Short range model discussion - into 2018

[knocker]

8 hours ago, Ukwoody said:

Thanks Knocker (or is it really Sidney that works all this out?..?)

Sidney was taking fuel on board this morning ready for a lengthy kip next week

 

[knocker]

The ecm 2-6 temp anomaly and the interesting disturbance over western Norway at T120 which developed.

Edited February 20, 2018 by knocker

[chrisbell-nottheweatherman]

3 hours ago, knocker said:

It's all happening around East Anglia. The 1500 geostationary

Triple point must have gone across above my area at 11.30!

Edited February 20, 2018 by chrisbell-nottheweatherman

[knocker]

Tonight's anomalies have the Canadian vortex tracking north en route to northern Russia in association with high cell continuing to move west and is currently in the Iceland area. To complete this complex scenario there is the fragment of aforementioned vortex and trough dominating the Atlantic linked to the other trough conduit running south west across central Europe. Thus there is a north easterly upper flow over the UK with temps below average, probably significantly so, but the surface analysis lends itself to some complexity with the UK being at the interface between systems and certainly not without interest.

[knocker]

The Norwegian  shortwave

Edited February 20, 2018 by knocker

[knocker]

The cloud and patchy precipitation that hung around the east yesterday associated with a frontal system will be more widespread over England and Wales today whilst the north and N. Ireland will be sunnier. Winds generally light as the high cell/ridge predominates but a bit breezier in NW Scotland.

The cloud will clear overnight and through tomorrow leading to frosty start in most places but the ridge has reorientated under pressure from the trough in the Atlantic to the north west and a fresh easterly wind has been initiated in the south making to it feel much colder. Less so in north west Scotland in the south westerly wind and the proximity of the front.

The consolidation of the easterly in the south continues on Friday so starting to feel  colder in the wind chill but complications are afoot in the north, The previously mentioned front associated with the deep depression south east of Greenland is now orientated WSW-ENE north of Scotland and this is associated with warmer air and upon which a shallow wave has formed.

Over the next 24 hours the shallow wave drifts south east to the Norwegian coast and this subtle pressure does impact the ridge to some extent which has the affect of veering the easterly somewhat and temporarily halting the progress of the much colder air to the east moving quickly west.

The scene slowly changes though to 1200 Sunday with the ESE wind continuing to freshen thus feeling very cold, particularly in the east and south with the greater wind chill factor, and the much colder air to the east edges much closer.

And by midnight Monday it has arrived and by now snow showers in the south are quite possible.

 

 

Edited February 21, 2018 by knocker

[knocker]

The ecm not dissimilar to the gfs in this time frame

[knocker]

To put more meat on the bone the updated fax charts for Friday/Saturday

[knocker]

And the sun is shining on God's Little Acre this morning

[knocker]

The midday geostationary (courtesy Dundee Satellite Receiving Station) showing the cloud over Wales and central England and the frontal cloud way out west. I'm not what to what the cloud running from the tip of Ireland is related

[knocker]

The high res. MODIS at 1340

[knocker]

From a weather perspective there is little detail of any significance within the time period of this thread apart from, of course, the slow decline of the temperature and increase of frosts and the wind chill factor as the time progresses so I will try to avoid waffling to much. Essentially it  will be dry and sunny for much of the period with a chance of snow showers in the east and south as perhaps the ESE surface wind backs a tad by Monday.

Anyway tonight will be clear in most places with a frost in the morning and this remains the story for tomorrow and Friday morning with slightly warmer air in the north west of Scotland courtesy of the proximity of the front. Might be the last time I say that for a while.

From T72-120 it is really suffice to note the progression of the colder air west

And throw in a sounding for 1200 Monday. Unstable but how much moisture will be picked up across the North Sea?

Edited February 21, 2018 by knocker

[wiltshire weather]

Thanks for all the analysis Knocker. Always very interesting and I think this particular thread may become a bit busier come next Monday!

A quick question in case anyone knows the answer. When do the MetO update their FAX charts? is it a set schedule or completely random?

Many thanks.

 

 

[knocker]

7 minutes ago, wiltshire weather said:

Thanks for all the analysis Knocker. Always very interesting and I think this particular thread may become a bit busier come next Monday!

A quick question in case anyone knows the answer. When do the MetO update their FAX charts? is it a set schedule or completely random?

Many thanks.

