Short range model discussion - into 2018

[Mike Poole]

Normally I'd post this in the MOD but they're otherwise engaged at the moment  so I'll put the shorter range stuff here, but it looks like it's going to be another nice weekend with some late warmth for the southeast.  GFS 12z at T102:

Max temps a smidgen higher than this with other models in agreement.  Nice.

Edited October 16, 2018 by Mike Poole

[knocker]

The pattern is evolving pretty much as expected with the amplification upstream of the Aleutian low/Alaska ridge and vortex/ trough down the eastern side of N. America  complex linking to the subsidiary vortex near northern Scandinavia, All neatly complimented by the burgeoning subtropical high in mid Atlantic. All of which portends a strong north westerly upper flow adjacent to the UK and generally a quieter and cooler spell of weather for same but there is still a lot of energy exiting upstream and the north could well experience more windy and changeable weather as systems swing around the high pressure.

So to a tad more detail starting with the 500mb and surface analysis at midnight

The front straddling the country will continue to struggle very slowly south east bhut weakening into a mainly cloudy feature with perhaps the odd patchy drizzle. Thus still pretty cloudy over much of England and Wales but not too bad in areas where this breaks with cooler and clearer air behind the front (note the different airmasses in the midnight Castor Bay and Nottingham soundings)

with th high pressure ridging north east. Still a fresh breeze with some showers in the far north west.

Overnight the front continues it's slow journey with the drier cooler air covering much of the country with a fair bit of frost around.

So tomorrow, after the chilly start, will be dry and sunny, except perhaps early on in the south east

Overnight Thursday through Friday the ridge generally stays in control but fronts associated with a low tracking north of Iceland do encroach and bring rain and freshening winds to the north west but remaining fine and relatively warm elsewhere

By Saturday it's worth remembering the opening comment as another very deep low swings swings north east on the very strong jet with once again the associated fronts bringing strong winds and rain the north west, albeit temps a tad above average.

The front(s) continue to move south east on Sunday accompanied by the rain and freshening wind so a rather N/S split temp wise with it remaining dry and warm in the latter before the rain arrives.

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

 

Edited October 17, 2018 by knocker

[knocker]

The lower strat. analysis has a familiar ring to it

[knocker]

The 0600 WV and surface chart. Patchy rain/drizzle in the south with some mist

 

[knocker]

The odd shower or two

[knocker]

Little change in outlook this morning. Essentially high pressure dominating but being centred to the W/SW systems will continue to swing around it on the strong upper flow, bringing strong winds and rain at intervals in the north and thus, with the south remaining dry with light winds and relatively sunny, maintaining the N/S divide.

The 500mb and surface analysis for midnight

As can be readily seen the high pressure ridging north east is the dominating feature which has resulted in a pretty clear and cold night in most places with some patchy mist and fog, the exception being the south where the front is still lingering. The 0300 surface chart illustrates this well

So after a frosty and misty start in many places today will sunny with light winds apart from the far south and south west where cloud may well hang around.

This leads on to a another clear night in most places. not as cold as last night, with again some mist and fog around but in the early hours cloud, rain and a strengthening south westerly wind will arrive in the north west, courtesy of a front associated with a low in the Iceland area.

The front will track slowly south east through Friday, tending as usual to weaken en route, but still bringing patchy rain to areas as far south as northern England and Wales  Elsewhere dry and relatively sunny.

Overnight and through Saturday the front continues south but again weakening considerable and in fact Saturday has the makings of being quite a warm day in many areas. In particular the north east and eastern regions in the warm south westerly and further south where the cloud breaks.The exception being N. Ireland, western Scotland and the north west of England where rain will encroach courtesy of a frontal system associated with another deep low that has tracked north east into the Iceland area.

By Sunday the low has deepened and tracked way north of Iceland but the strong flow around the high centred to the south west brings strong winds and rain to the north as the cold front tracks south east down the country. to the south of this sunny intervals and quite warm

By Monday a deep trough has tracked east to be over north east North America which has the effect of amplifying the high pressure to the west of the UK which in turn veers the wind over the latter and this will be quite strong, perhaps near gale force in the north with some patchy rain from another frontal system, Drier and calmer in the south but with variable cloud not a particular warm day.

Edited October 18, 2018 by knocker

[knocker]

The 0600 chart. Quite chilly with fog up north; warmer with mist in the far south

[knocker]

The cloud is beginning to break here

[knocker]

Risk of flash floods in eastern Spain over the next 36hours with some very heavy rain.

