Model Discussion - 10th March Onwards

[Summer Sun]

GFS ensemble for London sums it up this morning, very little rain till April with above average uppers

[reef]

I think the lack of posts in here says a lot about what is showing in the models at the moment, 'more of the same' is perhaps an appropriate description though there are some subtle changes. The overriding pattern is one of high pressure centred in the North Sea. This helps drag in rather warm uppers for the time of year, but leaves eastern areas with a weak flow to the east of south, which introduces more in the way of cloud than recent days. In these areas temperatures could struggle to 10-12C at most and will give the scenario of cool or average days and mild nights with temperatures held up by cloudcover.

http://www.wetterzen...s/Rtavn1081.png

http://www.wetterzen.../Rtavn10817.png

Although its always difficult to predict cloud amounts in these situations, with the sun slightly stronger than a week and a half ago and less input of tropical maritime air into this high sunshine amounts away from the east look to be very good indeed. As a result temperatures respond and reach the heights of 16-18C, with some areas eventually touching 19-20C:

http://www.wetterzen.../Rtavn18017.png

The flow does occasionally drift back to the south later in the period allowing eastern areas to join in the fun.

The ensembles show the extended anticyclonic spell and offer no hope to drought-affected areas anytime soon:

http://www.wetterzen..._London_ens.png

Though western areas who are wondering what all this drought business is all about get to enjoy the dry weather too:

http://www.wetterzen...chester_ens.png

Overall its looking dry, mild and settled, with perhaps some sunstantial sunshine totals away from the east. Pretty 'boring' in a sense of weather variety, but lots of 'usable' weather.

[MP-R]

Perfectly summed up by reef. Fantastic summer synoptics but rather uneventful for the foreseeable. In fact, the 12Z GFS is pretty anticyclonic throughout, backing away from the idea of a pattern change come the start of April. A very brief breakdown on the 1st/2nd April is quickly replaced by a renewed high from the SW by the 5th (albeit all FI). All in all, a brilliant spell of weather coming up for those who want prolonged sunshine but not great for weather enthusiasts such as myself.

[BlueHedgehog074]

Although it is at the end of the run, the ECMWF has recenlty brought back this idea of a retrogressing High-Pressure system ending up going to the West of the UK and extending towards Western Greenland. At the same time, a Low Pressure system is forced to go in a East-South-East direction towards the UK, although with the centre of the Low heading towards the Scandi area. Thanks to this, we end up with a Northerly flow at 240 hours (for the ECMWF 12Z run):

If an evolution like this does come off, there could be a risk of some rain (and I understand some places facing drought contitions really need some), and maybe even some snow, too, though the snow would probably be most likely restricted for Northern areas, unless we can get a really potent, sustained Northerly flow. Would still be cautious of the ECMWF's scenario as...

1) It is in Fantasy Island.

2) It still feels like the ECMWF is being a touch too progressive with retrogressing that large High-Pressure system over the UK/Southern UK.

3) There's not much support from other models except the JMA, which also shows a retrogressing High-Pressure system with Northerly flow developing. Though, to be fair, since some models only go out to 144 hours, then it could be possible these models would also end up showing a similar scenario to ECMWF's/JMA's outlooks, should they go out further.

Nevertheless, because the ECMWF showed a North-Westerly/Northerly evolution a day or two ago in FI, it could have picked out a trend that the other models, such as the GFS, are just not picking up on.

Edited March 21, 2012 by Rainbow Snow

[Cloud 10]

Strong support for the ecm operational run from the ensembles with high pressure moving west into the north atlantic

with the possibility of northerly/north-westerly's as we enter April,which ties in pretty well with the met office further outlook.

[damianslaw]

Mmm not much to talk about - very quiet conditions ahead with high pressure continuing to rule the roost - drifting NE pulling in a light SE flow which will mean cloud for eastern parts but sunnier conditions further west and particularly the NW. Unlike recent weeks, NW parts could very well see the highest temps in the days to come.

Longer term - GFS maintains heights over the country. ECM suggesting heights will move NW in time pulling in a northerly flow, this theme is backed up by the meto forecast as we move into April suggesting cooler and showery conditions by then - but this is 10 days away still.

