Short range model discussion - into 2018

[knocker]

The NH 500mb anomaly, in particular with regards to the our neck of the woods, continues to essentially be a battle between the energy exiting North America crossing the Atlantic south of the Canadian/Greenland/Franz Joseph vortex complex and the sub tropical high pushing north,  Complicated to some extent by long lasting cut off lows entering the mix. Last night's EPS illustrates this.

But back to the detail starting with the 500mb and surface analysis at midnight.

During today the Iceland low will track east and the fronts south east down the UK. This will essentially split the UK with Scotland and the north of England behind the cold front in the clearer and very windy weather, particularly over n. Scotland with perhaps the odd shower, whilst further south will be be in the warm sector and thus cloudy with some patchy drizzle. But in areas where the cloud breaks it will be quite warm

As can be seen the cold front trails back into the Atlantic and another wave is forming on it which tracks NNE through the night and Wednesday which effectively drags the front front back north east across the UK. It is very weak in the south where the ridge holds sway so it will be quite warm here again once any patchy rain clears with the wet and windy weather mainly confined to N. Ireland and Scotland. The main bulk of the rain should clear by mid afternoon.

Overnight and through Thursday the wave continues to deepen and track east of Iceland and although the warm front is now well clear into the North Sea the associated cold from is orientated close to the NW of the UK so again wet and windy and quite cool th in the north whilst it will be cloudy in the south in lighter winds and quite warm where the cloud breaks.

On Friday the front is meandering south, along with some patchy rain, and introducing much cooler air in it's wake but still quite warm in the south preceding it. But complications are arising just to west as an upper trough tracks east and another wave forms on the front.

By Saturday the wave has developed and is centred over Brest  and this could well bring some wet and windy weather to Wales and southern parts of England through the day. And as the ridge once again extends north east behind this activity t will be quite a cool day for most of the UK

And the NH profile at T120 which is pretty much where we came in

[knocker]

The 0500 surface chart

[knocker]

The ecm has the low over France at the weekend

Whilst at the same time a lobe of the vortex is ejected east over southern Greenland with the associated front swinging south west to TS Leslie

[knocker]

 

Edited October 2, 2018 by knocker

[knocker]

MODIS image at 1300 UTC

[knocker]

The cloud and milder air south of the front over Wales and much of southern England will persist this evening and overnight whilst Scotland and the north east of England will be much clearer in the markedly cooler air. But this regional differentiation will diminish as the wave to the west tracks NNE and thus returns the front  back north east over western regions bringing cloud and rain into N. Ireland and the western Isles by 0200

[knocker]

Snapshot at T120 showing the front trailing down to Leslie dividing the airmasses.

[johnholmes]

I think a word of thanks is once again due in here k.

To anyone new to meteorology I would recommend that you read this part of Net Weather. The mix of charts, Fax, rainfall, temperature etc with hardly any personal bias and interpretation is a model (excuse the pun). Maybe the team could make some suggestion in the main thread for new folk to make their way on to this thread.

I do so hope that once winter starts that this thread is kept free of the unpleasantness that does occur at times when some folk get frustrated with not getting the weather they hoped for and maybe they felt the models were showing.

 

[feb1991blizzard]

6 minutes ago, johnholmes said:

I think a word of thanks is once again due in here k.

To anyone new to meteorology I would recommend that you read this part of Net Weather. The mix of charts, Fax, rainfall, temperature etc with hardly any personal bias and interpretation is a model (excuse the pun). Maybe the team could make some suggestion in the main thread for new folk to make their way on to this thread.

I do so hope that once winter starts that this thread is kept free of the unpleasantness that does occur at times when some folk get frustrated with not getting the weather they hoped for and maybe they felt the models were showing.

 

I have to say though that a lot of the unpleasantness stems from people not being allowed to have fun and enjoyment out of the chase for snow, yes I agree also (I have been a victim myself) that sometimes when you point out that a cold spell isn't going tp happen when your clearly right, you do get rounded on.

[knocker]

This evening's ecm has the low quite an intense little feature on Saturday

[knocker]

Nothing to do with the short range but the ecm has gone off on one this evening with some explosive cyclogenesis of 50mb in 24 hours to a low of 939mb west of Ireland.

[knocker]

The overriding theme of a N/S split across the UK within the current pattern continues, albeit with a brief interruption this weekend.. Worth noting at the end of the short range is the displacement of the Canadian vortex into the north west Atlantic as illustrated by last evening’s EPS.

Back to the here and now and the 500mb and surface analysis at midnight

So following on from a post last evening the developing low to the west will continue to deepen and track NNE pushing the associated warm front north east across the north of the UK. The rain from this, currently down western Scotland, will do the same. So wet and quite windy here after a cool and clear start in the east, but the further south is in the warm sectors so fairly cloudy with perhaps some patchy drizzle early on in the west but where the cloud breaks it will be quite warm

The passage of the warm front will result in a fairly cloudy and mild night in most areas although the cloud could well break further south and here Thursday will develop into a warm day with light winds. But the aforementioned low is still deepening over Iceland and the waving cold front is in close proximity to Scotland so again it will be wet and windy here and as the front tracks south east the rain and freshening wind will do the same during the day

The front will continue to edge south overnight and through Friday as the low to the north continues on it's travel, with patchy rain accompanying it, leaving clearer showery conditions in it's wake. Quite a marked temp contrast either side of the front with temps above average in the south.

By Saturday the brief hiatus mentioned at the beginning is underway with an upper trough sinking south and a wave forming on the front which tracks into Biscay bringing some wet and windy weather to Wales and the south of England. And there is some quite cold air behind the front as the ridge builds in from the south west.

