Milder wet and at times windy about sums things up this morning.

Poor output for the UK this morning. good weather for filling up outdoor swimming pools though... so i suppose theres that

---

On the plus side we should soon be able to stop worrying about the possibility of hosepipe bans next summer. To the best of my knowledge we are now getting the right kind of rain to top up the reservoirs. 

Definitely needed - the local groundwater is still not only below long-term average, but also marginally below levels recorded at this time in recent years. The decrease in level has slowed down, but not yet rising, though this is not unusual for December.

The message is don't panic, but the rain is wanted to secure supplies.

https://www.bgs.ac.uk/research/groundwater/datainfo/levels/sites/ChilgroveHouse.html 

---

BBQ Turkey for Christmas day ?...If it's not raining might cut the lawn...put a bet on 14c to be reached somewhere in the S/SE...(current output disclaimer)

Wrong thread - you need the one for moaning.

As dissapointing as it is to see the chance of a seasonal cold spell next week diminish, it’s been interesting to see how each algorithm has handled the new signals that started with the GFS output on Tues morning. We saw a lot of ‘but the 06Z is notorious for Atlantic bias’ but I can’t see much evidence for that and to be honest I think the NWP did, and is doing a reasonable job at modelling the pattern given the timescales. I think people expect too much of it and taking a +144 chart at face value is not sensible, even when it’s supported by its peers. The challenge is to find the right blend from the suite of models and ensembles, not be blinkered by your preferences, and wait until there’s solid cross-suite support at +96.

Now, where is that EC46 output? 

---

Looking for straws to clutch at, I'm reduced to hoping that the 0Z GFS Parallel T+384 chart might come to pass, vanishingly unlikely though that no doubt is. :)

---

Well if you are looking for straws, UKMO is not all bad, especially the 168 Chart, let's see what the met update says today 

---

I haven't been able to see the GFS 00z run this morning as for some reason it hasn't updated on WZ. As far as ECM goes though, while it certainly looks to be unsettled it doesn't look to be a particularly mild run either. As I commented last night, it doesn't look a million miles away from the kind of pattern than we had through much of December, January and early-mid February of last winter.

While it would be a less good set-up for southern areas as far as cold is concerned, I would not rule out the chances of some wintry precipitation at times in northern parts if ECM were to verify.

---

Now I am getting interested - something happening on 16th - will it grow?

P.S. From what I have been reading, the mere presence of HP cells over Scandi and northern Russia increase the pressure on the Strat.

It should be interesting to follow the Strat forecast over the next week - it is far more accurate than trop forecasts a week ahead and more.

---

EC46 has seemingly picked up on the likely SSW towards month end. 

For such a time frame (5 weeks out) it has picked up a very strong signal for Greenland heights and Euro trough...

Pretty much bang in line with seasonal modelling.

If this holds, I would expect the Metoffice to start publishing some wintry sounding long range outlooks in the not too distant future.

Out of interest, did the EC46 pick up accurately the SSW of February this year which led to the Beast event at the end of that month/beginning of March?

I can clearly recall that SSW event being talked about in this forum at least 2-3 weeks before it actually took place (think it happened around mid-February but am not 100% sure about that).

---

 

Out of interest, did the EC46 pick up accurately the SSW of February this year which led to the Beast event at the end of that month/beginning of March?

I can clearly recall that SSW event being talked about in this forum at least 2-3 weeks before it actually took place (think it happened around mid-February but am not 100% sure about that).

I have been wondering that too David, I remember the long range met updates were very bullish about a cold spell post the ssw well before it happened and well before any models we see picked up on it.

---

Although the warming occurs high up at 2-5HPa it has to accelerate rapidly and propagate down to 10-30HPa in a defined magnitude to be an SSW, and it’s the subsequent reversal of the polar wind vectors to Easterly that weakens the jet and encourages HLB at the surface.
It’s all rather complicated and a warming at 10HPa as per above isn’t necessarily a prelude to an SSW, though the UKM seem to think it will lead to one this time.
Timings look to be around the 22-25th Dec, which if there is a vortex split or displacement any benefits we might see would be around New Year on.
Doesn’t help much I know but that’s my understanding.

---

Now I am getting interested - something happening on 16th - will it grow?

 

 

It does seem any cold spells in this country are now dependent on these events as they can override the supercharged Atlantic as we saw briefly last Feb/March

But any effects will only be felt in January so December is looking very mild to top off a record hot year globally

I just want it to stop raining so I would be happy to see a Euroslug to at least keep the SE dry

---

Although the warming occurs high up at 2-5HPa it has to accelerate rapidly and propagate down to 10-30HPa in a defined magnitude to be an SSW, and it’s the subsequent reversal of the polar wind vectors to Easterly that weakens the jet and encourages HLB at the surface.
It’s all rather complicated and a warming at 10HPa as per above isn’t necessarily a prelude to an SSW, though the UKM seem to think it will lead to one this time.
Timings look to be around the 22-25th Dec, which if there is a vortex split or displacement any benefits we might see would be around New Year on.
Doesn’t help much I know but that’s my understanding.

I agree with this. Its the rate of change in temperature in the stratosphere that seems to be the key.

Last February was 'sudden' in every sense of the word. IIRC it was something like 50C warming in 24 to 36 hours which had a huge impact on the troposphere about 10 days later. A gradual warming or a slow splitting tends not to have the same impact on hemispheric patterns as we had last February.  Blocked or more slowly progressive patterns are typical of more muted stratospheric events - not all of which deliver classic cold weather to the UK. The probability of SSW is also less when we move into a westerly phase of the QBO. 

All of this of course is not to rule out cold patterns that develop via another route.  

---

Although the warming occurs high up at 2-5HPa it has to accelerate rapidly and propagate down to 10-30HPa in a defined magnitude to be an SSW, and it’s the subsequent reversal of the polar wind vectors to Easterly that weakens the jet and encourages HLB at the surface.
It’s all rather complicated and a warming at 10HPa as per above isn’t necessarily a prelude to an SSW, though the UKM seem to think it will lead to one this time.
Timings look to be around the 22-25th Dec, which if there is a vortex split or displacement any benefits we might see would be around New Year on.
Doesn’t help much I know but that’s my understanding.

Hmm, well the chatter about this gathers pace as on the other side John Hammond 's forecast now mentions the impacts of an ssw.

---

What a dire set of GFS Op run on 06z if it's cold and now you're after! - Sick 

---

A POTENTIAL SSW at end of FI from the Siberian SIDE infiltrating into the Arctic looking at the 06Z run - the only hope we have at the moment seeing as there is nothing cold this side of Xmas:

A lift up of some 40c in the space of 3 days if this comes off and potentially more if we could have run on!? A big if though.

 

---

Beeb still open to the idea that the block has the potential to win out with atlantic being aimed at central Europe

https://www.bbc.co.uk/weather/features/46476591 

I actually think this is sensible, despite the output. From experience blocks never maintain strength all the way through all the output... typically winning out with only a day or two before T=0.

---

 

Hmm, well the chatter about this gathers pace as on the other side John Hammond 's forecast now mentions the impacts of an ssw.

Further to this, I have now read his forecast, very promising for coldies 

---

Win some & lose some but it does leave a sour taste in the mouth but the up-coming wave 1 activity on the strat elongating it & pushing it towards Russia could be the reason why the blocked pattern for next week has been blown away. Injection of vorticity/cyclonic pattern N Atl. pic.twitter.com/KNyTUuy9re

— Matt Hugo (@MattHugo81) December 7, 2018

Not much sign of cold and blocked outcomes. Perhaps the ECM is very different or otherwise the Met Office may want to see if there is a bug in Decider. 

---