Model Output Discussion - 23rd Jan - 12z onwards

[The Weather Dragon]

It will be interesting to know if the METO still see signals for blocking Mid Feb, if so then maybe some changes to the current mid term outlook will happen.  Not much sign of this happening at the minute but with a bit of strat warming in the offing maybe the models are not seeing the bigger picture medium - long term. 

MET also have access to different models

 

I think there is a bit of a lag between what we see in the latest model output and Media ouput/TV broadcasts

[Frosty.]

Nice ukmo 0z this morning, here's an idea, let's enjoy the cold while it lasts..when it arrives during midweek and especially the weekend arctic blast!

[bluearmy]

Nick s, the spread s of Greenland begins to look moe like a deep depression with each run!

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY MONDAY JANUARY 26TH 2015.

NEXT UPDATE TUESDAY JANUARY 27TH 2015 08:00

THE CURRENT GENERAL SITUATION A ridge of High pressure will follow the cold front out of SE Britain this morning. Then following the ridge will be a return to a milder SW flow with troughs affecting the NW by tomorrow gradually easing SE later.

MODELS-2 WEEK HEADLINE Becoming colder with snow showers or snow at times. Then becoming less cold and changeable again in Week 2.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Forecast shows a week long spell with a deep trough over Europe keeping the flow well South of the UK in NW winds. In week 2 the pattern flattens markedly over the Atlantic and Europe with the flow returning North across the UK between High pressure re-established to the South of the UK and Low to the North.

GFS OPERATIONAL The GFS operational today shows a colder plunge of Arctic winds later this week as Low pressure transfers SE down the North Sea and then further East over Europe. Winds from the NW then North will deliver snow showers to many later in the week with settling snow in places as well as longer sells of sleet or snow too here and there. Then as we move into next week less cold air spills down from the NW as High pressure becomes more dominant again close to SW Britain with outbreaks of rain and wintry showers at times in the North the likely pattern by the end of next week.

THE GFS CONTROL The GFS control run follows the operational this morning firming up on a rather quicker change back to less cold Westerly winds next week with some rain at times mostly in the North.

THE GFS CLUSTERS The GFS Clusters today support the operational and control runs much better than yesterday with a return to normal service of Westerly winds around Low pressure to the North and High pressure to the South as we move through next week with an almost two thirds majority supporting this pattern.

UKMO UKMO this morning continues to illustrate a dip into cold and wintry conditions later in the week as from Wednesday the currently benign weather pattern turns into strong NW then North winds with snow showers peppering all exposed locations facing North and giving rise to frosts by night and the risk of more sustained snowfall as disturbances will no doubt pop up at short notice and move South within the flow. This pattern taking us round to next Sunday though by then a ridge lies closer to the West to likely cut off the north flow early next week.

THE FAX CHARTS The Fax Charts follow the tracks of the raw data well but due to their human input illustrate much clearer how unstable the cold airflow will be late this week with bands of organised wintry showers, many of snow sweeping down over the UK at times later this week and next weekend.

GEM GEM today is a little different to GFS in as much as it makes much more of the ridge over the Atlantic next weekend and over the start of the new week with ridging all the way to Iceland. The net result is shifting winds around to the NE and prolonging the cold for several more days than GFS as the High only slowly dislodges the cold winds from the NW late next week.

NAVGEM NAVGEM today shows the shift to cold and windy conditions too after Wednesday with Low pressure close by over the North Sea bringing showers or longer spells of wintry precipiation in places especially thise with exposure to the North and NW. The end of the run does illustrate a backing of winds towards the NW as the High pressure ridge over the Atlantic steadily collapses and eventually allowing milder winds to move into the Uk from the NW and west as we move through next week.

ECM ECM this morning also takes up the baton of somewhat less cold air filtering into the UK from the West and NW early next week as the High pressure ridge over the Atlantic collapses under pressure form Low's exiting Canada. It looks like taking quite a while for anything significantly less cold to reach the South with a High pressure ridge extending from the Azores across Southern Britain to Denmark with frosty conditions still possible here while the North sees milder Westerly winds and occasional rain.

ECM 10 DAY MEAN The 10 Day Mean this morning supports the evolution that Low pressure will lie to the NE and East of the UK over Scandinavia and Europe as well as Greenland. Contrastingly High pressure is shown to most likely to be ridged between the Azores and Iceland keeping the UK under a cold feed from the North.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend remains for much colder and windy weather later next week and through next weekend. The longevity of the spell has firmed up somewhat on milder conditions returning from the West as we move deeper into next week.