[knocker]

The ecm continues to have the high cell too far west or the wrong configuration, as we move into next week. as frontal systems track south east on Sunday with rain and accompanied by quite strong winds.The wind will continue to effect Scotland on Monday with patchy rain in the west  and more so Tuesday as the wind veers and thus effecting the eastern half of England as well albeit the heavy rain confined to Scotland. The best weather over Wales and the south west/

Quite a warm day on Sunday, particularly in north east regions; generally cool on Monday and quite warm in NE Scotland on Tuesday

And the heavy rain in eastern Spain

Edited October 18, 2018 by knocker

[knocker]

Nothing particularly to add to previous brief summations of the outlook. With the center of the high pressure remaining  to the SW/W, and at sufficient distance for the period, the quite marked N/S divide will continue as systems can run around to the north of the high cell on the strong upper flow and infiltrate the former.
The 500mb and surface analysis for midnight and WV image for 0300

As can be seen the cloud associated with the approaching trough/occlusion has already encroached the north thus under this temps have not fallen as far as further south where some mist and fog patches will be around first thing. And following on from this they will clear fairly quickly giving a  clear and sunny day for much of England and Wales. But rain associated with the front is already into N. Ireland and western Scotland and this will track slowly south east with the front during the day but tending to fizzle out en route.

Overnight the movement of decaying front, which is now just a cloudy feature, more or less ceases but the western section does push back north as the connected next frontal system approaches from the west and thus rain returns to north west Scotland by the early hours.

Through Saturday the aforementioned frontal system duly arrives bringing rain and strong winds the N. Ireland. western Scotland and the north west of England. But this south west flow does advect in some quite warm air so elsewhere drier and quite a warm day, including north east Scotland

Overnight and through Sunday the rain and strong winds will persist in the north with the rain pushing south east along with the cold front and thus illustrating the N/S divide quite well with much cooler air behind the front

Monday and Tuesday are a pretty good illustration of the opening comment with the strong high well to the WSW and a strong flow around it which is slowly veering. Thus patchy  rain over N. Ireland and Scotland for a time with some regional variation of temps but overall around average

And this is the position at t120 with the trough in the western Atlantic poised

Edited October 19, 2018 by knocker

[knocker]

The 0900 geostationary image

[knocker]

We have kept a layer of Sc down here, around 3,000ft, for most of the day although did partially break for a while

[knocker]

Again this morning no significant developments during this period. With the center of the high cell initially a fair way to the south west the N/S divide remains relevant with systems able to sweep around to the north and thus windier with spells of rain in that region with the south drier and calmer. This tends not to be quite as relevant towards the end of the period as the high adjusts it’s position and becomes more influential.

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

A fairly cloudy picture up north with the weak front straddled across the country and some cloud further south but large clear areas which will be conducive to fog formation in a few areas which may be slow to clear. But once they have much of England and Wales will be sunny and quite warm, perhaps a bit cloudier in western regions. But as the depression in the Iceland area deepens and tracks north east, the associated front will bring rain to the west of Scotland about now and track it east during the morning, soon clearing the east coast. But the next pulse arrives by early afternoon which will bring patchy rain to western Scotland again, but also N. Ireland and NW England This will not reach Aberdeenshire where it will also be quite warm (Foehn effect?)

Overnight the cold front associated with the aforementioned system will start it's journey south east down the country bringing heavier rain into Scotland and N. Ireland as the warm front decays further south

The cold front continues south east down the country on Sunday and the rain will tend to become sporadic en route but it does introduce much cooler air in it's wake, illustrated quite well with the 925mb temps. Thus a cloudy day in central regions but still warm in the far south with showers over Scotland

Overnight and trough Monday the front continues south and clears the south coast heralding a brighter and cooler day in England and Wales  But fairly windy further north with showers, mainly confined to western Scotland, as fronts are forced adjacent on the strong WNW upper flow around the high cell

Over Tuesday and Wednesday the high cell to the west adjusts it's position and amplifies somewhat as a trough drops south into Europe to the east of the UK, which veers the wind NW over the UK, quite fresh over northern and eastern regions, with showers continuing over western Scotland. Some regional variations vis the temps but generally around average or a tad above on Wednesday, The best of the weather probably over Wales and the south west.

And the NH profile at T120 as the next 'wave' begins

Edited October 20, 2018 by knocker

[knocker]

After the early Ci went a cracking morning in these parts.

