Model Output Discussion 1st Nov.2013

[Summer Sun]

Latest from Gibby on the models

 

All models show that the weather will remain changeable between now and the start of next week as High pressure holds to the SW of Britain. Occasional cold fronts will cross SE, one such one overnight tonight and another on Sunday with rain for a time for all. Through this 5 day period temperatures will be close to normal but rather chilly at times in the North. Sunshine after today and tomorrow will be at a premium as cloudier skies from the Eastern Atlantic invade the UK over Friday and Saturday holding temperatures back somewhat even in the South at the weekend.

 

GFS then shows a spell of colder and unsettled conditions early next week with spells of rain with sleet or snow over the hills and the risk of overnight frosts as skies clear overnight. However, this situation doesn't last long as High pressure reverts to a position SW of the UK allowing milder Atlantic weather to return. As a result the rest of the run becomes a case of changeable and sometimes wet conditions with wind, rain and showers occurring for all areas periodically with temperatures close to average.

 

UKMO shows Low pressure up to the NE with a rather cold WNW flow with showers and sunny spells following a band of rain SE through the day on Tuesday. Snowfall will be reserved for the higher ground of the North.

 

GEM shows a more sustained cold period developing from early next week with Low pressure close to the East giving a cold Northerly airflow. A ridge then develops across the UK briefly with another surge of cold Northerlies as Low pressure deepens to the East of Britain at the end of the run. Rain or wintry showers would be the order of the day through the period with temperatures below average and frost developing at night as the ridge towards the end of the week allow skies to clear.

 

NAVGEM maintains it's quest of dropping Low pressure down to the West of Britain early next week with wet and windy weather with temperatures on the low side of average without ever being desperately cold. As a result of this the weather will be very unsettled and often wet in cyclonic winds. Snow would reserved mostly for the high ground of Scotland.

 

ECM today shows deep Low pressure migrating SE across the North Sea to SE Europe next week as pressure builds from the NW later. The weather will become cold and unsettled next week with rain or sleet at times and snow over all higher ground in a blustery and chilly wind from the North. Late in the run drier conditions move down from the NW with cold and frosty weather developing later with freezing fog problems likely to become an issue.

 

The GFS Ensembles clearly show a trend towards a rather colder and unsettled period next week. Things never become desperately cold however and any snowfall will be reserved for the hills of the North for the most part. The north look like it may become somewhat less chilly later while the SE appear to hang on to the rather chilly conditions for longer though at the outer limits of the run there is much spread between the members as normal.

 

The Jet Stream shows the flow ridging North high over the Atlantic at the moment and away across Northern Europe. Later in the weekend and next week it dives South across the UK and then some output shows it setting up a position to the South and West of the UK by the end of next week, this mostly shown by ECM.

 

In Summary today the weather is now more or less guaranteed to turn rather colder next week. With Low pressure close to the East and a fresh Northerly airflow it will feel much colder than anything we have experienced so far this season. There will be showers or longer spells of rain too moving through in the flow with some snowfall on all Northern hills and mountains with high level routes subject to some disruption. Longer term it looks likely that a change to more settled conditions from High pressure to the NW, (ECM) West, (GEM) or SW (GFS) is likely and depending on which solution is right will determine conditions over the UK. Any ridging from the NW will mean cold, frosty and foggy conditions being possible while from the SW would allow milder Atlantic winds to topple over the UK to return milder and cloudy conditions with occasional rain.

 

http://www.norton-ra...is(2859336).htm

[Gavin Hannah]

The negative AO and NAO is one of the things we need for a good winter in my opinion.  The two epic winters of 09 and 10 each had severely negative NAO and AO months. It looks as though the start of winter / end of autumn will be quite cold now.  I still don't see any signs of any blocking being set up atm but lest we not forget the Nov/Dec period of winter 2010/11.  The models just now are pointing towards wintry weather next week (Currently waxing my board  ) and while I'm not an expert (far from it), I still think it's possible to see the HP ridging to our NW, then migrate into a favorable position, and get "stuck" there. I.E End of Nov 2010.

[draztik]

The NAO likely to turn negative next week, with unity for the 19th. Tho the decline thereafter is weak, and a more neutral level seems likely. The AO remains positive throughout its forecast period, but the signal becomes a weak positive nearer the end of Nov.

[garbagebags]

The negative AO and NAO is one of the things we need for a good winter in my opinion.  The two epic winters of 09 and 10 each had severely negative NAO and AO months. It looks as though the start of winter / end of autumn will be quite cold now.  I still don't see any signs of any blocking being set up atm but lest we not forget the Nov/Dec period of winter 2010/11.  The models just now are pointing towards wintry weather next week (Currently waxing my board  ) and while I'm not an expert (far from it), I still think it's possible to see the HP ridging to our NW, then migrate into a favorable position, and get "stuck" there. I.E End of Nov 2010.

