Short range model discussion - into 2018

[knocker]

It has to said the ecm is markedly different to the GFS over the weekend and thereafter, It does not develop the small but quite intense low within the general circulation that the GFS does on Saturday that affects the south and in fact it fills the main area of low pressure and shifts it rapidly south east. This paves the way for the next low to move in from the west on Sunday.

Still wet in the south on Friday and showery elsewhere in the south easterly which backs a tad on Saturday as the rain moves away from the south.

Max temps Friday ranging from 5C in Scotland and 8C in southern England and Saturday 5C -11C.

[knocker]

The occasionally heavy rain belt, perhaps some snow on the hills, currently over south Wales and the south west will track east during the morning clearing the south east coast by mid afternoon. Elsewhere and behind the passage of the rain scattered showers and sunny intervals. The showers will die out over night leaving a clear night with a frost in many areas and even some freezing fog. The exception may well be NE Scotland as the low and the occlusion are still in the vicinity producing snow showers.

Early Thursday, with the large area of low pressure to the west, the next frontal system swings in from the south west and through the day tracks north east bringing a broad area of patchy showery rain , perhaps even thundery, on it's journey. Over northern Scotland the waving occlusion still hasn't moved very far so still some snow showers which may even reach lower levels.

By Friday the main center of the low pressure area has slipped to the south west with the UK in the northern quadrant thus a brisk showery north easterly in the north and generally unsettled elsewhere with disturbances running around in the circulation.giving out breaks of rain interrupting the sunny intervals. Temps still in the 5-8C range.

Still much the same early on saturday but changes are afoot. The main area of low pressure is filling and moving south east thus the surface wind backs initiating the ingress of colder air in the north with wintry showers as can easily be seen on the temp spread at 1800.

Meanwhile whilst this has been going on another upper trough has exited North America and is being forced south east by further ridging in the Atlantic so that by 1800 on Sunday the large surface low with associated fronts is situated south west of Ireland and the latter are poised, so to speak, to track north east over the UK where the colder air has slipped much further south.

This detail is of course according to the GFS

 

Edited March 28, 2018 by knocker

[knocker]

Satellite at 0430 UTC

[knocker]

he ecm is still differing from the GFS vis the main low to the south west and associated front over the weekend. It has the front aligned SW of Ireland at T96 and tracks it steadily NE through the next 24 hours to portend a very wet and Windy day on Monday.

The current surface analysis showing a lot of moderate rain in the south

[knocker]

To be more precise Friday > Saturday

To supplement this the ecm has Wales and England pretty wet at 1800 on Friday max temps north to south 5C-8C

Saturday still unsettled but showery rain further north temps 5C-10C

Sunday much drier with lighter winds temps 5C-9C but frontal rain on the doorstep poised.

 

 

[knocker]

The 0900 UTC geostationary (courtesy DSRS)

[knocker]

The 1050 UTC MODIS showing the wodge of rain over the SE and the North Sea occlusion still quite close to NE Scotland) (image courtesy DSRS)

Edited March 28, 2018 by knocker

[knocker]

Surface chart for 1300 UTC with still moderate rain over the south east/East Anglia

Edited March 28, 2018 by knocker

[knocker]

This evening and tonight sees the upper trough slipping south under pressure from some renewed amplification to the west, which sets the tone for the weekend, and thus at 06 tomorrow we have this expected surface analysis with low centers to the west and an occlusion bringing a belt of showery rain into the south west and then north east during the day. The old low and occlusion still affecting north east Scotland.

Edited March 28, 2018 by knocker

[knocker]

The key to the GFS hinting at a possible significant snowfall at the beginning of next week would still appear to be about the movement of the upper trough and the ingress of the colder air from the NE in conjunction with the approaching trough to the south west.

Edited March 28, 2018 by knocker

[knocker]

The UKMO pretty dry over the next five days

https://weathermodels.com/index.php?r=site%2Fmodels&mode=animator&set=UKMET 17 km&area=Europe&param=Total Precipitation&offset=0

[knocker]

The main feature of the current analysis is a large area of low pressure to the north west/west which is in the process of swiveling south.and then south east and will be a major player in the UK weather over the next three days. At the moment within the circulation of this there is a stationary, waving occlusion, still bringing snow showers to north east Scotland and a front over the south west of England currently producing rain showers that will travel north east during the day to bring similar to the rest of southern England, Wales and the Midlands.

Similar story overnight in Scotland and the rain band, snow on the high ground, will edge further north in England  Quite a chilly night in northern regions with frost in many places.

Through Friday the front continues to track north but further south a small low has formed in the circulation of the main low and has tracked north, along with associated front, to bring heavy rain to southern England and south Wales. The front and rain continue to move north overnight into Saturday morning but by then another wave has formed  and is over the south west bringing more showery rain. All of this initiates a much cooler south easterly/easterly flow over northern England and Scotland with frequent wintry showers.

