Remaining very cold - Bitterly cold Easterly winds later - Snow at times

The latest available overnight Guidance sees a continuation in a trend towards the development of an Easterly flow. Notably, present indications would suggest that the main area of High Pressure will build quite a distance further north than was the case with the Easterly flow earlier in February. Of course this is subject to change, however that's what the latest indications suggest.

The latest 6/10 & 10/14 Day CPC 500mb Height anomoly charts indicate the pattern quite well, with a mean variable Easterly flow, generally varying between Northeast & East. Suggestions have been there for more than 5 days now of a transition to this pattern, but exact details will be uncertain for some time yet.

http://www.cpc.noaa.gov/products/predictions/814day/814day.03.gif

As DM2 has mentioned, there is a threat of wintry precipitation towards midweek or slightly later as a residual disturbance/energy in the flow backs Southeastwards, as HP builds to the North. This risk is primarily indicated on the overnight UKMO Guidance:



The latest 00Z GEFS Mean Guidance has a mean Easterly flow developing at T+120:



ECMWF remains relatively constant on the pattern indicated last night, with much colder conditions spreading across the country from the Northeast towards T+120 (Day 5). Notably, there has been a shift on the last two ECMWF evolutions away from a dry stable Easterly flow to a more unstable Easterly/Northeasterly flow, with an intensification of the cold.

The latest ECMWF Ensembles for De Bilt, which are important in an Easterly flow, show a significant cooling of conditions across the near continent. Indeed, indications suggest exceptional anomalous cold for the first 10 Days of March - considering increasing solar influences etc. There is also an increasing signal for precipitation (sleet & snowfall) in that region as the flow back Northeasterly, trending Easterly.

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.html

GEM & GME also indicate a relatively potent & prolonged Easterly flow on the 00Z Guidance.

Summary

In summary then, a pattern change is occuring as we head into March. There is an increasing signal for high pressure to develop North of the UK & Ireland in the coming 5 days approximately. While it may become somewhat less cold during the transition phase, present indications suggest mean troughing over Iberia & secondary cold troughing over the near continent. As a result, indications suggest a renewed cold phase is possible as we head into March, which would be quite remarkable indeed. We are some distance away yet from being certain, but the latest trends do favour a well below average & and quite possibly wintry pattern as we head into the first third of March.

However, with any Easterly flow, cross model continuity is needed at T+96 in order to have high confidence in the outcome.

SA

I agree Deep Easterly & I also think another crucial aspect to the evolution will be the residual trough development, as that, almost exclusively will determine as to whether any flow would be cold but dry or cold and wintry.

For example, the GFS 12Z Evolution moves this residual energy further north and it then fills, therefore even though 850mb temperatures of -11 spread across the country from the East/Northeast, the time period for snowfall potential is greatly reduced compared with the 06Z evolution because mean troughing is much further to the south.

It is paramount that we see the troughing as close to the south of the UK in particular as is possible, to support and undercut and Easterly flow.

In that regard, UKMO 12Z Operational is quite impressive at both T+120 & T+144 and follows the main evolution, similar to that of the 00Z ECMWF Operational, with a Northward, then Southward progression of the main area of residual energy. With pressure around 1000mb, then there would ample opporunity for wintry developments in a very strong Easterly/Northeasterly airflow.

It's a fine balance, between having the centre of the HP far north enough but not too far, the main area of HP being elongated but not too elongated, along with mean troughing close enough from the South to support and undercut the high, but not too close that it would lead to a mixing of the airflow.



Not asking for much is it :pac:

SA

-0.4/-1.7
frost here and was foggy earlier,coldest in a few days.

2 Weekends in a row now with the rte farming forecast being redundant by that evening. It looks quite Springlike to me from Thursday with temps possibly hitting double figures. The eagle said it would be much colder next wkd than this one - yes going by out of date, yesterday charts!!

Deep Easterly wrote: »

ECM tonight, while still showing a build of pressure to the north, delays it and to be honest, it is no closer to us than this time yesterday, and when it does arrive, we just remain in the usual slack, tiresome area of it, which is typical of the pattern this winter. Sick of this now. Roll on summer for Christ sake and let us put this pointless winter to death, it has gone on long enough! :pac:

Pesky shortwaves...

We have just had the coldest ,most severe Winter for decades yet I fully agree.
It's been wierd, for some reason we mainly missed out on snow and in fact have seen more snow in very mild Winters.
Which does leave me wonder, just what exactly do we have to do to get snow in this country:rolleyes: