Model Discussion 12Z 25/02/13

[Milhouse]

With a southerly feed throughout much of next week temperatures would be on the mild side with 5c upper temperatures making it as far north as Scotland. Eastern parts would stay drier for longer but all the while its turning more unsettled from the west. The week looks to end on a fairly wet and mild note.

[nick sussex]

The latest ECM is similar in trend to this mornings run with the jet well to the south, low pressure to the sw slow moving.

At 144hrs the ECM and UKMO both agree, the GFS does develop rising pressure to the ne in its lower resolution.The pattern is to a degree stalemated until the western negative NAO breaks down but theres no sign of a typical zonal pattern.

Its still look ne for a reminder of winter, I'd expect to see a continued split in the ECM ensembles because at 144hrs the pattern could develop more quickly with more forcing on low pressure near the UK.

In terms of a realistic chance of wintry weather datewise I think this stalemate will have to last a while but second week of March is where we could see a change, for those who don't like slush then if its to be something of note this late into the season it really has to come from the ne.

[Purga]

Yes that's why we haven't seen a Greenland high, there was much discussion at the time over at NOAA because the models wanted to do one thing but past history was against that, historically there isn't a strong correlation between Greenland highs and a ridge in the east Pacific, for that reason the main cold that's effected the UK has been those height rises to the ne in January, and recently the easterly all came about with that east Pacific ridge.

Its for this reason that in this instance for those wanting cold we want rid of the western negative NAO and that's likely to happen once the east Pacific ridge takes charge.

That ridge is then expected to transfer more to Alaska which is strongly correlated with pressure rising sw out of Svalbard.

Maybe so Nick and I hope GP is right because ECM 12z was nothing more than a mildfest especially for the south.

Let's put it this way, I won't be expecting any posts from S Murr anytime soon at this rate!

[nick sussex]

Maybe so Nick and I hope GP is right because ECM 12z was nothing more than a mildfest especially for the south.

Let's put it this way, I won't be expecting any posts from S Murr anytime soon at this rate!

Yes with that troughing stuck there its likely to be much milder than of late. We'll see later how many of the ECM ensembles have some colder options with low pressure disrupting and further south.

At least theres some decent cold to the n/ne which has a chance of making it further south when the western negative NAO relents.

[Frosty.]

Disappoining 12z for coldies, ecm 12z no better than 00z, it's going to be trending milder and more unsettled next week with temps in the 11-13c range, the gfs 12z has an FI cold incursion but it's beyond T+260 hours so take that with the huge pinch of salt it deserves. The current anticyclonic spell looks like becoming a cloudy one again just in time for the weekend and then pressure falls from early next week with rain and showers spreading from the southwest but some sunshine and dry weather too, winds becoming Sly to SEly next week, increasingly mild.

[No Balls Like Snow Balls]

GFS Ensembles show temps rising into double figures in some places for at least a few days next week, before cooling off slightly again later in the week. ECM ensembles also showing the same.

[Tim Bland]

CFS still showing some hope http://www.meteociel.fr/modeles/cfse_cartes.php?ech=240&code=0&carte=0&mode=2&run=10

Little else appealing on offer.. Appart from GPs post..let's hope he right, he usually is

[Panayiotis]

New model?

http://www.meteociel...eose_cartes.php

EDIT:These maps show the model data GEOS5, experimental model of NASA. Forecasts are up to 120h for two runs of the day. The resolution of the maps is 0.25 °.

Quite a high res model! Im going to follow it and see how it performs..

Edited February 27, 2013 by Panayiotis

[Carlrg]

Thanks for that Pana. HP not wandering far from our shores at all on that run.

http://www.meteociel...&mode=0&carte=0

Edited February 27, 2013 by Carlrg

[bluearmy]

looks like any wintry action is now well into week 2. as soon as we all accept that we should be givng up on wintry conditions, you can be sure that something will crop up!

I wonder if the trough to our sw will make it over the uk? Having suffered for months, its been a fair while since we've seen a wet trough astride us.

[Gibby]

Good evening. Here is the report of the 12z output from GFS, UKMO and ECM for tonight Wednesday February 27th 2013.

All models show High pressure close to Northern Britain for the next 72 hours bringing largely dry conditions for all areas spare a little drizzle moving south over Scotland and England over the next 24-36 hours. There will be a lot of cloud about at times restricting sunshine amounts and holding temperatures down somewhat by day but where sun occurs it will feel very pleasant and where clear skies occur at night a frost is highly likely. Winds will reduce to a light breeze still mostly from East and North across the South. Early next week all models sink the High East and SE over Europe allowing pressure to fall over the UK with a moderate SE flow developing ahead of troughs of Low pressure edging North and East towards SW Britain by midweek.

