Model Output Discussion 31/03/14 onwards.

[Captain Shortwave]

It does look wet next week with spells of rain and also showers (both home grown and imports from France). Though I do get the feeling that it could be very hit and miss with somewhere getting a few inches whilst an area 20 miles down the road might see no rain whatsoever.

Looks warm until Thursday where there might be a more organised band of rain pushing northwards to introduce fresher and more average conditions.

Monday-Wednesday look the best bet for home grown storms, though there may be some isolated ones on Saturday in the south east generated by the high temperatures.

 

Any further sharpening of that trough (and subsequent westward corrections) would be ideal to get some more heat into the mix next week. 

Edited May 15, 2014 by Captain shortwave

[damianslaw]

Looks like the longwave trough will be stuck across the country next week hemmed in by strong heights both to the west and east - an elongated trough it has to be said with a sharp temperature gradient developing right over us, in time it looks like the cooler air will win, but it could be a bit of a battle and certainly ripe conditions for heavy thundery downpours - it could end up a very wet period for some. All very messy stuff..

[Summer Sun]

ECM continuing to bring in some very warm air next week +12 850's by Wednesday on south easterly winds the best of any drier weather still looks to be the further north and east you are, the west and south west looks most prone to longer spells of rain but given the warmth thunderstorms could crop up anywhere

 

 

By t168 a change to fresher air commences for all areas except Scotland and the far north of England

 

Edited May 15, 2014 by Summer Sun

[Cloud 10]

Looks like the longwave trough will be stuck across the country next week hemmed in by strong heights both to the west and east - an elongated trough it has to be said with a sharp temperature gradient developing right over us, in time it looks like the cooler air will win, but it could be a bit of a battle and certainly ripe conditions for heavy thundery downpours - it could end up a very wet period for some. All very messy stuff..

 

I think last night's 120 hrs fax chart shows what to expect with a waving front straddling the country with pulses of heavy thundery rain and showers moving up from the south.

 

[East_England_Stormchaser91]

Getting pretty safe to say that into next week is looking like convective heaven for many this is awesome stuff

[A.J]

Getting pretty safe to say that into next week is looking like convective heaven for many this is awesome stuff

a face value, the FAX charts show more of a thundery rain scenario, with pulses of heavy rain with the odd embedded convective element spreading up from the south/south west. Not had at look at the models in depth tonight, but those FAX charts infer high PWAT values thus saturated profiles throughout the atmosphere, which would promote large rainfall totals but hinder convective activity unless decent cloud breaks in fortunate areas and/or MCS type setups spilling across from the near continent giving night-time elevated storms......just my thoughts, and subject to change of course as the model output evolves 

[ANYWEATHER]

Looks early next week we will see some high rainfall totals across the uk, coutersy of a strong temperature gradient between here and the continent. Some localised flooding is possible in this scenorio, the second half of the week becons the Atlantic in so more in the way of best of british.....

[William of Walworth]

Lets face it, any hopes of avoiding a washout (and I'm thinking of the Bank Holiday weekend itself as well as earlier in the week) look distinctly low at the moment for the majority of places. Can't see many signs from recent output of the trough/LP complex positioning itself further West, or further away at all for that matter ...

Edited May 15, 2014 by William of Walworth

[knocker]

The ECM EPS to round off proceedings.

Edited May 15, 2014 by knocker

[Frosty.]

Impressive Ecm 12z op run this evening in terms of very warm and humid weather next week for most of the uk with +10 or higher T850 hPa spreading northwestwards, a big very warm plume with temperatures in the 25 celsius range, give or take a degree or two so 80 F could be breached, it also looks like turning very unstable /  showery as pressure falls with some big thunderstorms rumbling around the uk with torrential downpours, the atmosphere looks like becoming explosive with hot sunny spells triggering storms. In the meantime, this weekend is perfect for a BBQ with temps in the 22-24 celsius range, high pressure staying in charge through the weekend for the bulk of the uk apart from the northwest corner where it will be cooler and more unsettled..not long ago the models were hinting at a cold northerly, now it's a hot & sultry SE'ly on the way.

