Model output discussion - hot spell beckons but then what?

[mb018538]

Anyone got any idea how many days we’ve had high pressure over Greenland since May? It’s ridiculous now. Full blown again at day 7. We all know too well it’ll vanish between December and February, such is the law of sod. Barring one odd day in late July, we’ve had -ve NAO for nearly 4 months straight. It’s bonkers.

[Frosty.]

Well the Ecm 12z finally updated..an hour late and there's a bit of a ridge (suckers-gap) at T+240 hours

Edited August 5, 2019 by Jon Snow

[knocker]

The bare bones of the EPS mean 5-10 have been discussed previously so with the influence of the trough and two upper flows still looking at unsettled and temps below average

And NOAA in the same ball park

Edited August 5, 2019 by knocker

[Guest]

Well I’ve taken as long a break as possible from any in-depth model reviews and to be honest having a poke about today sort of makes me wish I hadn’t bothered. Looks like summers going out how it began with stinking northerly blocking and either a succession of Atlantic moisture or slow moving trough near the UK and another pretty naff August. Fridays low wouldn’t be too bad if it was over Denmark by Saturday but it looks like dragging its heels big and still holding an influence into Saturday, Sunday and even Monday. Think I already need another break from the models.

[johnholmes]

Looking at the 500 mb anomaly charts over the past 2-3 days they seem to have a degree of similarity to one another and to have decent consistency over this 2-3 days. When this happens it is rare for the overall average upper flow to be wildly different from what they show. Obviously they can be wrong just as other model types can be but not very often. 

Thus the chart shown by knocker above is the most probably 'average' upper air pattern in the 6-10 day period. This would suggest fairly changeable for the UK for much of the time. Short 'windows' of more settled weather allowing temperatures to get to decent levels but, to me, no signal at all of major heating.

[Man With Beard]

56 minutes ago, mb018538 said:

Anyone got any idea how many days we’ve had high pressure over Greenland since May? It’s ridiculous now. Full blown again at day 7. We all know too well it’ll vanish between December and February, such is the law of sod. Barring one odd day in late July, we’ve had -ve NAO for nearly 4 months straight. It’s bonkers.

Taken me by surprise this one. Normally it gives up by July but the heatwave really beefed it up again. Of course it's much easier for it to form in the summer months than in the winter months. 

[Frosty.]

I'm going to be very diplomatic here, tonight's Ecm 12z ensemble mean @ T+240 hours doesn't look very...erm.. summery.

[Singularity]

Looks like those seeking settled summer weather will need to exercise a great deal of patience this month. 

The simplest route that I can see from current modelling involves stair-stepping westward progress of the mean 'cold' pool on the southern flank of the high latitude blocking across Greenland, making it a step further with each new trough formation. Those troughs also step west, and eventually - most likely sometime between the midpoint of the month and the start of the final week -  we escape their direct influence as ridges build across from the south or southeast.

Considering the tropical forcing at play, the reality may prove more complicated, perhaps involving a trough deconstructing and facilitating sudden ridge development close to our east or northeast.

The strong trade winds for the next 5 days correspond to a pattern change such as modelled, but not necessarily one that lasts more than a week after those trade winds wind down. The final third of the month remains up for grabs.

[MATTWOLVES 3]

To much panic going on tonight, take a deep breath and have a goodnights sleep, things will seem better in the morning. Still awaiting the EC46 run tonight, but the CFS or the chronic fatigue syndrome model is hinting at a much better end to the month... Just a little patience required folks... Seriously though, I think we are going to be having a major upturn by week 3, it happened in June, and it happend in July... So why not August!! And we still have September to come yet!! Or even October and November, where it can be quite spring-like even then...

[tinybill]

all i say this  is a bit of a worry if this comes  off

[knocker]

The North Atlantic 500mb and surface analysis for midnight and the 0300 WV image

The center of the low will drift east to western Scotland during the day and with all of the UK within it's circulation a day of sunshine and showers beckons which will be heavy and thundery in places with some persistent downpours where they coalesce with any embedded troughs, The greater concentrations of these showers and storms will be over N. Ireland, Scotland (where there is already some persistent rain) and perhaps the north west of England.Further south more sunshine and not an unpleasant day

The showers will tend to die out this evening over much of England but will still persist in western regions as weakening fronts track east and in particular they will remain frequent and heavy over the southern half of Scotland and NW England as the center of the low drifts east across Scotland.

By Wednesday the low is in the North Sea but the country is still within it's circulation so still some showery activity but less so than today and thus more sunshine but not so in Scotland where there will be frequent heavy showers and thunderstorms and there could well be some significant intense downpours as they will be quite slow moving.

By Thursday the low has moved away to the North east so a much better day albeit still some showers around but the low to the south west that has been discussed previously is tracking north east and fronts associated with this will introduce some thundery rain into the south west by late afternoon

Over Friday and Saturday the whole caboodle tracks north east so a couple of days of frequent thundery showers with some longer periods of rain, sunny intervals and possibly gales along the south coast.

