Model Output Discussion - Into Winter

[Gowon]

14 minutes ago, Nick F said:

Always the optimist!

The trop PV is not one for splitting to allow height rises over Greenland on recent GFS runs, maybe a new trend that won't reverse and get worse just before Xmas, or it may revert back to decent splitting into separate vortices over N Canada and NE Europe like the more colder runs of previous days. More runs needed.

12z GFS does at least drag down some cold arctic air, but with the TPV not splitting to allow the Atlantic ridge to build north over Greenland, any cold incursion would be prone to being toppled from the NW by mild sectors.

Because of where he lives.. Put him in over here and see how long that optimism lasts

Edited December 9, 2023 by Gowon
two longs lol

[Dennis]

Just now, Gowon said:

Because of where he lives.. Put him in over here and see how long long that optimism lasts

haha well i know your feelings very well  , i moved from the Netherlands to Norway

 

[alexisj9]

5 hours ago, jmp223 said:

One thing I noticed In the run up to our recent cold spell, the 06z always seemed to throw out stinkers of charts, which then be modified (positively for coldies) in the 12z.  It seems to be doing it again!

0z with improvement on 6z, then best on 12/18z pattern has changed to with 6z worse than 0z.

[Met4Cast]

 

Slightly concerned with what’s going on with the MJO, the EC & GFS continue to predict it collapsing whereas BOM remains more amplified but with increasing spread. 

Latest outputs have downgraded the strength of the next WWB event too. 

I’m certainly less confident of the UK high amplifying over the Xmas period as I was a couple of days ago. 

[Dennis]

9 minutes ago, Met4Cast said:

 

Latest outputs have downgraded the strength of the next WWB event too. 

 

houston we have a problem 

[Mike Poole]

5 minutes ago, Met4Cast said:

Slightly concerned with what’s going on with the MJO, the EC & GFS continue to predict it collapsing whereas BOM remains more amplified but with increasing spread. 

Latest outputs have downgraded the strength of the next WWB event too. 

I’m certainly less confident of the UK high amplifying over the Xmas period as I was a couple of days ago. 

The MJO is never a basket you want all your eggs in!

The modelled push of heights north has not been sufficient to reach Greenland on any run really.  So some additional forcing is required, if that is not going to materialise, then the pattern will collapse.  I think Christmas was always optimistic re timescales however, so I’m not giving up the ghost just yet.

[alexisj9]

4 hours ago, Midlands Ice Age said:

Johncam..

No problems with the Barents sea ice this year it is second highest in the last 5 years,

MIA

Agreed, and last cold spell bought snow to Dover from the north sea, so air coming down is plenty cold enough this year.

[Bricriu]

The wheels are coming off the Greenland  express it seems. A northern toppler at best looks the most likely outcome now. Will we even get a decent cold spell  to  see out the year?

The background drivers not playing ball it seems. Did someone mention a SSW in January...?  On to the next chase!

[summer blizzard]

1 hour ago, LRD said:

I know weather apps aren't up to much but I'm still seeing 7s and 8s for next weekend onwards. It'll be double that I reckon

1 hour ago, Nick F said:

I looked at the long draw SWly flow at 850 hPa, with T850s of 10C reaching the UK from the Azores around the 17th and all's not what it seems at the surface ...

Even the highs in the afternoon of 17th aren't screaming overly mild - more average.

All an educated guess that far off though ...

 

59 minutes ago, LRD said:

Thanks Nick. That's really strange. SW wind, high uppers and only producing those temps.

As Nick explains, when the high builds initially it traps the cooler air that passes the UK on the 14th.

Because the high is sufficiently strong, even the intrusion of warm upper air does not entirely remove this at the surface over England. 

By the time the incoming low is mixing out the air, the GFS has the next cold push.

 

 

[BartyHater]

1 hour ago, ANYWEATHER said:

I would say the reliable timeframe is not 8 days away thats in FI.

All depends....in a N'erly, E'erly or S'erly then yes FI can be 2 or 3 days at times, but with the kind of pattern being touted by all models now, 180-240hrs is almost in the reliable....and I wouldn't be at all surprised if the 384hr for Xmas Day has already nailed the broad pattern. 

