Model Output Discussion - 5th December - 11th December

[lorenzo]

This area of low pressure @ 168hrs is also evident in the immediate time frame at 6 hrs, why is this region ejecting severe lows? Is this a trend or is this GFS at its over excited best. Cannot help wondering if this is in relation somehow to the classic pacific ridge?

[The Enforcer]

Can someone please write

1 A definition of the term short wave

2 A definition of the term slider

Thanks.

For the 'mother' of all sliders select "1978", "December" and "31" here: http://www.netweathe...ction=gfs;sess=

Edited December 5, 2011 by The Enforcer

[legritter]

evening , a message for the new ones or learners . dont get down if what you see is not what you want ,. iv had 50 odd years obsessed with the weather , being told when a small boy to get back in bed by my mother in the middle of the night when i used to open the window for lamp post watching etc . listening to the shipping forecast aged 10 . having weather charts delivered by post when in my late 20s ,5 day outlooks ,by the time i got them they were out of date ,all changed . this computer lark is out of this world but addictive . iwas totally stressed 24 hrs ago so i stayed of computer, looked on site late tonight and now i feel good .atleast this weekend could be full of surprises ,with different air masses about ,and next week could go severall ways ,i find it helpfull sometimes to go onto some of the webcams in north america or canada ,winnipeg as got some good ones, watch their weather it soothes you .,then come back on NET WEATHER when youre relaxed a bit , i just feel that we need pressure to fall about 10mbs over the south of us ,.as an ex fellow of the royal meteorological society i have met many a knowledgable e ..professor and research scientists and they all say well most , dont put much trust beyond 120 144 hrs unless its a massive agreement , i must admit things have moved on over the last 10 20yrs . always remember someone is wishing in scotland for their fix ,and someone in cornwall is wishing . so you will need to read between the lines ,the white stuff can come at fairly short notice ,if a good mix is around , any how my wife as just said on the weather again no wonder you cant sleep ,cheers legritter ,.

[lorenzo]

Great example and an interesting evolution especially from here http://www.wetterzentrale.de/archive/ra/1978/Rrea00119781222.gif

[yorkieblade]

Not sure if this is the correct thread for this ..apoligies in advance if not and please point me in the correct direction for future...

Newbie to this but an avid lurker...find all of you posts fascinating.

Is this what is known as a "Greenland Blocker" or a "Greeny High"? and did this encourage the easterly for Jan 10..?

http://www.netweathe...action=gfs;sess=

Sorry please choose Jan 2010 from list

Thank you in advance

Edited December 6, 2011 by yorkieblade

[k19]

Not sure if this is the correct thread for this ..apoligies in advance if not and please point me in the correct direction for future...

Newbie to this but an avid lurker...find all of you posts fascinating.

Is this what is known as a "Greenland Blocker" or a "Greeny High"? and did this encourage the easterly for Jan 10..?

http://www.netweathe...action=gfs;sess=

Sorry please choose Jan 2010 from list

Thank you in advance

No a greenland high is when the high pressure is centred over greenland, effectively blocking the atlantics low pressure conveyor belt from us, sending it south a long with the jet.

I believe that evolved from a greenland high a few days prior to it though

Edited December 6, 2011 by K.1000

[Cecil Hogmanay Melchett]

Evening All-

I know I keep on but Im convinced the ECM & the GFS are wrong with ramming the atlantic down our throats at 168-

Im expecting more trough Disruption over Southern Greenland - so we get a long trough extension all the way from South Greenland all the way out to France...

The Control is Interesting-

Heres a thought- we have had endless after endless ensembles that have all shown repetative zonal weather crashing into Europe- & yet to date we havent got there with one low & SW winds..

Looking forward to a possible change in the 00z's!

S

I'll bet my bottom dollar theres very little of interest for coldies on the 0z runs.The pattern is bloody awful and i think most of us in our hearts of hearts know there will be absolutely nothing of interest coldwise this side of christmas.

(aside from the odd 24/36 hour pm incursion).