Edited August 6, 2019 by knocker

[Frosty.]

Morning campers

The Gfs 0z operational gradually turns into a trough magnet with occasional transient ridging pushing across the south from the west. Temperatures this week actually look ok further s / se but cool for northern scotland and then it gradually turns much cooler for all..and did I mention rain?..there's plenty of it!

[knocker]

The later half of the gfs output has three key features relevant to the UK imo. The upper low anchored near Iceland and the ridge/trough combination over the Labrador Straits and north east Canada.Thus we have twin flows over the UK, one running around the Iceland low and the other exiting the eastern seaboard across the Atlantic. All of which portends and unsettled period with temps generally a tad below average but the usual caveat applies of regional variations with the phasing of the Tm and Pm airmassess

[Guest]

1 hour ago, tinybill said:

all i say this  is a bit of a worry if this comes  off

Only three days away, hard not to see something like this happening. Output terrible this morning and summer really does look like being book-ended by some awful conditions.....

[knocker]

This morning's updated fax charts Thurs/Frid

 

Edited August 6, 2019 by knocker

[Frosty.]

I'm sensing an improvement for the south on the GEFS 0z mean once we hit the last third of august with heights from the azores encroaching, actually through low res there's a tendency towards a north / south split with the most unsettled weather further n / nw as time goes on. 

Edited August 6, 2019 by Jon Snow

[Methuselah]

10 minutes ago, Jon Snow said:

I'm sensing an improvement for the south on the GEFS 0z mean once we hit the last third of august with heights from the azores encroaching, actually through low res there's a tendency towards a north / south split with the most unsettled weather further n / nw as time goes on. 

Which is supported by the ensembles, karl...though, with all the scatter, I wouldn't want to bet my house on it!

   

   

The August monsoon is upon us?

[knocker]

The ecm pretty much in the same ball park as the gfs

[Frosty.]

I get the impression that during the last ten days or so of august there will be some relaxation in the unsettled pattern and the azores high will have a chance to ridge in, even the Ecm which currently goes out to the 16th shows high pressure waiting in the wings for the trough to clear away to the NE...anyway, that's just me not giving up on August completely!!!

Edited August 6, 2019 by Jon Snow

[Captain Shortwave]

One thing to keep an eye on is the potential for another nasty low to develop near the Bay of Biscay early next week, this comes about as the trough splits over the weekend (the trough which associated with the unusually deep low moving in on Friday). This could bring a lot of rain and potentially wind across more southern and Eastern areas as that trough engages a plume of very hot air building over France.

[mb018538]

10 minutes ago, Jon Snow said:

I get the impression that during the last ten days or so of august there will be some relaxation in the unsettled pattern and the azores high will have a chance to ridge in, even the Ecm which currently goes out to the 16th shows high pressure waiting in the wings for the trough to clear away to the NE...anyway, that's just me not giving up on August completely!!!

On face value the 120 and 240 charts look quite similar. At 120 hours we get more low pressure piling through keeping things unsettled. To get a better idea you need a hemispherical view...



Looks slightly better at 240 hours, with pressure starting to fall over the NW/Greenland which may encourage pressure to slowly rise in our locale. One to watch, but the extended model runs certainly aren't sniffing out any change in the UK trough pattern just yet:


 

[Man With Beard]

This morning's ECM op is a true video nasty - the Atlantic lows are not merely threatening anymore, they are ganging up on us. As CS mentions above, a new explosive low is magic'd up for early next week in the southern half of the UK (gusting close to 80mph in the channel) - could come to nothing, but a worry. If you have a camping trip planned from this Saturday onwards and you can cancel it, think long and hard! 

Edited August 6, 2019 by Man With Beard

[Paul_1978]

11 hours ago, Alderc said:

Well I’ve taken as long a break as possible from any in-depth model reviews and to be honest having a poke about today sort of makes me wish I hadn’t bothered. Looks like summers going out how it began with stinking northerly blocking and either a succession of Atlantic moisture or slow moving trough near the UK and another pretty naff August. Fridays low wouldn’t be too bad if it was over Denmark by Saturday but it looks like dragging its heels big and still holding an influence into Saturday, Sunday and even Monday. Think I already need another break from the models.

On the contrary, the upcoming "storm" has piqued my interest and I've returned to the forum after a break of a couple of weeks. For me, much more interesting than model watching hot oppressive weather, especially at this time of year - quite unusual for August to have such a windy spell. The irony is that the storm may not be named as we are not in the 'right' time of the year. 

[Frosty.]

Whisper it but the Ecm 0z ensemble mean looks marginally less awful at day 10 compared to last night's 12z but it may be because I'm wearing rose tinted spectacles!

Edited August 6, 2019 by Jon Snow

[h2005__uk__]

What are the chances that some realigning of these low pressure systems could result in some hot air being dragged up to the UK, at relatively short notice?