Model Output Discussion - 15th April Onwards

[Summer Sun]

Changes could be coming as we end May and enter June, thats changes to some warmer drier weather in southern and eastern areas

http://forum.netweat...60#entry2301497

[johnholmes]

the promised pdf

500mb comments 8 may 12.pdf

[picog]

Thanks John. A little warmth would not go amiss, even if its wet. At least the garden will grow.

[bluearmy]

at least the general rise in heights to our south and east remains consistent on the fi ens modelling. still a couple of weeks away but i would think the NOAA cpc charts should begin to show a change in the 8/14day 500mb pattern as we head through this week.

[Thundery wintry showers]

Those hints of height rises to the E and SE in a couple of weeks' time look rather tentative to me, although I agree with John's pdf that a gradual shift towards a westerly (rather than northerly or north-westerly) pattern looks likely, which should bring temperatures up to the seasonal average. Sunshine and rainfall amounts will be sensitive to the strength and track of the jet stream but the NOAA 8-14 day charts suggest a predominantly cyclonic outlook, especially in the north. It probably won't be as wet or cloudy as the second half of April turned out to be though, with the jet perhaps weaker and further north.

[Zenarcher]

Looking at the time period from Saturday the 12th of May to Tuesday the 15th we are likely to see more changeable weather.

This weekend Southern parts will see high pressure building up giving settled weather. For Northern parts it will be the opposite with a low pressure system working its way down on Sunday this will bring wet and windy weather on Sunday night and Monday. From there the trend seems to be this low will slowly sink down and weaken at the same time over all of the UK and high pressure is never far away and may play a role later on.

Saturday and Sunday mostly high pressure around but a low to our North is slowly approaching,

Turning more unsettled across Northern parts on Monday,

After this low weak pressure stays with us,

[Summer Sun]

GFS remains unsettled into next week after a decent weekend, there are hints of somthing slightly more settled from the 20th but low pressure is never to far away

http://www.jp2webdes...o.uk/ds/gfs.htm

UKMO starts of settled but it soon goes down hill into next week once the next low pressure system makes its way down

http://www.null/ds/ukmo.htm

Edited May 8, 2012 by Gavin D

[Thundery wintry showers]

Despite a strong-looking area of high pressure I am doubtful about Saturday's weather. The GFS is progging shallow convection and light showers, and while the GFS is almost certainly overdoing the shower activity, it suggests a high probability of convective cloud sprouting up around mid-morning, hitting an inversion and spreading into stratocumulus giving most of us a cloudy afternoon. However with light winds and daytime temperatures close to normal it will probably feel relatively warm out there, and areas close to south and west-facing coasts should get plenty of sunshine due to the winds off the sea hindering convection. It's a similar story on Sunday but with rain spreading across Scotland after midday, and the UKMO is rather more progressive than the GFS suggesting that the wind and rain may get further south.

[Summer Sun]

ECM remains the same tonight settled for the weekend in england and wales then unsettled into next week

Edited May 8, 2012 by Gavin D

[William of Walworth]

Gav pattern changes don't run for a period of three months and then change.. Moreover the pattern which is established in May tends to last thru until the end of August.

And if I were a betting man. The wet April was really not part of the pattern, and more of a bonus, as its topped up our reservoirs and rivers. My bet would be a continuation for for the next four months of this weather, following the absurdly wet April. At last we have a more mobile westerly flow for the foreseeable future. Whilst it will often be dull and wet for most of the time, the raw cold from last week will have gone so at least we should see temps topping out in the mid teens rather than in single digits like last week. The rest of europe will be loving it though as away from the channel and north sea. All other areas should bask in warm summery weather. Its the price we pay here in the UK, for the heat on the continent. At least we should see less in the way of torrential thundery downpours which caused such high rainfall totals in April.

What an utterly absurd gamble may I say?

How can ANYONE on this forum honestly say that unsettled weather can in any way at all be predicted (even in a betting shop!) to continue through to August/September? Or even that this is likely?

You are right on one thing -- patterns don't change every three months at set periods. But neither are patterns set in stone for entire seasons!

Methinks the wish may be the father of the thought in that earlier post by you. Dubious meteorology though, and not all that much better in terms of model interpretation either.