 

But arent the AO and NAO graphs produced from info taken from the model runs? They don't come before the models, they come after.

[Gavin Hannah]

But arent the AO and NAO graphs produced from info taken from the model runs? They don't come before the models, they come after.

 

They do come after. But its what we want (perhaps need in 9 out of 10 winters) for good wintry weather patterns. 

 

I'm assuming many folks are watching the 06Z roll out lol so getting in there early with this one.

 

Both 06Z and 00Z for t.96 showing plenty of N.american amplification. The Vortex is an utter shambles.  

 

 

Edited November 13, 2013 by IBringTheHammer

[Summer Sun]

As already stated NAO is now going to go negative during next week it was about 50/50 at one stage but its firmed up now

 

[radiohead]

06Z GFS at T144

 

[Frosty.]

I think this is the most wintry looking Ecm 00z ensemble mean of the season, very amplified with cold air flooding south early next week and lasting all week, high pressure staying out to the west and the PFJ digging down as far as central spain, low pressure to the northeast. I think there will be snow showers in a number of areas next week with widespread frosts, some sharp, and max temps struggling in low single digits celsius with frosts soon setting in each evening..an early bonus taste of winter, the opening salvo.  I love cold weather

Edited November 13, 2013 by Frosty.

[cyclonic happiness]

So the GFS is having is traditional 'pre cold spell wobble' where is goes against all the other models , usually for two days before joining in the party with some stunning charts (should be tonight on the 18z).

 

The best cold spells we've had all feature the GFS 'wobble' just beforehand. 

 

So worry not guys! :-)

[swfc]

Id agree with one or two posters on the pv being in a weak state at least but if any push towards greenland is to happen imo the pv to the north of greenland needs to trasfer east .It still looks a bit to strong altho as sm stated on the ukmo at 144 hrs there are tentative signs of a split.id go for a mlb block after the initial cold-cool spell but thats only based on the current output regarding the pv to the north of greenland.Also as stated good amplification coming off the eastern seaboard is a good sign and all in all very interesting mo atm!!

Edited November 13, 2013 by swfc

[Gavin Hannah]

Id agree with one or two posters on the pv being in a weak state at least but if any push towards greenland is to happen imo the pv to the north of greenland needs to trasfer east .It still looks a bit to strong alth as sm stated on the ukmo at 144 hrs there are tentative sighns of a split.id go for a mlb block after the initial cold-cool spell but thats only based on the current output regarding the pv to the north of greenland.Also as stated good amplification coming off the eastern seaboard is a good sign and all in all very interesting mo atm!!

 

The LP that moves into Greenland is a key feature. Its positioning will determine the duration of the northerly and the conditions it delivers for next week. 

[draztik]

Those North of the border will definitely feel the chill next week. The ECM ens keep you well below average for this time of year.

ECM ens 0z / Glasgow

[swfc]

The LP that moves into Greenland is a key feature. Its positioning will determine the duration of the northerly and the conditions it delivers for next week. 

It needs to go up the west side of greenland if the pressure rise is to build over greenland imo

[Frosty.]

Arctic air incoming on the GFS 06z op run, snow showers spreading south and frosts becoming widespread..it will feel like winter next week.

[radiohead]

Not much change on the 06Z GFS from the previous run in hi res. Same theme.

 

[garbagebags]

00z and 06z are twins in high res.

[Frosty.]

This really is the most wintry Ecm 00z ensemble mean so far, next week will be very cold and wintry for the time of year if it verifies.

[swfc]

For me fi on the 6z is in the 162 range.Expect some eye candy out the latter stages of the later runs todayAnd on cue here it comes!!!!  

Edited November 13, 2013 by swfc

[Gavin Hannah]

FI rocks lol.

 

The blocking is "locked and loaded"!

 

 

 

Is that a Greenie on the Horizon????  

Edited November 13, 2013 by IBringTheHammer

[radiohead]

Hey now...

 

 

An interesting end to FI for sure.

 

Edited November 13, 2013 by radiohead

[shaky]

My word what an fi for cold lovers on the gfs 06z . atlantic completely blocked off.

[swfc]

The low takes the waa up the west side of greenland an indeed does form a greenland high be it a very lightweight one,if only

Edited November 13, 2013 by swfc

[Frosty.]

At least the Gfs 06z op run shows cold weather bossing the outlook for a change, cold spells and mild blips instead of the other way around and those FI charts are gradually morphing into a potentially much more wintry retrogressing pattern, nov/dec 2010?

[Cecil Hogmanay Melchett]

My word what an fi for cold lovers on the gfs 06z . atlantic completely blocked off.

But little or no cold air to tap into.Still,Europe would cool down very nicely as we head towards December.

[Gavin Hannah]

But little or no cold air to tap into.Still,Europe would cool down very nicely as we head towards December.

 

This could be the watered down version though ...