MY THOUGHTS There is little change in the output this morning with regard to the onset of the sharp cold spell midweek. However, there is some shift away from extending the cold too far into next week as most output has firmed up on the Atlantic ridge supporting the cold flow later this week collapsing SE and allowing a feed of less cold West or NW winds across the UK. It comes down once more to the inability of pressure to be able to build far enough North across the Atlantic towards Greenland or Iceland with only GEM offering much support in that field this morning. Nevertheless, this was always likely to be the most likely scenario to come out of this cold spell and unlike yesterday it is just that we now have almost cross model support for this to become the case. Coldies should not be disheartened however as in the short term nothing has changed and all parts of the UK can look forward to 5 or 6 days at least of cold North or NW winds driving down across the UK with sleet and snow showers and no doubt some longer spells of snow too in places. Frosts and windchill will be notable factors for many and no doubt some disruption is likely to develop in the North especially. Then as we move into next week winds look like backing more NW then West with more changeable conditions returning with bands of rain crossing East and followed by colder weather with wintry showers in the NW, in other terms a return to the pattern of much of the Winter thus far. This change looks likely it will be last to reach the SE with ECM indicating a cold ridge still across Southern Britain by Thursday of next week though this scenario is less likely having looked at the ECM 9 and 10 day mean chart. My own thoughts this morning that the cold will likely wane next week but I still think we are likely to see further attacks from the North later in February as the persistent pattern of the Winter up to this point now looks like persisting in the period towards the end of the meteorological Winter with little support for much chance of anything likely from the East while the polar vortex in the Greenland area remains so strong. For thise who like cold and snow sit back and enjoy what transpires from Wednesday. It is an ocean away from what we witnessed last Winter and is about the normal standard cold snap we experience in the UK, both in strength and duration.

[phil nw.]

I must confess to being a little surprised  at some of the comments this morning.

Anyone following the ens. and trends in the op runs will have seen that the coming cold spell was always likely to ease around the 4/5th February as the Azores high started to come back in.

 

The 2m Ens graph for yesterday and today shows this

 

a prolonged spell of more than a week has never been on the cards from all the runs i have seen recently so the trend to something less cold remains as before.

 

The ECM mean showing the cold air being pushed away by day 10

and the Azores ridge toppling this way.which is pretty much as expected. 

 

[Kentish Snowman in Yorks]

Unfortunately the absence of upstream blocking with a flattened jet without bifurcation makes any northerly on these shores likely to be transient. It's toppler territory, at best.

Yes there has been and still is a lack of blocking to our North this winter, particularly in the Greenland area which makes the chances of any 'prolonged' freeze up unlikely.

And yes I suppose that in the strictest sense of the setup, we do have a Northerly toppler.

However, I do believe that you are not doing the current projected setup justice. To me, a standard transient toppler is a 24 hour affair with a few wintry showers around the coast.

This looks far more potent than that and there is still the potential, despite the continuing negativity in here, for snow to fall and settle just about anywhere in the UK between now and this time next week. All of the models around the 144 mark this morning show a screaming Northerly which could well contain troughs and disturbances etc.

Lets enjoy the next seven days and see where we are then. We have a cold spell starting in 48 hours which could last five days, maybe longer.

Even if the whole pattern collapses early next week, I firmly believe there will be more opportunities for cold and snow as we go into February...

Edited January 26, 2015 by Kentish Snowman

[nick sussex]

Nick s, the spread s of Greenland begins to look moe like a deep depression with each run!

Yes I agree especially when you look at the De Bilt ensembles, there is also a  cluster that looks like it takes a low se to the sw of the UK between T168 and T192hrs but overall those extended ensembles look in the majority to be bringing in much more mobility. Still a few there that keep things colder but overall the signal looks pretty strong to me.

[frosty ground]

I must confess to being a little surprised  at some of the comments this morning.

Anyone following the ens. and trends in the op runs will have seen that the coming cold spell was always likely to ease around the 4/5th February as the Azores high started to come back in.

 

The 2m Ens graph for yesterday and today shows this

w2.pngw3.png

 

a prolonged spell of more than a week has never been on the cards from all the runs i have seen recently so the trend to something less cold remains as before.

 

The ECM mean showing the cold air being pushed away by day 10

EDH0-240.gif

and the Azores ridge toppling this way.which is pretty much as expected. 

Spot on...... nothing has changed........ And you have even used charts to back it up...... 

[winterof79]

There are going to be some unhappy bunnies if it is cold and dry that you are expecting.Showers driven well in land Wednesday

                   

And plenty of instability Thursday 

[Summer Sun]

Amongst any snow later this week and early Feb the wind chill is going to make it feel bitter

 

 

Whilst daytime highs get upto around 3c to 5c the wind chill will make it feel much colder so even if you don't get any snow it will still be felling bitterly cold

 

Edited January 26, 2015 by Summer Sun

[Alexis]

There are going to be some unhappy bunnies if it is cold and dry that you are expecting.Showers driven well in land Wednesday

 

                   

And plenty of instability Thursday 

 

 

Widespread snow showers in the north west and NI in 2004, in 850s of -6 and -7.

Edited January 26, 2015 by Alexis

[winterof79]

Seems to have a decent handle on the situation when compared to the fax charts

 

 

http://www.myweather2.com/synop/player.aspx?synop=2

[sorepaw1]

This cold snap was always going to be short lived.i read a reference to someone comparing it to 2010.in 30 years of forecasting. Unless we get a blocking high pressure at or above 1055mb in either Greenland or a scandi high.we won't get a prolonged period of snowy cold weather.we can look at all computer data and models till we are blue in the face.but in my experience that's the basic principles of a prolonged period of cold weather . I'm looking forward to seeing 4 days of snow showers all the same.i will update this post tonight when I get back to my ipad at home.