This unsettled scenario continues through Saturday but the main low pressure area is slipping south east and by 00 Sunday the surface wind has backed a tad and allowed ingress of colder air in the north of the UK. Whilst at the same time a new upper trough has formed in th Atlantic and is situated to the south west.as there is still a fair amount of energy exiting the eastern seaboard.

All of this sets Sunday up to be the best day of the weekend with far fewer showers, light winds and temps not too far below average. But by 1800 fronts from the system to south west are fast approaching bringing rain, and who knows, perhaps some snow as they track north east.

Edited March 29, 2018 by knocker

[knocker]

Satellite at 0430 UTC

 

[knocker]

Some updated fax charts to supplement the above.

[knocker]

At 1800 on Monday the ecm has dew points north of a line (the front) Bristol to Lowestoft,as far up as Carlisle, 29-33F and south of it 46-50F Scotland down to the low 20s

Edited March 29, 2018 by knocker

[knocker]

The 0900 UTC geostationary (courtesy DSRS) which shows the main low to the west and the patchy rain over the south west.

 

[knocker]

A quick glance at the NH pattern which shows the Aleutian block that has displaced the Canadian vortex lobe and plunged Arctic air down over North America which at he same time feeds troughs east south of  the Greenland block to phase with our own N. Russian lobe and trough.

[knocker]

Another brilliant high res. MODIS at 1133 UTC (courtesy Dundee Satellite Receiving Station)

 

[cheeky_monkey]

1 hour ago, knocker said:

A quick glance at the NH pattern which shows the Aleutian block that has displaced the Canadian vortex lobe and plunged Arctic air down over North America which at he same time feeds troughs east south of  the Greenland block to phase with our own N. Russian lobe and trough.

yep tis freezing here...snow and temps down below -20c more like end of a December than the end of March going into April...miserable spring weather

[knocker]

The belt of patchy rain and hill snow will continue to track north through the Midlands this evening and overnight while the outbreaks of rain and snow continue over north east Scotland. Tomorrow heavy rain will develop over the south of England.

[knocker]

Today rain from the occlusion is still affecting the north of England and southern Scotland, and wintry outbreaks still in the far north east, whilst further south showery rain is already affecting the counties in the far south. This will spread north during the day with occasional heavy bursts, to affect most areas up to the northern Midlands by evening. The driest weather being northern England and western Ireland and Scotland. Temps below average, particularly in Scotland.

Tonight much of the same but some wintry showers in the north east and eastern Scotland as the low in the Channel drifts slowly east initiating a fresh south easterly wind.

The rest of Saturday remains unsettled with outbreaks of rain and some hill snow as the low nudges it's way east and feeling quite cold in the easterly wind that has backed a tad and particularly in N. Ireland and Scotland where colder air has ingressed from the north.

Sunday will be generally cloudy but dry with light winds as the low continues to track east but not particularly warm as the colder air slides further south, albeit it's not that cold. But come evening a front associated with the rather diffuse low pressure system to the south west is already bringing rain into Cornwall.

The front(s) and rain will track north east overnight Sunday through Monday  with the possibility of the rain turning to snow along the leading edge over the midlands and the north, particularly over the higher ground. By 1800 on Monday there is a marked delineation between the colder air to the north and the warmer air in the south.

The front which by now has occluded will continue to move north slowly through Monday night and Tuesday and of course it's precise position is critical to determining the boundary between the airmasses and as can be seen the temps in the milder air are above average. Haven't said that much of late.

This is of course according to the GFS and with some fine margins involved other interpretations are a distinct possibility.

Edited March 30, 2018 by knocker

[knocker]

Satellite at 0545 UTC

[Eastnorthwest]

The weather's version of the battle of Britain is going to happen on Monday with those on the cold side of the low seeing heavy snow especially away from the coast and those in the marked warmer zone of the low will see heavy rain with flood issues becoming more apparent 

The models are still fairly unreliable beyond 3 days so the areas at risk to snow might still change over the next 48 hours so lots to keep an eye on in the coming 2 to 3 days,a real weather fest for us all ,fascinating times for weather fans

[knocker]

At 1200 on Monday the ecm has the main rain/snow belt across N/ Wales the Midlands and East Anglia. There is again a marked boundary between the dew points norh of a line around Bristol to Great Yarmouth and south of it, 32-38F > 40-50F This would make snow on low ground extremely marginal. By 00 Tuesday the boundary has only adjusted slightly north. I bet you are glad you are retired John.

The 0600 surface chart

Edited March 30, 2018 by knocker

[knocker]

Quite a lot of rain under that wodge of cloud over southern England at the moment (Sat. image courtesy DSRS)

Edited March 30, 2018 by knocker