Model Output Discussion - 18z 31/10/15 onwards

[knocker]

The GEFS 6-10 this morning has HP GOA and ridging Greenland with the trough Scandinavia. The cold spell looks pretty much nailed on. The 11-15 going for less amplification with low pressure over the Pole and a weak trough Greenland to the north North Sea extending down as far as the eastern Med with HP away to SW.  So a much more zonal flow with temps around average.

http://www.tropicaltidbits.com/

 

[Severe Siberian icy blast]

The GFS this morning continues to show a very cold wintry blast from the North next weekend, With -8/-9 even a cluster of -10 850's pushing South over a vast swath of the UK. After a very stormy week coming up..

Agreed it's going to feel much more seasonal , but most snow has been removed from the models this morning apart from exposed areas and further north , but don't see much further south , but yet it's still a week away so set to change .

[johnholmes]

Latest EC-GFS 500mb output, much as before with the cold look but notice that the upper ridge is being moved east so the deepest cold air is also moved east.

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

for comparison the NOAA 6-10 from last night below

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

 

and to see how another 500mb anomaly chart looks the NAEFS output last evening

http://www.meteociel.fr/modeles/naefs_cartes.php?code=0&ech=384&mode=0&map=1&runpara=

 

So for sure cold is coming but for how long is the question. Who will get snow, etc?

Edited November 15, 2015 by johnholmes

[Polar Maritime]

But yet it's still a week away so set to change .

 

Yes I'd expect so re-snow. As usual up until a few hours.. With the usual now-cast being the best option. 

Edited November 15, 2015 by Polar Maritime

[Captain Shortwave]

Day 6 charts

 

GFS

Strong cyclonic flow, winds veering northerly across the UK as the day progresses. It will become cold everywhere by the afternoon with snow even to low levels in any showers.

 

UKMO

North westerly flow but with any cold struggling to push south as the Atlantic high pushes in more quickly compared to other outputs. The shower risk will be lower here too due to higher surface and 500mb heights.

 

ECM

A strong north to north west wind, cold everywhere though the 850s not as low as the GFS.

 

GEM

Again the north to north west flow is there, it will be cold but with a secondary feature looming to the north west of the UK which rolls around the developing Atlantic high.

 

So overall it will turn colder from late on Friday with the risk of wintry showers, the UKMO showing the lowest risk and probably the least potent cold snap. The other 3 show something decent with showers down coastal locations but with some low heights you could see something more widespread develop. Also the ECM/GFS and GEM develop at some point a secondary low which moves across the UK or down the north sea giving a second push of cold air as we head into week 2, though it is probably worth sticking to the initial push for the time being.

Edited November 15, 2015 by Captain shortwave

[Frosty.]

Lovely Ecm 00z with an Arctic blast bringing wintry showers turning increasingly to snow from the north, ice and widespread frosts.

[snowblizzard]

I was just about to answer when I notice Yarmy has already done so. Some time ago JH did a more detailed answer using the NOAA charts which may be of interest.

Thanks very much guys.

[tinybill]

http://www.meteociel.fr/modeles/gefs_cartes.php?code=16&ech=192&carte=&mode=0

 

just a look into fantasy world  could be interesting weather heading our way   at  least 3 storms   965.965. 985  all bring very cold air our way

[joggs]

The GEFS 6-10 this morning has HP GOA and ridging Greenland with the trough Scandinavia. The cold spell looks pretty much nailed on. The 11-15 going for less amplification with low pressure over the Pole and a weak trough Greenland to the north North Sea extending down as far as the eastern Med with HP away to SW.  So a much more zonal flow with temps around average.

http://www.tropicaltidbits.com/

Yes but these were showing nothing like this a few days back!.

[johnholmes]

Yes but these were showing nothing like this a few days back!.

 

Just goes to show how quickly the weather can change

[Frosty.]

