Model Discussion - 10th March Onwards

[Nick F]

00z ECM looks a lot more cyclonic than previous runs and vs 00z GFS. It brings the troughing to the N/NE closer initially then allows Atlantic troughing back in. Be interesting to see the 00z ECM ens to see where the deterministic lies among the members wrt to precipitation.

00z ECM op could be an outlier, though the 00z GEFS mean do show a general drop in pressure as we head into early April, the 00z GFS operational an outlier wrt to slp in FI with higher pressure than members around 7th April.

I am not so secretly hoping this morning's ECM will verify to a more unsettled pattern into early April, as quite frankly this stubborn high is worrying in terms of lack of rainfall and interest for weather other than maximum temp records being broken.

[snowmadchrisuk]

Well looks to me that a Greenland High is on the cards into April, If the UK will see a final Winter Cold blast out of it though really depends on how it set's up . Still possible Midlands North for some Snow , although highly unlikely it would be lie . Some interesting Model watching non the less.

[Thundery wintry showers]

Interestingly the model outputs appear to have "swapped" relative to yesterday's- now it's the GFS showing a continuation of dry sunny weather into the weekend and a drop in temperature, with high pressure sticking around into next week (though probably with more cloud, especially in the north, due to the positioning of the high).

UKMO/ECM have both toned up the Friday/Saturday northerly, re-introducing the chance of some wintry showers on Saturday towards the northeast, which would provide a stark contrast with recent weather. In fact the ECM operational suggests that it could turn pretty wintry across Scotland and northern parts of England through to the middle of next week with the possibility of some organised frontal-type snowfalls, though falling as rain in the south.

The crucial difference is that UKMO/ECM take the high pressure further away to the west, which as well as allowing the northerlies in to begin with, also sets us up for that more unsettled cyclonic/south-westerly type as we head into April. Note though that the ECMWF ensemble mean suggests a middle ground between UKMO/ECM and GFS which would probably keep south-eastern areas dry under a ridge of high pressure, so I'm not going to commit to any predictions regarding the northerly outbreak(s) or aftermath until I see this evening's runs.

[tinybill]

i know its deepf1 and it wont happen who like snow next week!!!

[shedhead]

00z ECM looks a lot more cyclonic than previous runs and vs 00z GFS. It brings the troughing to the N/NE closer initially then allows Atlantic troughing back in. Be interesting to see the 00z ECM ens to see where the deterministic lies among the members wrt to precipitation.

00z ECM op could be an outlier, though the 00z GEFS mean do show a general drop in pressure as we head into early April, the 00z GFS operational an outlier wrt to slp in FI with higher pressure than members around 7th April.

I am not so secretly hoping this morning's ECM will verify to a more unsettled pattern into early April, as quite frankly this stubborn high is worrying in terms of lack of rainfall and interest for weather other than maximum temp records being broken.

I'm also hoping that a more unsettled pattern will take hold as we move into April, otherwise there's a danger that much as last year we'll use up all of our fine, warm and sunny weather quota long before Summer officially begins. Some encouragment in that direction this morning with UKMO and ECM, but GFS remains very reluctant to break the dry spell down, with just less sunshine and lower maxima being the best it can come up with for now...

[Costa Del Fal]

The GFS 06z again looks quite unsettled but the ensembles say otherwise. Even the control run and the majority of members disagreeing with the OP in FI, maintaining a more settled theme and much warmer than the Op suggests. Not saying the OP is wrong but the general consensus is for a mainly settled theme still but temperatures returning to average, warm in the sun and a few showers/light rain at times.

[johnholmes]

I'm also hoping that a more unsettled pattern will take hold as we move into April, otherwise there's a danger that much as last year we'll use up all of our fine, warm and sunny weather quota long before Summer officially begins. Some encouragment in that direction this morning with UKMO and ECM, but GFS remains very reluctant to break the dry spell down, with just less sunshine and lower maxima being the best it can come up with for now...

I doubt there is any such thing as a weather 'quota'. although it has to be said that the weather does tend to even things up over a long period. This is perhaps where this suggestion comes from?

Edited March 27, 2012 by johnholmes

[shedhead]

I doubt there is any such thing as a weather 'quota'. although it has to be said that the weather does tend to even things up over a long period. This is perhaps where this suggestion comes from?

I wasn't talking about a 'quota' in the literal sense John, but nature always balances itself out, the trick is knowing when that balance will come. However based on statistics, I'd suggest IF M/A/M were dry, warm and sunny, there is a greater chance that J/J/A would not be. That's not to say it couldn't happen, but the chances of it must be somewhat reduced.

[Weather Wizard]

I wasn't talking about a 'quota' in the literal sense John, but nature always balances itself out, the trick is knowing when that balance will come. However based on statistics, I'd suggest IF M/A/M were dry, warm and sunny, there is a greater chance that J/J/A would not be. That's not to say it couldn't happen, but the chances of it must be somewhat reduced.

Thats like saying that since I just flipped a coint 10 times and got a head every time that the next time I am more likely to get a tail.

In fact the chances remain 50/50

I think it will be a warm summer overall

[Zenarcher]

Long Range

Comparing the latest ECM, GFS and GEM runs for the start of April. The ECM shows high pressure the the West of the UK and low pressure to the East so things would turn a bit cooler and a tad more unsettled compared to what we have now. GEM shows something similar but the high pressure to our West covers a larger area and seems more dominant despite this still lower pressure is shown over the East. The GFS seems to back up the GEM model more with a wider area of high pressure but it has the high covering all of the UK so it would stay settled. Overall each is on its own with the GEM being in the middle and may be the more likely outcome at the moment.

Wednesday to Friday Summary

Things are expected to change mainly over the Northern parts. On Wednesday staying clear and sunny for most but Scotland will gradually become more partly cloudy. On Thursday these partly cloudy conditions with sunny spells will remain in Scotland however mist is likely over the North and the partly cloudy conditions is likely to spread across Northern England and across some parts of Ireland. Meanwhile the rest of England and Wales continue to get clear and sunny weather. For Friday Scotland, Ireland and Northern England will continue to see either cloudy or partly cloudy conditions and over the far North of Scotland will remain misty and a few showers are likely. The rest of England and Wales will yet again continue to have clear and sunny weather. The wind will be light over the UK but gales in the very far North of Scotland.

Weekend Summary

On Saturday its looking mainly cloudy across much of the UK with only short sunny spells in some places however the far South of Ireland, Wales and England will remain clear and sunny. On Sunday turning cloudy with mist and showers over most of Scotland meanwhile the rest of the UK looks to see mainly partly cloudy weather with sunny spells and Ireland looks to see the best of the weather by being clear and sunny. The wind across the UK will be light but a strong breeze is likely in Northern and Eastern Scotland and may touch gale force at times.

[Methuselah]

I wasn't talking about a 'quota' in the literal sense John, but nature always balances itself out, the trick is knowing when that balance will come. However based on statistics, I'd suggest IF M/A/M were dry, warm and sunny, there is a greater chance that J/J/A would not be. That's not to say it couldn't happen, but the chances of it must be somewhat reduced.

But, far more likely, June, July and August would (over all) average out to within a hair's breadth of the long-term mean. And that might't happen either. When was the last time we experienced a season wet enough to offset all the dry months?

[johnholmes]

Thats like saying that since I just flipped a coint 10 times and got a head every time that the next time I am more likely to get a tail.

In fact the chances remain 50/50

I think it will be a warm summer overall

That is not strictly true with the weather.

IF we knew every variable that has an effect on the weather, and understood them all much better than we currently do then it would be quite untrue.

Not knowing this however does not make it 50:50 as you suggest.

[The PIT]

Well 12 oz begins giving the cool down a bit of downgrade with temperatures now staying above normal. The main thrust of cooler/cold air pushed further east. Looking remaining dry well in to FI although FI does offer a chance of some rain. Reliable time frame very warm then mild becoming more cloudy than at present.

[IDO]

The GFS 12z keeps HP right through to 8th April over the majority of the UK. Temps overall down 4-6c on this week but still relatively mild. The cooler uppers forecast for this weekend are kept to our east, though glancing blows to the Eastern coasts are possible. Nothing really cold though.

Around the 8th the OP run has another PM excursion. However, looking at the GFS 12z ensembles (London) the OP is in the bottom 10% of cooler members (around -5c to -7c at T850) and as the ensemble mean (London) stays above 0c for most of the latter part of FI, it looks like the odds are (currently) against any wintry stuff . The main ensemble cluster is between 0 and -5 so a cooling does look a strong contender from the second week in April (troughs in the Atlantic and US mainland disrupt the jet-stream). Precipitation flat lines on the ensembles (London) for most of the 12z run, though there are a couple of small spikes, but nothing like what is needed.

