Model Output Discussion - Colder but how cold and for how long?

[blizzard81]

Just now, IanT said:

…but 11 days away!

All the models are converging on this now though. 

[WINTRY WALES]

Over and out on this chase ….lots of anticipation yet nothing majorly out of the ordinary. Good spot tho for those who punted for the cold a couple of weeks back  

[blizzard81]

1 minute ago, tight isobar said:

The mother lobe truly regaining her throne!!   Not a good Synoptic at all for immediate/ mid range cold for the uk thereafter.!

Amazing turnaround. 

[damianslaw]

Keep an open mind model wise beyond 120 hrs.. whilst the models are keen to bulldoze the atlantic through, we have a distressed PV - and I would not be at all surprised to see height rises to our NE begin to show in model runs next week for late Jan as the PV continues to stretch and weaken, early next following week (21-25th) may see it perform a last gasp so to speak, but it is clearly on the ropes. 

Edited January 12 by damianslaw

[tight isobar]

Just now, blizzard81 said:

Amazing turnaround. 

Indeed !!!!

[blizzard81]

Just now, damianslaw said:

Keep an open mind model wise beyond 120 hrs.. whilst the models are keen to bulldoze the atlantic through, we have a distressed PV - and I would not be at all surprised to see height rises to our NE begin to show in model runs next week for late Jan as the PV continues to stretch and weaken, early next week may see it perform a last gasp so to speak, but it is clearly on the ropes. 

Tell the EC46 this. 

[Bricriu]

Just now, Purga said:

Ugly - with a screaming jet right over us.

There was a GFS run around 10 days ago showing the above chart or something very smiliar to this.  It was  scoffed at the  time as unlikely,  but now it could well come to pass. I suppose looking  at it another way maybe that GFS fi chart showing a High in the Scandi  area will be shown again in future runs.

[josh-weather]

Snow aside, I can't really see much difference between today and yesterday. Still going to be cold, not dramatically so but nothing much different to what has been showing for a while. Snow wise isn't it partly a matter of seeing what turns up anyway?

 

edit: Fair enough, the low did move south again - quite a shame for southern regions if that's what happens.

Edited January 12 by josh-weather

[Hotspur62]

2 minutes ago, tight isobar said:

The mother lobe truly regaining her throne!!   Not a good Synoptic at all for immediate/ mid range cold for the uk thereafter.!

Look at North America as well!!Looks like the whole continent is under High Pressure-a very odd looking chart

[Continental Climate]

Just now, tight isobar said:

The mother lobe truly regaining her throne!!   Not a good Synoptic at all for immediate/ mid range cold for the uk thereafter.!

An ugly chart for sure. Even the USA is locked out of the cold with the expansion of the high pressure cells to the south. Is it called a Hadley cell? All the cold just bottled up over the poll with nowhere in the mid lat NH getting any. Horrendous. Plenty of time for a change though late Jan early Feb. 

[weathercold]

4 minutes ago, tight isobar said:

The mother lobe truly regaining her throne!!   Not a good Synoptic at all for immediate/ mid range cold for the uk thereafter.!

Wow! That’s some turnaround- long way back for winter from there.

[Richard Fisher]

I must be the only one that thinks the Wednesday low will reach up to the M4 producing 15-20cm of the white stuff. I just can't see it staying in France based on the Mets low probability of this.

[WYorksWeather]

Final point on temperatures in February, and my earlier point about not worrying about the clock running out. See the temperature average chart below - ignore everything except the black line.

February is very flat, and its temperature is virtually identical to January overall. There is absolutely no basis, none whatsoever, for saying that February is less likely to deliver than January, at least from a climatological point of view.

The temperature trend begins to turn steeply upwards only in early March, when sea surface temperatures begin to bottom out in the Northern Hemisphere, and so the inexorable rise in solar heating becomes the dominant force. Under the right conditions, you can get very mild days in February, especially late February, and like almost all months, the average February is warmer now than it was 30 years ago, but if we're comparing February to January, there really isn't much of a difference.

I would continue to say that we have at least a month to go yet before we have to start worrying about running out of time. I'm far too risk-averse to say that we will get a cold spell that includes widespread snow this winter, but what I will say is that I think we'll get at least one or two more decent chase possibilities before the coming of Spring slams the door shut.

[blizzard81]

Just now, Richard Fisher said:

I must be the only one that thinks the Wednesday low will reach up to the M4 producing 15-20cm of the white stuff. I just can't see it staying in France based on the Mets low probability of this.

24 hours behind the curve. Not for the first time and not the last. 

[North Easterly Breeze]

18 minutes ago, blizzard81 said:

Try April

Come back in November

[Metwatch]

Even the cold that has been stuck around Scandi in recent months is just blown away like it's paper

A while to get there, but more likely than not we are back into a zonalfest for the final 7-10 days of the month. Next opportunity for something of interest is in early February perhaps after next week is over and done with? MJO, rising +AAM anomalies, weakening strat winds etc could come into play, but it's anyone's guess at the moment what those drivers will do to the troposphere in 3 weeks time and if the UK will be on the lucky or unlucky side of any blocking.

18 minutes ago, blizzard81 said:

So many questions aren't there? How could there be such a complete 180 degree flip? Especially as it goes against those background signals.