[knocker]

Some nice wave clouds and Foehn at 1300UTC

 

[knocker]

Still cloud with some patchy light/drizzle/rain in the north this evening and overnight, but further south under clearer skies mist and fog patches will form again by morning.But by this evening the cold front associated with the low tracking west of Norway, will bring more concentrated rain to western Scotland, and later N. Ireland, as the cold front associated with the low tracking west of Norway, tracks slowly south east

[knocker]

Essentially high pressure remains influential over this period but this requires quantifying a little. The position and orientation of the high is such that that some inclement weather does encroach the north, particularly Scotland, and towards the end of the period the south west quadrant of the mainland will tend to become the favoured area for the better weather. But it should be noted that by the end of the period this rather static period is on the cusp of coming to a rather abrupt end

And out of interest the current state of play in the Atlantic ocean

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

Pretty much cloud free in the south overnight so some mist and fog patches forming around now butt further north some cloud around the decaying front  and further north over north west Scotland rain associated with the cold front. This rain belt, along with the front, will track south east during the day, but as has been the case so often, will tend to fizzle out en route to essentially a cloudy feature. South of this another fine and quite warm day but in it's wake cooler air with showers.

The front continues on it's travels south during the evening, eventually clearing the south coast, with breezy and showery conditions continuing over northern Scotland and a much cooler night generally with some frost and mist and fog patches around by morning

But during Monday the ridge has come under pressure from the energy running around it's northern flank and rain and strong winds associated with a frontal system are impacting the north. Calmer and drier further south under the rather elongated ridge but the temps not particularly impressive.

Overnight and through Tuesday quite breezy in many areas as the wind veers with still some patchy rain over Scotland, Elsewhere dry and fairly warm.

Wednesday is essentially the last day before the start of the transition alluded to at the beginning with an upper trough dropping south over eastern North America and the high cell realigning adjacent to the UK, resulting in a generally quite warm and dry day with the odd shower still over western Scotland.

By Thursday the transition is well underway with the amplification in the western Atlantic and an upper trough approaching the UK from the north west. But still a relatively benign day over the UK with temps around average but some showery rain over Scotland from a shallow low and associated fronts.

And at T120 the upper trough is dropping south east over the UK and about to introduce much colder to the UK

Edited October 21, 2018 by knocker

[knocker]

Plenty of mist and fog around in central and southern England on the 0600 chart, and quite interesting temps in NE coastal regions

Edited October 21, 2018 by knocker

[knocker]

The High res. MODIS at midday (courtesy the DSRS)

[Rocheydub]

6 hours ago, knocker said:

The High res. MODIS at midday (courtesy the DSRS)

Love those Sat images knocker. I use them to illustrate to people the huge gradients in weather on such a small island as ours.  Thanks again

[lottiekent]

10 hours ago, knocker said:

The High res. MODIS at midday (courtesy the DSRS)

A gorgeous day here again, warm and sunny by day and nice and cool in the evening.

[knocker]

The outlook initially remains unchanged for this period with high pressure generally in charge but, as previously mentioned, the position and orientation is such that that the north, particularly Scotland, is still susceptible to systems running around the northern flank of the high cell,  But towards the end of the period this changes very quickly, courtesy of upstream developments, and much colder air plunges south over the UK down the eastern quadrant of the burgeoning subtropical high in the western/central Atlantic.

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

After a pretty clear night over much of England and Wales. a little more cloud further north. it will be a dry and sunny day in many areas, albeit not overly warm, but rain will effect the north of Scotland as a front skirts the coastline and the wind will pick up during the day and will touch gale force over Scotland.

During the evening and overnight further rain over north west Scotland but the main feature is the strong wind, still touching gale force which has veered north westerly and moved south to also effect the north of England.

This is pretty much the story through Tuesday with rain across north west Scotland and continuing windy in the north with gales in exposed areas. Further south continuing dry and sunny and perhaps warming up a tad.

Wednesday sees the start of the transition with developments in the western Atlantic but the immediate effect closer to home is to realign our high cell which becomes more influential, thus winds abating in the north and resulting in a generally fine day with sunny intervals and relatively warm. Still some patchy rain across the west coast of Scotland

By Thursday the transition is well underway with the trough over the eastern seaboard initiating rapid amplification of the subtropical high in the western Atlantic which in turn facilitates the trough and cold air to plunge south to the north of Scotland. So that by midday the cold front is just about across the north coast of Scotland. Thus rain will spread down the west coast and to N. Ireland during the afternoon whilst the rest of the country again remains dry with sunny intervals.

Overnight and through Friday the cold front will track south reaching the south by the afternoon leaving in it's wake much colder air in a very strong northerly wind which could touch gale force in the north and north east. In this very unstable air frequent heavy showers will develop which will be wintry in the north with snow on the high ground and possible even at low levels. It goes without saying it will feel very cold.

And the NH profile at T120 sums it all up

[knocker]

The 0900 sat image. Some broken Sc here and a fresh NE breeze

Edited October 22, 2018 by knocker

[knocker]

Skies will be clear over much of England Wales tonight leading to some mist/fog patches by morning. But the main feature overnight will be the strong winds over Scotland stretching south to the north of England which could gust to 60 -70 mph in exposed areas. Some rain may well encroach the far north as well from the adjacent front.

.