[Captain Shortwave]

I think for storm lovers I do think Monday could be our best chance.

 

Definite chance for homegrown showers during the day along the decaying cold front, plus very promising signs over in France. There could be some big storms developing there which should be steered northwards to perhaps hit the UK overnight into Tuesday.

Edited May 15, 2014 by Captain shortwave

[East_England_Stormchaser91]

Another big westward shift modelled on the pub run! We tap fully into those 10+ uppers this time. Is this it? Is this going to be the first major plume since 05/06? It's definitely looking that way!

[summer blizzard]

Some truly awful outputs tonight suggesting mainly humid, warm and wet weather will dominate.

[knocker]

Just to concentrate on Monday and Tuesday for the moment and the GFS take on this. One musn’t over cook the flash flood scenario.

 

At 06z on Monday there is a slack area of low pressure over SW England and Ireland with a front lying along the east Irish coast with some rain. By 12z the front is situated N/S along the west of the UK with extensive rain covering all of the UK apart from the south east and northern Scotland. By 18z the front has reached the spine of the UK and the rain has now reached the south east but the south west is now in a clearance. By 00z Tuesday the frontal rain has now cleared all but Scotland.

 

Tuesday is interesting. By 06z a low has formed in the channel 999mb bringing extensive rain to southern England and Wales. By 12z the low is over Aberporth with the rain confined to Wales, the Irish Sea and eastern Ireland  By 18z the low is over western Ireland with the rain now also confined to Ireland with mainland Britain dry. By 00z Wednesday the low is now west of Ireland with an outbreak of rain covering East Anglia and the midlands,

 

Temps low 60s in west on Monday rising as you travel further east. Tuesday a ver warm day for most with temps in the mid 70s apart from in the west.

 

It has to be said this scenario doesn’t receive unanimous approval.

 

 

[Captain Shortwave]

A lot of uncertainty for next week still. Monday and Tuesday looks warm with rain around. Beyond that, most models try and clear the warmest air away on Wednesday and try to clear some of the low heights away allowing the Azores high to build in from the west. This would bring a cooler but mostly dry weekend (GEM/GFS do this).

The ECM is the odd one out for midweek with a stronger ridge bridging over the top of the cut off low. This means the warmer spell lasts until Thursday and the pattern allows a re-load of warm/thundery conditions to move northwards over the bank holiday weekend.

 

GEM

[knocker]

The ECM is not quite singing from the same hymn book as the GFS. As always the crux is in the detail so convective forecasts from now are still fraught with uncertainty IMHO opinion.

Edited May 16, 2014 by knocker

[Gibby]

HERE IS THE LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM TODAY FRIDAY 16TH MAY 2014.

 

THE CURRENT GENERAL SITUATION. High pressure remains slow moving across Southern Britain while NW Britain sees a waving front to the NW with SW winds ahead of it and occasional rainfall over NW Scotland.

 

GFS The GFS Ensembles show Low pressure becoming the dominant player in the UK weather over the next few weeks. It sinks South to a position SW of the UK for a while before filling slowly as it drifts over the UK late next week. as a result thundery rain and showers will be frequent and heavy especially in the South and west with a lot of warm and humid air in tow for many. Longer term the model continues to feed slack low pressure areas across the UK at times with further showers and probably slightly cooler conditions.

 

UKMO UKMO ends it's run with Low pressure anchored close to SW Britain with a slack Southerly flow extending outbreaks of rain and showers across the UK, heavy and thundery in places especially towards the South and West. After a warm start to the week temperatures will fall back through the week but the humidity will be quite high.

 

GEM The GEM operational shows low pressure to the SW of the UK too for much of next week with bands of rain or thundery showers spilling North over the UK in humid air. Later on the Low pressure will cross NE over the UK with cooler and fresher air developing later as showers decrease in response to High pressure building from the SW.

 

NAVGEM NAVGEM still shows Low pressure down to the SW early next week before it crosses NE across the UK and NW Europe later next week. As a result showery weather seems likely with slack winds and some thundery showers at times with some warm and bright intervals as well at times before things begin to cool down somewhat later as light winds turn NW.

