Short range model discussion - into 2018

[knocker]

The very sharp impact of the upper trough on the jet as it tracks east tomorrow in front of the burgeoning ridge, before all back to 'normal' with the resulting cut off low.

And the midday MODIS image. Some quite large Cu here but the main cloud is As/Cs

Edited October 5, 2018 by knocker

[knocker]

Regarding the above ref. to As/Cs

[knocker]

As the upper trough slips east this evening the rain on the front straddled across central England and Wales will pep up considerable and push slowly south east during the night. To the north of this and particularly over Scotland much clearer skies with a few showers and thus quite cool by morning. To the south east in front of the front cloudy and mild.

[knocker]

Not the least remarkable aspect of the forthcoming pattern amplification, apart that is from the possibility of some nifty cyclogenesis in the Atlantic, is the advection of some very warm air into Europe,

[knocker]

The outlook is essentially a battle between the energy in the Atlantic and the block to the east. Taking last evening’s EPS this would indicate an initial victory for the latter with the upper flow backing SW. or even SSW, in the vicinity of the UK which would likely only serve to emphasise a NW/SE split. with some fairly warm advection into the latter.

Back to this morning and the sharply defined upper trough and the surface analysis at midnight

The waving front and rain belt are currently orientated the Humber >Wales>south west and will track south east through the day, finally clearing Kent by around 2100. Further north much drier and cooler with some showers over northern Scotland and the clearer weather will spread south during the day as the front clears. Temperatures will be severely depressed over much of central England under the rain in the very brisk north easterly wind.

Once the rain has cleared it will be a clear and cold night under the ridge with a widespread frost by morning

But the next frontal system is quickly arriving on the scene to the north west and this will bring rain and strengthening winds to N. Ireland and western Scotland by dawn which will spread to much of Scotland and parts of northern England during the day. Further south it will be a pretty sunny day, albeit not overly warm.

With low pressure continuing to reside to the north west of the UK and the associated front remaining straddled across Scotland the wet and quite windy weather is set to continue in the north on Monday, the rain tending to be concentrated over western Scotland, whilst further south remains under the influence of the ridge and thus sunny and dry.

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Over Tuesday and Wednesday we are progressively getting into opening comment territory with the upper flow backing

And thus over the two days any rain and breezy conditions pretty much confined to N. Ireland and north west Scotland with the rest of the UK having some fine and dry weather and getting quite warm with temps above average

And he NH profile at T120 which is more or less where we came in

Edited October 6, 2018 by knocker

[knocker]

The 0500 chart this morning illustrates the three way split. Clear and cool in the north; moderate rain across wales and central England and mild with mist in the south east

[knocker]

The ecm precipitation

[knocker]

The 0900 UTC geostationary image and the developing wave west of Brest

Edited October 6, 2018 by knocker

[knocker]

MODIS image at 1240 and midday chart. The front well through here, just some small Cu. Not overly warm at midday

Edited October 6, 2018 by knocker

[knocker]

The wave is a little further south than forecast yesterday on the 1500 geo.

The front was just through here

Edited October 6, 2018 by knocker

[knocker]

Another upper low swings SE within the complex trough N. Canada/Greenland in the highly amplified pattern over N. America

Which sets in motion downstream the changes that result in the WAA into Europe

Edited October 6, 2018 by knocker

[knocker]

The short range outlook remains virtually unchanged with the major trough in the Atlantic plunging south whilst the block to east remains unmoved. Thus the upper flow adjacent to the UK backing SSW and a continuation of the NW/SE split, and in fact becoming more pronounced, and with the WAA this initiates into Europe impinging on parts of the UK. The downside to this is some very wet and, at times, very windy weather over western Scotland.

A little more detail starting with the 500mb and surface analysis for midnight.

The waving front finally cleared the south east last evening leaving much of the UK with a clear night under the ridge with temps dipping quite low by this morning with a touch of air frost in places .But the next frontal system has already arrived on the scene to the north west and rain and strengthening winds are already effecting N. Ireland and western Scotland. The rain will spread over the rest of Scotland, and down to northern England, during the day with gales along western coasts. Elsewhere mainly sunny if not overly warm.