[BLAST FROM THE PAST]

On 08/12/2023 at 17:08, BLAST FROM THE PAST said:

In that note….I’m sitting in the camp that Xmas week can be very interesting but no real locked in Northern blocking (not an issue imo and potential pretty stormy conditions)….but comfortable with further stronger shots as we go through Jan and Feb.  
 

BFTP

With the way MJO is getting, I think this 12z GFS won’t be too far off the mark.  It gets some decent cold air in, but the blocking in Atlantic doesn’t ridge up and hold so the cold isn’t locked in.  (However, it isn’t a mild outcome with GFS 12z scenario….and Summer B post explains it well.)
That scenario of Atlantic ridging north to HLB seems to slipping away unfortunately….but I don’t mean for the winter, just Xmas period….which could still pack a punch for some places.

I’ll be keeping an eye on some storm potential approaching and over Christmas with NW and N’ly gales.

BFTP

Edited December 9, 2023 by BLAST FROM THE PAST

[swfc]

1 minute ago, Bricriu said:

The wheels are coming off the Greenland  express it seems. A northern toppler at best looks the most likely outcome now. Will we even get a decent cold spell  to  see out the year?

The background drivers not playing ball it seems. Did someone mention a SSW in January...?  On to the next chase!

Evening. Not sure about the wheels coming off its the 9th of December? I've not seen any runs this week that showed a strong push of heighths high up into Greenland. High over the uk and way out in fi atlantic ridge. A dry spell will be most welcome by a lot of folk.

[summer blizzard]

23 minutes ago, Met4Cast said:

Slightly concerned with what’s going on with the MJO, the EC & GFS continue to predict it collapsing whereas BOM remains more amplified but with increasing spread. 

Latest outputs have downgraded the strength of the next WWB event too. 

I’m certainly less confident of the UK high amplifying over the Xmas period as I was a couple of days ago. 

Worth remembering that this is decaying WWB from November as per that chart. There was always a chance that it would wane, especially relative to the last orbit. 

[bluearmy]

1 hour ago, Dennis said:

AO forecast after 15th to neg value to most members

Assuming that’s generated from the gefs Dennis, we pretty much know this and mainly due to the Arctic high. But it isn’t predicted to be a particularly strong -AO and the 06z run was less negative too 

[northwestsnow]

I'd like to see a better EC det this evening.

The trend today is not good at all,IMHO.

[Bricriu]

17 minutes ago, swfc said:

Evening. Not sure about the wheels coming off its the 9th of December? I've not seen any runs this week that showed a strong push of heighths high up into Greenland. High over the uk and way out in fi atlantic ridge. A dry spell will be most welcome by a lot of folk.

 

Well, that's the point no models are showing a push of heights into Greenland which was the hope given background drivers looked favourable, at least on some output  Yes, it will be dry, but some of us were hoping for a bit  more for the Christmas period but the chances of that  happening are fading  based on current output. Perhaps there is still time for it to change for the better, but we don't really see broad support for a proper cold spell in the extended outlook. Perhaps a northern  toppler might deliver to some areas during Christmas week. Let's hope so anyway.

Edited December 9, 2023 by Bricriu

[Kasim Awan]

GFS and GEM look like setting up a Bartlett into Christmas.

[BartyHater]

37 minutes ago, Met4Cast said:

Slightly concerned with what’s going on with the MJO, the EC & GFS continue to predict it collapsing whereas BOM remains more amplified but with increasing spread. 

Latest outputs have downgraded the strength of the next WWB event too. 

I’m certainly less confident of the UK high amplifying over the Xmas period as I was a couple of days ago. 

Indeed, it's already got that 'if it can go wrong.....' feel about it. I've already parked all expectation of a cold Christmas across the last 48hrs and I've significantly lowered my sights to it just being dry....whether it's 5 or 10c and dry makes little difference now, but I fear the High sinking sufficiently south in the end to give us a 'typical' UK Xmas.

Just now, Kasim Awan said:

GFS and GEM look like setting up a Bartlett into Christmas.

Don't us the B word please

[northwestsnow]

Just now, Kasim Awan said:

GFS and GEM look like setting up a Bartlett into Christmas.

Wonderful,TBF Exeter are banging the Euro High drum,drier SE Wetter NW.