 

ECM today shows a showery start next week as Low pressure becomes established to the SW of the UK. With South or East winds from Europe wafting up across the UK,  it most likely will stay warm and humid away from North Sea coasts. This would probably result in thundery outbreaks carried North at times with nowhere immune and this process looks like being maintained throughout the week and into next weekend as slack Low pressure continues to remain close to UK shores.

 

MY THOUGHTS  This morning's output still show a slow dip into more unsettled weather next week. This will be most felt across SW areas of the UK but will occasionally affect other areas too. Low pressure is shown to lie to the SW of Britain for much of next week with relatively warm and humid air wafting up across the UK encouraging some thundery weather at times. Through the later stages of this morning's output there seems a gradual trend to shift the Low pressure either NE or East across the UK with a slack pool of unstable air remaining close to the UK encouraging further heavy and thundery showers at times as well as lowering temperatures away from the warm category towards more average temperatures for most late in the period in a more Westerly flow.

[Frosty.]

Truly wonderful BBQ weekend weather in store for most of the uk with high pressure holding on for a few more days, we will be basking in low to mid 20's celsius, a high uv index means the sun is as strong as it is in july / august... only exception is the far northwest where fronts will brush around the top of the high with temperatures closer to average. Into next week, very warm and increasingly humid with SE'ly winds and falling pressure to the southwest with an increasing risk of thundery showers by monday, then it looks more unsettled with thundery torrential downpours but fine spells too, under persistent rain the temperatures will suffer but either side it looks warm and humid next week, however,  northeastern coastal areas look like having a lot of sea mist / fog and low cloud at times but it should burn off to the west of high ground with sunny spells, the more northern parts of the uk could have a fine week, more unsettled further south.

[TonyH]

Some of us truly in for a washout next week with rather disappointing temperatures and sunshine amounts!

Edited May 16, 2014 by TonyH

[knocker]

The EPS for Monday and Tuesday.

Edited May 16, 2014 by knocker

[shaky]

Slightly further south and west again from the gfs!!it actually remains warm and humid with temps touching the low 20s right up until the end of next week on this run!!

[johnholmes]

The 500mb anomaly charts show just how difficult predicting more than 3-5 days is. They correctly picked out 5-6 days ago the change from an upper ridge to an upper low and fairly quickly all 3 decided on the cut off upper low variation but what was not clear for some time was just where the upper flow and thus the surface flow would be.

Thus using these results in not getting the warmth early on in the sequence but getting the unsettled fairly well.

As an exercise in trying to link the upper air (on which the surface pattern depends, not the other way round), watch the Met O Fax charts that, at the bottom of the sequence, show their raw surface and 500mb flows. Interesting to see how they match the two up, make alterations on their Fax charts(beyond 48h these show the main 'thickness' lines) so some guide to the link of surface weather systems to that upper air pattern.

In my view well worth the effort of seeing how these interact and how the senior man has to change the emphasis as more data becomes available from different models as well as their own.

 

ps

first class summary in her weather alert from Jo Farrow, explaining the complexities and uncertainties-thanks Jo.

I hope you do not think I am being 'clever' with this post Jo, it is genuinely meant.

Edited May 16, 2014 by johnholmes

[summer blizzard]

Looks like the trough will stick around for a while so warm nights and heavy rainfall seem the order of the day.

 

[legritter]

Interesting times on the weather front ,something to get our teeth into ,sizzling BQ Sausages tonight and the weekend then an interesting spell as humid unstable air arrives next week adding some interest to our hobby .dont forget the sun hats ,i did not bother with one yesterday ,and surely suffered for it ,youd have thought at 62 years of age nearly that i would have known better ,Enjoy the sun  i,ll catch up with you all later ,cheers .

[knocker]

The 06z GFS has a low situated Scottish borders with associated trough and rain at 12z on Wednesday.. This follows the cyclonic circulation in the next 24 hours and by twelve Thursday the low is just west of Shannon with the rain belt running from there to Stornoway. No appreciable build up of convective cloud for either of the two days but plenty of action in northern France.

Edited May 16, 2014 by knocker