Models, teleconnections and nowcasting

[knocker]

See Ryan Maue's tweet

[knocker]

Interesting that the ecm appears to be disagreeing with Exeter vis Thursday's low. Stronger ridge?

[knocker]

A further look at the vortex and severe cold over Alaska in the nearer time frame with the ecm

[knocker]

Perhaps indicative of the expected pattern

[Interitus]

2 hours ago, knocker said:

See Ryan Maue's tweet

Just for context, most parts of Alaska display a continental temperature range such that difference between the average monthly minimum and daily mean minimum is typically quite a bit more than we are used to in the UK - (for December) varying from 11.5 degrees C for Anchorage in the south with more Pacific influence, to 13.5C for Bethel and Fairbanks and 16.2C for Bettles further north in the cold interior. So these anomalies typically appear annually on average and are a long way from December records (Anchorage -34, Bethel -42, Fairbanks -52, Bettles -51). 

[knocker]

this morning's updates find the fax and 06 gfs pretty similar at midday Thursday and from this point the gfs continues thus

Even at this short range the models appear to be struggling with the depth and track of the low as it quire quickly fills. Put simplistically, and to my untutored eye, it appears to be down to the energy distribution around the main atlantic trough, not forgetting the trough to the NE, and the amplifying subtropical zones. The ecm 06 is not without interest

 

[knocker]

[knocker]

Apart from showery rain over western Scotland and N. Ireland, courtesy of the low and associated occlusion, the rest of the country is currently quite dry. But as can be seen on the Camborne sounding Cs and Ac are encroaching the south west as the next frontal system approaches The rain from this will arrive around 1600 and track north east through this evening along with the occlusion as the triple point moves east across northern France

[Kirkcaldy Weather]

 

[knocker]

The mean EPS anomaly this evening has a rapid NH pattern change and de-amplification in the Atlantic/Euro sector between t144 and 216

which leads on in the ext period to the pattern that has been indicated a while. Essentially a strong vortex northern Canada with trough extension south east north of Scotland ans a strong westerly upper flow across the Atlantic

[knocker]

Apart from western Scotland fairly dry for more most places over the next ten days according to the EPS The 5-10 anomaly illustrates the reasons quite well with the subtropical high being quite influential as systems track around it

And then onwards to the ext period with the vortex and associated troughs running the show as the amplification disappears with a much flatter and strong westerly upper flow across the Atlantic

 

Edited December 24, 2019 by knocker

[knocker]

Signs of the trough on the midday sounding with 120kt wind at 500mb with 160kts just below the tropopause

 

[Dorsetbred]

52 minutes ago, knocker said:

Signs of the trough on the midday sounding with 120kt wind at 500mb with 160kts just below the tropopause

 

Sorta borne out with the current radar showing the patchy versus the showers...

[knocker]

6 minutes ago, Dorsetbred said:

Sorta borne out with the current radar showing the patchy versus the showers...

Quite a funny day here with some squally rain/showers becoming more frequent around midday but now more persistent rain and quite a foul afternoon. Breezy as well gusting 45mph

[knocker]

Once Thursday's low is out of the way the subtropical high amplifies over the UK on Friday and thereafter over the weekend and the beginning of next week it's a battle between the east bound energy and the strength of the ridge which, according to the gfs results in very much of a N/S split as systems are forced around the high cell. The process also advects some warmer air from the south but we all know there is not a direct correlation between the 850mb temp and the surface

But I digress so moving back to the main point.................................

Edited December 24, 2019 by knocker

[knocker]

The pattern change involving some restructuring of the tpv and de-amplification of the European high continues apace with this evening's GEFS

Edited December 24, 2019 by knocker

[knocker]

The ecm is similar to the gfs early next week so just a bit more detail for the weekend

[knocker]

As can be seen there are subtle differences (perhaps not so subtle) with the NH pattern, between the ext GEFS and EPS. In particular, with the UK in mind, the structure of the tpv/trough which facilitates the retention of much more influence from the subtropical high and thus not very unsettled but still indicating a N/S split

[knocker]

NOAA favoring the GEFS

 

[knocker]

The North Atlantic 500mb and surface analysis for midnight

Once any early morning fog/mist has cleared today will a largely sunny day as the ridge nudges east. The exception being northern Scotland where showers will persist for a while. But later in the day cloud will encroach in the west as fronts associated with the low to the south west track north east

Rain from these fronts (which become occluded) will arrive around midnight and track north east through the rest of tonight and tomorrow morning, followed by blustery showers in the south west

The band of rain will continue to push north east through Thursday but to the west the filling low and further fronts are beginning to track east so further bands of rain will effect Wales and England through Thursday afternoon and it will also become quite windy in the south, albeit warmeer air is creeping in here

Over Thursday night and through Friday the low and front move into the North sea and become a non feature but another frontal system tracks north east and the warm front will bring a band of rain through Friday but temps now above average in the south westerly winds of the warm sector

By the weekend the fronts are out of the way as further amplification occurs and the battle between the energy and ridge gets underway with the ridge just about prevailing, albeit it will be quite breezy and rain will effect the far north west

[knocker]

The above mentioned battle is pretty much the story of the next five days according to the gfs with a quite intense vortex Northern Canada and a strong westerly upper flow

[knocker]

Little to add vis the GEFS anomalies this morning

[knocker]

[Dorsetbred]

49 minutes ago, knocker said:

 

Thanks Knocker for the continued in depth analysis you post. Has to be said this latest one looks like a blood bath of warmer air...

Edited December 25, 2019 by Dorsetbred

[knocker]

Thanks Dorset

And the ext EPS this morning retains the influence of the subtropical high, probably indicating a N/S split again