Winter Model Discussion - Cold Hunting -12Z 30/12/12

[pyrotech]

Lots of positive things happening and yes they are starting to show in the models

but

Firstly the polar vortex will be disrupted, the SSW will disrupt it and models showing this, it does not mean we will get cold and blocking in right place, it gives us a great opportunity.

Remember a few weeks back, it can block to our East and send cold down to Greece instead.

Secondly a second part of the puzzle will be the Greenland high, again hints from the models that it will form, if it does that helps us hugely with my first part above.

One or two members are getting excited, it understandable but i just do not want to see disapointment in 10 days time.

Much is in place, models hinting at putting the picture together correctly for us, and mid to end Jan could be exciting, but lets not get excited and light that cigar yet. There is still much indecision on the models and things can still go very wrong if we get stuck with blocking in the wrong place. It could still end up stuck in mild and wet for us, Mainland Europe and USA in the freezer. I want something seasonal more than anyone but its a very tentative situation. Hense why the Meto update hints at possible change to colder in MRF.

[Bobby]

The CFS for what it's worth has a pesky piece of Vortex around Greenland and above average temperatures and rainfall for January.

Quite a lot of high pressure over the North but a pesky bit of vortex around Greenland, typical. I guess this shows what happens if we get a SSW and wet get unlucky with where the blocking positions itself.

Temperature anomalies, most of Europe is anomalously warm

It's only the CFS though so obviously a big pinch of salt.

Edited December 30, 2012 by Bobby

[Mr Frost]

The CFS for what it's worth has a pesky piece of Vortex around Greenland and above average temperatures and rainfall for January.

Quite a lot of high pressure over the North but a pesky bit of vortex around Greenland, typical. I guess this shows what happens if we get a SSW and wet get unlucky with where the blocking positions itself.

Temperature anomalies, most of Europe is anomalously warm

It's only the CFS though so obviously a big pinch of salt.

Yes, I would check the CFS often in the past. It changed from week to week and I wondered how reliable it was...until Ian F gave us the information that it was never used by them.

It is about as much use as a cat flap on a submarine.

Edited December 30, 2012 by Mr Frost

[IDO]

The CFS for what it's worth has a pesky piece of Vortex around Greenland and above average temperatures and rainfall for January.

Quite a lot of high pressure over the North but a pesky bit of vortex around Greenland, typical. I guess this shows what happens if we get a SSW and wet get unlucky with where the blocking positions itself.

Temperature anomalies, most of Europe is anomalously warm

It's only the CFS though...

It is always a worry that the UK will be on the wrong side of the block. Will the reset from the SSW be enough to dislodge 2012's background signal. This year has been a non-stop train of cyclonic westerlies, leaving us with the highest rainfall since records began. What triggered this wet year i am not sure and I have not seen any conclusive arguments; maybe the warmer Atlantic or melting Arctic ice? Certainly a SSW will bring a higher chance of HLB but will it disrupt the undercurrents that have driven the jet stream over the UK. The GFS at T384 still has a rampant jet:

Time will tell.

[bradymk]

The CFS for what it's worth has a pesky piece of Vortex around Greenland and above average temperatures and rainfall for January

Hi Bobby, yes the CFS can be unreliable however if you want to use it, the weekly anomalies are imo the best http://www.cpc.ncep.noaa.gov/products/people/sweaver/cfs_fcst/ here is the link, Z500 you want for pressure and it shows +ve anomalies over Greenland week 3 and 4. I think it also factors in stratospheric forecasts Edited December 30, 2012 by bradythemole

[Timmytour]

In the short term, the models appear to be showing us an end to the respite from the drought!

[Panayiotis]

Ensembles show the cooling trend, after the high sets in for 5 days, for my area (Cardiff), however on the right are Greenland's ensembles, look at the scatter there!

Edited December 30, 2012 by Panayiotis

[bluearmy]

Good gefs with as many as 30% snow chance for london by the end of the run. Still quite a few mobile runs so we'll wait to see if tomorrow brings a trend to moe colder solutions. No doubt that the 12z ncep suite has a tendency to a quick trop response to the SSW.

[Iceni]

Ensembles show the cooling trend, after the high sets in for 5 days, for my area (Cardiff), however on the right are Greenland's ensembles, look at the scatter there!

The air pressure scatter doesn't look like an entrenched GL polar vortex to me. There's hope!

PS can anyone tell me how to attach postage stamps? If this one doesn't work.

Edited December 30, 2012 by Iceni

[Panayiotis]

The scatter doesn't look like an entrenched GL polar vortex to me. There's hope!

Exactly!

[J10]

At least some dry weather is in the models at the moment, and in the absence of any now, at least that is a good thing, at least to me.