Just goes to show how quickly the weather can change

It's ebb and flow, we could equally have wintry upgrades in the next few days but I'm just so happy we are going to have an early cold snap in autumn, what a bonus for all the coldies, enjoy it guys, even if it only lasts a few days...winter is just around the corner.

[NorthYorksWeather]

6z GFS very smililar to 0z so far although slightly warmer uppers especially in the east next Saturday due to the low sinking south closer to the east coast. Still a long way to go with more changes likely but all in all pretty happy with this chart in late Autumn.

 

[Ice Day]

Looking at the GFS 6z, next weekend is now looking likely to be chilly, in fact very raw in the wind (especially down the eastern side of the country).  This for Saturday lunchtime:

 

 

The Scottish mountains should fair very nicely.  Not an extreme outlook, but given last years wash out a very welcome start to winter 15/16.

Edited November 15, 2015 by Ice Day

[stratty]

Looking at the GFS 6z, next weekend is now looking likely to be chilly, in fact very raw in the wind (especially down the eastern side of the country).  This for Saturday lunchtime:

 

 

...I'd be happy waking up to this as a little pre-winter dusting!  

[Ice Day]

...I'd be happy waking up to this as a little pre-winter dusting!  

 

Absolutely, not much for the south east contingent but a cracker further north. Cairn Gorm looks like the place to be!

[shaky]

Absolutely, not much for the south east contingent but a cracker further north. Cairn Gorm looks like the place to be!

even the midlands has a dusting of snow!!that says a lot!!!

[Iceaxecrampon]

Goodness....!

 

 

 

 

Interesting times.

 

 

 

 

 

 

 

 

[damianslaw]

All models showing a significant change as we move through the coming week, a change from very mild with the longwave trough stuck out to our SW/W and ridge/high pressure to our south pumping up constant SW airstream, to the trough finally making inroads across the country to our east enabling heights to build northwards from the mid atlantic ushering in a cold NW/N airstream.

 

Looking towards the latter week of the month - the theme looks to be strong mid atlantic heights with distrubances running down from the NW, maintaining the chilly theme but cutting off any more direct northerly influence, every chance the ridge could build in towards the country meaning a settled frosty but also 'sunny' - shock horror end to the month. November here is turning into an exceptionally dull month, we haven't seen hardly any brightness since the 3rd!

[bluearmy]

Would I be right in thinking that the bias corrected GEFS are currently not too relevant as they would be bias correcting the bias' of the old model?

[Polar Maritime]

Would I be right in thinking that the bias corrected GEFS are currently not too relevant as they would be bias correcting the bias' of the old model?

 

Sounds about right Blue, With the up-grade a few months back. Surly there will still be 'some' bias either way but at this stage nothing really stands out and possibly 'hopefully' never will to the degree it did. 

Edited November 15, 2015 by Polar Maritime

[johnholmes]

I am not sure what bias is in this context. Is it perhaps the difference NOT of the model to its past but more simply the ACTUAL heights for example as an average in November over x number of years. Not sure what time scale they would use, one sees 61-00 and others?

Ideas?

[nick sussex]

So the UKMO has been invited to the party but prefers to stay at home and wash its hair!

 

The party I'd put as colder a chance of some snow but not really a 5 star cold snap, I'd rate it at 3 stars at the moment. The UKMO looks about 1.5 to 2 stars if I'm being generous.

 

Things may well upgrade and the ECM looks more interesting as we see that high pressure cell developing near Scandi.

 

In an effort to get to the bottom of the UKMO turning down the invitation been seeing what USA forecasters like upstream because essentially that's the reasons for the less enthused UKMO output. If we put aside what happens post T144hrs and deal with the respective upstream patterns especially in the west USA the UKMO stands out like a bacon buttie salesman at a vegetarian convention.

 

We have the ECM/GFS/GEM all similar in the west USA, the UKMO has a shortwave digging south into Montana from Arctic Canada. In terms of the pattern over the eastern USA, forecasters are expecting a frontal wave there and the eastwards progression has been the subject of model divergence, currently they prefer the ECM.

