Model Output Discussions 12z 03/05/2016

[phil nw.]

There's no getting away from it a change to more unsettled and cooler weather is on the way.

The approaching low to the south west is modeled to sweep wind and rain across the UK by Friday with further showery bands swirling around this feature as it moves across the country over the weekend.

quite a change from the current warm and sunny conditions almost nationwide.Looking into next week some improvement as the low moves away. The current Gefs for a week today does show attempts of ridging from the south

but with the jet aimed across our latitude again it does look like a more changeable setup going forward.Not all bad by any means,especially further south.With continuing +ve height anomalies over the near continent some areascould still see some pleasant,if shorter interludes. 

Trending towards the old NW/SE split by the looks.

 

Edited August 16, 2016 by phil nw.

[Cloud 10]

Yes,certainly a case of bad timing for the breakdown this weekend.

 

Looking further afield,quite a persistent area of low heights over the Arctic at the moment and for the medium term,which looks rather out of place for the time of year.

 

[Matthew.]

Day 10 evolution by the ECM. A provider of hope

Edited August 16, 2016 by Matthew Wilson

[ANYWEATHER]

Good Evening All . Big changes for the Uk s weather....

[William of Walworth]

3 hours ago, coldcomfort said:

Still no real point in attempting to put lipstick on a pig, the 12 GFS is another out and out stinker bar a rogue and very unlikely plume, so IF it verifies we can pretty much write off the final fortnight of meteorological summer...or am I simply guilty of putting another unduly negative slant on things?

Yes.

Because it's surely very iffy for any meteorogist to 'write off' anything beyond the very closest next-few-days outlook unless the overwhelming majority of forecasts are in agreement.

I'm not saying the opposite, there are of course plenty of plausible outcomes showing more unsettled conditions than settled, but there are also dissenting outputs showing SOME CHANCE of warmer and more HP influenced possibilities for FI -- at least in the South.

I think you could be guilty perhaps, at least in the above post anyway, of ignoring or at least underplaying the differences in opinion between various evolutions.

Edited August 16, 2016 by William of Walworth

[William of Walworth]

That said, I do agree that pretty much all the current/most recent ouput shows a pretty damned unsettled weekend upcoming, for the W and SW especially. All I can (personally) pray for, SW bound as I am from Thursday, is that rain amounts will be somewhat less than shown on most models right now.

Edited August 16, 2016 by William of Walworth

[cheese]

Weekend looks pretty bad, but beyond then looks reasonable. Temps back into the low 20s for most of us, maybe mid 20s on some days. Can't see why people would be writing off the rest of summer based on the 12z. 

Edited August 16, 2016 by cheese

[knocker]

The anomalies tonight are still in pretty fair agreement. The overall pattern is much as it has been recently so no need to repeat just to mention some height rises in the western Atlantic and the trough just to the west of the UK. Ergo remaining unsettled but with the trough stretching a little south this wouldn't preclude some WAA in the day to day surface evolution that could bring some transient warm weather to the south/south east. Otherwise temps in general around average.

The later period looks very much a familiar story with low pressure to the NW and high pressure to the SW suggesting a N/S split over the UK but with the usual caveats regarding phasing so periods of drier and quite pleasant weather but probably confined to the south

[northwestsnow]

UKMO looks a tad plumey this morning-

http://old.wetterzentrale.de/pics/Rukm1201.html

http://old.wetterzentrale.de/pics/Rukm1441.html

Better than GFS at 144 with some warmer southerly based air is pushed north as the low stalls, very fine margins though, a shift east of the trough and all that Iberian air is shunted into mainland Europe.

In contrast GFS is pretty poor with the Uk struggling to escape the effects of the trough.

[knocker]

Morning campers.

Today

Another fine day for most with the exceptions being the NE and Ireland and the far south west where the weak front encroaches.

This morning's GFS.

The depression, 988mb, arrives just off SW Ireland by Friday 12z with associated fronts orientated down the western part of the UK. This depression and fronts meander slowly across the UK to be in the North Sea by Monday bringing a wet, showery and windy couple of days to most before some brief ridging behind them. I say brief advisedly as the next frontal system associated with next depression which tracks more NNE arrives on Monday bringing some more rain. These fronts quickly dissipate and with the main depression stalled to the west of Scotland some drier weather is likely in England for a time.This drier spell comes to an end when a depression that formed in the far western Atlantic tracks south east, phases in with the circulation of the main low, and swings NE over the UK by Friday. At the moment I'm inclined to take this evolution with a liberal dose of Saxo.

Edited August 17, 2016 by knocker

[Man With Beard]

The big three at T144

    

UKMO far more pronounced with the southern/northern heights link up. Not many GEFS members remotely similar. Needs to be discounted as an outlier for now?

ECM and GFS both fairly dry and sunny for the SE, but risk of unsettled weather for the NW

[Summer Sun]

Well, this is certainly an improvement from UKMO!

