In article
,
Dawlish writes:
On Jan 29, 8:48*pm, Nick wrote:
On Jan 29, 8:34*pm, "Keith (Southend)G"
wrote:

On Jan 29, 8:11*pm, John Hall wrote:

Both models' 12Z operational runs now bring in warmer air next Saturday.
That's as far as the UKMO run extends, but after a milder weekend the
ECMWF brings the easterly back on Monday and for the rest of its run.
The ECMWF ensemble isn't out yet, but will be interesting.

Before then, Thursday and Friday still look like being very cold, and I
reckon based on the 850mb temperatures that the maxima of 1-3C shown on
the Countryfile forecast for those two days are on the high side. I
reckon that in the eastern half of England temperatures are unlikely to
get above freezing on those two days.

The models are struggling with setting in this easterly. By Wednesday,
it will probably look completely different, but which course it will
take, beats me! One thing going for it is the last week of January and
the first week of February are when the average tempertures drawn
through the year bottom out, so it couldn't come at a better time.

No expert on this, but one observation I will make based on previous
examples is that models not infrequently break down cold spells faster
than actually occurs. I distinctly remember in the closing days of
2009 three or four consecutive model runs suggesting the whole thing
would be over by Jan 5th.. instead that's when it got exciting and not
"just another cold spell".

snip

My observations too, Nick. Predicting when the Atlantic will re-
establish itself has ruined several of my 10-day forecasts in the
past.

For the last three runs - yesterday's 12Z and today's 00Z and 12Z - the
ECMWF has been consistent in how it develops things after this weekend's
rather milder weather, a consistency that the GFS hasn't shown. And it's
supported by its ensemble. So it could well be right when it shows the
easterly becoming re-established early next week, at least in the south.
The milder incursion will have got rid of the really cold upper air, but
I imagine that next week's easterly - should it occur - will still be
pretty cold near the surface.
--
John Hall
"The power of accurate observation is commonly called cynicism
by those who have not got it."
George Bernard Shaw