So HP hangs on, and the forecast pattern change has been pushed further back, to possibly around the 8th April onwards. We will have to wait though, as this may change again, that is, knowing the reluctance of the Azores High to move away.

[summersnow]

I must admit, I'm struck at the contrast between ECM and GFS. While ECM continues to show a northerly starting in 4 days for northern areas and lasting some 4 or 5 days, GFS 12z shows a much less potent scenario with it all happening a bit further east. This has been pretty much the theme with this event from the onset - ECM keen, GFS not so keen!

But also of interest is how consistently GFS is showing a sustained cool down after about 10 days. It has been showing this scenario in FI for some time now and has been fairly consistent with it. Clearly well into FI, it should be treated with extreme caution but when GFS is as consistent as this in FI, the synoptics do often gradually filter into the reliable time frame before other models start picking up on it. It's often at this stage GFS seems to wobble about a little and then jumps back on board within the even closer time frame! It's quite odd!

Edited March 27, 2012 by summersnow

[IDO]

I must admit, I'm struck at the contrast between ECM and GFS. While ECM continues to show a northerly starting in 4 days for northern areas and lasting some 4 or 5 days, GFS 12z shows a much less potent scenario with it all happening a bit further east. This has been pretty much the theme with this event from the onset - ECM keen, GFS not so keen!

But also of interest is how consistently GFS is showing a sustained cool down after about 10 days. It has been showing this scenario in FI for some time now and has been fairly consistent with it. Clearly well into FI, it should be treated with extreme caution but when GFS is as consistent as this in FI, the synoptics do often gradually filter into the reliable time frame before other models start picking up on it. It's often at this stage GFS seems to wobble about a little and then jumps back on board within the even closer time frame! It's quite odd!

Yes, the anomaly charts were showing the difference yesterday:

http://policlimate.c...fs_z_panel.html

Subtle differences modelled upstream give us two different outcomes. I favour GFS, especially as:

MattHugo81

Latest EC 32 showing a more settled and slightly warmer opening week to April, than earlier expected, but still cooler/unsettled thereafter

27/03/2012 10:17

Seems the EC32 going against the OP run? Should come closer tomorrow, probably.

Edited March 27, 2012 by i'm dreaming of...

[Summer Sun]

ECM is a mixed bag tonight

Chilly over the weekend, but dry

http://www.wetterzen...ics/Recm961.gif

http://www.wetterzen...cs/Recm1201.gif

Next week stays chilly with the chance of rain for some

http://www.wetterzen...cs/Recm1441.gif

http://www.wetterzen...cs/Recm1681.gif

But we don't have to wait long till high pressure re-builds once more, but it stay's chilly

http://www.wetterzentrale.de/pics/Recm1921.gif

http://www.wetterzen...cs/Recm2161.gif

http://www.wetterzen...cs/Recm2401.gif

I wonder if the move to high pressure can last through the easter weekend?

Edited March 27, 2012 by Gavin D

[ANYWEATHER]

April Showers anyone!!!!

[Methuselah]

Could even be April 'wintry' showers with those cold uppers combined with strengthening convection?

[PersianPaladin]

Some notable differences between the UKMO and ECM runs at T144, with a more potent and westward oriented trough heading southward to the UK on the former.

I'd put F.I within this time-frame, as there are quite a few complications upstream as to how far south that Azores high is likely to go as its orientation changes and "flattens" out with the re-orientation of the jet-stream.

Edited March 27, 2012 by PersianPaladin

[Thundery wintry showers]

I think both UKMO and ECMWF show potential for some snowfalls in the north following on the back of this exceptional warm sunny spell. The high pressure just about holds on over the weekend on the UKMO run, though probably retreating enough to allow a few (possibly wintry) showers to develop, but at T+144 low pressure is close by to the NE promising something rather more unsettled as well as cold.

On the ECMWF run high pressure is very close by over the weekend so it would probably be dry with sunny intervals then, but again it looks wintry into early next week- the high pressure is following the incursion of -8C 850hPa air is quite slack and I would expect to see a scattering of wintry showers develop in eastern areas.

The GFS 12Z though is having none of the wintry weather (except well out in FI) and it shows that the weather beyond Friday is somewhat uncertain.