I hold my hands up ,EC46 sucked me in.

[Catacol]

Lots of jitters in here today. Eyes seem to have gone freely to the FI zone - and folks are getting frustrated because op runs at 300h (22 Dec) aren’t showing Siberia knocking on our door. Similarly now with the MJO - because there isn’t a high amplitude phase 8 signal on the EC or GFS out at 10-14 days it is a disaster.

There is never a guarantee of anything. But to be fraught over the accuracy of NWP at this kind of range is not sensible. Instead look for patterns. There is no doubt that the MJO is going to run into phase 7/8 territory soon. There is little to no doubt that in a week’s time there will be a mid lat block - and a strong one - in place over the U.K. Similarly, little to no doubt that the strat vortex is going to come under significant pressure as this month progresses. Ensemble runs are showing a very strong North Pacific trough consistently and that will keep the US mild as well as promote the ridging potential in our sector.

So….nothing has changed. We are going to be in a holding pattern now for several more days, until we see the block emerge, find out just how much amplitude the MJO will have as it hits phase 7/8, assess the impact of what looks to me a very likely chain of positive torque events, first East Asia courtesy of a trough descending towards China and that North Pacific trough running up against the Rockies. A combination of these is still highly likely to promote Nino phases within the GWO orbit, and that means more blocking potential.

By all means pull up op runs at 300h and look for trends. Focus more on ensembles. But be clear that NWP is going to struggle to resolve the Xmas period and beyond until  a particularly uncertain phase in the development of key drivers is resolved. It might all go belly up, but we certainly aren’t going to know one way or another for a while yet.

[Kasim Awan]

Just now, northwestsnow said:

Wonderful,TBF Exeter are banging the Euro High drum,drier SE Wetter NW.

I hold my hands up ,EC46 sucked me in.

No doubting there is no real strong signal for amplification, very strong jet with a strong signal for mid Atlantic ridging, in this set up temperatures often fluctuate between mild southwesterlies and cooler polar maritime influences, if we're lucky a potent toppler. But the ridging is often overpowered by the strong jet, leading to a lack of cold from the NE/N in general. 

[BartyHater]

2 minutes ago, Catacol said:

Lots of jitters in here today.

Not without good cause though....and that's the point.

[Chesil View]

6 minutes ago, Catacol said:

Lots of jitters in here today. Eyes seem to have gone freely to the FI zone - and folks are getting frustrated because op runs at 300h (22 Dec) aren’t showing Siberia knocking on our door. Similarly now with the MJO - because there isn’t a high amplitude phase 8 signal on the EC or GFS out at 10-14 days it is a disaster.

There is never a guarantee of anything. But to be fraught over the accuracy of NWP at this kind of range is not sensible. Instead look for patterns. There is no doubt that the MJO is going to run into phase 7/8 territory soon. There is little to no doubt that in a week’s time there will be a mid lat block - and a strong one - in place over the U.K. Similarly, little to no doubt that the strat vortex is going to come under significant pressure as this month progresses. Ensemble runs are showing a very strong North Pacific trough consistently and that will keep the US mild as well as promote the ridging potential in our sector.

So….nothing has changed. We are going to be in a holding pattern now for several more days, until we see the block emerge, find out just how much amplitude the MJO will have as it hits phase 7/8, assess the impact of what looks to me a very likely chain of positive torque events, first East Asia courtesy of a trough descending towards China and that North Pacific trough running up against the Rockies. A combination of these is still highly likely to promote Nino phases within the GWO orbit, and that means more blocking potential.

By all means pull up op runs at 300h and look for trends. Focus more on ensembles. But be clear that NWP is going to struggle to resolve the Xmas period and beyond until  a particularly uncertain phase in the development of key drivers is resolved. It might all go belly up, but we certainly aren’t going to know one way or another for a while yet.

In my humble opinion. This is probably most sensible post of the day.

[Kasim Awan]

6 minutes ago, Catacol said:

Instead look for patterns.

The only pattern I see is a strong Iberian high with some slight tendency for polar maritime air to briefly affect highland Scotland.

[That ECM]

1 minute ago, Kasim Awan said:

The only pattern I see is a strong Iberian high with some slight tendency for polar maritime air to briefly affect highland Scotland.

Someone has moved Spain.