GFS then shows this extending to all areas later in the week as winds switch to more of a SW element bringing milder weather in with a mix of sunshine and showers. Then a cold front crosses East bringing strong winds and rain for a time before things clear from the West over the second weekend with some showers in the North and the risk of night frost as a ridge crosses East. Later in FI a block of High pressure sets up again North and Northeast of the UK but the UK would end up hopefully on the milder side of the block this time though the North of the UK would probably see some hill snow as fronts move North into it.

The GFS Ensembles show reasonable agreement of fairly average temperatures over the coming week with plenty of dry weather. Conditions at the surface though during this time could be rather colder at times. Then things look far more unsettled with a wide spread of members undecided on where we should go longer term. The operational's cold block in FI was not well supported making it a bit of an outlier in the North with all areas seeing rain at times by then as the Atlantic nudges in.

The Jet stream shows the main arm of the flow still blowing West to East well South of it's normal position. It continues in this way for another week before signs of it pushing slowly North at latitude 45-50 deg N in just beyond a weeks time.

UKMO tonight shows the breaking down process well under way by early next week with a SE flow having picked up for all. With falling pressure it's only a matter of time that the troughs down to the SW make inroads into at least Southern and western parts by the middle of next week.

ECM too shows the same trend developing the synoptic pattern in a very complex manner. A series of depressions move ever closer to SW Britain meaning rain would gradually spread North and East over the UK with time but always with the heaviest of this reserved for areas in the SW. For the most part near normal temperatures look likely but low temperatures are still lurking to the North and Northeast and it wouldn't take much of a pattern adjustment to bring Northern Britain at least into rather cold and windy conditions again with the risk of snow.

In Summary there is little change from the models tonight, maintaining the trend to more unsettled conditions as we move through the middle and end of next week with rain progressing North and East over the UK through the period. The rain will be heaviest in the SW where the highest temperatures are also likely to be as milder SW winds begin to show there hand in the South towards the end of the output. In the mean time we have another 4-5 days of anticyclonic weather with it's usual variable cloud cover and sunny spells with night frosts before it all recedes away SE early next week.

[Steve C]

Ahh looking back I remember the start of march 2006 being very cold.

Also have a look at this chart for 5th March 1947 and the note about it in the link below. The original comment, which started all this, was very broad brush imho!

http://en.wikipedia.org/wiki/Winter_of_1946%E2%80%931947_in_the_United_Kingdom

[davehsug]

CFS still showing some hope http://www.meteociel.fr/modeles/cfse_cartes.php?ech=240&code=0&carte=0&mode=2&run=10

Little else appealing on offer.. Appart from GPs post..let's hope he right, he usually is

Really? Along with other experts, they were wrong in December & wrong in January. Why should this time be different. No disrespect to GP & others, but they haven't had a great winter....except in FI.

[Panayiotis]

Really? Along with other experts, they were wrong in December & wrong in January. Why should this time be different. No disrespect to GP & others, but they haven't had a great winter....except in FI.

Yes a lot were wrong including the Met in December but January delivered for me where I had 4-6" of snow, so from my perspective they called it right..

[bluearmy]

naefs spreads showing some interest for coldies around the 10/12th march. looks like possibilities of some very low uppers from the ne this period. seems to be in association with a depression tracking west to east just south of the uk. has to be high heights to the north or northwest to complete the equation.

[Panayiotis]

naefs spreads showing some interest for coldies around the 10/12th march. looks like possibilities of some very low uppers from the ne this period. seems to be in association with a depression tracking west to east just south of the uk. has to be high heights to the north or northwest to complete the equation.

TEITS did mention those dates a couple days back, if we get cold around that period hands up to him! Ensembles from both GFS and ECM support this with more colder options around that period.

Edited February 27, 2013 by Panayiotis

[LomondSnowstorm]

Really? Along with other experts, they were wrong in December & wrong in January. Why should this time be different. No disrespect to GP & others, but they haven't had a great winter....except in FI.