So the outlook remains very settled very dry and largely very mild for the time of year - it does feel a bit like last April when blocked conditions ruled the roost though obviously we haven't the same level of temps - things broke in early May mind and that was the end of the lengthy blocked pattern until mid september....

[Geordiesnow]

Again subtle but fairly significant changes, it looks like to me that both the UKMO/ECM has backed off there more cooler cloudier set up with this high and gone more like the GFS option of keeping it warmer and more likely much sunnier aswell. Further afield, the ECM FI outputs suggest a more blocking set up which may result in a Northerly once again but whilst the foundations may of move closer to the reliable, any Northerly hasnt and some runs did suggest high pressure may stay in control.

People may say shame this is not 3 months later but you would not get a blocking high like this in summer because of the more flabby nature of the weather patterns during the summer months

[Cheese Rice]

Sunday is looking warm.

20.c likely across Yorkshire, Lincolnshire, East Anglia, South East and Southern Central England- the usual areas.

I'm really pleased with the output. It's looking likely that March 2012 will be top five sunniest on record here. Rainfall totals while on the low side seem to be fine, we've had some rainfall during nighttime allowing it to soak in for longer aided by water supplies coming from the rainy far North West (?).

Hopefully this dry sunny weather will continue well into April although the signal is for something cooler and possibly wintry as we head into April.

[damianslaw]

Again subtle but fairly significant changes, it looks like to me that both the UKMO/ECM has backed off there more cooler cloudier set up with this high and gone more like the GFS option of keeping it warmer and more likely much sunnier aswell. Further afield, the ECM FI outputs suggest a more blocking set up which may result in a Northerly once again but whilst the foundations may of move closer to the reliable, any Northerly hasnt and some runs did suggest high pressure may stay in control.

People may say shame this is not 3 months later but you would not get a blocking high like this in summer because of the more flabby nature of the weather patterns during the summer months

Last point - goo point, it is much more difficult to maintain strong robust heights over the country during summer than it is during spring - when the atlantic tends to be in a much less sluggish and static state, this is one of the factors which helps to lock the position of heights in one place for so long.

Looking ahead and the energy in the PV looks very weak in the coming days and the atlantic longwave trough is sinking well south into the mid atlantic - not sure what the NAO is forecast to do, but given the meto longrange forecast I suspect it is set to go negative for the first time in a long while which will enable heights to transfer NW in time, with scandi trough formation. Remember ECM outperforms GFS hands down when it comes to blocking set ups.. I'm expecting the GFS to begin to show heights moving NW in time in coming model runs, but it may be another week before we see consensus on this theme, so expect only subtle variations from the models in coming runs.

Along with September I rate March as generall a very 'trying' month weatherwise, often very benign especially in recent years, where have the March winds gone this year, we've had barely a breath of wind so far this month, indeed apart from the opening days of the year it has been an exceptionally 'windless' year so far, which has contributed significantly to the very benign feel of recent weeks, the general calmness and much as the lack of rain has been the most notable feature of our weather since late Jan.

[johnholmes]

my view on the end of the month and start to April

Pattern change by the month end-wed 21 mar 12.pdf

[Cloud 10]

my view on the end of the month and start to April

Pattern change by the month end-wed 21 mar 12.pdf

Thanks for that,a good read as usual.

Today's charts for the AO and NAO looking a bit more neutral.

[Zakos]

Wow, another HP dominated run. Not a single drop of rain for most of England on the 18z, infact the whole of the UK is very dry throughout this run.

Northerly topplers, Easterlies, South Easterlies, you name it, this run has it. Everything, that is, except rain bearing westerlies.

Even in deep FI, the GFS is showing complete HP dominance. Not even a hint of any unsettled westerlies. This is a recurring, and worrying theme.

Edited March 21, 2012 by Zakos

[phil nw.]

my view on the end of the month and start to April

Pattern change by the month end-wed 21 mar 12.pdf

Thanks John.

A fair summary i reckon and very much agree looking at those charts.