NB I'm in no way predicting the opposite -- I'm certainly not saying we're due any time for a change to months and months of setlled weather -- far from. Just advocating the usual caution when it comes to predictions beyond the short term!

You might want to try that yourself.

Edited May 8, 2012 by William of Walworth

[William of Walworth]

Have read the subsequent posts now, and played quick catchup with some more of the latest model detail. On Publius's post -- I tend to agree with Alex and a few others (so sorry if I went a little OTT with my initial response)

For now, though, I still think that for later in May and onwards at least, there's all still to play for at this stage. TWS posting his commendably cautious summaries still, and thanks to John H for his latest pdf as well (which isnlt especially positive for sumemr lovers at this stage, but does lead to some hope that washout conditions may become less dominant that in recent weeks ... )

Current output (ever changeable as always!) tends to support the case (IMO) that even from 7 days away from now, there's plenty still up in the air, devil in the detail as always

BTW Hello again to all the regulars whose posts I've mostly been missing in the winter, I don't tend to join in model watching outside the May to September period.

Edited May 8, 2012 by William of Walworth

[Milhouse]

BTW Hello again to all the regulars whose posts I've mostly been missing in the winter, I don't tend to join in model watching outside the May to September period.

Welcome back . Fingers crossed we will have a lot of summery conditions to discuss over the next 4 months. Bring on the heat, sunshine and thunderstorms.

[skifreak]

The ECM looks quite promising for another 2 weekends at least out of the season on CairnGorm Mountain!

[k19]

I think it needs to be noted that FI is quite markedly spread in the ensembles across the country (as usual), interestingly though, once the members spread apart at around the 15th of May, they don't diverge as much as usual on the 850 charts. Also the members which give higher 850 temps and higher pressure at the far reaches are not always, but more often than not the same members which suggest a relatively warm weekend coming up. I know the ensembles aren't set in stone but it's very possible that a good weekend could bring better things further down the line.

[ribster]

BTW Hello again to all the regulars whose posts I've mostly been missing in the winter, I don't tend to join in model watching outside the May to September period.

Welcome back WoW, and as some would, I won't slate you for daring to have a weather preference and not wishing to post during seasons in which you are not particularly interested in following the models.

Edited May 8, 2012 by ribster

[William of Walworth]

Cheers for the welcome back folks.

Those ensembles above do look pretty widely spread don't they?

So I'm going to try and put off attempting predictions for next week until we know more about the coming weekend -- even that's not too easy to call yet ....

Edited May 9, 2012 by William of Walworth

[shedhead]

Well despite the odd decent day or two here and there for most, the overall picture across the middle third of May at least is an unsettled one, with plenty more rain to come. Any sign of a pattern change thereafter looks fairly unlikely too as things stand, with the last week or so of the month also appearing little to write home about, unless of course cool, wet weather floats yer boat...

Edited May 9, 2012 by shedhead

[Summer Sun]

GFS 06z remains mostly unsettled and cooler than average for the time of year there are some settled periods showing this weekend for one then the end of FI shows high pressure building

http://www.null/ds/gfs.htm

UKMO

Settled for the weekend unsettled from Monday

http://www.null/ds/ukmo.htm

ECM

Settled weekend then unsettled from Monday though parts of the south may stay fine

http://www.null/ds/ecm.htm

[phil nw.]

Indeed those runs all show an Upper trough never far away from the UK with the flow mostly from between West and North apart from the odd brief period.

The weekend does offer a brief respite as the High noses in from the west,although with temperatures still mainly below average

Then a renewal of cyclonic conditions are modelled for next week-so yes often wet and cool.

[Robbie Garrett]

The key for me this Summer, now appears to be Northern Blocking such as massive Greenland high. We are looking at 13*C max in the CET zone for the week ending 22 May, and week ending 29th May. First 5 days of June, very similar to May with MAX 13*C mean temperature. Week ending 12th June looks like weather coming in from the Northwest, so plenty of rain. Week ending 19th June 2012, looks a tad dry with a max of 18*C in the CET as a mean temperature. As we near the end of June, temperature dropping again and more rain. July starts off with a mean in the CET of 17*C and plenty of rain.

