Model Output Discussion - 30th November onwards

[Smiler1709]

I'm crossing my fingers for a raging easterly by Xmas, wouldn't it be great. And as stated the models are starting to warm to the idea, very encouraging update from fergie. So maybe just maybe this failed northerly might just turn into something much more potent and pleasing to the uk in general. Hopefully a nice countrywide event around the festive period.

[forecaster]

The model output on the UKMO page really shows that Saturday/Sunday is turning out like almost none could have expected 3-4 days ago:

 

 

Overnight lows, will be hard to get right, but no widespread frosts "across the snowfields" there!

 

Max temps on Saturday, which for a while was looking like a cold and crisp day:

 

 

Winds light, but from SW quarter. 

[TEITS]

PS the update from Ian F is encouraging, that would suggest that the UK does at least tap into some cold uppers, but I'd stress easterlies are incredibly difficult to model don't bank on anything until its at T72hrs.

Morning Nick. Based on recent years I would say even earlier than +72!

 

The update from Ian F does not surprise me but I still feel a true bitter, snowy E,ly is a long shot. I do feel some form of flow off the continent is likely i.e SSE/SE,ly in the 10-15 day range and it could be potentially very cold if the skies remain largely clear. The main reason I say this is because historically E,lys via Scandi HP are more frequent during late winter/early spring than early winter.

 

I will add though that as you know the models are useless when it comes to modelling E,lys via Scandi HPs. The main reason being is they cannot seem to accurately model what happens when Atlantic LPs encounter the blocking to our E. Sometimes, especially the GFS will always want to model the Low pressure systems NE rather than SE under the block.

 

So a couple of notes for the next 2 weeks.

 

1. Don't expect much wind or rain.

 

2. Don't expect mild temps unless you live in the extreme SW/W that are away from the influence of a continental flow.

 

3. Follow the UKMO if an E,ly is be suggested by the ECM/GFS. I say this because the GFS is useless in these situations whereas the ECM is the other extreme and often projects a repeat of 1947!

[TEITS]

Think that very much depends on location to be fair John.  Hard to see much in the way of persistent mild weather for your neck of the woods and indeed much of central/eastern England, but the west and much of Scotland could get some mild, even very mild spells of several days duration. Would not be at all surprised to see the normal Foehn suspects topping out at 13-15c next week.

Very good point.

 

I posted yesterday that potentially over the next 10 days we could have a situation where the extreme W/SW are experiencing temps of 13C whereas locations such as say London are only reaching 1-3C as a max and even lower if fog is stubborn to clear.

[Frosty.]

 

 but no widespread frosts "across the snowfields" there!

 

 

Yep the high drifts further southeast allowing the atlantic low to have more influence and allows a warm front to brush around the top of the ridge with a warm front sector and light rain spreading north and east during saturday but the further southeast you are, colder and drier.

Edited December 3, 2013 by Frosty.

[garbagebags]

I'm crossing my fingers for a raging easterly by Xmas, wouldn't it be great. And as stated the models are starting to warm to the idea, very encouraging update from fergie. So maybe just maybe this failed northerly might just turn into something much more potent and pleasing to the uk in general. Hopefully a nice countrywide event around the festive period.

 

I don't see how this is a failed northerly? Sure i'ts downgraded but its still a stonking northerly bringing -10! uppers over a lot of the country and even -12 uppers over scotland. There could well be blizzards and heavy snow drifting in the north. How is this a "failed northerly"?

 

Definitely a Northerly. And a biting one at that.

Edited December 3, 2013 by garbagebags

[shedhead]

Yep the high drifts further southeast allowing the atlantic low to have more influence and allows a warm front to brush around the top of the ridge with a warm front sector and light rain spreading north and east during saturday but the further southeast you are, colder and drier.

Indeed, what looked like a widespread cold, frosty weekend just 48hrs ago now appears rather different, so perhaps a good lesson to learn here for some who pour over every run and say stuff like 'Wow...the 528 line is 11 miles farther south on the T+168hr.

 

These were definately not the kind of values expected early on Sunday just a couple of days ago....

 

Edited December 3, 2013 by shedhead

[radiohead]

I don't see how this is a failed northerly? Sure i'ts downgraded but its still a stonking northerly bringing -10! uppers over a lot of the country and even -12 uppers over scotland. There could well be blizzards and heavy snow drifting in the north. How is this a "failed northerly"?

 

Definitely a Northerly. And a biting one at that.

 

 

The ECM has gone from this :

 

 

To this....in the space of 3 days.

 

 

There has been a very significant downgrade in terms of the severity, potential snowfall, longevity and extent of area at risk.

[Gavin Hannah]

A failes northerly would be a complete backtrack to a different pattern ala the beasterly of last december....

And by their natutre, northerlies tend to be brief and useless at inland snow prospecta apart from the north of scotland.

This one could be quite good for snow for a decent area, but, it will be brief.

Edited December 3, 2013 by IBTHToThoseShortwaves

[SomeLikeItHot]

 

The ECM has gone from this :

 

 

To this....in the space of 3 days.

