Short range model discussion - into 2018

[knocker]

Perhaps not quite as intense as once feared?

[Sky Full]

18 minutes ago, knocker said:

Perhaps not quite as intense as once feared?

That little kink in the western approaches has just passed over south west Wales bringing an hour of very heavy rain and violent wind gusts - nasty conditions outside right now.  Looks like it will clear here in a couple of hours moving north east across the rest of the country, losing strength but still bringing strong winds to many parts this morning.

 

Edited November 29, 2018 by Sky Full
.

[knocker]

There is a lot of moderate rain around on that 0600 chart

[Dbarb]

The pressure already down to 984mb not sure if thats below or above forecast.

[knocker]

0800

[knocker]

A clearance here with a mixed bag of cloud including some Cu

[johnholmes]

Good to have your charts and comments back k

[knocker]

Pressure now 979mb with the moderate rain over Scotland. Heavy showers down here

[knocker]

The high res. Modis at midday clearly showing the cold front

[knocker]

The sun sinking in the west at 1500 highlights the main low, today's cold front and in particular the heavy showers behind the latter.

These showers will continue to effect western areas during this evening and overnight, and in particular Scotland, where the low and occlusion are in close attendance, This also ensures a strong westerly wind reaching gale force. A dry and relatively mild night elsewhere

 

[knocker]

Outlook - staying unsettled with periods of rain, windy at times, and temps around average generally but with perhaps some marked regional variations.

The NH 500mb profile and surface analysis at midnight

Currently the main low just to the NW of Scotland is still dominating proceedings and heavy squally showers will persist in western areas in the very brisk westerly wind. In particular over Scotland where the wind may touch gales force early on. Eastern and central areas of England less windy and dry. Temps around average

The showers will continue over Scotland though this evening but by 0200 rain from the next frontal system approaching from the west is already effecting the south west, Wales and N. Ireland. This will spread east during the rest of the night effecting most areas by 0600

The fronts and rain continue to track east through Saturday clearing into the North Sea by the afternoon leaving sunny intervals and showers in their wake and quite a marked N/S temp variation.

Overnight and though Sunday it remains unsettled with periods of rain/showers as frontal systems slide east on a little conveyor belt, courtesy of a positively tilted trough orientated from north of Scotland down through the central Atlantic. Again a marked temp contrast with the colder air creeping south

Monday sees the next system arrive and given the temp contrast there is the possibility of snow over the higher ground in the north along the frontal boundary.

This theme continues on Tuesday with patchy rain in the warmer air to the south with again much colder air to the north and with the next low waiting in the wings to the south west.

And the NH profile at T120

 

[knocker]

Not difficult to see where the showers are at 1245

 

[knocker]

Apart from the west coast of Scotland, where the showers and quite strong winds will continue for a while this evening, the showers elsewhere will slowly fizzle out. But come 0100 rain from the next frontal system, which is the forerunner of a conveyor belt stretching south west of Cornwall, will effect the south west, and by 0600 moderate rain will have spread to much of England, Wales and N. Ireland, accompanied by freshening winds.

[phil nw.]

A very unsettled look to the next 3 days at least as the active Jet stream staddles the UK.

Chart for T24hrs alongside the fax

We could call those Atlantic lows a family of depressions with a number developing as waves along the thermal boundary and heading across the UK to give rain quite widely over the next 3 days and probably beyond..

Some quite stark temperature differences at times between north and south because of the wavering jet-next Monday looks quite typical

 

This setup would likely see some snow for higher ground where the polar air moves in from the north west.

 

[knocker]

Outlook - Remaining unsettled but the detail far from straightforward with some marked regional variations

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

The rain as expected arrived in he south west in the early hours and is currently moving rapidly north east across the country to effect everywhere apart from central and northern Scotland. But it will start to clear from the west shortly and by mid afternoon will clear the east coast, but note by 1800 the next batch of rain is already impacting the Scilly Isles. Very mild in the south, much cooler in the north.

The aforementioned rain will quickly move north east through this evening and overnight, effecting all areas,

But much like today, the rain  and snow on the northern mountains, will quickly clear all areas, apart from northern Scotland, giving way to blustery showers that will be concentrated in the south west/west. Another marked N/S temp contrast.

By Monday we are now in the position, touched upon previously, of the positively tilted upper trough orientated north of Scotland to a position way to the south west of the UK with a surface front trailing from the latter to the base of the trough. Thus patchy rain in the south where pulses run along the front but the position complicated further as another front slips south over the north introducing much colder air in that area.

Tuesday starts relatively quietly but an active depression has formed on the front away to the south west as is rapidly tracking north east and rain from the warm front will swing across England and Wales during the afternoon  The front may get as far north as the borders with maybe snow on the high ground along the boundary.

By Wednesday the low is in the North sea but with the occlusion still trailing across southern England it will take a wee while for the rain to clear here. Another day of stark temp contrasts.

And so on to the NH profile at T120 which speaks for itself

[knocker]

At 0500 the shallow low is over south west Ireland with moderate rain across the south west

[knocker]

Quite a N/S temp contrast today

[knocker]

At the moment there is a large complex low pressure area sitting under the upper trough, comprising various separate lows and trailing fronts, lying over and to the west of the UK. In the immediate future this means the grey dank weather in the wake of today's rain, Scotland being the exception here, will quickly give way to further pulses of rain traveling up the strong WSW flow.

