Models, teleconnections and nowcasting

[johnholmes]

2 hours ago, knocker said:

Monday > Weds with the 600 ecm

Current sat image

I live in hope that it is correct re cloud as the wind is not pleasant. My time in the east makes me very suspicious of strong easterly and no low cloud, I hope I am wrong.

[knocker]

13 minutes ago, johnholmes said:

I live in hope that it is correct re cloud as the wind is not pleasant. My time in the east makes me very suspicious of strong easterly and no low cloud, I hope I am wrong.

It will be interesting to see how it pans out. The old Boulmer and Hemsby soundings might have helped

[knocker]

I think the overall trend is pretty much nailed but the detail regarding the low featured on this evening's ecm is not

[knocker]

Climate - the month so far

http://www.met.reading.ac.uk/~brugge/CURR.html

[knocker]

The North Atlantic 500mb and surface analysis for midnight and the current sat image

Another bright and sunny day and quite warm if you are not effected by the stiff easterly wind where the usual caveats apply.To save repetition takes this as read for the next three or four days.The only exception being the far south west where it will be cloudy with possibly the odd shower

Clear tonight apart from the south west

A similar day tomorrow with the gusty easterly still the only drawback

Over Tuesday night and through Weds little change but the south west may lose the cloud and the wind will ease and getting warmer

By Thursday changes in the NH profile, as mentioned in previous posts, are underway and the high pressure to the NE is migrating west leaving the UK in a slack gradient and another warm and sunny day

The transition continues on Friday with frontal systems creeping east across the Atlantic but the UK remains in a very slack gradient and a another warm day is on the cards with perhaps more chance of a few showers popping up

Edited April 20, 2020 by knocker

[knocker]

According to the gfs another slack gradient day on Saturday with perhaps more chance of showers in the south

But as can be seen the Atlantic is now open for business south of the high cell and a low pressure area moves east across the UK Sun/Mon and thus more generally unsettled

 

[knocker]

I have absolutely no idea how much credence one can give near time model cloud forecasts but out of interest the spot check at 1500 for the total amount today > Thursday from the ecm. Today and tomorrow it is mainly medium cloud and Wed/Thursday Ci

 

 

[knocker]

And predictable the ecm wants nowt to do with the gfs idea of tracking the trough east over the UK next weekend and has a resurgence of the subtropical high and thus a ridge stretching NE over Sun/Mon

 

Edited April 20, 2020 by knocker

[knocker]

As has been mentioned by others it's interesting that no low cloud along the east coast is included in the forecasts. Just an observation as this is way above my pay grade but the SST's of  North Sea are over a degree C above average and looking at the Schleswig sounding the air is very dry so one assumption could be that there  is not sufficient mixing in the boundary layer for St to form 

This morning's rainfall from the EPS

Edited April 20, 2020 by knocker

[knocker]

There were major differences between the gfs and ecm this morning regarding next weekend.The gfs has changed drastically with the 0600 but still differing so a quick glance at the clusters At t132 the det run is close to the first cluster but as van seen that isn't a slam dunk

The same can be said at t144 but as can be seen there is virtually an even spread on the different interpretations of the orientation of the upper trough and ridge. Place your bets

 

Edited April 20, 2020 by knocker

[knocker]

The Ci and Ac over the SW is an extension of the main low pressure area over the Mediterranean

[knocker]

Tricky business next weekend. This evening the gfs has a shallow trough breaking away from the main trough in the Atlantic and ducking south east a the subtropical high amplifies, which promotes a showery low over the UK on Sunday

[knocker]

The ecm is not having any of this. A possible movement to track a breakaway trough east at t120

But further amplification of the subtropical high puts paid to that and by Sunday the UK nestles in the eastern flank of the new high cell

 

 

[knocker]

Apart from being the lower half of the H/L UK squeeze fronts associated with the low pressure to the south are bringing cloud and rain to Devon and Cornwall at the moment