 

For the timebeing I'd discard the UKMO solution and go with the GFS/ECM/GEM combo.

 

In the state discussions for New York they're also talking about possible changes to the NH pattern, its very interesting and does have repercussions for Europe. Of most interest is what they're saying about troughing setting up over central Canada, now the importance here is the centre bit rather than ne east Canada. Anyway heres the full quote:

 

GENUINE COLD WEATHER HAS BEEN TOUGH TO COME BY SO FAR THIS FALL...
AS THE COMBINATION OF SEVERAL GLOBAL TELECONNECTIONS HAVE GENERALLY
KEPT ANOMALOUSLY COLD AIR LOCKED NORTH OF 60N. A STRONG PACIFIC
JET...TYPICALLY ASSOCIATED WITH STRONG TO MODERATE EL NINO EVENTS...
HAS BEEN THE MOST NOTEWORTHY FACTOR IN BLOCKING ANY SIGNIFICANT COLD
AIR INTRUSIONS UP TO THIS POINT. THIS RESULTED IN NEAR NORMAL
TEMPERATURES FOR THE MONTH OF OCTOBER AND WELL ABOVE NORMAL READINGS
THROUGH THE MIDDLE OF THIS MONTH. THIS PATTERN MAY BE SHOWING SIGNS
OF BREAKING DOWN THOUGH.

SIGNIFICANT SNOW COVER ACROSS SIBERIA HAS LIKELY HELPED TO INTENSIFY
THE COLD AIR OVER THAT REGION...AND NOW SEVERAL ENSEMBLE GUIDANCE
PACKAGES ARE SUGGESTING THAT SOME OF THIS COLD AIR MAY SOON BE ON
THE MOVE. AFTER MORE THAN SIX WEEKS OF A PREDOMINANTLY POSITIVE NAO
WITH PERSISTENT LOW PRESSURE OVER THE NORTH ATLANTIC...MEDIUM TO
LONG RANGE GUIDANCE IS SUGGESTING THAT BLOCKING MAY FINALLY SET UP
OVER THAT REGION WHILE WEST COAST RIDGING SETS UP OFF NORTH AMERICA.
THIS WOULD RESULT IN A DEEP TROUGH OVER CENTRAL CANADA THAT WOULD
ENCOURAGE THE AFOREMENTIONED COLD AIR TO CROSS THE NORTHERN
LATITUDES OF THE CONTINENT...POSSIBLY TAKING AIM ON THE U.S. PLAINS.

THIS SCENARIO WOULD NOT TAKE PLACE UNTIL LATER THANKSGIVING WEEK OR
THANKSGIVING WEEKEND...BUT IT IS THE FIRST TIME THAT IT IS BEING
STRONGLY SUGGESTED BY SO MANY OF THE VARIOUS ENSEMBLE MEMBERS OF
BOTH THE ECMWF AND GFS. IT WILL BE INTERESTING TO SEE HOW THIS ALL
PANS OUT.
 

Edited November 15, 2015 by nick sussex

[shaky]

So the UKMO has been invited to the party but prefers to stay at home and wash its hair!

 

The party I'd put as colder a chance of some snow but not really a 5 star cold snap, I'd rate it at 3 stars at the moment. The UKMO looks about 1.5 to 2 stars if I'm being generous.

 

Things may well upgrade and the ECM looks more interesting as we see that high pressure cell developing near Scandi.

 

In an effort to get to the bottom of the UKMO turning down the invitation been seeing what USA forecasters like upstream because essentially that's the reasons for the less enthused UKMO output. If we put aside what happens post T144hrs and deal with the respective upstream patterns especially in the west USA the UKMO stands out like a bacon buttie salesman at a vegetarian convention.

 

We have the ECM/GFS/GEM all similar in the west USA, the UKMO has a shortwave digging south into Montana from Arctic Canada. In terms of the pattern over the eastern USA, forecasters are expecting a frontal wave there and the eastwards progression has been the subject of model divergence, currently they prefer the ECM.