The first batch of moderate rain will track east over Wales and central southern England this evening whilst another line runs north east over northern England, N. Ireland and south west Scotland from the early hours. The north east of Scotland will avoid this which accounts for a widespread frost here compared to very mild temps in the south.

[knocker]

Outlook - Continuing unsettled with a marked regional variation regarding some parameters.

The NH 500mb profile and surface analysis for midnight and as has been noted previously there is a complex array of fronts and low centers sitting under the upper trough.

At the moment it is cloudy over much of England and Wales with bits and bobs of rain/drizzle (note the N/S temp difference)

But this morning and through the afternoon more concentrated rain will track NE across N. Ireland, N. England and southern/central Scotland with snow on the mountains. Further south it will be quite breezy with showers, mainly in the west. A marked N/S temp variation.

The initial rain in the north will soon clear this evening but a more concentrated band of showers/rain on the cold front will effect N. Ireland and western Scotland quite quickly.before moving SE Further south cloudier and quite breezy still with showers in the west and thus much milder that the north.

Through Monday the rain in the north will clear leaving a fair amount of sunshine but further south a band of more concentrated showers will track east across Wales and Engand south of the Humber. A continuation of the very marked temp contrast

Over Monday night and through Tuesday much of the frontal activity will clear which, after a widespread frost, should give a fine day for most. But a depression has formed at the base of the deconstructing trough to the south west which is swinging north east and this will bring rain through the evening with snow on the high ground along the northern edge of the front.

The low clears into the North sea by Wednesday with some very transient ridging in it's wake but the trailing occlusion ensures that it remains cloudy and much milder in the south

But by Thursday another complex upper trough has tracked into the Atlantic and the surface fronts associated with this are driven across the north west of the UK on the strong WSW flow bringing rain and strong winds but also much milder air with temps way above average in the south.

And the NH profile at T120

 

Edited December 2, 2018 by knocker

[knocker]

It's been a cloudy, breezy and warm day ever much of England and Wales with outbreaks of rain/drizzle with a marked N/S temp contrast as can be seen with a glance at the 1500 chart.

The overall scenario is much the same as mentioned this morning with with an array of fronts under the upper trough. So pulses of showery rain will persist this evening over Wales and the south, perhaps fading in the early hours  before more concentrated rain arrives by 0600,  But further north a line f frontal rain, currently over N. Ireland, SW Scotland and NW England  will swing north east during this evening and overnight clearing NE Scotland by 0600. Another mild night in the south but frost in Scotland in the clearance.

 

 

 

Edited December 2, 2018 by knocker

[knocker]

Outlook - Remaining changeable and becoming wet and windy by the end of the week

The 500mb NH and surface analysis for midnight.

As can readily be seen we are still under the upper trough with it's myriad of low centers and trailing fronts and thus some quite marked regional variations with the weather. Much of the rain over Scotland cleared away during the night leaving clearer skies resulting in a drop in temp, contrasting greatly with the cloudier and milder weather in the south

But in the south, anywhere south of North Wales, rain will quickly spread east this morning and not clearing East Anglia until mid afternoon. elsewhere drier with maybe some showers in northern Scotland but here the trade off it will again be much cooler temps.

As the rain and associated front will have cleared a much clearer night ensues generally leading to a widespread frost by morning.The exception being northern Scotland where there will showers associated with the shallow low and occlusion.

By Tuesday we are at last no longer under the auspices of the upper trough so a much brighter and cooler day for all, still showers lingering in the north, but rain from the frontal system associated with the low to the south west will bring rain to Cornwall and south Wales by 1500

As the warm front slides ENE overnight and through Wednesday then so will the rain and it is quite possible along the cold/warm air boundary for a good dose of snow to fall on the higher ground. Say the Pennines for example.

This system soon clears into the North Sea but by Thursday we are quite quickly back into familiar territory with another upper trough creeping east across the Atlantic and fronts associated with this will bring patchy rain, mostly in western areas through Thursday along with some very mild with temps way above average.

What happens from this point is crucial and yet to be finalized as the gfs differs from the fax update, A low develops in the south quadrant of the aforementioned trough and deepens and moves north east but the fax has it 975mb west of Scotland by 1200 Friday and the gfs 964mb further north. For the moment I will stick to the former but either way it portends some wet and very windy weather, particularly in the north, with severe gales.

And on to the NH profile at T120

 

Edited December 3, 2018 by knocker

[knocker]

The high res. MODIS at 1130 UTC. The trailing occlusion across the Midlands?

[knocker]

And two hours later and the 1200 analysis

[knocker]

The 1400 chart illustrates well the cloudy drizzle/rain,and mild south the north cooler north in the northerly breeze

 

[knocker]

Not much to say about this evening and tonight except a few showers, snow on the high ground, in Scotland. courtesy of the wee occlusion and after a clear night with much less wind a widespread frost in the morning.

A quick shufty to later as the warm front slides north east and possible snow on the high ground

Edited December 3, 2018 by knocker