Winter Model Discussion 12Z 22/1/13 onwards.

[Summer Sun]

Well the GEFS are hardly "Mildmageddon" are they! Overall trending colder again after the two milder blips this coming week. Not a bad set as we enter what is often the most blocked month of winter.

Looks like a drier trend as well as we progress through early February

ECM at t144 now it remains unsettled with temperatures around or just below average

[Summer Sun]

Notice the Azores high creeping a bit closer at t168 we need to keep an eye on that it could quite easily scupper a cold spell

Milder air edges closer as well with the cold air over eastern Europe

High pressure edges closer at t192 and sets up a potentially short lived north westerly

Edited January 26, 2013 by Gavin.

[Panayiotis]

If anyone hasnt noticed the GFS ensembles are getting better, at 240hrs and we have the Azores ridging north....hopefully the 18z will show more members going for this type of signal...

[nick sussex]

The ECM still develops several opportunities upto 168hrs for an undercut with the flattest upstream pattern out of the big 3!

Thats a positive sign, the ECM postage stamps should have some interesting options when they come out later.

Theres still low confidence upstream with that developing low with uncertainty regarding amplitude and how quickly it moves east. The general trend is agreed on across the models but detail near the UK looks more uncertain.

Once you get low heights in central Europe thats a good step forward to cold as it stops the Azores high trying to edge towards the Med.

A bit of retrogression in the pattern could bring some wintry potential to the UK so overall not a bad ECM run.

Edited January 26, 2013 by nick sussex

[chris55]

Cheeky little link as it's quite in here, was walking with the dog on Friday, before the thaw, with the strong southerly wind. The blowing snow was amazing, the drifts had been cleared the day before on the lane but were being blown back by the strong wind, about 45 seconds in is where the wind kicks in. (phone cam doesn't really do it justice though)

Edited January 26, 2013 by chris55

[Tim Bland]

Big potential for a return to cold after next weekend from the GFES and now the ECM just need that pesky low around Iceland to do one so ridding can get further noth

http://www.meteociel.fr/modeles/ecmwf.php?ech=72&mode=1&map=1&type=0&archive=0

[Methuselah]

i would be concerned if i were you with what is and has been happening across the pacific and N America...the pattern has become locked into a rinse and repeat cycle that statred to set up about 4 weeks ago...and is having a knock on effect acroos the atlantic hence the shift to a more mobile pattern.

there is no hint of a pattern change over here...no hint of the Alaskan high which can aid height rises around Greenland etc the pv is locked in over eastern Canada and western Greenland and is going no where..thers is a big high pressure cell of the Vancouver and western US coast which is again not moving and underpinning the whole set up across N America.

Not sure that we need a major change of pattern, cm?

I recall someone citing 1968-69 as a suitable analogue for, what we've been having so far, this winter. I do recall (I think!) that we had many instances of battleground snow-events in that year, too...And (again I think) in that year, as in this, no particular air-mass dominate for very long...

It's mainly for the above reasons, that I don't expect the models to arrive at, and stick to, any pattern dominance for all that long...Two-weeks at most?

Edited January 26, 2013 by Rybris Ponce

[Summer Sun]

With the high pressure clinging to southern England the real cold is struggling to get in at the moment

Edited January 26, 2013 by Gavin.

[Weathizard]

Nice to see the models have got seriously cold air over Europe though, if we do get an easterly/north easterly shot at least it looks like very cold uppers there.

[Summer Sun]

ECM ends with a blocked Atlantic and allows a colder NW flow to set up

[nick sussex]

I think looking at the trend of the ECM we're going to be looking east or ne.

Overall once we see heights drop in Europe then we can say goodbye to the mild dross and from there plot our way back to cold.

[Tim Bland]

The evolution from 216 to 240hrs looks a bit suspect to me!? How does that deep low over Iceland at 216hrs suddenly vanish 24 hrs later?