[Terminal Moraine]

The ECMF continues to toy with idea of the high retrogressing well into the north western Atlantic allowing a northerly blast by the end of the month as low pressure moves east to the north of Britain. The GFS shows a very watered down version of this set of events with the high beginning to retrogress but then temporarily sinking southward before ridging north east again, much as we have seen in recent weeks.

Whilst the ECMF would not constitute a pattern change, in as much as the Atlantic would remain blocked, there would certainly be a significant change in the weather in this part of the world if it were to materialise.

[summersnow]

I must admit, I'm quite interested in the continuing divergence between ECM & GFS. Another fairly distinctive watershed event as regards model performance this year - something that I believe GFS is winning so far, when it comes to 7 days and beyond? I don't have stats to back this up, but my gut feeling is that ECM has been the model to suggest more solutions such as this all year (2012), whereas GFS has been much more keen on Azores HP default dominance. I refer obviously to medium range trends ie a week to 10 days, rather than specific detail for shorter range forecasts, which is where I suspect GFS falls down somewhat. I'm sure there are those who will willingly correct me if this gut feeling is way out...please feel free to do so!

I have also maintained since late Feb, that I expect a pretty notable northerly at some stage during Spring, as the equinox, solar activity and sea ice melting all start to impact. Maybe this will be it, although a good couple of weeks later than I had originally expected! I guess, ECM has got to win one of the big battles at some point as well... but then again, maybe it will end up being a hybrid solution as it often does!

[johnholmes]

I'm not sure I would agree with you regarding ECMWF and GFS, certainly not over the hemisphere as a whole in the 6 day area anyway. It has recently suffered possibly its worse run of verification but its rarely below GFS and normally outscores Met.

As to specifics in the UK area then of course we all rely on our own interpretations of how our memories tell us. Not reliable in my view be it mine or anyone elses'. Someone has been doing model checks (apologies to the poster as I have forgotten just who) which does seem to show the models in the time scale he is checking are closer in their scores for the UK area.

[BlueHedgehog074]

With the GFS attempting to shift the High-Pressure system further West, I'm starting to feel a bit more confident about a possible Northerly in FI. I think what may end up happening, though, is we may end up with a solution between both the GFS and ECMWF outcomes, but it does look like the GFS are backtracking towards the ECMWF regarding the possible Northerly outbreak.

The GEM also shows a Northerly in FI, although this is seems to be a brief affair, as Low Pressure systems spread out to the West of the UK causing the flow to become more Westerly.

Could still be easily possible for this Northerly to get downgraded despite some fairly good support from the models for a Northerly of some kind. The GFS could just decide to go back to its High Pressure dominated outlook with the High not retrogressing that much West at all. I suppose it will also depend how the Low Pressure systems to the North and West behave, too, and where they track.

Xtra Info: In fact, looking at the 0Z ECMWF as an example, the Low Pressure system out to the West ends up going over the UK High Pressure system, (while varying in strength and joining with other Lows), until it reaches Scandi at 216 hours. But with that happening, the UK High-Pressure system becomes 'squeezed' North-Westwards and we end up with that block in the Atlantic.

Arrow showing the rough track of that Low, (from 24 hours upto 216 hours)

Reaches Scandi at 216 hours, but with the High pushed out to the West, the Low has room to stretch out a bit and attempts to drag colder air down from the North.

Edited March 22, 2012 by Rainbow Snow

[summersnow]

With the GFS attempting to shift the High-Pressure system further West, I'm starting to feel a bit more confident about a possible Northerly in FI. I think what may end up happening, though, is we may end up with a solution between both the GFS and ECMWF outcomes, but it does look like the GFS are backtracking towards the ECMWF regarding the possible Northerly outbreak.

The GEM also shows a Northerly in FI, although this is seems to be a brief affair, as Low Pressure systems spread out to the West of the UK causing the flow to become more Westerly.

Could still be easily possible for this Northerly to get downgraded despite some fairly good support from the models for a Northerly of some kind. The GFS could just decide to go back to its High Pressure dominated outlook with the High not retrogressing that much West at all. I suppose it will also depend how the Low Pressure systems to the North and West behave, too, and where they track.

