Model output discussion - proper cold spell inbound?

[shotski]

On 02/02/2018 at 07:11, Steve Murr said:

Looks like the Grange Hill sausage

Not sure why I’m quoting this post ???? But hey. Nothing that you would call mild all the way out to 360 on the EPS ensembles. A very good trend I would say. 

[jvenge]

4 minutes ago, Nick F said:

The trouble is in MOD many are always concentrating too hard on the demise of a cold spell. Doesn't look like milder air arrives across all areas until Sunday on current GFS and reliable timeframe for the models atm IMO is around t+144. Temperatures in low single digits at best for most this coming week, some spots, mostly with elevation or well inland, perhaps barely above freezing. Some snow potential, though nothing significant. 

I did the unusual thing of checking the ECM for mins and max this morning. Quite a range on offer and will probably mean most forecasts will opt with the higher max. Just one runs output, but based on it, surface cold likely lower than most forecasts suggest.

Probably change next run ;-)

[Polar Maritime]

A cold week coming up adding on the Wind Chill charts for 12noon Mon/Fri.

[winterof79]

Best sticking with UKMO this morning only out to 144z to save your sanity trust me..Once we have established cold the fun starts

 

[bluearmy]

If we leave the near term and look further ahead, the low heights to our south currently fail to verify in the 8/12 day period (hence the slight  pull back of the colder mean) but they do re establish beyond. Ssw predicted around day 10 at the moment and looking at the gefs zonal flow, the trop has a slightly stronger than average flow prior to the reversal downwelling back end week 2. I would be looking at the period beyond the 16th for the hemispheric fun to commence! 

[tight isobar]

3 minutes ago, winterof79 said:

Best sticking with UKMO this morning only out to 144z to save your sanity trust me..Once we have established cold the fun starts

 

Id buy that...144!!

Awaiting 6z gfs with anticipation.

Mild sector being overplayed imo..as well as the more progressive-ness of partial outs.

6z notoriously a tad more progressive-on mobility than its sisters runs/suites...so lets see what she offers up!!??

 

[johnholmes]

I agree with that overall assessment Nick. It is a close run thing but deep cold from an easterly direction is not going to happen beyond the next 24-48 hours as the effects of the surface high over Scandinavia work west over the UK at low level.

At higher levels there is nothing to support any prolonged air coming from E or NE. see links below

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

This is the last evening NOAA, showing on the 6-10 and 8-14 an overall rather cold Atlantic flow divergeing in the UK area, part flow ENE and part SE. Just what this will give at the surface I am unsure of. Not a NE block though

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

The output of the above this morning shows a slightly different way of showing a similar upper pattern with quite marked troughing in the UK area. They both show 500 mb air originating from a more northerly part of North America. All 3 models have been consistent with the outputs shown above for several days.

Overall then I would expect rather cold for the UK, perhaps a touch less so for extreme western areas over the next 1-2 weeks. The patterns shown are MEAN values do temporary adjustments may well allow colder bursts of air but nothing prolonged. Will it snow-I don't know to be honest, on hills for sure, lower down, probably in places now and then but widespread disabling snowfall at low levels seems unlikely on what I can see in the time scale of the above charts.

Edited February 3, 2018 by johnholmes

[BlueHedgehog074]

Just to let you know our Netweather skip is already overflowing with all the trash we had to get rid of from this thread last night.

We’re gonna have serious problems with our skip if we have to remove anymore off-topic posts, including the “is it going to snow/rain/etc here ?” posts! 

Let’s continue to keep things Model related in here. Thanks!  

[Summer Sun]

t168 and UKMO, GFS & ECM all have a similar idea of winds swinging around to more of a westerly maybe less cold for a time at some point next weekend

[Duane S.]

I admit to being stuck between saying let’s just get the cold in (which is now a certainty) then see what happens and saying there is no getting away from the fact that we are trending towards a more Atlantic (albeit relatively very cold) driven period. Both could apply I suppose.

There’s a bit of time left for this to reverse in our favour and it will be transient anyway  IMO. With the Pacific activity and the expected strat warming event, the models are going to struggle (even more than they normally do) and I fully expect another cold spell to be just around the next corner.

Edited February 3, 2018 by s4lancia

[joggs]

Well for me the models have been downgrading the upcoming cold now for the past 36 hours or so.

I think our(as a nation)best chance,for disruptive snow,will come mid month(looking at long rangers and telecons.

[bluearmy]

1 minute ago, Ramp said:

Just read the cold spell has been cancelled, looked out of the window and yep it's snowing.

 

Hmmmm who to believe?

Wintry nirvana has been cancelled (for the time being) but it will definitely be a cold  spell .........

meant to say that the gefs show the East Asian vortex becoming the main centre end week 2 as the Canadian relaxes - we have seen that prediction before this winter ......

[BLAST FROM THE PAST]

So this really cold air coming in....an anyone explain why the Beeb are forecasting 4-6c in the SE on Monday?

The models are showing pretty low temps yet it isn’t seemingly getting translated in forecasts.

 

BFTP

Edited February 3, 2018 by BLAST FROM THE PAST

[shaky]

Just now, BLAST FROM THE PAST said:

So this really cold air coming in....an anyone explain why the Beeb are forecasting 4-6c in the SE?

