Model Output Discussion 01/09/17

[Frosty.]

Holy ice cubes, Quick..to the ensembles robin!..

silly me, it is the Ecm 12z ensemble mean.. and it shows arctic air flooding south from next tuesday onwards, really impressive mean tonight for a sustained cold outbreak with high pressure to the west and low to the East / Northeast!

Edited November 24, 2017 by Frosty.

[Tim Bland]

ECM has snow cover over a large portion of the UK as early as Tuesday afternoon! 

 

[Dennis]

#snow showers in cold air on this beautifull sat.picture

[cyclonic happiness]

19 minutes ago, Dennis said:

snow from the west this evening/night

I've got a temp of 2'c here and a dew point of -3'c, looks not too bad? It would be great!!!

[Dennis]

Just now, cyclonic happiness said:

I've got a temp of 2'c here and a dew point of -3'c, looks not too bad? It would be great!!!

then snow is on the run   hope you like to send pictures whe's snowing (pls)

[cyclonic happiness]

Just now, Dennis said:

then snow is on the run   hope you like to send pictures whe's snowing (pls)

both temps and dew point will probably go up when the precipitation gets here, I'll not hold my breath

[tight isobar]

2 minutes ago, cyclonic happiness said:

both temps and dew point will probably go up when the precipitation gets here, I'll not hold my breath

Shower activity appears to be decaying as they move inland!!

But worth a watch!?

[V for Very Cold]

3 minutes ago, cyclonic happiness said:

both temps and dew point will probably go up when the precipitation gets here, I'll not hold my breath

Very true... heavy rain here atm

[Dennis]

4 minutes ago, cyclonic happiness said:

both temps and dew point will probably go up when the precipitation gets here, I'll not hold my breath

its cold air around your area too -  it would be nice snow

Edited November 24, 2017 by Dennis

[Captain Shortwave]

Can we stick to the models please, there are threads for specific weather events or even the daily chat thread.

As for the models, aside from the UKMO it looks like we will keep a feed from a northerly quadrant with temperatures below normal (albeit not very cold). The pattern looks good enough to produce snow to low levels during the second half of next week.  Again probably not a snowfest but maybe a dusting in some spots at low levels perhaps. Not bad for late November. 

[knocker]

Pretty good agreement between the three anomalies this evening

Upstream the Siberian vortex with Canadian lobe, ridge in the eastern Pacific, trough western North America and a in ridge SE Untied States, Downstream is extremely amplified with strong ridging mid Atlantic into Iceland and in eastern Europe and a high cell over the Arctic In between the ridges a deep trough running south east of the UK. So the Atlantic is blocked curtailing any zonal west-east momentum and thus the flow over the UK is from the NW-N direction.This poses some problems for the det. runs to sort because the precise orientation and intensity of the surface features ( high cell-trough) is crucial .It can be safely said that the temps will be below average but the weather detail put on hold although it will probably be pretty dry in many areas.

No major changes in the ext period apart from slackening of the amplification to some extent with the upper flow backing more to the NW with the temps still below average. At this range not a lot of point attempting more detail but the earlier caveats vis position of surface features obviously still applies.

So in summation good agreement on temps remaining below average for the 14 day period, perhaps rising to near average towards the end.and probably not a great deal of precipitation in many areas but with a bias towards the north and east.

Edited November 24, 2017 by knocker

[tight isobar]

7 minutes ago, Dennis said:

blue colors (cold air) over the UK and Ireland

Current conditions thread open now.

Edited November 24, 2017 by tight isobar

[Nick L]

45 minutes ago, Tim Bland said:

ECM has snow cover over a large portion of the UK as early as Tuesday afternoon! 

 

As someone who can see the full EC suite, I am puzzled at this chart. Certainly no snow for lowland southern UK on it!

[tinybill]

this should bring a  smile  to the coldies

[feb1991blizzard]

7 minutes ago, Nick L said:

As someone who can see the full EC suite, I am puzzled at this chart. Certainly no snow for lowland southern UK on it!

Yes, for a start off even if snow falls over the weekend it would be washed away over most habitable altitude locations over England by the rain on Sunday and Monday (all models) and Tuesday looks bone dry inland England and only rain showers if anything at all on East coast, Scotland may be different of course as always.

[Nick L]

Just now, feb1991blizzard said:

Yes, for a start off even if snow falls over the weekend it would be washed away over most habitable altitude locations over England by the rain on Sunday and Monday (all models) and Tuesday looks bone dry inland England and only rain showers if anything at all on East coast, Scotland may be different of course as always.

Any falling precip over the southeast on Tuesday coincides with 850 wet bulbs of 4/5c, unless you're on a plane over the SE you're not gonna get snow on the EC!

[Man With Beard]

14 minutes ago, Nick L said:

As someone who can see the full EC suite, I am puzzled at this chart. Certainly no snow for lowland southern UK on it!

These weather.us snow charts are a mystery. When looking at all the other charts available (on the weather.us site for ECM) you can't see a sniff of snow. I'm starting to ignore this one unless there's a really significant amount on it. Having said that, I do think all parts of the UK are in snow game to some extent around the turn of the month.

Edited November 24, 2017 by Man With Beard

[Nick L]

1 minute ago, Man With Beard said:

These weather.us snow charts are a mystery. When looking at all the other charts available, you can't see a sniff of snow. I'm starting to ignore this one unless there's a really significant amount on it. Having said that, I do think all parts of the UK are in snow game to some extent around the turn of the month.

Yep, whatever algorithm they're using for those charts is nonsense.

[Man With Beard]

1 hour ago, Frosty. said:

Has the gem ever come off though?..first time for everything I suppose☺??

Don't you remember it trumping the other models several times last year?? though usually when showing mild ...

oh while I'm here I'll give my reaction to the 12Zs - the pattern looks set enough to keep the UK cold until at least D8 - but interactions over the North Pole are really not worth taking as gospel after D4/D5. -AO and -NAO rules apply: models are going to struggle over the interactions of shortwaves in the vicinity of the pole. I would not rule in nor rule out the apparent break down over the pole at this stage, and I would not rule out a rebuild of pressure towards the pole a second time even if there is an interruption around D5/D6/D7.

Edited November 24, 2017 by Man With Beard

[karlos1983]

6 minutes ago, Nick L said:

Yep, whatever algorithm they're using for those charts is nonsense.

I think @Frosty. is the coder 

[tight isobar]

Ridicoulously early but worth a mention.

18z making much less drama early on' of shortwaving around greenland/iceland location...

Something that would be a big bonus via other mods!!!

Edited November 24, 2017 by tight isobar

[shaky]

No change at 72 hours on the 18z which is brilliant!!!!up the heights go into the arctic!!!

[ANYWEATHER]

Some incredible cold charts for this time of year but, snow is likely  in the North even possible further south especially on high ground! Lesson , don't take the opp models literally even a few days ahead, the cold looks like it's here to stay for a while so folks enjoy the rollercoaster

Edited November 24, 2017 by ANYWEATHER

[SMU]

Evening All

so lets be really honest- despite have painted a picture of the background signal & residual polar heights supporting a cold snap - not many expected to see a chart like this @T72 !!

S

[snowice]

Please explain steve

Edited November 24, 2017 by snowice