Xtra Info: In fact, looking at the 0Z ECMWF as an example, the Low Pressure system out to the West ends up going over the UK High Pressure system, (while varying in strength and joining with other Lows), until it reaches Scandi at 216 hours. But with that happening, the UK High-Pressure system becomes 'squeezed' North-Westwards and we end up with that block in the Atlantic.

Arrow showing the rough track of that Low, (from 24 hours upto 216 hours)

Reaches Scandi at 216 hours, but with the High pushed out to the West, the Low has room to stretch out a bit and attempts to drag colder air down from the North.

Good summary! The Met Office still seems to be backing the idea of he Atlantic block. Due to its pretty good record so far this winter on 6 day + forecasts, I reckon it won't be too far off the mark - although I agree a half way house between current GFS and ECM solutions is quite likely.

I would also agree that GFS 12Z is at last showing signs of jumping into bed with ECM!

Edited March 22, 2012 by summersnow

[Robbie Garrett]

Still got this in Fantasy Island.... that would be a nice washout!! Those wanting warm dry weather for the unforeseeable future, get a grip I don't want to be queuing for water with 150 members of state watching me this Summer.

Edited March 22, 2012 by Robbie Garrett

[phil nw.]

It looks like we may well continue with the high dominating unill at least month end with warm and dry conditions for many.

http://www.wetterzentrale.de/pics/Rukm1441.gif

Mean hts for 8-10days show heights still across the UK

http://www.meteo.psu.edu/ewall/ECMWF_0z/test8.gif

The weekend and into next week looks very pleasant for outdoor activities with light winds and sunshine and temperatures maxing out around 16-18C quite widely.

[phil nw.]

ECM 12z shows a breakdown of the warm and settled conditions from the north west around T192hrs as the high regresses west into the Atlantic

http://www.wetterzen...cs/Recm1921.gif

low pressure moving across to the north of the UK into Scandinavia.

Differences here with the GFS which prolongs the settled outlook to the month end.

http://www.wetterzen...s/Rtavn2041.png

although some sign of the high moving a little to the west.

So uncertainty on any breakdown around day 8 but untill then it continues to look like another week of mainly dry and fine weather with some warm afternoons.

Edited March 22, 2012 by phil n.warks.

[snowmadchrisuk]

The Morning model runs pretty much all agree on a gorgeous week coming up , I'm sure somewhere in the SE will get up to around 25 deg at some point in the next 7 days , After this a breakdown from the North is still showing at around +192 , but the ECM is not very keen on holding it and powers up the p/v a little and pushes the pattern Eastwards . The GFS is more keen on keeping High pressure out West . I would say odds are about 1 in 3 that after this Warm spell we will get a Cold Easter with Snow for some ..

[MP-R]

I think the headline on the home page pretty much sums up this weather - we are well and truly stuck in a rut.

However, fortunately there are tentative signs of a breakdown in about a weeks time with some more interesting and lively weather on offer in GFS 06Z FI with some much needed rain for many. The GFS even throw a brief northerly in there for good nature which may actually happen as there have been signs for a while of heights transferring to the west of the UK.

Until then, not much worthy of note at all.

[Robbie Garrett]

Fantasy Island has been rather consistent, lets see if the 1530-1645z update brings something very similar and the GFS is not defaulting to zonality. But rather impressively, the hights will have to fall, or move westward before we can even consider anything remotely wet. Odds are on for a wet April at this time. I also cannot think when the last time we had an April shower (Monsoon)

Edited March 23, 2012 by Robbie Garrett

[summersnow]

While ECM 00z now allows the northerly to break down quickly, the Met Office sticks to its guns with the "cooling trend" from 6-10 days and continues on that theme into the 16-30 day outlook!?

GFS meanwhile, has jumped from a very cold outlook from next weekend at 00z to a much wetter outllook at 06z.

I personally interpret this as a rather watered down northerly break down followed by "business as usual"! Could still mean some rain for the south though, after the coming week of pleasant weather!

Edited March 23, 2012 by summersnow