Edited December 6, 2011 by happy days

[The PIT]

Plenty of interesting weather to come. Very windy at times if you like photographing waves it will be worth walking down to the beach. Some sleet and snow and times for northern hills. Plenty of action to come and very interesting unless you like dull foggy weather...

[IDO]

Plenty of interesting weather to come. Very windy at times if you like photographing waves it will be worth walking down to the beach. Some sleet and snow and times for northern hills. Plenty of action to come and very interesting unless you like dull foggy weather...

Yes for anyone North of Birmingham but for the South little till January at the earliest. Even up North it is transitional and very normal Winter fare. Models are beginning to merge to zonal with no apparent change in the medium term.

[snow drift]

Yes for anyone North of Birmingham but for the South little till January at the earliest. Even up North it is transitional and very normal Winter fare. Models are beginning to merge to zonal with no apparent change in the medium term.

January is a long time away in terms of weather.

Many times I have viewed the models and thought what you are saying, only for it all to change.

In my opinion, past Friday is fi.

I know many are holding January as the month when things will happen but this is based on what people have read and it may not work out the way people think.

Therefore you will have been wishing time away to get to a time where it doesn't deliver what you wish for and then huge disappointment.

In terms of model viewing and learning, this is a fantastic time. There is so much going on, with models giving different ideas and changing from run to run.

A great time to increase your learning and gain experience on how subtle differences can affect what falls from the sky.

We are very keen to look at the models to see what will/may happen. I would encourage looking back at the models and viewing what actually happened on a specific day.

This will increase learning enormously.

[Zakos]

As the met office had said, potential for wintryness from the midlands northwards. After seeing a sleet shower yesterday, I have woken up to it snowing outside, and I live in central england, on the border with east anglia. I have seen on my iPhone apps radar that the snow has been quite widespread In western areas, sometimes coming in further inland. Nothing substantive south of, say,Manchester. But, snow itself certainly not confined to scotland or high ground, as some said it would be. The models, again, are upgrading the length of this polar maritime dominated spell. This looks like lasting quite a long time, with only minor mild blips. Friday, unlike today, has the potential to produce widespread, and in places heavy snow. It wil be a more potent snap. Things are looking good IMO.

[nick sussex]

Not much change this morning, overall its zonal and very unsettled.

The ECM shortwave still shows up but its now programmed much further to the south, thereafter its looking close to average in the south with milder interludes, the north looks a bit cooler.

Generally the models have a tendency to over do how southerly low pressure tracks in these situations so if any PM incursions are shown in later timeframes best wait till nearer the time.

The ECM looks a bit more amplified upstream than the GFS and we have seen over the last week a tendency for the models to overplay any amplification from 120hrs onwards.

In the nearer term it looks very wild and decidely wintry for Scotland on Friday and early into Saturday, certainly not a time to be taking a hill walk !, blizzards likely looking at the latest fax chart for areas with some elevation.

[DeepSnow]

Just posted this in the wales thread

If this was to come off, then I would say most people would be in with the chance of some snow for a period from friday into saturday?

[weather_it_will]

If this was to come off, then I would say most people would be in with the chance of some snow for a period from friday into saturday?

Only if you live in Scotland or the far NW England/Wales

Edited December 6, 2011 by xanadu

[DeepSnow]

Only if you live in Scotland or the far NW England/Wales

Is that because of the wind direction from the NNW, so showers not getting far enough south and east? or it would be too marginal for snow in the south?

[KTtom]

Only if you live in Scotland or the far NW England/Wales

I'd dissagee with that, NE Scotland and NE England would be the favoured spots IMO. The ridge to the SW is tto close for western parts, it'll also be too warm here.

[Weather-history]

I'd dissagee with that, NE Scotland and NE England would be the favoured spots IMO. The ridge to the SW is tto close for western parts, it'll also be too warm here.

Not sure I agree with that, it looks a Cheshire gap set-up to me.

[Zakos]

Anywhere North of the M4 COULD see snowfall in that setup IMO. Although the snow chances decreases slowly as you go further east and south of of course.

Edited December 6, 2011 by Zakos

[cyclonic happiness]

Not sure I agree with that, it looks a Cheshire gap set-up to me.

