Short range model discussion - into 2018

[knocker]

The ecm temp anomaly and contours

[knocker]

Good 0900 geostationary showing the systems to the west and, if here is anything to go by, a sheet of Sc over the south west and south Wales, (Image courtesy DSRS)

[knocker]

Another excellent MODIS at 1130 illustrating the current east/west split. (courtesy DSRS)

[johnholmes]

1 hour ago, knocker said:

Another excellent MODIS at 1130 illustrating the current east/west split. (courtesy DSRS)

It for sure is not clear here now, has been mostly cloudy since about noon. Nice mid morning though, and at last the wind felt less like the Arctic!

[knocker]

4 minutes ago, johnholmes said:

It for sure is not clear here now, has been mostly cloudy since about noon. Nice mid morning though, and at last the wind felt less like the Arctic!

There was another overhead at 1315

[knocker]

Rain becoming patchy during night

[knocker]

A key part (or one of them) of the GFS evolution next week appears to be the increased ridging in eastern North America, This cuts off a fragment of the vortex lobe to travel east and suppress the Azores ridge and to phase with the N. Russian/European trough. At the same time it links to the high pressure over eastern Greenland thus cutting off any energy transfer from N. Canada across the Atlantic

Edited March 22, 2018 by knocker

[knocker]

At 00 the surface analysis was quite complex with a series of fronts traversing the UK with a low 992mb over south west Ireland. Further to the WSW of Cornwall there is a wave that is about to rapidly develop. The fronts duly clears most of the country by now whilst the low over Ireland tracks north east and as mentioned the wave to the west is intensifying rapidly as it moves east/south east to skirt Cornwall by 1800 today

So in a nutshell rain will quickly clear the east this morning whilst rain associated with the low will affect N. Ireland and Scotland clearing by the middle of the afternoon. At about this time rain and strong winds.associated with the developing low will impact the south west  During the evening and overnight this rain will spread to south Wales and further east By this time clearer and colder weather is into N. Ireland and Scotland.

The sequence

Through Saturday the intense low to the south west tracks rapidly south east into the Mediterranean under the auspices of the jet whilst the other low continues it's journey away to the west of Norway. Essentially this leaves England and Wales in a slack gradient and mainly cloudy with light rain which is slow to clear and more concentrated in the south with brighter showery weather further north in a light westerly.

Sunday is a fairly quiet day of sunshine and showers as the Azores ridges north east but at this point I think it's worth a look at the bigger picture, particularly upstream where the ridge in eastern North America is starting to intensity and release a fragment of the vortex to track south east as a very influential upper trough.

Monday starts off in similar vein to Sunday but the aforementioned upper trough has continued to track east, dare I mention two energy flows?, and the associated surface low and fronts associated with it are bringing rain and strong winds to western areas by 1200.

By the time we get to 1200 Tuesday the importance of the upstream ridging becomes more evident as we now have a high cell over eastern Greenland, promoted by the Aleutian and the east N. American ridges, with the elongated vortex trough running south of it and phasing with the trough associated with the main vortex lobe over northern Russia. The latter is the conduit for the very cold air from the Pole so the ingress of the Atlantic trough east is critical to the advection of this colder air into Europe and in particular in the direction of the UK. This is of course according to this morning's GFS as we are all aware last night's ecm had a different interpretation of this key area. As can be seen in this version the surface fronts have swept though on Tuesday leaving the UK in a complex area of low pressure and quite windy with temps just a little below average. It does not take a huge adjustment to the upper pattern to change this surface analysis.

 

 

Edited March 23, 2018 by knocker

[knocker]

This morning's updated fax charts 00 Saturday > 00 Monday

And satellite for 0530 (courtesy DSRS)

Edited March 23, 2018 by knocker

[knocker]

The ecm continues to disagree with GFS on the evolution of the upper pattern between T96 and 120 and in particular the orientation and position of the Atlantic trough and Greenland/Iceland high cell. Thus the ecm interpretation allows the European trough/cold conduit further west and of course at the same time alters the surface analysis in the eastern Atlantic.Thus at T120 it has a front straddling the middle of the country dividing the cold air to the north and warmer further south with a fair amount of snow in northern England. Obviously the detail of all of this is a long way from being decided

Edited March 23, 2018 by knocker

[knocker]

*I'm thinking there might well be some interesting satellite images to day and the 0900 geostationarywill do  for starters. (Image courtesy Dundee Satellite Receiving Station)

 

[knocker]

The MODIS at 1210 (Courtesy DSRS) A lot of medium and high cloud from the low here now

[knocker]

The fronts associated with the deep depression to the south west will continue to affect most of England and Wales this evening and overnight as it swings SE into Biscay. Thus a continuation of the cloud and rain already affecting many areas, not clearing the south west until morning. A relatively mild night in these areas but nearer freezing in N. Ireland and Scotland.

 

[knocker]

Not much to add vis the GFS output within this time frame from this morning so just some spot charts at T108 to attempt to illustrate the point that the orientation and position of the Greenland high cell and Atlantic trough, and by association the energy tracking east, is still critical to the surface analysis in the eastern Atlantic and the GFS does not appear to have moved very far from this morning

[knocker]

Today Britain can essentially be divided into two weather wise with most of England and Wales staying cloudy with patchy rain as the front(s) associated with yesterdays low hang around. Northern England N. Ireland and Scotland much clearer weather with sunny intervals but some scattered showers that may even be thundery in places. Temps around average, maybe a little below in Scotland

.