The models are showing pretty low temps yet it isn’t seemingly getting translated in forecasts.

 

BFTP

Mate am still trying to get my head round how euro4 is predicting dew points of 1 and 2 degrees tomorrow evening for parts of east england despite the very low thickness and 850 temps of -10!!

[Weather-history]

Can I point out that this time last Saturday, GFS 0z wasn't even pointing to any wintry hopes for this Saturday morning, places are seeing snow currently. So whether any cold spell is being downgraded or not, be grateful that the models from last Saturday's GFS 0z haven't proven correct at the longer range, so cold lovers should be grateful for small mercies

And for Monday

Edited February 3, 2018 by Weather-history

[TEITS]

After reading some of the disappointing posts from yesterday and this morning I simply had to post.

Let me start by saying this coming week isn't going to be a typical Feb spell of weather, neither is it going to be a classic cold spell from the past either. Let me start by focussing on Sun/Mon.

Snow showers are expected to develop across the SE/E Anglia from tomorrow onwards and especially Monday. The temps near the coast of Kent/ E Anglia may still reach 5 or 6C due to the warming influence of the N Sea. Take note if your expecting lying snow!

Tues looks to be the coldest day. The day will start with very low min temps especially in W areas with the W Midlands possibly recording very low mins. During the day a front moving SE is likely to bring a lengthy period of light snow.

Much has been said about snowfall amounts on this front but frankly its impossible to predict. I recall an occasion back in the early 2000s when a front from the NW petered out to the NW of me. This suddenly reinvigorated as it approached Peterborough and gave me 6 inches of snow.

Towards the end of the week and we could have the dangerous situation of snow turning to rain, back to snow then freezing overnight.

 

[Duane S.]

I realise this is the wrong thread but it’s worth posting this EC chart from the Berlin site as it will affect our weather later on...

It has been on the cards for a while but it’s nice to see it come into D10 range. Going to have some interesting and varied  FI charts in the next few days and week.

[East_England_Stormchaser91]

The fun is starting, and the models are all over the place now. So many evolutions beginning to show up. 

What I have never seen before though is still those remarkable -10's invading us from the west, which 9/10 would be a transient snow to rain event from the west (Feb 2012 being a good example), but now, a snow to rain and possibly turning back to snow on the back edge. Remarkable. 

The thing is, we could still see some drastic flips within this next 48 hours regarding the cold to our east. I've noticed the models have not had a clue on handling that Russian low/trough coming up from the Ukraine which is currently progged to drag that real cold pool of -20's back towards the pole/Siberia, one to keep an eye on. 

All in all, possibility for a brief lull after the first bit of excitement, then towards the end of the month with the strat warming, a real sting in winters tail to unfold perhaps? 

Intereting times. 

[karlos1983]

It will feel bitter tomorrow as the cold air digs in by mid day.with snow flurries briefly pushing well inland. Nothing significant at all, but nice to see.

Edited February 3, 2018 by karlos1983

[snowblind]

10 minutes ago, BLAST FROM THE PAST said:

So this really cold air coming in....an anyone explain why the Beeb are forecasting 4-6c in the SE on Monday?

The models are showing pretty low temps yet it isn’t seemingly getting translated in forecasts.

 

BFTP

That's what I don't get. Are we misinterpreting the models? Are the forecasts over estimating the max temps, but not sure why they would do that? Or is it because the surface flow is coming over a realtively warm North Sea modifying the surface temps..

Whatever it is it doesn't look very conducive to any significant settling snow.

[craigore]

24 minutes ago, Ramp said:

Just read the cold spell has been cancelled, looked out of the window and yep it's snowing.

 

Hmmmm who to believe?

The point we need to make here is even at 6 hr forcasts we have changes. Apparently todays front would not make it as far as kent , sussex .. well let me tell you its raining here in ramsgate.

Which tells me the will it wont it snow imby is completly up in the air until it happens , and its the same wth the moddeled cold & how long it will last.

Let it play out and there may be some surprises.

[shaky]

Hmmm interesting gfs falls in line the ukmo at 66 hours with more of an upper low to the south east coming out the continent!

[MattStoke]

6z has has Tuesday's front a touch slower but the mild sector is still the same size. Still probably going to be the most progressive of all the models with that. GFS does tend to be over progressive in such situations but it's odd how it differs quite markedly to all other models at the moment and sticking with it so far.

-8 uppers widely before that on Monday in the east/north east flow. -10 in places. More in the way of snow showers/flurries coming in from the east across England too, with heavier snow showers across the South East. Bit of an upgrade there.

Edited February 3, 2018 by MattStoke

[karlos1983]

I would actually say that if the front is taking longer Matt then it’s is less progressive. Might be wrong, but that’s my take on it. But we aren’t talking big changes, so we run the risk of over analysis here. 

[MattStoke]

6 minutes ago, karlos1983 said:

I would actually say that if the front is taking longer Matt then it’s is less progressive. Might be wrong, but that’s my take on it. But we aren’t talking big changes, so we run the risk of over analysis here. 

Yeah. Sorry, I meant it is less progressive than previous runs but more progressive than other models. Baby steps in the right direction. Increases the risk of snow showers for the south east and flurries into the Midlands too ahead of that. 

Looks worse beyond that though :-/ Far more progressive with Thursday's front.

Edited February 3, 2018 by MattStoke