 

 

There has been a very significant downgrade in terms of the severity, potential snowfall, longevity and extent of area at risk.

On the brightside though GFS has gone from this.

 

To This.

 

In the space of three days! A big improvement if you don't live in scotland.

Edited December 3, 2013 by SomeLikeItHot

[shedhead]

This chart, IF it were to verify has 14c written all over it for Moray and parts of E Scotland on Monday.  Not inconceivable that somewhere like Aboyne could see a 20c swing in temps between dawn on Fri and dawn on Mon.....as I said the other day, from the sublime to the ridiculous!

 

Edited December 3, 2013 by shedhead

[TSNWK]

I think the 06:00 is more inclined to push heights further northeast around 168

[Frosty.]

The GEFS 00z mean is showing a stronger Arctic flow on friday with snow showers, especially for the north and east with icy stretches and temps hovering around freezing point for a large area of the uk and sub zero for the north, a frosty night to follow. Looking further ahead, signs that the mean is latching on to the signal for a colder, blocked european outlook, the GEFS is work in progress and catching up to the thoughts of the met office further ahead.

[garbagebags]

This chart, IF it were to verify has 14c written all over it for Moray and parts of E Scotland on Monday.  Not inconceivable that somewhere like Aboyne could see a 20c swing in temps between dawn on Fri and dawn on Mon.....as I said the other day, from the sublime to the ridiculous!

 

 

Is it too late for the term "Indian summer?" Im genuinely curious?

[Ali1977]

Looking at the Northern hemisphere I think its safe to say, polar vortex and Zonel type weather which was talked about lasting till xmas is no longer there.  Surely when they are out of the equation we are more likely to see extreme cold type scenarios rearing their heads......Weather they come off is another thing.

[forecaster]

Is it too late for the term "Indian summer?" Im genuinely curious?

 

Depends on the definition you use. But probably too late I would think. 

 

As for the chart shown by shed, that's bad news for Scottish ski resorts, having to put up with temperatures several degrees above freezing for a few days. Will there be a snoweating foehn effect happening?

[Gavin Hannah]

Is it too late for the term "Indian summer?" Im genuinely curious?

 

I think the temps may be a little 'over-amped'. I wouldn't be too surprised to see some of the 850's diluted a bit more as we approach the weekend.

[lorenzo]

With the usual caveats re: extreme FI and paying attention to the mid/long term trend as advertised by the ECM weeklies this morning.

 

The control run shows this.

 

 

Would be a nice week before Xmas on Netwx model thread if we were being tempted with retrogression and a Greenland high..

[frosty ground]

Is it too late for the term "Indian summer?" Im genuinely curious?

not for that chart....... http://www.wetterzentrale.de/pics/Rtavn15617.png

[Gavin Hannah]

If the NAO and AO both go negative in the 2nd / 3rd week of December, we could be in for a good Xmas.  The Negative NAO and AO will only serve to allow an Easterly to flow. 

Will we benfit as per 2009 and 2010 and march 2013?  Only time will tell.

[Frosty.]

Ecm 00z ensemble mean is also showing a stronger arctic airflow for friday with snow showers and high windchill with temps -0c in many areas, barely above freezing in other areas, the further outlook is looking very anticyclonic with widespread frosts and fog patches.

[garbagebags]

What would qualify for an Indian summer? Mid to High teens? I remember a couple of years ago it was 16 degrees on Boxing day. That was weird. (If anyone could find me that chart I would be very happy, I remember it was very blowy too)

 

This must have been it - 

Edited December 3, 2013 by garbagebags

[shedhead]

What would qualify for an Indian summer? Mid to High teens? I remember a couple of years ago it was 16 degrees on Boxing day. That was weird. (If anyone could find me that chart I would be very happy, I remember it was very blowy too)

Not sure if you could call it an Indian Summer in Dec garbagebags, but I think the important point to make is any anomolously high temperatures should be confined to a relatively small number of areas next week, primarily those to the north and east of high ground.  That said, temperatures do look set to be above average across much of Scotland, Ireland, west Wales and western England early next week, but the farther east you go the colder it gets, perhaps to a point where some parts of the extreme east are on the cold side...even without the aid of fog.  Later next week there are hints even on the 06GFS that the flow will back east of south, meaning the colder air gets advected farther west and brings and end to any localised Indian Summer...

 

Edited December 3, 2013 by shedhead

[Joe Levy]

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=190&y=176 The spread on the 850s is still quite considerable for only a few days away, especially in the south (as shown here for Exeter) where the depth of cold is most uncertain. 

[snow freak]

Depends on the definition you use. But probably too late I would think. 

 

As for the chart shown by shed, that's bad news for Scottish ski resorts, having to put up with temperatures several degrees above freezing for a few days. Will there be a snoweating foehn effect happening?

The scottish ski resorts have never really been a viable or reliable skiing destination anyway.  Yes they have periods of good snow but there is no way i would pre book my skiing holiday there months in advance.  Just too unreliable to say the least.