[Panayiotis]

I must say the ECM at 240hrs is great with a blocked Atlantic and weakish heights to the north (above Norway), cold opportunities will become more favourable. You might have noticed my post above, which was showing the GFS ensembles at 240hrs. You can see the similarities between those and the ECM.

[bradymk]

The evolution from 216 to 240hrs looks a bit suspect to me!? How does that deep low over Iceland at 216hrs suddenly vanish 24 hrs later?

it doesnt vanish though?

[Panayiotis]

The evolution from 216 to 240hrs looks a bit suspect to me!? How does that deep low over Iceland at 216hrs suddenly vanish 24 hrs later?

It doesnt 'vanish', 24hrs is a lot of time when looking at the weather, and that deep low moves SE into the trough in Europe. Edited January 26, 2013 by Panayiotis

[nick sussex]

The evolution from 216 to 240hrs looks a bit suspect to me!? How does that deep low over Iceland at 216hrs suddenly vanish 24 hrs later?

I nuked it as it was getting on my nerves!!! lol

It actually heads se into central Europe and weakens.

The set up is one where we'll see shortwaves being spawned in the ne USA running anti clockwise around the PV, the question is can we get one of these to head se further west?

[nick sussex]

The GEM at 180hrs is pretty similar in trend to the ECM:

Trough disruption to the west with the shortwave to the south of Iceland, back the pattern further west with that shortwave heading s/se and its back to lamp post watching for you all in the UK!

[Gibby]

Good evening. Here is the report of the 12z output from GFS, UKMO and ECM for tonight Saturday January 26th 2013.

All models show the UK now under the influence of a strong and mobile West or SW airflow with Low pressure centres Northwest of the UK with a strong west to SW wind with troughs crossing East in the flow bringing spells of strong winds and heavy rain interspersed with spells of rather chillier and equally windy weather with showers, some heavy with snow on Northern hills. This weather then becomes replaced on Monday with another spell of wet and windy weather with severe gales in the NW. On Tuesday the SW flow will become quite mild in the SW with further rain at times before a cold front crosses East on Tuesday night to re-introduce blustery and showery conditions on Wednesday.

GFS then shows further spells of rain through the latter stages of the next working week and start of the weekend before things quieten down somewhat as a ridge topples down from the NW bringing drier and rather chillier conditions for a while though the NW quickly sees a return to the wind and rain. Through FI this more unsettled theme returns South to all areas though not as mild as previously with a trend for cold zonality weather to take control with rainfall falling as snow on hills at times even in the South later.

The GFS Ensembles show a trend to somewhat lower uppers again after the coming three or four days as cold zonal weather looks a feasible option over the coming model run period. The operational and Control Runs were somewhat colder option than most members with all members showing rain at times in a continuing Atlantic dominated pattern.

The Jet Stream shows the flow continuing to pump Eastwards strongly over the Atlantic in a sine wave pattern over and around the British Isles in the forthcoming reliable time frame.

UKMO for midday on Friday shows Low pressure over Scandinavia with a trough SW over Scotland. Cold air lies to the North of the Scottish trough with a showery Westerly flow over the Southern half of the UK. More general rain or sleet is more likely over Scotland through the day.

ECM shows increasingly colder conditions later in the run with Low pressures trending to move more SE across the UK with rain or showers continuing over the UK falling increasingly as sleet and snow over hills at times and more especially in the North and East.

IN Summary there is a trend for rather chillier weather to develop over the UK beyond the early days of next week. It looks like staying very unsettled throughout the period tonight with rain and showers trending to be more wintry, especially over the hills with time.

[bradymk]

Looking at the 12z GEFS suite individually, there are some stunning runs, member 18 caught my eye with a beauty of a run for cold with the cold starting at only 168 timeframe.

The GEM at 180hrs is pretty similar in trend to the ECM:

Trough disruption to the west with the shortwave to the south of Iceland, back the pattern further west with that shortwave heading s/se and its back to lamp post watching for you all in the UK!