[winterof79]

Looking at the weekend and the Low filling somewhere east of us,it can bring very wintry conditions and has in the recent past.Localised streamers can easily set up

 

 

Here in 2009 

 

And yes that is the ever present Azores high

Edited January 26, 2015 by winterof79

[mulzy]

Some interesting weather ahead this week.  No nation-wide freeze but a cool/cold spell with a few wintry showers in places.  Scotland and north western parts of England as well as parts of Wales likely to get some decent accumulating snow especially if aided with some elevation.  For most of lowland England this upcoming spell is unlikely to deliver - however with the wind it will feel bitter at times though temperatures will comfortably be above freezing by day.

 

The medium term outlook is very poor - strong positive NAO with a strong Polar Vortex over Greenland and the high Azores High taking up it's normal residency.  The Debilt ECM ensembles attached...

 

Edited January 26, 2015 by mulzy

[Dr. Astro]

This cold snap was always going to be short lived.i read a reference to someone comparing it to 2010.in 30 years of forecasting. Unless we get a blocking high pressure at or above 1055mb in either Greenland or a scandi high.we won't get a prolonged period of snowy cold weather.we can look at all computer data and models till we are blue in the face.but in my experience that's the basic principles of a prolonged period of cold weather . I'm looking forward to seeing 4 days of snow showers all the same.i will update this post tonight when I get back to my ipad at home.

 

Not wrong there sorepaw1 - Not only that we have the following:

 

Roaring Jet

 

 

All the way through to the end of the run:

 

 

The PV strongly around Canada / Greenland

 

 

Again, all the way through to the end of the run:

 

 

Pluz zero signs of any blocking.

 

This charts sums this Winter up for me:

 

 

Cold & sometimes snowy incursions, quickly followed by a breakdown, followed by a transient wet & windy small "storm" in a rinse & repeat fashion.

 

It's better to view the NH Charts to get a good scope of how things are:

 

 

 

What I would say is any cold incursions from the West, North West or North, enjoy them when they come, because I doubt we will see any sustained cold for the foreseeable future.

[karyo]

Looking at the weekend and the Low filling somewhere east of us,it can bring very wintry conditions and has in the recent past.Localised streamers can easily set up

 

 

Here in 2009 

 

And yes that is the ever present Azores high

The 2009 chart has decent high pressure further north which is missing from this week's picture.

[winterof79]

The 2009 chart has decent high pressure further north which is missing from this week's picture.

We may not have high pressure to the north but that does not affect wether we get snow from any particular trough setting up in our locale.

 

The 06z chart not looking three bad either

 

 

Edited January 26, 2015 by winterof79

[TEITS]

This is the period of interest for me at +144!!

 

http://www.wetterzentrale.de/pics/Rtavn1441.gif

 

Some of the GEFS ensembles last night hinted at pressure rising towards S Greenland and instead of low pressure toppling the AZH we see low pressure going underneath. Now this is very much an outsider but a sudden flip at +144 towards a much colder NE/E,ly cannot be ruled out!

[Liam J]

Better 6z so far, trough not as deep upstream and further south with better ridging in the Atlantic. I know we shouldn't scrutinize each run but worth a mention! Cold spell may get extended on this run, better wait for all the 12z's later to see how we stand. 

 

 

 

[winterof79]

Mr Benn is at it again Nick.....

 

 

 

 

 

 

Edited January 26, 2015 by winterof79

[Man With Beard]

And back to the here and now. Wednesday - Friday: dew-points looking ok for snow pretty much everywhere throughout this period, except temporarily on a couple of coasts:

Now further ahead - whilst I agree with the logic of most posts here (i.e. no northern blocking = no sustained cold), we have to remember that all our recent short cold spells have appeared quite late in the day. The low-level snow opportunities for this week were non-existent until T168/T192 IIRC. There's definitely a pattern this winter for the Azores High to drift ever so slightly NW-wards as T0 approaches - that tendency could prolong the cold a bit more. So it would be unwise to shout from the rooftops that the cold spell will end next Monday/Tuesday just yet.

 

In fact the latter stages of GFS 06Z demonstrate what could happen: slightly different interaction off Newfoundland and suddenly we're almost getting energy going south under a block.

[shaky]

I really do think the met office warnings will extend the warning area today!! This northwesterly that is coming up has plenty of troughs coming across the uk im very cold air!! Could mean streams of snow showers one after the other!! Gfs 06z looks brilliant so far with a stronger atlantic ridge!!

[Ali1977]

There looks to be a front crossing North to South on friday with a fair bit of precip within it, looking at the precip type it shows rain...and slightly warmer 850s. 

Is it possible this could be a snow event??

Early next week could have a substantial snowfall on latest GFS, big uprade for longevity of cold too.

Edited January 26, 2015 by Ali1977

[TEITS]

This is going to be unusual should it occur.

 

I am so used to looking for snow showers from the NE/E but never coming from the cheshire gap.

 

http://www.wetterzentrale.de/pics/Rmgfs813.gif

 

Derbyshire tend to do well in these situations as does Wales.