Overnight the rain will edge a tad further south as the cold front from the above system does the same

But through Monday the front continues to straddle the north without moving far and heavier pulses of rain run along it resulting in a wet day for N. Ireland and Scotland accompanied by strong winds. Further south sunny intervals and warming up a tad.

The waving front continues to reside over Scotland overnight Monday through Tuesday so more periods of rain, heavy at times there with strong winds whilst the rest of the country is dry with temps continuing to improve.

By Wednesday and Thursday the deep trough mentioned at the beginning is dominating the Atlantic and with the very strong jet running around the base of it resulting in some very rapid cyclogenesis (dual divergence zones?)

All of which leaves the UK in a dry and very warm southerly flow.with temps way above average

 

Edited October 7, 2018 by knocker

[knocker]

The 0500 surface chart. Moderate rain north west Scotland and quite chilly Wales, central and northern England

[knocker]

The ecm also with a very disturbed Atlantic and pushes the front through on Friday

[knocker]

MODIS image at 1130 UTC. A fine day with a lot of Ci and some small Cu here

[knocker]

The important question over the next couple of days may well be,how far east will the effect of the possible intense lows next week be felt?

 

Edited October 7, 2018 by knocker

[Andy Bown]

4 minutes ago, knocker said:

The important question over the next couple of days may well be,how far east will the effect of the possible intense lows next week be felt?

 

Their proximity will mean the difference between 'beach/barbecue' chances next Saturday or a muggy washout.

[knocker]

Regarding the almost total cover of thick Cu here. The moisture above the inversion Could well be down to the proximity of the warm front. Much the same applies at Nottingham

[knocker]

The waving front will slip a little south overnight into central Scotland. The accompanying belt of rain will follow and ease to ease to some extent for a while, Thus cloud will clear in the far north where it will get a bit chilly, as will also the far south of England, but in between will remain cloudy so temps not dipping so low.

 

Edited October 7, 2018 by knocker

[knocker]

This would be very bad news

 

Edited October 7, 2018 by knocker

[knocker]

A lot of rain in two days

[knocker]

The current pattern continues to favour a NW/SE split highlighted by some significant rainfall over the former and some unseasonably warm temps the latter. For a change a look at the lower strat, 100mb analysis for T120 which in fact mirrors the analysis lower down in the trop.

Some more detail starting with the 500mb and surface analysis for midnight

The rain associated with the waving front across Scotland has slackened a tad and is currently effecting Central/south Scotland and N. Ireland. This will move  north during the day and pep up again as further pulses track in from the west with the heavier rain mainly effecting N. Ireland and western Scotland accompanied by quite strong winds. Further south mainly cloudy in the west but tending sunnier the further east you go.

A very similar story during the evening and overnight with the heavier rain concentrated over western Scotland again

And this continues through Tuesday so by the end of the day some considerable rainfall totals in western Scotland.Meanwhile over England and Wales a much sunnier day with temps on the rise.

Wednesday the pattern change is underway with a deep trough dominating the Atlantic and some serious WAA into Europe

And with the front finally moving north and clearing Scotland a much drier day all round and temps way above average as the UK catches the westerly flank of the WAA in the southerly drift

By Thursday the developing low to the west has tracked south of Iceland and the associated cold front traverse the UK bringing rain and strengthening winds as it goes.

Meanwhile the very deep low that has rapidly formed in the southern quadrant of the aforementioned trough is swinging rapidly north east very close  to Ireland. The precise track of this low is self-evidently very important as severe gales over Ireland and western coastal regions are distinctly possible. At the moment there is no clear consensus on this so for the time being I will stick to last night's fax chart which would not be good news for Ireland

And the NH profile for T120

 

 

Edited October 8, 2018 by knocker

[Jordan S]

9 hours ago, knocker said:

A lot of rain in two days

Yes perhaps upto 100 -150mm of rain on higher ground of western Scotland by the time the rain has cleared through.

[knocker]

The ecm has the low a little deeper and a tad further west with the follow up secondary low and front portending some heavy rain.

[knocker]

The updated morning fax for 00 Thursday. Looking at this got me reminiscing as Ocean Stations Juliet and India,. 52.30n 20.00w and 59.00n 19.00w would have been in the perfect positions,