Does look like into July it's a westerly dominated pattern, with plenty of rain and temperatures probably average. 4 weeks ending August 2012 looks fairly average too, with temperatures in the CET maxing at 18*C with you guessed it plenty of rain.

September (4 weeks ending 23rd) are now looking relatively dry, with a mean temperature in the CET of 19*C. Temperatures consistently below average till at least early June. Cannot disagree that the CFS has been relatively good in predicting April and May so far, so don't cut it out just yet.

[Summer Sun]

GFS 12z

Settled weekend for England and wales, it then turns unsettle and cooler than average for the time of year into next week, high pressure is shown to build once more from the 20th

http://www.null/ds/gfs.htm

[camiscool]

The key for me this Summer, now appears to be Northern Blocking such as massive Greenland high. We are looking at 13*C max in the CET zone for the week ending 22 May, and week ending 29th May. First 5 days of June, very similar to May with MAX 13*C mean temperature. Week ending 12th June looks like weather coming in from the Northwest, so plenty of rain. Week ending 19th June 2012, looks a tad dry with a max of 18*C in the CET as a mean temperature. As we near the end of June, temperature dropping again and more rain. July starts off with a mean in the CET of 17*C and plenty of rain.

Does look like into July it's a westerly dominated pattern, with plenty of rain and temperatures probably average. 4 weeks ending August 2012 looks fairly average too, with temperatures in the CET maxing at 18*C with you guessed it plenty of rain.

September (4 weeks ending 23rd) are now looking relatively dry, with a mean temperature in the CET of 19*C. Temperatures consistently below average till at least early June. Cannot disagree that the CFS has been relatively good in predicting April and May so far, so don't cut it out just yet.

[Milhouse]

The majority of the models look to be opposing the ECM by taking next weeks low on a more northerly path which will bring more in the way of dry weather for the southern half of the UK. Although this outcome would mean the liklihood of a northerly developing as shown on the UKMO at 144h. How long this would last is still up in the air.

The GFS, which was until recently showing LP engulfing the UK is now showing high pressure not that far from southern England keeping the fairly dry theme going here on into the middle of next week. Eventually on the a showery northerly develops with very cool temperatures.

[phil nw.]

The key for me this Summer, now appears to be Northern Blocking such as massive Greenland high. We are looking at 13*C max in the CET zone for the week ending 22 May, and week ending 29th May. First 5 days of June, very similar to May with MAX 13*C mean temperature. Week ending 12th June looks like weather coming in from the Northwest, so plenty of rain. Week ending 19th June 2012, looks a tad dry with a max of 18*C in the CET as a mean temperature. As we near the end of June, temperature dropping again and more rain. July starts off with a mean in the CET of 17*C and plenty of rain.

Does look like into July it's a westerly dominated pattern, with plenty of rain and temperatures probably average. 4 weeks ending August 2012 looks fairly average too, with temperatures in the CET maxing at 18*C with you guessed it plenty of rain.

September (4 weeks ending 23rd) are now looking relatively dry, with a mean temperature in the CET of 19*C. Temperatures consistently below average till at least early June. Cannot disagree that the CFS has been relatively good in predicting April and May so far, so don't cut it out just yet.

That`s Summer written off then Robbie-oh dear!

Seriously though let`s not put too much faith in the CFS outputs..We have enough trouble with reliability within 5-15days where we try to forecast using the 4 times daily models and the NCEP 500hPa upper air charts.

Even these vary in their outputs and if you read the comments by the forecasters on the site they often have only low or medium confidence in them.

Granted the medium term outlook out to 10 days or so is mainly unsettled and cool but let`s keep an open mind beyond that.

[AWD]

After tonight/tomorrows rainfall, there doesnt look to be any more heavy persistent rainfalls for the foreseeable, just further heavy showers and periods of light rain in places after a settled weekend.

What is noticable throughout the model runs tonight though, is regardless of it being high pressure or low pressure in FI, there is very little warmth being shown. Therefore if high pressure towards the end of the month does verify ( as shown in GFS FI ) then there is a good chance it could be a dry but cool flow, with temps only hitting average in most places.

As an aside, this is a very good read from Liam Dutton on the prospects of the rest of May and where Summer currently is!

http://blogs.channel4.com/liam-dutton-on-weather/summer-350-miles-precise/1221