@fergieweather  2 hrs2 hours ago

W COUNTRY After a milder phase this weekend, there's evidence for an extended period of below-normal temps rest of Feb into early-mid March

erm.... he didnt say theres going to be cold, he said "extended period of below normal temperatures", which is not really the same thing. it is of course as anything is looking 4 weeks into the future - a prediction based on current data which could change at any given point. true, this might mean that there might be a 'cold' spell, but it might also allow for a mild spell. 

the current anomaly charts, whilst not 100 % confident, do paint a broad picture of an unsettled spell with (as john holmes said earlier) the mean upper flow north of west. this would support fergies tweet (or vice versa).

thats a pretty much no win situation either for those hoping for late cold, or those now looking for spring warmth.

[Alexis]

4 minutes ago, mushymanrob said:

erm.... he didnt say theres going to be cold, he said "extended period of below normal temperatures", which is not really the same thing.

Surely it is in winter?? Not July obviously.

[Methuselah]

And...back to the models, please...

[snowangel32]

I would be very sceptical of any snow charts the gfs shows. Today is a perfect example even high ground not seeing much snow. Just an absolute rainfest

[Summer Sun]

Still the chance of some back edge snow tomorrow morning further south

[nick sussex]

Big differences between the GFS and UKMO as early as T96hrs.

Although the GFS brings some colder weather in earlier its the UKMO which is much better moving forward with a decent ridge to the nw.

The differences are in relation to the handling of southern jet stream lows in the Atlantic, the UKMO doesn't phase this with the troughing over Canada and this allows a ridge to develop to the nw, the GFS does. The UKMO has made a big change from its morning output which was similar to tonights GFS.

Because the UKMO hasn't phased the low you can then see how this changes the evolution going forward:

 

Even though the GFS is not as good as the UKMO it still looks to dive a low se towards the end of the higher resolution output.

Looking at the MJO update I'd be surprised if the models don't start showing some more interesting outputs.

 

 

 

Edited February 17, 2016 by nick sussex

[feb1991blizzard]

The GFS 12z is going to show something quite spectacular by 384!!!

[pip22]

GFS 12z is showing Low pressure being forced south by next weekend next week bringing in easterlies.

Edited February 17, 2016 by pip22