I mentioned it yesterday but forgetten by now. I believe the cold air outbreak impacting the lower 48 is indirectly to blame. Temperature gradient increases allowing the jetstream over the Atlantic to strengthen, causing further intense storms over north east USA, overiding any blocking over Greenland, and then sending it all into north west Europe / north east Atlantic.

 

Edited January 12 by Metwatch

[Met4Cast]

If we look at the GFS strat forecasts I think we can find an answer to where this zonal push within the modelling is coming from.

The Canadian lobe of the sPV appears to get sucked towards Siberia by the stronger SIberian lobe, this occurs 17th-20th, around the time we're seeing modelling flatten the Atlantic pattern out and return the tropical jet northwards. This could perhaps be a response to the minor SSW we've recently seen, perhaps a case of the worst timing ever? (I did muse that a SSW minor or otherwise could potentially disrupt any cold spell a while back).

Once that transition has occurred & based on the current background forcing I see no reason why we wont see high pressure beginning to re-establish itself in a more favourable place for further cold weather outbreaks, Tamara has outlined this far better than I can in a few of her recent posts on this thread. 

[blizzard81]

1 minute ago, Metwatch said:

Even the cold that has been stuck around Scandi in recent months is just blown away like it's paper

A while to get there, but more likely than not we are back into a zonalfest for the final 7-10 days of the month. Next opportunity for something of interest is in early February perhaps after next week is over and done with? MJO, rising +AAM anomalies, weakening strat winds etc could come into play, but it's anyone's guess at the moment what will happen in 3 weeks time.

I mentioned it yesterday but forgetten by now. I believe the cold air outbreak impacting the lower 48 is indirectly to blame. Temperature gradient increases allowing the jetstream over the Atlantic to strengthen, causing further intense storms over north east USA, overiding any blocking over Greenland, and then sending it all into north west Europe / north east Atlantic.

 

Absolutely. Predictable now and just a given every winter. 

[mountain shadow]

17 minutes ago, Ali1977 said:

Need a SSW , to smash that NH PV to pieces 

And with the lag time between the SSW reaching the troposphere expect a cold March but not cold enough for snow.

[weathercold]

Today’s charts are a sobering reminder to not get carried away with wintry nirvana charts circa 2 weeks in advance. For those based in England, Wales and Ireland it almost aways ends in a damp squib…. And today has confirmed just that.

After a chilly week the pv looks like moving over to the Canadian side, it’s a long slog from there.

[blizzard81]

4 minutes ago, Met4Cast said:

If we look at the GFS strat forecasts I think we can find an answer to where this zonal push within the modelling is coming from.

The Canadian lobe of the sPV appears to get sucked towards Siberia by the stronger SIberian lobe, this occurs 17th-20th, around the time we're seeing modelling flatten the Atlantic pattern out and return the tropical jet northwards. This could perhaps be a response to the minor SSW we've recently seen, perhaps a case of the worst timing ever? (I did muse that a SSW minor or otherwise could potentially disrupt any cold spell a while back).

Once that transition has occurred & based on the current background forcing I see no reason why we wont see high pressure beginning to re-establish itself in a more favourable place for further cold weather outbreaks, Tamara has outlined this far better than I can in a few of her recent posts on this thread. 

That was always my biggest fear about this particular warming. I think you're right unfortunately. You couldn't make it up could you? 

[TSNWK]

15 minutes ago, IanT said:

…but 11 days away!

Right let's put this 11 days and only one run etc business to bed.

The pattern collapse starts with lobe closing of the two lobes of vortex middle next week!  around day  5 across all models they are  not getting that  wrong and if anything it  has  accelerated it throughout todays modelling!  it is going to happen and is the 1st domino the rest that follows is the  domino vortex reforming  effect... its a long way back from the below chart and already ec46 is pushing anything of interest to February week 2.. tick tock......

 

Edited January 12 by TSNWK

[Lord Grogon]

“Don’t worry too much about snow chances. Small features will always pop up at short notice that the models won’t yet see”.

I must have read this comment a thousand times in some form over the last few days. 
 

So what has changed? I know people may be a bit grumpy that the models are firming up on an end to this cold spell. But there seems to have been a complete collapse in excitement for the next week. Are people simply overreacting to Wednesdays low no longer going in the desired direction. Or is there something else?

[mountain shadow]

What I find interesting with the MJO is that when it gets into so cold favourable cold sectors for us, that we just get a mid latitude block or brief cold spell like next week.

Yet, now that the MJO is moving into unfavourable sectors for cold the NAO goes rock solid positive for weeks.

The opposite never seems to occur.

[Nick123]

3 minutes ago, mountain shadow said:

What I find interesting with the MJO is that when it gets into so cold favourable cold sectors for us, that we just get a mid latitude block or brief cold spell like next week.

Yet, now that the MJO is moving into unfavourable sectors for cold the NAO goes rock solid positive for weeks.

The opposite never seems to occur.

It's 

 

4 minutes ago, Lord Grogon said:

“Don’t worry too much about snow chances. Small features will always pop up at short notice that the models won’t yet see”.

I must have read this comment a thousand times in some form over the last few days. 
 

So what has changed? I know people may be a bit grumpy that the models are firming up on an end to this cold spell. But there seems to have been a complete collapse in excitement for the next week. Are people simply overreacting to Wednesdays low no longer going in the desired direction. Or is there something else?

To be fair I understand folk in the South being disappointed. Only a couple of days ago they were promised a intense snowstorm, now they'll be lucky to see a few flakes.