[knocker]

The ecm is quite interesting this morning. It also has a depression forming in the western Atlantic, tracks it SE and phasing in with the main low, before it dissipates off the Iberian coast and morphs into a general area of unstable low pressure which proceeds north bringing some very active convective activity to the UK by Friday. That's the theory anyway.

Edited August 17, 2016 by knocker

[MP-R]

August 31st 2005 anybody? 

Anyway, looks like tomorrow could be a half decent day just with a bit more cloud around before Friday and Saturday brings a much more autumnal spell of weather with some quite notable winds for the time of year in the SW. I notice the UKMO has issued a weather warning to that effect for Saturday.

Thereafter, it could turn warm and humid again early next week before a brief blip midweek then an improvement during the Bank Holiday weekend. In summary it looks like a typical repeated plume attempts pattern interspersed with the Atlantic trying to nudge in. Could take until September for it to fully take force though.

[Man With Beard]

Well I said I would limit myself to one ridiculous outlier per day, so here it is ... BOOM!!!

Seriously though, can any forecast be made for next week given an ensemble spread like this?

The best we can say right now, I think, is that there will be a rush of heat from Spain to somewhere in Europe, considering a dipping trough like this, with the south east UK most likely to join in if anyone does

(bear in mind this is a MEAN chart which would probably iron out some of the extremities in the output):

[knocker]

It's not a bad idea to iron out some of the extremities as it stops the hare getting exhausted.

Having said that with the upper trough slipping a little further south the possibility does exist for some transient WAA, particularly as the jet is more meridional for a time over this period, although one would like a tad more amplification before a more zonal flow sets in. You can see where this could come into play on this morning's det outputs but at the moment it isn't really the percentage play.

[Summer Sun]

2 updates running from UKMO showing the potential for some warmer air on Tuesday

00z

[I remember Atlantic 252]

GFS too SS

[Summer Sun]

It's not only UKMO which shows some warm to hot air GFS is also showing another spell of high temperatures for 48 hours or so

[Man With Beard]

Yes UKMO and GFS quite close at T144. Looks like fine weather returning to most of England at least after a mixed weekend. Possibly hotter than last week, and those 90F+ runs keep cropping up in the GEFS so who knows at the moment?

[Summer Sun]

GEM shows high pressure starting to dominate once it builds early next week it lasts into the BH weekend

[Singularity]

We've very nearly gone full-circle back to the output of a few days ago with respect to the setup for mid-next week; the cool air has been corrected back west to head toward the Azores and this is promoting LP development to the west of Europe... or perhaps more like over the far-west of Europe, which is the key adjustment that will probably limit the longevity of the plume.

Not definitely, though. This ECM 12z det. run is looking interesting to say the least! I feel sorry for Spain and France which seem to have seen more than their fare share of what some might call 'brutal' heat (maximums widely in the high 30s to low 40s) in the past four weeks or so.

If these incremental adjustments west can continue... well, now I'm getting ahead of myself. I must say, long-range indications back in July did not inspire expectations of chasing plumes in the final week of August 2016! The refusal of GLAAM to take on a negative GWO orbit has really shaken things up - and in a very good way based on the past few days!

Edited August 17, 2016 by Singularity

[Summer Sun]

ECM is joining the party for next week sending up some very warm to hot air

[Captain Shortwave]

Well the ECM finally cracks out a crazy hot run this summer after the GFS did the same thing a week or so ago with respects to our current weather.

It doesn't look likely we will see the same sort of backtrack with respect to the heat being sheered away from both the east and west and hence the more usual southeastwards adjustment of the heat building over Iberia will be likely and hence those in the south east look good with chances dropping the further north and west we go.

That said this looks decent for the south at 5 days away.

   

So after a rather wet weekend we see conditions turn drier and warmer again into next week, especially in southern and eastern areas. Can we cut that low in the Atlantic off and hence allow the heat to push northwards to affect more of the UK? We will have to wait and see but the developments model wise do give some hope that we could see some late summer heat.

Edited August 17, 2016 by Captain Shortwave

[knocker]

Taking a closer look at the ecm.

At T168 and T192 it has quite a deep upper Atlantic trough south of Iceland stretching south to west of Iberia with ridging in the western Atlantic and Germany into the North Sea. Quite a marked amplification and not a complete surprise and bodes for some interesting surface developments.

As far as these go it is in the same ball park as this morning if not in complete detail. At the beginning of next week short waves develop in the southern circulation of the static Atlantic low and then swing north east on a now meridional jet just to the west of the UK leaving the latter in a rather slack complex LP area with some light S-N WAA

The main area of low pressure then drifts south which tends to reinforce the WAA and temps of 32C-34C being indicated on Thursday, The jet still meridional and running NE over the UK.

Of course this is all quite complex and a long way away.

Edited August 17, 2016 by knocker