Yes a very pleasing set of 12z runs! And all this is not in far FI. I agree with what you said earlier Nick in regards to looking East and North East rather than North, ECM and the GEM you post above reinforce this.

[winterof79]

low heights moving s/e in to europe http://www.meteociel.fr/modeles/ecmwf.php?ech=168&mode=1&map=1&archive=0

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=162&mode=0&carte=1 http://www.meteociel.fr/modeles/geme_cartes.php?&ech=144&mode=0&carte=1

I feel a repeat of the latest episode coming on.

[Cheshire Freeze]

CFS continues its trend very similar to EC32. Atlantic completely blocked off. Anomalous heights right across our north and spreading down into the north Atlantic. Low pressure over the continent. Very wintry if it's anywhere close to the mark.

Images courtesy of Meteociel

Temperature anomalies (850's)

Edited January 26, 2013 by CreweCold

[winterof79]

CFS continues its trend very similar to EC32. Atlantic completely blocked off. Anomalous heights right across our north and spreading down into the north Atlantic. Low pressure over the continent. Very wintry if it's anywhere close to the mark.

Image courtesy of Meteociel

Beat me to it CC low pressure over the continent.The east/south east coming in to play,maybe more of a n/e element than a s/e that we had this time.

Edited January 26, 2013 by winterof79

[Duane S.]

Models certainly starting to back away from any prolonged zonal onslaught predicted by many. I suspect we are going to get some interesting charts to look at soon and not necissarily at +384!

For me there is often a big difference between the vortex being centred N / NW Greenland as opposed to the South of it. In my opinion we have actually been very lucky through January to get the snowy weather we did as the energy was situated S. Greenland, often the death knell for winter weather for us but other factors went in our favour and it ended up providing us with some lovely slider LP systems.

Now, to me it looks like the tendancy is for the dominant vortex to remain around Greenland not to the NE despite hints otherwise but, although it will be a fairly strong wound-up vortex I can also see it centring NW of Greenland allowing an Atlantic ridge to eventually build, perhaps with an initial G/L high but then migrating the heights over Scandi bringing us cold from the NE.

Could be a classic month ahead

Ah and the ECM by D10 has evolved into pretty much much exactly what I had in mind. Doesn't mean it's going to happen but it's certainly a growing trend...

[Cheshire Freeze]

Ah and the ECM by D10 has evolved into pretty much much exactly what I had in mind. Doesn't mean it's going to happen but it's certainly a growing trend...

Not surprised the ECM is starting to pick up on this trend in it's later stages and ensembles now. Right on cue aswell!

[BLAST FROM THE PAST]

The ECM is looking very interesting now. I urge folk to have a look at the chart archives and see how Feb 1986 developed, something I've had in mind with the descending winter. I believe if/when the next cold spell comes we need to look initially NE and not NW. That is where our COLD HP will develop from due to retrogade motion, GHP prob later down the line as the retrograde continues. I'm not surprised the models are showing something interesting as we are getting into the range of when the next proposed cold spell is developing or in place, hence why I suggested it over last day or so.

Just to add a little interest.....much milder temps for many tomorrow.....and tomorrow is 27th. This is exchange I received from RJS on the PM....note ALL dates

Sent 07 January 2013 - 04:27 - As to the ongoing pattern change, I am looking at it in detail to see if I can relate it directly to the research, but my output shows the coldest period delayed to about 5-15 Feb so whether that turns out to be a late error, remains to be seen. There is one more warm spike in the output before that cold period, also whether that even shows up or gets overwhelmed by the [upcoming] event remains to be seen (about 27-31 Jan is shown to be warmer than most of the month which has ups and downs).

If the dynamic cause of this pattern change is what I suspect, then it could be on a large scale and perhaps this is what we are now seeing first indications (of)

Take from it what you want...

BFTP

Edited January 26, 2013 by BLAST FROM THE PAST