 

 

I don't actually know whether there is a schedule but they tend to get updated around 1800 and 0600 as well as the nearest current one. Somebody will probably clarify this.

[wiltshire weather]

Thanks. I'll keep an eye on Meteociel around those times then as at least they clearly show when each one was last updated!

Wish the NW Fax viewer did something along the same lines though...

[knocker]

25 minutes ago, wiltshire weather said:

Thanks. I'll keep an eye on Meteociel around those times then as at least they clearly show when each one was last updated!

Wish the NW Fax viewer did something along the same lines though...

You can also find them here

http://www.weathercharts.org/ukmomslp.htm#t120

Or Roger Brugge's excellent site

http://www.met.rdg.ac.uk/~brugge/

[Paul]

30 minutes ago, wiltshire weather said:

Thanks. I'll keep an eye on Meteociel around those times then as at least they clearly show when each one was last updated!

Wish the NW Fax viewer did something along the same lines though...

Yep, good point - will see if we can get that added shortly. 

[knocker]

Tonight’s anomalies are merely a continuation of the evolving pattern change and given this it is not a major surprise that differences that will be apparent will certainly influence the interpretation of the surface analysis by the det runs. But having said that the general overview is not bad.

The Canadian vortex lobe is over the Pole and the major influential high pressure area is slipping west towards Greenland leaving the Eurasian/European/Atlantic troughs to form an exceedingly long conduit with the UK, for a time during this transition, the interface between these systems, with the upper flow backing north easterly. This could well lead to fairly complex surface analysis which the det runs will need to sort and quite possibly some substantial snow episodes as the temps will still be below average and likely significantly so.

Edited February 21, 2018 by knocker

[knocker]

As I'm sure everybody is aware the UK is in the process of moving into a colder regime so for the this period we will mainly be looking east, but not exclusively, and a general overview is gradually getting colder, becoming very cold by the end of the period with snow showers becoming more widespread in the east and south.

A tad more detail. Once early fog has cleared today will be mainly sunny with light winds as the ridge dominates and feeling colder in the south where the easterly wind is picking up. The exception being the far north west where the cold front is very adjacent where it will also a be a littler warmer (relatively) in the south westerly wind. It will even bring some patchy rain later and tonight before clearing and by morning the will be a hard frost generally.

Friday will be another clear and sunny day with temps struggling to 5-6C but the with the the ESE wind increasing the wind chill becomes a bigger factor so by 1800 we have this scenario. It is worth noting here that the front(s) and warmer air have made inroads a fair way east north of the UK reaching as far as the Norwegian coast as the gfs makes more of this later.

Saturday portends another clear and cold day but by 1800 a shallow low/wave has formed on a front over the Norwegian coast and becomes something of interest as we move into next week.

By Sunday 1800 this feature is tracking slowly SWS and the colder air in the east is moving steadily west so the wind chill factor is increasing over the UK as is also the likelihood of snow showers in the east and south which may well spread a fair way inland.

By Tuesday 00 the low is in the North Sea which does mean an easing of the easterly flow for a time but by this time it's bitterly cold over the UK

A just a note about model temps. At no time should they be taken as definitve

 

Edited February 22, 2018 by knocker

[knocker]

Regarding the shallow wave over the Norwegian coast the updated fax charts show a weakening occlusion in the area. Not to make too much of this

[knocker]

The ecm also has the small feature in the North Sea by Tuesday 00 which will temporarily affect the low level flow and may impact on the distribution of snow showers.

[knocker]

Forecast sounding for 00Tuesday in the North Sea showing the very cold unstable air that will be flowing cross sea temps in the 5=6C range and nearer 9C in coastal waters. A situation that has some [potential, so to speak

[knocker]

Some interesting cloud on the 1100 high res. Modis Image courtesy Dundee Satellite Receiving Station.

[swebby]

16 minutes ago, knocker said:

Some interesting cloud on the 1100 high res. Modis Image courtesy Dundee Satellite Receiving Station.

Out of interest, is that high lev cloud or fog banks in the western channel out into the Atlantic?

[knocker]

7 minutes ago, swebby said:

Out of interest, is that high lev cloud or fog banks in the western channel out into the Atlantic?

Good question and first up I'm no expert on Satellite image interpretation which is quite a specialized skill. The cloud further west will be associated with the cold front but the short answer to the stuff in the Channel is I don't know, sorry.