[cooling climate]

Early days I know but the models and ens runs give the impression that we should look

towards the east, northeast for our first wave of cold from the coming pattern change

in FI.

I still think we are in a prime position for cold from what the strat charts are showing us

of the position of the displacement and split.Time will of course tell.

[ITSY]

I have no science to back up my opinion, but this year has seen such an Atlantic dominated climate that any blocking could be blown away by a rampant jet stream - something which could potentially lead it to set-up shop elsewhere after the SSW. On the other hand, it could create prime conditions for serial dumpings of snow...either way, I think the Jet Stream will be the most crucial element to this possible development.

Today, the models seem to be leaning towards an extension of heights NE, with this comparison particularly illustrative:

ECM 12Z, t+192

ECM 00Z T+216

Edited December 30, 2012 by ITSY

[IDO]

A tweet by Big JB suggests that the real cold air from the SSW will head to the US.

Another article suggests the cross polar flow is from Siberia to the Midwest hence why they suspect it will bring extreme weather to the US (that is a good signal for cold for them).

I therefore checked the 2m mean temps with CFS:

Jan:

Feb:

Get over to Canada and NE America if you want to see some astonishingly low temps. The UK just cool/average on this CFS run.

Somewhere in the NH around our latitude will go into the freezer for weeks. Not the UK at the moment but still time for things to turn favourable.

Edited December 30, 2012 by i'm dreaming of...

[ITSY]

A tweet by Big JB suggests that the real cold air from the SSW will head to the US.

Another article suggests the cross polar flow is from Siberia to the Midwest hence why they suspect it will bring extreme weather to the US (that is a good signal for cold for them).

I therefore checked the 2m mean temps with CFS:

Jan:

Feb:

Get over to Canada and NE America if you want to see some astonishingly low temps. The UK just cool/average on this CFS run.

Somewhere in the NH around our latitude will go into the freezer for weeks. Not the UK at the moment but still time for things to turn favourable.

Given this year's strength of the Atlantic, that wouldn't suprise me. If that occurred, then some potentially record-breaking cold could be headed for Canada, Alaska and the USA

[AWD]

At T192, the GFS & JMA aren't too far away from each other with a ridge being sent up towards Iceland & a deep depression in the Mid Atlantic;

The ECM has the pattern further east though;

Edited December 30, 2012 by AWD

[nick sussex]

Absolutely zero interest from the ECM, that was painful! The last few days its at least thrown a little interest out but tonight its as flat as a pancake upstream with the PV refusing to budge.

The GFS looks better at 240hrs but overall this looks like a very boring period of weather and model watching. A quick initial response to the SSW currently looks unlikely so the boredom is likely to last for quite some time yet!

[Jayces]

A tweet by Big JB suggests that the real cold air from the SSW will head to the US.

He also said towards the end of November that the UK would be getting severe cold and snow this winter.....

[nick sussex]

He also said towards the end of November that the UK would be getting severe cold and snow this winter.....

Unless he's got a crystal ball then at this stage no one knows exactly where any blocking is likely to set up.

He's known for his theatrics, just ask him about GW!

[Summer Sun]

A good run from ECM tonight just about high pressure dominated through out epically over the areas which need the dry weather

The new year will finally bring with it a much needed pattern change to drier weather

http://www.null/ds/ecm.htm

[Froze were the Days]

Yep ECM again not playing ball, in fact ECM really around the 240z mark wants to bring the Atlantic in (very similar to the 0z theme).

Wasn't the op run for the 0z meant to be a mild outlier? strange we have another run very similar!

[cooling climate]

Yep ECM again not playing ball, in fact ECM really around the 240z mark wants to bring the Atlantic in (very similar to the 0z theme).

Wasn't the op run for the 0z meant to be a mild outlier? strange we have another run very similar!

Would not be at all surprised to see this run end up the same in the latter stages.

Although its hard to tell where the blocking will set up first there is quite a few hints from the

GFS ens for it to be to our north or northeast.

[bluearmy]

The models are fishing for a solution post day 8. Any number of directions are available and you will see quite different themes in the op runs over the next cole of days. One would hope that the direction of travel between the block and the response of the trop to the ssw will become evident by wednesday.

[Snowman.]

Where is the PV?

Just too add

For fun of course but still looking better.

Edited December 30, 2012 by SN0WM4N

[Mark Neal.]

Roll on high pressure next weekend, i'm at a balloon meet down in Savernake Forest, Wiltshire ( www.icicle.org.uk) . Calm winds and High pressure will do the trick. It will make a good change from this unsettled regime we have been in for a few weeks now. Personally I think it will be mid month onwards before some of us can begin to get excited about cold prospects again.