In the meantime though plenty of warm sunshine to come for most of us during Wednesday and Thursday.

[damianslaw]

Short term - more of the same, high teen and low 20 maxima away from the north of Scotland, but becoming cooler more generally from Friday onwards as the high shifts to the NW and we pull in much more cloud and a chilly wind from the north.

Weekend looks much cooler for everyone compared to recent days, with much more cloud and the chance of the odd spit or two of drizzle esp in NE parts and eastern coastal areas. but in the main it looks like staying dry.

Next week - differences between GFS and ECM/UKMO, the former wants to send the cold Northerly shot to our east meaning more settled but cloudy conditions with temps close to average under a light NW flow, ECM/UKMO suggesting more of an influence from scandi trough so potentially quite cold with some much needed showers esp in the NE. However, all models are not hinting at any major chance to unsettled conditions anytime soon with the mid atlantic high staying too close to our shores preventing any atlantic onslaught.

I suspect we will see quite a cloudy cool start to next week becoming milder by the easter weekend, but still rather cloudy esp in the north and west as the mid atlantic heights begin to ridge NE again, but developments to the NW will kill the chances of any sustained ridge, allowing a much more unsettled and cool flow to set in just after easter with hopefully some much needed rain.

Whilst the past few weeks have delivered some superb sunny and mild/warm conditions at times especially now, I have to say the weather since the end of the cold spell in the second week of Feb has been as trying as I can imagine in terms of 'interesting changeable weather'- with hardly anything to discuss - stuck in a rut springs to mind, indeed we seem to be having very lengthy spells of similiar weather in the past 2-3 years - with long dry periods thanks to high pressure ruling the roost - giving either colder weather than normal i.e. winter 09/10, dec 2010, or warmer than normal i.e April 2011, sept-nov 2011 and feb-mar 2012 with the only lengthy unsettled conditions reserved for the summer unfortunately or in shorter sharp bursts such as Nov 2009, Feb 2011 and Dec 2011. It reminds me of similiar periods such as spring 05 - spring 07 and further back spring 95 - spring 97 (except we saw much warmer drier summers.. and therefore even less in the way of unsettled weather).

[bluearmy]

yes I did have a quick look at their discussion and noted they score things at 1/10 for 6-10 and 8-14 day outlooks-its for their own neck of the woods but it does give a flavour of the overall ideas for the northern hemisphere around our patch as well.

I wonder what it is that is giving so much model trouble?

from what i can see, there is no consistency in the modelling of the arctic from run to run, day to day. the demise of the vortex from n america could be the culprit here. after all, its been there for several months.

[Thundery wintry showers]

The temperature at 850hPa bears little relevance to convection (should say, in the context of current model output), it's the temperature profile at 500hPa that is of most importance. Cold air through the mid-upper section results in a steep environmental lapse rate, promoting convection -- warm land surface temperatures and cold temperatures at 850hPa isn't in itself sufficient.

So in that regard, I can't see much in the way of widespread vigorous convective potential on the current run from the ECM as the coldest air above the mid-section is reserved towards the north and east of the UK, with here being in closer proximity to the digging trough over Scandinavia (as is modeled at T+168).

Maybe a misinterpretation of my post there- I had no intention of inferring that the -8C 850hPa air was the cause of the possible convection.

I imagine that with the relatively cold air at 500hPa and the weakness of the high pressure, together with winds off the North Sea, many eastern parts would see a scattering of wintry showers from that T+168 chart, though nothing particularly intense (the 'interest' would stem mainly from wintry, rather than thunder, potential). Western and southern parts though would probably be dry. Indeed, I think wintry potential for next week is generally low away from north-eastern Britain on the basis of today's outputs, but if UKMO/ECM verify it would be relatively high for eastern Scotland.

[Thundery wintry showers]

Hope I didn't come across the wrong way- it's easy for confusion to ensue when replying to someone else's post only for someone else to post in between! Anyway I do agree with your assessment there.

The GFS 18Z now suggests some shallow convection over the weekend as the high retreats south-westwards, with temperatures falling close to average- I think convective cloud spreading into stratocumulus may be an issue in that sort of setup. After that, it suggests a fairly warm but often cloudy (especially for the north and east) scenario with weak systems moving around the high pressure, so here we have yet another possible scenario.