 

For the timebeing I'd discard the UKMO solution and go with the GFS/ECM/GEM combo.

 

In the state discussions for New York they're also talking about possible changes to the NH pattern, its very interesting and does have repercussions for Europe. Of most interest is what they're saying about troughing setting up over central Canada, now the importance here is the centre bit rather than ne east Canada. Anyway heres the full quote:

 

GENUINE COLD WEATHER HAS BEEN TOUGH TO COME BY SO FAR THIS FALL...

AS THE COMBINATION OF SEVERAL GLOBAL TELECONNECTIONS HAVE GENERALLY

KEPT ANOMALOUSLY COLD AIR LOCKED NORTH OF 60N. A STRONG PACIFIC

JET...TYPICALLY ASSOCIATED WITH STRONG TO MODERATE EL NINO EVENTS...

HAS BEEN THE MOST NOTEWORTHY FACTOR IN BLOCKING ANY SIGNIFICANT COLD

AIR INTRUSIONS UP TO THIS POINT. THIS RESULTED IN NEAR NORMAL

TEMPERATURES FOR THE MONTH OF OCTOBER AND WELL ABOVE NORMAL READINGS

THROUGH THE MIDDLE OF THIS MONTH. THIS PATTERN MAY BE SHOWING SIGNS

OF BREAKING DOWN THOUGH.

SIGNIFICANT SNOW COVER ACROSS SIBERIA HAS LIKELY HELPED TO INTENSIFY

THE COLD AIR OVER THAT REGION...AND NOW SEVERAL ENSEMBLE GUIDANCE

PACKAGES ARE SUGGESTING THAT SOME OF THIS COLD AIR MAY SOON BE ON

THE MOVE. AFTER MORE THAN SIX WEEKS OF A PREDOMINANTLY POSITIVE NAO

WITH PERSISTENT LOW PRESSURE OVER THE NORTH ATLANTIC...MEDIUM TO

LONG RANGE GUIDANCE IS SUGGESTING THAT BLOCKING MAY FINALLY SET UP

OVER THAT REGION WHILE WEST COAST RIDGING SETS UP OFF NORTH AMERICA.

THIS WOULD RESULT IN A DEEP TROUGH OVER CENTRAL CANADA THAT WOULD

ENCOURAGE THE AFOREMENTIONED COLD AIR TO CROSS THE NORTHERN

LATITUDES OF THE CONTINENT...POSSIBLY TAKING AIM ON THE U.S. PLAINS.

THIS SCENARIO WOULD NOT TAKE PLACE UNTIL LATER THANKSGIVING WEEK OR

THANKSGIVING WEEKEND...BUT IT IS THE FIRST TIME THAT IT IS BEING

STRONGLY SUGGESTED BY SO MANY OF THE VARIOUS ENSEMBLE MEMBERS OF

BOTH THE ECMWF AND GFS. IT WILL BE INTERESTING TO SEE HOW THIS ALL

PANS OUT.

what do the last 2 paragraphs mean for the uk?cold or mild?

[bluearmy]

Could be either shaky. (Or possible average)

It does mean cold for the eastern half of n America though.

perhaps better to view it as a pattern change upstream offers up the possibility for the pattern to change for nw Europe too. No guarantees that this would be a colder pattern though.

[nick sussex]

what do the last 2 paragraphs mean for the uk?cold or mild?

You'll see they're not talking about cold in the ne/east USA which is good news for the UK. I think there are three possible scenarios, two good one bad for the UK.

 

So either high pressure north Atlantic/southern Greenland, cold northerly for the UK.

 

The high further west Greenland, low pressure central Atlantic, depending on the amplitude high ahead of that low near Scandi.

 

The it sucks outcome is if we end up with a western negative NAO and the block west but not west enough with troughing slow moving near the UK.

 

Much depends on how amplified that Canadian trough is. Overall at least the UK has a chance of something wintry as compared to the Autumn so far and that update is overall good news for those who like colder weather.