I wouldn't say they were wrong, the blocking signal were certainly much less prevalent in December than expected given the easterly that failed to materialise but the January spell driven by the initial SSW reaction was broadly in line with what was expected in terms of a much below average temperature signal with a signal for relatively high precipitaiton, and the further downwelling causing the second cold spell into February was also broadly speaking flagged up. The failure to get really strong heights building over Greenland has been the one factor which has moderated the cold through the winter, but otherwise I think the long range guidance has been fairly reasonable, certainly when compared to the performance of the likes of the GFS.

When all is said and done Stewart's composite heights map for the winter is not dissimilar to this one, and that's pretty much all that I'd ask of it:

[Cleeve Hill]

Really? Along with other experts, they were wrong in December & wrong in January. Why should this time be different. No disrespect to GP & others, but they haven't had a great winter....except in FI.

Sorry mate, your wrong there. GP forecast a colder than average winter with waxing and waning of temperatures. Nothing v cold was ever forecast, and that is pretty much what we got.

[davehsug]

Sorry mate, your wrong there. GP forecast a colder than average winter with waxing and waning of temperatures. Nothing v cold was ever forecast, and that is pretty much what we got.

I see so I imagined those posts about even colder from the North East in January & "it's coming" in December! His overall winter forecast has been pretty good agreed, but some of the forecasts along the way have not been. I'm not picking on anyone or trying to cause any trouble. Mid March may produce a very cold & wintry spell, but then again it may not, that's all.

[mulzy]

Sorry mate, your wrong there. GP forecast a colder than average winter with waxing and waning of temperatures. Nothing v cold was ever forecast, and that is pretty much what we got.

Yes, he got the temperature forecast reasonably spot on but synoptically he got it very wrong (eg NAO forecast to be negative when it actually was positive or neutral most of the winter). Anyway, seasonal forecasts are a total waste of time - I don't know why folk put too much faith in them.

Edited February 27, 2013 by mulzy

[damianslaw]

Little to discuss with very slow day to day changes is it has to be said making for dull model watching. The theme is still for a gradual warm up next week but also more unsettled, Its in these set ups i take a bit of a break from model watching awaiting a more significant or interesting outlook. Still all this dry weather is just what the country needs.

[peterf]

i concur.

[Panayiotis]

As damianslaw says not much to discuss as the reliable shows high pressure in control, average or just below temperatures for many with cloud cover, which may break up late weekend/early next week.

To keep on topic here are the models at 120hrs:

So above is the GFS,ECM,UKMO,JMA,GEM,NAVGEM,BOM,CMA and the new model GEOS5. Putting the models like this you can see which one may be an outlier at that timeframe and what is features are consistent.

Evidently the BOM looks to be the oulier as it shows the least amount of energy to the east of Greenland which all the other models show. Like the other models this energy has a tendency to spawn shortwaves and hang them around Iceland something missing from the BOM (this feature is what has stopped our high from retrogressing to Greenland, cold isnt easy to get to the UK!)

Things at this timeframe which are consistent is the low to the SW (west of Spain). There are small variations of how the low is modelled eg. the depth/size etc of the low.

The movement of the PV to N Europe.

The high over mainland Europe (Austria/Czech Republic) which edges over to the UK. The CMA and the GEOS5 have the core of the heights over S Britain. So precipitation unlikely especially from a SE wind.

And the low over Russia, which contains deep cold pool and low thickness values (on some of the models) for example the JMA,CMA and the new model have the deepest uppers and lowest thickness values. The GFS,JMA and NAVGEM have this feature, the furthest east,which is due to the high being further east.

So the start of next week looks dry but cloudy due to the location of the high pressure, with a gradual warm up as the SE wind drives warmer air from Spain towards us.

One thing for sure though if we want a cold March we need that high to sink as fast possible, because with this over Europe doesnt help us. To overcome I hope the majority of the PV moves to N/NW Europe therefore as it does so it sinks the high pressure over the Med.

Edited February 28, 2013 by Panayiotis

[syed2878]

im sure this post will be removed, but i do agree with some of the posts regarding the winter forecasts even last week rjs was going for 20-30cm of snow when the likes of the met wasn't buying into it. Im not having ago at any1 just wanted to point out it wasn't only gp who got it wrong.

[winterof79]

GFS brings the Arctic high in to play and has some serious result if you run the sequence

http://www.meteociel...&mode=0&carte=1 850s not an issue

ECM has the high modelled early on too http://www.meteociel...map=1&archive=0

March has the halmarks of being below average this year.All in all it has been cold since Jan 15th with the odd milder incursion early on.

Edited February 28, 2013 by winterof79