This can be well illustrated by looking at the midnight soundings for Camborne and Nottingham. The former, although reasonable dry in the lower regions, indicates multiple cloud layers above whilst the latter with a touch of surface cooling, is very dry above. Also worth noting the light NE surface wind veering to 085/39ks by 961mb

[knocker]

Moving on to the elusive analysis for the weekend

This is the 500mb and surface position on Friday indicating a very slack gradient over the UK  More cloud than earlier in the week but still warm with showers, heavy in the south

A very similar day on  Saturday

And again little change on Sunday although the gfs has slipped the weak trough south east from Iceland

 

Edited April 21, 2020 by knocker

[knocker]

The ecm makes a bit more of the trough to the north on Sunday as it phases with the main trough to the north east. This brings some rain to northern Scotland and does impact on the temps.

This then develops into a separate low over southern Scandinavia but still leaving western Europe, including the UK, in a very slack low pressure area

Edited April 21, 2020 by knocker

[knocker]

By the time we get to the ext period this morning the tpv has realigned and lost the trough to the NE to be replaced by height rises over Scandinavia, At the same time the main trough ii negatively tilted south east from Greenland. The precise intensity and alignment of these features is critical to the detail of the surface analysis but suffice it to say nothing .nasty would appear to be lurking in the woodshed

 

[knocker]

Weds > Friday with the 0600 ecm

Current sat image

[knocker]

A glance at today's EC weeklies update for the last two weeks of May

15 - 22

A ridge NW North America adjacent to a benign tpv aligned Franz Joseph to N. Canada with associated trough to the NW Atlantic. A weak westerly upper flow to some height rises and positive anomalies in the east with a ridge into south east Greenland and apparently a slack gradient south of the UK over western Europe/ Portends dry and not unpleasant

23 - 30

The Atlantic trough a tad more influential and losing the positive anomalies and ridge in the east but really little overall change for the UK except perhaps a tad more unsettled which will favour the north rather than the south

Edited April 21, 2020 by knocker

[knocker]

According to this evening's ecm next weekend looks like finding the UK in a light gradient with perhaps a few showers but more persistent rain arriving in the NW Sunday afternoon

[knocker]

I think most are aware of the current situation so keeping the waffle to a minimum

Today a dry dry and sunny day with the usual caveat

After a clear night with perhaps some bits and bobs of cloud around in the north another fine day tomorrow but the fresh wind will ease

Another fine day on Friday but note the very slack pressure gradient over western Europe

By Saturday the low pressure area to the SSW is developing a tad so a few showers in south western areas and a shallow trough is tracking south east south of Iceland

The trough will bring cloud and some patchy rain to the NW on Sunday and showers may well be more frequent in the south west but dry and sunny again elsewhere

Edited April 22, 2020 by knocker

[knocker]

Next week is a work in progress so wise not to venture too far so in a nutshell the gfs version for the next three days,

Our trough continues east and develops over southern Scandinavia as it phases with the main trough  This partially opens the door to the Atlantic but the subtropical high and the trough over the western Mediterranean are still players as this pans out and it raises doubts as to how quick any unsettled weather from the west will arrive over the UK

[knocker]

The ecm is not quite as keen to track the trough east and phase it with the main trough thus the Atlantic door is opened a tad wider and a developing wave tracks east over the UK by Weds

 

Edited April 22, 2020 by knocker

[mb018538]

3 hours ago, knocker said:

 

 

Good to see these are as accurate as ever. Going for 19-20c max temperatures tomorrow, when 24-25c is likely to be achieved. Is there a reason these consistently under-do maximum temperatures??

 

[knocker]

It is rather a tad premature to accuse them in being wrong 36 hours prior to the event but the short answer to your question is that I'm afraid it's  above my pay grade. I assume everyone is aware of the vagaries of model max temps forecasts and don't put implicit faith in them but, short of not posting them at all, I'm not sure what else one can in a model discussion thread. Do you find there are similar problems with min temps, air not grass, as topography might be part of the equation?