Winter Model Discussion - Cold Hunting -12Z 03/01/13

[IDO]

Impressive chart in terms of 500mb height anoms!

http://raleighwx.ame...htAnomalyNH.gif

M.

The UK high migrates to Greenland and co-joins with the polar high maintaining a v. strong GH (on this run in FI):

[BLAST FROM THE PAST]

I'd be looking at the 00Z ECM tonight/tomorrow. Hoping for further amplification of the HP ridging into the arctic/scandi. If the ECM keeps its cold outcome, along with more amplification from the UKMO, I for one would be happy!

And so you get your wish. ECM now on board, UKMO much much better. A good set of 00z runs. I have been catching up and I see caution etc used a lot. I'm actually very bullish about this approaching period now, it looked a decent prospect back on 21/12 when I posted my Jan update, and now we see the models and timings coming into play. My view is that we are heading towards a potential 'extreme' episode and all I'm seeing now is models solidifying the building blocks. Pleasing to the eye the runs this morning.BFTP

[nick sussex]

This from the overnight NOAA discussion really does shout easterly for western Europe given the SSW and reversal in zonal winds:

MULTI-DAY MEANS STILL INDICATE A TRANSITION TOWARD AN AMPLIFIED

PATTERN CONSISTING OF AN ERN PAC RIDGE... WRN-CNTRL NOAM TROF...

AND WRN ATLC RIDGE BY LATE NEXT WEEK INTO THE WEEKEND. ASSOC HGT

ANOMALY CENTERS BY THE D+8 TIME FRAME HAVE BEEN FAIRLY CONSISTENT

AND AGREEABLE OVER THE PAST DAY OF RUNS.

As long as we see an amplified trough to the west digging far enough south then that should eject enough energy se under building pressure to the east and ne.

The ECM ensembles are all over the place but amongst that some very nice solutions there bringing some snow and much colder weather by 168hrs.

http://www.ecmwf.int/samples/d/inspect/catalog/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!168!pop!od!enfo!enplot!2009112700!!/

Edited January 5, 2013 by nick sussex

[Duane S.]

Well I was going to make some comments on the 00z suite but Teits has covered everything I was going to say really!

The GEFS ens are top drawer, even for tropical Dorset looking very tasty...

[johnholmes]

nice to see that it looks like the 500mb charts and the 30mb spike all gave correct guidance; the 30mb from 23 December and the anomaly charts from about 4 days ago.

Mind you it could still of course go pear shaped!

[Frosty.]

We are starting to see some very wintry charts which are typical of a major stratospheric warming event and it's surely only a matter of time before the first proper wintry spell arrives. It looks like turning colder from the middle of next week with frosts becoming widespread, mild is on the way out, cold is on the way in, hopefully it will then remain cold or very cold for several weeks with lots of snow.

[cold snap]

Haha it's going to snow if john Holmes is ramping

Anyway back to the models westward correction is the theme today , we need no margin for error

With westward correction upgrades will appear it goes hand it hand

[Gibby]

Good morning. Here is the report on the 00z outputs from GFS, UKMO, GEM and ECM for today Saturday January 5th 2013.

All models continue to show a very mild and fairly cloudy couple of days to come before falling pressure early in the week brings a more meaningful band of rain Eastwards on Tuesday. Once cleared High pressure re-establishes itself close to Britain in rather colder air with frost and fog at night in places but some sunshine by day. The models then diverge in a slow route towards rather cold conditions.

GFS shows another band of rain moving slowly into the UK from the West late next week which dies in situ over the start of the weekend as a strong Scandinavian High builds a ridge across it. After cloud from the front breaks up frost and fog would develop under a cold drift from Europe. Through FI this morning the High slowly pulls west to the UK before retrogressing NW to Greenland with a cold and potentially wintry situation developing with some snowfall in places, chiefly towards the North.

The GFS Ensembles show a general cooling over the next two weeks. The operational is on the warm side of the pack right from the start with a rather colder outlook than the output I have described above more likely. A couple of the members take the UK right into the freezer with more unsettled conditions with time, especially in the North with precipitation likely to be of snow at times.

The Jet Stream shows a strong ridging of the flow North around the UK and down over Europe. With time the flow weakens as well as become disorganized before taking a more Southerly route late in the period in response to building pressure to the North of the UK.