Overnight the cloud will generally clear, except for the south east and still showery in the far north west.and this is reflected in the min temps tomorrow morning.

Once the rain has cleared the south east and not forgetting the showers in the north west Sunday could well turn out to be the best day for a while with the Azores ridge being prominent with plenty of sunshine in most areas, light winds, and and temps around average reaching 10-11C in England and Wales and 7-9C further north.

 

Much the same initially on Monday but to the west things are gearing up for a new pattern regime with the lobe fragment/upper trough tracking ESE from northern Canada, tending to deconstruct as it goes,  and also  a lot of energy exiting the south east seaboard of the US as well. Thus by 1800 there is a surface low 987mb south of Iceland with the associated front starting to affect western Ireland.

Overnight and through Tuesday the front tracks east across Britain initiating a spell of windy and wet weather, perhaps some snow on the high ground in Scotland. And as can be seen both the upper trough to the west and the cold trough to the east are taking closer order as both become aligned under the high cell to the north in the Greenland/Iceland area. By 1200 Tuesday the UK is still in the 'milder' air.

During Tuesday evening a wave forms on the front in the vicinity of Ireland and by 00 Wednesday it is over Carlisle 983mb om it's way east and this could well produce some significant snowfall on the high ground in the Scotland and the north of England and even down to lower levels as the colder air moves in. As can be seen the colder Arctic air swinging south around the aforementioned high cell is still to the east.

And the NH pattern at this stage is not a major surprise

 

Edited March 24, 2018 by knocker

[knocker]

The ecm has the rather elongated low and front across the north of England at 1200 Tuesday  By 1200 Wednesday the low is over northern Germany and the next front has approached from the west. This scenario would also give some snow on the high ground in Scotland and perhaps Wales and the north of England. Max temps on Weds in the 6-7C range. The detail over these two days is certainly not yet sorted,

Edited March 24, 2018 by knocker

[knocker]

The 0600 surface analysis. Much rain around in England and Wales

[knocker]

The 0900 geostationary (courtesy DSRS) showing the low in Biscay and associated fronts still lingering over England and Wales and showers NW Scotland

[knocker]

This morning's fax charts 12 Mon. > 12 Tues. and 06 GFS for 12 Tuesday and 00 Wed. as thing's start getting complicated along the active front

And the high res. MODIS for 1115 (courtesy Dundee satellite Receiving Station)

Edited March 24, 2018 by knocker

[knocker]

The little waves on the active front over Tuesday/Weds are tricky to pin down

 

[knocker]

Certainly looking at a wet and windy day Tuesday

[knocker]

Today will be a pretty good day for most areas with light winds, plenty of sunshine and temps reaching 9-10C in many areas but cooler as you travel north west and just 3-4C in northern Scotland.. Some light rain in the south east first up will quickly clear and some light rain showers will become slightly more frequent in north western areas by mid afternoon but ceasing later.

The clear periods overnight will lead to temps taking a dip and a light frost can be expected in rural areas by morning. Also by then rain from the next frontal system will be affecting the far west of Ireland.

By 1800 on Monday the evolution that is to play a major role for the rest of the week is underway. Ridging in eastern North America has isolated a segment of the vortex and sent the resulting upper trough on it's way east (note the breakaway little upper low) which in turn puts pressure on the Azores ridge resulting in a high cell in the Greenland/Iceland area. Thus a surface low 988mb south of Iceland with the aforementioned associated front and rain and increasingly windy now affecting western areas. Elsewhere another pretty good day with some showers, mainly in Scotland, and temps in the 10-12C region.

Wet and windy overnight Monday into Tuesday as the front tracks east, perhaps snow on the higher ground in Scotland as the 'warmer' air is shunted out of the way and after the front has cleared to the east very unsettled with heavy showers and remaining very windy from the north west.

From this point further complications arise as more amplification of the high pressure in the western Atlantic forces reorientation and configuration of the upper trough and it sinks south east over the UK This results in a complex surface analysis with low pressure dominating central and the eastern Atlantic with  an active front and a wave straddled across Scotland. This would portend a continuation of unsettled and windy weather through Wednesday with snow on the higher ground in the north and generally temps a little lower than of late.

Keeping in mind my earlier comment vis the forthcoming evolution by Thursday further amplification has brought to halt any eastward pattern movement with the jet relegated a way south so the upper trough settles down in the vicinity of the UK portending a continuation of unsettled weather, the detail yet to be decided.

 

 

Edited March 25, 2018 by knocker

[knocker]

To supplement the above this morning's updated fax charts 00 Monday > 12 Wednesday

And the satellite for 0500

 

Edited March 25, 2018 by knocker

[knocker]

The 0900 geostationary (Courtesy DSRS)

[knocker]

Cracking MODIS at 1200 UTC (courtesy Dundee Satellite Receiving Station)

 

Edited March 25, 2018 by knocker