The rain will clear the south overnight and after a cold start with a frost in many places Sunday will be a sunny and cool day but by late afternoon the next frontal system will bring freshening winds and some rain to the north west.

And the NH profile at T120 keeping in mind the opening comment.

Edited October 3, 2018 by knocker

[knocker]

The ecm on the low on Saturday

[knocker]

The 0600 surface chart. Typical warm sector muck here. Sky obscured, slight drizzle and fog.

[knocker]

The MODIS sat image at 1200

[knocker]

The vortex/trough exiting N. Canada en route the Denmark straits and the front with tenuous connections to Leslie approaching the UK

[knocker]

Not much happening this evening and overnight with the main low over Iceland the UK resides in the broad warm sector thus a mainly cloudy and mild night with perhaps some breaks in eastern regions. But with a couple of fronts in close proximity some bits and bobs of rain, mainly in the north west but also down western regions further south. And breezier the further north you trek from the Midlands.

[knocker]

Snapshot at T120. Main trough to the north west with frontal boundary Leslie to Scotland

[knocker]

Nothing significant to report regarding the short range outlook but just to mote that the pattern change that has been indicated for a while is starting to emerge. That is a deep Atlantic trough accompanied by height rises’ in central/eastern Europe.

So in the interim a quick look at the oceanic and atmospheric picture over the Atlantic which does appear to be mutually supportive of the above.

Meanwhile back to the detail and the  500mb and surface analysis at midnight

it has been a cloudy and mild night in all areas with some bits and bobs of rain in western areas and this essentially will be the same through the day, and where the cloud breaks, likely central and eastern areas, it will be quite warm. But the cold front just NW of Scotland on the above chart will gradually track south east, preceded by another front sliding in from the west, bringing rain to Scotland and northern England by late morning and through the afternoon. Showery and cooler weather in the wake of the front

The front will continue to slip very slowly south overnight and through Friday, virtually coming to a standstill over central England. Thus cloudy with patchy rain in this area, whilst either side of the front quite a contrast. Very warm in the south and much cooler with showers in the north.

By Saturday the front has eventually cleared the south coast but complications have arisen with an upper trough slipping south west of the UK and a wave forms on the front over Biscay. Thus it is going to be quite wet and breezy over Wales and central/southern England though Saturday and also a very cold day in the north westerly wind as the ridge stretches north east behind the front.

By Sunday the rain has cleared and the ridge is influencing the southern half of the UK but the next frontal system is rapidly approaching from the west bringing rain and strong winds into N. Ireland and Scotland by the afternoon

.

The front(s) will continue to move slowly south east overnight and through Monday thus patchy rain and quite breezy in the north of England with showery conditions behind but temps on the whole are around average but a tad above in the north in the south westerly flow.

And on to the NH profile at T120 which is not a million miles away from where we came in

Nothing to do with this thread but interesting to note that Leslie thumbs a lift later

 

Edited October 4, 2018 by knocker

[knocker]

The 0500 surface chart, Rain in the north and plenty of mist in the south. Very mild

The ecm for Saturday

And by T120 deep Atlantic trough with developing low west of Scotland on the front linked away to the south west to Leslie

[knocker]

What looks like being a quite intense pattern change gets underway quite early in the piece with the ejection of a lobe of the vortex from northern Canada into the north west Atlantic, from whence it develops, eventually in conjunction with fairly rapid height rises to the east of the UK Apparently the deformation of the jet quite so sharply over North America is quite unusual. There is a lot of energy swanning about here

Edited October 4, 2018 by knocker

[knocker]

Apart from a brief hiatus tomorrow the overriding theme of the outlook is a continuation of the NW/SE split vis the UK. In fact it even gains momentum within the emerging pattern change as illustrated by last evening’s EPS anomalies.

On to a tad more detail, starting with the 500mb and surface analysis for midnight. Note the upper trough to the west as the high cell slips away east.

The front on the above chart virtually comes to standstill over northern England and Wales during today thus the patchy rain is confined to this area, To the north of the front over N. Ireland and Scotland cooler and breezier with showers whilst further south it will be cloudy but where the cloud breaks, more likely in the south east, it will be quite warm.

From around this point the rain on the front starts to pep up as the aforementioned upper trough moves east and a wave begins to form on the front to the south west of the Brest Peninsula

Through the night and Saturday the wave develops and tracks east accompanied by a band of rain, quite likely heavy at times, which will impact Wales  and much of England, and not clearing the south east until late evening. Furthermore it will also be quite windy and along the north west flank of the front under the rain, and very chilly.

By midnight the wave is over NE France as the ridge becomes more influential resulting in quite a clear night with some frost around leading on to a dry and sunny day on Sunday over England and Wales but the next frontal system is rapidly approaching from the west and this will bring wet and windy conditions to N. Ireland and Scotland from early morning

Over Monday and Tuesday the tendency for the NW/SE split to gain momentum, as mentioned earlier, becomes more apparent as high pressure holds on in the south and fronts along the airmass boundary straddle the north bringing rain and windier conditions there. But one upshot of this scenario is that temps generally rise above average in the south westerly flow.

And by T120 the NH profile is showing every indication of the aforementioned pattern change emerging.

Edited October 5, 2018 by knocker

[knocker]

The 0500 surface chart illustrates the clearer cooler air in the north and the mild mist/fog conditions in the south. A fait mixture of cloud down here this morning with some straggly St but mainly Ac, Ci.

And a forecast sounding behind the front on Saturday highlighting the advection of the colder air in the lower atmosphere in the strong ENE wind.

[knocker]

The 0600 sat image neatly illustrates the current position

[knocker]

The 0900 sat image and the front trailing down to the south west