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I don't think anyone can call a solution on this just yet. When you look at two 6z models this morning that at T+114 show this:
GFS 6z Op:
and this (ICON 6z):
Originally Posted by: Arcus
Absolutely. The GFS 06z op run for example is different to the ECM, UKMO and ICON but it is also different to the 00z GFS op run. When the day comes, all will have been wrong at some time stage and many may also have been right, as so many scenarios have been shown. Trying to pinpoint details should probably be limited to events on Monday and Tuesday, beyond then it will have to be a case of watching developments as they change once ,twice or even more a day
A poor 06z rolling out, though drier than the ECM. What's really worrying is how poor it is upstream.
Very cold air agonisingly close on the 6z this really would be a kick in the wotsits.
06z plants the high to our south west with dire consequences for our cold spell. Whatever background signals for a severe end to Jan were must have been barking up the wrong tree for too long.
Originally Posted by: White Meadows
That's an effect of the changed jetstream profile, not the cause.
The issue is still as it was earlier in the week, i.e. Modelling correctly the track and intensity of that LP exiting the Eastern Seaboard. It would appear that the more likely track is NE and not north: that topples the ridge and opens the door for the next LP.
But I'm unaware of any signals for 'severe cold': that's not what the long-range forecasts were indicating. They were saying an increased probability of colder than normal weather. Anyway, the current output doesn't make the background signals for the end of the month wrong, although I agree the trend seems to be away from severe cold.
Originally Posted by: Shropshire
We cannot get away from the fact that it is all very frustrating. We are definitely chasing rainbows here.
Interestingly this one op run seems to reverting to the pattern which persisted for days until recently: Colder shots from the northwest with less cold interludes. I suspect such options (along with the more recent easterlies), have persisted in the ensemble sets throughout.
Originally Posted by: doctormog
Was actually thinking the same thing this morning.
GFS 6z at 216 has the -10 isotherm close to NW Ireland and more especially western Scotland and from the WNW. This, in itself, would be quite rare to see in any winter.
http://www.wetterzentrale.de/maps/GFSOPEU06_216_2.png
Originally Posted by: Gusty
Yes I’m furious this morning.
06z op is a real kick in the goolies.
Still too early to call though. :)
Yes, this is slipping away and hopefully the agony wont be prolonged and we can move on.
The evening runs may finish off the easterly
Ironically I would not be surprised if sections of this run were very much on the colder side of the t850hPa ensembles for some parts of the country.
As invariably happens with a UK cold spell, we have been fooled again. ECM has gone from hero to zero (I never put much faith in the GFS output to begin with ) .
Back to grey, grizzly reality this morning. Why do we torture ourselves with fake model output time and again?
Yes, once the frigid cold air dig deep south over the US, hello mid-Atlantic cyclogenesis machine and goodbye to prolonged cold for us here at the UK.
Originally Posted by: idj20
But it doesn't work like that, does it? Ian makes the same comment periodically - it depends on the jetstream. Cyclogenesis off the Eastern Seaboard doesn't mean LP systems have to race across the Atlantic.
The longer term output remains consistent. Cool to cold with not much deviation in general pattern.
There's been a lot of volatility in the MO over recent weeks and no more so than the last few days. Whilst I wouldn't be surprised to see the output flip again, experience tells us that the recent potential for a significant cold spell has diminished with recent runs.However, if the set up continues for energy to dive SE over the UK from the NW then we could easily hit the jackpot next time. Onwards and upwards. No point getting down about it as the weather will do what it will do.
FI looks good though ;)
Originally Posted by: Rob K
It does look like that even if this first easterly is dead which looks likely at the moment because of the SSW we will get 2,3,4 ,5 maybe more bites of the cherry.
Originally Posted by: Chunky Pea
Basically, nothing beyond t+120 is to be trusted at the moment whatever it shows. For the British Isles the marginality is such that in any case a 100 mile difference in the output at t+96 can make all the difference down the line between wintery Nirvana and typical grey misery with cold rain.
Originally Posted by: Ally Pally Snowman
https://www.youtube.com/watch?v=OZBWfyYtYQY
Originally Posted by: Maunder Minimum
You don’t need to look beyond 120hr for interesting conditions though
(That’s from the 06z GFSP)