UKMO for midnight on Friday shows a Low pressure over the Baltic sea and the Atlantic with high pressure to the South and North of the UK. A weak ridge in association with the High to the South slowly crosses the South of Britain in a Jet stream that is sinking South of Britain. The weather will likely be dry and much colder with a frost likely for many with a few showers in the East, perhaps wintry over the hills for a time.

GEM shows High pressure remaining in close proximity to the UK in the latter stages of its run before a Low pressure to the North and a rise in pressure over Grenland forces cold Arctic Northerly winds down over the UK by Day 10 with rain followed by snow showers from the North.

ECM also shows High pressure more in dominance close to the UK with a different outcome to GEM, bringing lower temperatures, quite settled conditions with overnight frost and fog after a little rain from a trapped and small Low pressure gets squeezed out next Sunday. the run ends with a strong UK anticyclone with frost and fog widespread night and morning.

In Summary today there is firm agreement on a route to colder conditions from Tuesday onwards. The route is slow and complicated and doesn't result in anything particularly wintry for many as shown today. Nevertheless, these details are unimportant at this stage and will in no doubt change from subsequent runs. The GFS Ensembles are very notable this morning with a strong trend to colder weather shown. In more general terms a change to colder weather will be welcome to many people as it more or less guarantees no return to the wet and mild disruptive so much of the Winter this far has delivered for many with the drying process able to continue over the up and coming two weeks.

[Timmytour]

Good runs...ones that keep the hopes up high and raise the expectations a little...the potential definitely remains.

One observation regarding the GFS... a good run in terms of potential...but if we were looking at it to verify, there might be a suspicion that the infamous Abingdon snow shield had got itself a little empire in the southern UK!

Deep in FI this precipitation chart is awesome...rain but very very close to a huge dumping and perhaps indicative of the kind of battleground scenarios what could develop in the projected set-up...

[Mark Parsons]

We are starting to see some very wintry charts which are typical of a major stratospheric warming event and it's surely only a matter of time before the first proper wintry spell arrives. It looks like turning colder from the middle of next week with frosts becoming widespread, mild is on the way out, cold is on the way in, hopefully it will then remain cold or very cold for several weeks with lots of snow.

Nothing noteworthy with that example frosty, all I see there are average temps........

[phil nw.]

nice to see that it looks like the 500mb charts and the 30mb spike all gave correct guidance; the 30mb from 23 December and the anomaly charts from about 4 days ago.

Mind you it could still of course go pear shaped!

It is John.As have the mean 500hPa `s if we take in to account that sometimes they tend to smooth out the ridging in time.The general placement of the main features for next week`s developing heights and troughing either side of the UK modelled in these are now being shown in the operationals.

All these outputs if used wisely have been a good guide when the Operational outputs have been rather volatile.

We are looking now at a switch to falling temps from the middle of next week which have again been showing for sometime in the temperature ens.graphs.

Some very cold synoptics starting to come into the HR frames now.

[Snowfan50]

Not to be negative, only problem is that the high could stick on the UK and have the cold go into spain like last Feb, other wise alot of potential with northen blocking around, just to worry about the posistion.

[bluearmy]

This from the overnight NOAA discussion really does shout easterly for western Europe given the SSW and reversal in zonal winds:

MULTI-DAY MEANS STILL INDICATE A TRANSITION TOWARD AN AMPLIFIED

PATTERN CONSISTING OF AN ERN PAC RIDGE... WRN-CNTRL NOAM TROF...

AND WRN ATLC RIDGE BY LATE NEXT WEEK INTO THE WEEKEND. ASSOC HGT

ANOMALY CENTERS BY THE D+8 TIME FRAME HAVE BEEN FAIRLY CONSISTENT

AND AGREEABLE OVER THE PAST DAY OF RUNS.

As long as we see an amplified trough to the west digging far enough south then that should eject enough energy se under building pressure to the east and ne.

The ECM ensembles are all over the place but amongst that some very nice solutions there bringing some snow and much colder weather by 168hrs.

http://www.ecmwf.int/samples/d/inspect/catalog/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!168!pop!od!enfo!enplot!2009112700!!/

Six clusters says it all nick !

Edited January 5, 2013 by bluearmy

[UV-RAY]

Fantastic cross model agreement now on a cold spell starting from midweek, a gradual drop in temps to start with from Tuesday with frost becoming nationwide by the end of the week. Looks to be a fairly dry week but it's an ever evolving set up so it's a case of watch this space.

[lorenzo]

Impressive chart in terms of 500mb height anoms!

http://raleighwx.ame...htAnomalyNH.gif

M.

This 100mb is even more impressive. Think we might be seeing the black hole anomaly on the ECM ens run very soon with it hovered over Greenland. Storming solution. Nudge things along from there a little and cross polar flow well on the table.

Any model not depicting a negative AO you could afford to be very sceptical about, the zonal wind profiles are also stunning, Cohen comes good with Greenland, right on the climatology. Ian, forecast was the best stratospheric exposure / ramp with caveats I have seen on the telly box, great stuff.

Saturday 00z are usually a dull affair with the 12z slowly redeeming matters, what a set of runs we have to look forward to over this weekend.

[Timmytour]

Not to be negative, only problem is that the high could stick on the UK and have the cold go into spain like last Feb, other wise alot of potential with northen blocking around, just to worry about the posistion.

I agree. What's happening here is not an increase in certainty, but an increase in potential only.

Just hoping it lifts Teits up rather than goes tits up!

[Robbie Garrett]

The MetOffice update at 0400 does the short range outlook I take it? As the last bits never get updated, they only change at 1600?

[The Beast From The East]

Calling Nick Sussex,

Newby here but even I can see all the potential building up on the models this morning, this really is a great forum and so addictive that I have to keep coming back on here to have a read..

Anyway back to my question and I know that nick seems to be the expert on this subject but is it possible we could get (dare I say it) a short wave develope like before and spoil everything or do you think we are in a much more stronger position this time round? Thanks.

PS-

Keep up the good work everyone on here especially , Glacia point, Eye in the sky, Steve Merr, Ian Ferguson , Nick Sussex , John Holmes and everyone El's .. You all give this forum/ thread a great place to be in.

Sorry if my post is not model related, I will now go back into to background and carry on reading this thread.

[sebastiaan1973]

Colder Pluim for De Bilt. http://www.weerplaza.nl/15daagseverwachting/?r=midden&type=eps_pluim

[lorenzo]

Solar Max within a maximum that is overall low was my understanding if that makes sense CH.

[bluearmy]

Incidentally, whilst i am looking for the undercut from the west, it seems its just as likely to come from the east in a 'reverse zonal world'!!

[Timmytour]

The potential in the models this morning is getting me a tad excited.

But what's really getting me excited thus far is the lack of a Daily Express front page "Big Freeze" headline!. They are worse than shortwaves for tripping up potential wintry scenarios The BBC weatherman are getting more and more confident at dropping hints...it's very unlike the Express to be so behind. That surely has to be the best sign ever!

[Catacol]

Solar Max within a maximum that is overall low was my understanding if that makes sense CH.

Agreed. This is all off topic now... but my little inserts last night were just to suggest that if GP is right about December then a solar boost of activity, expecially at time of max, could still be a factor. Thankfully at present the sun is steady.

[Ian Brown]

Calling Nick Sussex,

Newby here but even I can see all the potential building up on the models this morning, this really is a great forum and so addictive that I have to keep coming back on here to have a read..

Anyway back to my question and I know that nick seems to be the expert on this subject but is it possible we could get (dare I say it) a short wave develope like before and spoil everything or do you think we are in a much more stronger position this time round? Thanks.

PS-

Keep up the good work everyone on here especially , Glacia point, Eye in the sky, Steve Merr, Ian Ferguson , Nick Sussex , John Holmes and everyone El's .. You all give this forum/ thread a great place to be in.

Sorry if my post is not model related, I will now go back into to background and carry on reading this thread.

What I would say to start with SX, is that there is no clear synoptic development going forward from day 5/6. It is not a question at the moment of shortwave spoliers because we don't know if or where the High pressure will develop.

What we do see this morning is the jet being pulled back West as High pressure tries to build in the vicinity of the UK. As more runs come out we want to see the jet energy going South under emerging High pressure. However to get the cold uppers we need a high latitude block, which is shown as possible on some of the GFS and presumably ECM ensemble members, these will always be more difficult to achieve and model, and any shortwave development could be picked up nearer the time.

[Jaffusmaximus]

Agreed. This is all off topic now... but my little inserts last night were just to suggest that if GP is right about December then a solar boost of activity, expecially at time of max, could still be a factor. Thankfully at present the sun is steady.

Not quite right regarding steady, there is one sunspot with enough energy to unleash a massive solar flare that could have a potential impact, other than that yes very quite!

http://spaceweather.com/