We had a couple of rather large snow showers come through the Cheshire gap last night and hit us and we're a long way east from there!

[johnholmes]

A reality check on any amplification I think?

There is nothing in the 500mb charts over the last few days that would support the idea of any noticeable amplification, either over this part of the world, or west into north America in the next 10-14 days.

They do suggest much of the same with little sign at the moment of the Azores ridge(upper ridge) extending much NE that would settled the weather down in the south. A fairly strong 500mb flow into the UK, on the cold side with values between about 540 to 546 perhaps 6DM lower at times(this for central England). So at or below average temperatures on the surface for the south temporarily above as surface lows track west to east. Generally below in the north and verging on cold(Met O definition) at times behind the lows.

Briefly sleety type stuff at lower levels in the cold slots for parts of the Midlands and some wet snow for low lying areas of parts of England north of that. Further snow for the hills from the Peak District/Wales north, take a look at the web cams for the Derbyshire/Staffs border for what it looks like just now, wet snow settling at times for other areas further north with continued accumulations for the higher hills into Scotland and probably N Ireland. Windy in these parts at times too(also briefly for further south as the lows track near the north of Scotland at times)

Any attempt to give detail day to day more than 3 days ahead is most probably going to be wrong. Timing and depth of features is always going to be difficult to get right, as is will it snow for 'me' in my location.

Edited December 6, 2011 by johnholmes

[karyo]

Not sure I agree with that, it looks a Cheshire gap set-up to me.

Indeed, the Manchester area should see numerous showers Fri-Saturday.

Karyo

[weathe20]

Bor fest again. Seems something wintry for the far north and high elevations at the end of the week but appart from that just zonal. You dont even need to look at 850hpa temp & slp charts to understand whats happening, just use the uk wind speed/direction charts and you will see how zonal it is throughout the 0z output.

[Nick F]

A reality check on any amplification I think?

There is nothing in the 500mb charts over the last few days that would support the idea of any noticeable amplification, either over this part of the world, or west into north America in the next 10-14 days.

They do suggest much of the same with little sign at the moment of the Azores ridge(upper ridge) extending much NE that would settled the weather down in the south. A fairly strong 500mb flow into the UK, on the cold side with values between about 540 to 546 perhaps 6DM lower at times(this for central England). So at or below average temperatures on the surface for the south temporarily above as surface lows track west to east. Generally below in the north and verging on cold(Met O definition) at times behind the lows.

Briefly sleety type stuff at lower levels in the cold slots for parts of the Midlands and some wet snow for low lying areas of parts of England north of that. Further snow for the hills from the Peak District/Wales north, take a look at the web cams for the Derbyshire/Staffs border for what it looks like just now, wet snow settling at times for other areas further north with continued accumulations for the higher hills into Scotland and probably N Ireland. Windy in these parts at times too(also breifly for further south as the lows track near the north of Scotland at times)

Any attempt to give detail day to day more than 3 days ahead is most probably going to be wrong. Timing and depth of features is always going to be difficult to get right, as is will it snow for 'me' in my location.

Yes, the low heights to our north and northwest or polar vortex - whatever you want call it, show no signs of breaking down this side of Xmas. So a continuation of zonal - always colder in the north under those lower heights which will bring snow to the hills and lower levels at times - but for southern areas it's looking unlikely there will be much in the way of snow to look forward to before Xmas.

We maybe stuck in this rut for much of December, but not such a bad rut to be stuck in for those who like snow and live in the north.

[Weather-history]

Its notable how the GFS pressure ensembles over the last few runs have dropped in pressure indicating no high pressure development

Manchester 18z GFS ensembles

http://expertcharts.weatheronline.co.uk/daten/proficharts/en/gefsts/2011/12/04/basis18/pslv/03334_0418.gif

Current 0z ensembles

http://expertcharts.weatheronline.co.uk/daten/proficharts/en/gefsts/2011/12/06/basis00/pslv/03334_0600.gif

[Weather-history]

Look how tightly wound up those two lows are. Almost twins.

http://www.wetterzentrale.de/pics/Rtavn721.png