Model Output Discussion

[bluearmy]

just looked through the ensembles and there is a sypnotic spread regarding the path of the shortwave mid next week. however, the ridge coming down behind looks well supported. if the shortwave doesnt follow an advatageous path, we may have nothing wintry at all before next weekend. it is a possible evolution and needs to be said to calm some expectations. there is, of course, no guarantee what will happen over a week away from the pattern that follows the ridge so need to remain cautious.

[ChartViewer]

GP suggested a slight wobble in the Models last 24 hours so lets hope we could get subtle upgrade

and my Model Santa stocking would read like this -

SHORT TERM

1. HP Cell moving slightly further North so the whole Country can get in the ENE act.

2. NE/SW energy bringing down colder air for all of us

3. Continuing low heights over the Med

MEDIUM TERM

1. Contnued re loading of that huge HP Cell over Greenland, 1060mb and reload after reload

2. Continued cold continent

3. Cold patterns bringing NE and North blasts to the UK

LONG TERM

1. Continued negative AO/NAO

2. Mid Feb beast with a VERY cold Europe

3. Feb ends with a lovely snowy event for all

Not much to ask is it

Edited December 11, 2009 by ChartViewer

[fromey]

good afternoon, just caught the 1355 weather on the bbc and he said that the real cold weather wont be reaching us until mid week onwards, which set of data/ models would have that come from?? any ideas

Edited December 11, 2009 by fromey

[MR EXTREMES]

That's certainly a danger!

GP sounded quite positive about staying on the north side of the polar front but he also mentioned the high pressure cell gradually transferring westwards - destination Canadian Artic.

Let's hope if this happens, the transition will be slow so that we can benefit from a northerly in the process!

Karyo

infact correct me if im wrong but he said the high transfer to canadian arctic then we stay on the polar side,

regardless the cold build up is going to be good for europe and us.

models are wobbling most likely to the progression to fase4.

Edited December 11, 2009 by badboy657

[Megamoonflake]

No offence

ps where is 'Cardiff'

Is Arctic oscillation (AO) still predicted to be in very –ve terrorty.

I did ask in the previous thread.

I suppose we don't have data re AO and 1947,1963 etc

I'm looking at the wider trends, rather then all this 'will it snow in my back yard' or why is he/she interested in his/her local weather. Most of the 'Pros' on here publish world wide data

Here's a good website with historical data back to 1950 http://www.newx-forecasts.com/ao_2.html

Also you can get the info in tabular form for each month here http://www.cpc.noaa.gov/products/precip/CWlink/daily_ao_index/monthly.ao.index.b50.current.ascii.table

[Duane S.]

Talking about the AO, at last we see the projected drop in values take place. Today's update...

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index_ensm.shtml

Interesting to note that in 5 days time not one member goes for anything above -4 This has been on the cards for a while and I really believe this is affecting the chart's behaviour.

The NAO too has started to drop and there is fairly uniform agreement that it will a bit more before plateauing for a few days, before slowly heading back up - but there is no sign of anything positve (in term of the pressure anomoly, not the outlook!)

Not sure what the MJO is likely to do next (i.e head to phase 8 or dropdown into phase 1/2?) but it is in a very favourable position ATM, which ties in with what we are seeing.

There is quite a lot of doom and gloom at the mo on here, all things considered. Under a more 'normal' recent-type setup I would think we may be looking at a gradual small daily downgrade to something cold, frosty with occasional snow next week but that is not the case. I just have a feeling that over the next few days, with plenty of blips, we are going to see upgrades and good ones.

Edited December 11, 2009 by s4lancia

[johnholmes]

reference the post about some members of the team not posting in here-yep I'm one-I have said before I'm too old to join in the frenetic activity in the model thread, at times a post every second.

Rest assured I will try, when I am around, to give a balanced view as the count down to the cold spell really closes down. For the WHOLE country.

I'll drop something into my blog this evening and it will be updated at some point each day,

there will be my lrf, covering 21-31 December at some stage

assuming CFS updates then the Christmas Day forecast or rather what the CFS shows compared to the GFS output

and finally come Monday my video will obviously cover the UK for next week.

Then of course I do have most of the responsibility for doing most of the Watches/alerts as required, oh and I sometimes do the Front Page update on a Saturday to give Paul M a bit of a break..

so all in all I am quite a busy chappy.

back to the models so the team don't bin this waffle!

As to how cold, well we have to wait until nearer the projected time

for snow ditto

how long will it last then perhaps read what GP and other sensible posters have to say?

and for those seriously interested in finding fact from fiction - will it snow-then please try the link in my blog to the Guides where that article lives.

enjoy the winter spell, however long it lasts and may it snow copiously upon you.

Edited December 11, 2009 by johnholmes

[Frosty.]

Some of the GFS runs have been so 'out-of-this-world,' it's hard to see how they could possibly 'upgrade'?

It's a shame the meto update has downgraded and it's looking a lot more marginal now with sleet probably the most likely apart from high ground...pity

[Jan_Bromley]

good afternoon, just caught the 1355 weather on the bbc and he said that the real cold weather wont be reaching us until mid week onwards, which set of data/ models would have that come from?? any ideas

Hi fromey,

The Meto have much more input and info from all the models than we do. GFS is the only model that is free for the public. Everything else the public gets is a far watered down solution. Met O would also gather information from ALL of the models, not just one.

Regards

Jan

[glasgow-guy]

in relation to the models i kind of thought we maybe looking at the wrong side of December for any real snow to occur however it can only get better

from here on in

[Matt Jones]

It's a shame the meto update has downgraded and it's looking a lot more marginal now with sleet probably the most likely apart from high ground...pity

Yes I think that was to be expected today, as the meto update is pretty much what the latest outputs are showing, GFS overcooked the strength of cold on many of it's outputs. Just hope in the longterm we can get a better setup.

[nick sussex]

The very latest from NOAA about the upstream pattern, most relevant quotes for here in western europe:

HELPING TO LOCK IN A MEAN LONGWAVE TROF OVER THE E COAST

OF NOAM WILL BE STRONG BLOCKING/POSITIVE HEIGHT ANOMALIES WORKING

BACK FROM THE N ATLANTIC TOWARDS SRN GREENLAND

WED-FRI...ASSOCIATED WITH A NEGATIVE NAO.

For newer members this suggests the high pressure to the north will edge westwards as this does so this will bring the low pressure in relation to a trough over Scandi westwards,this ties in with the models bringing low pressure south in the extended outlook.

UPDATED PRELIM PROGS SOUGHT TO SIMPLY AN OTHERWISE REASONABLE

EARLY PRELIM FORECAST SCENARIO BY SWITCHING TO 100% UKMET HI

RESOLUTION FOR DAYS 3-5...THEN CHANGING TO AN ENHANCED GEFS

ENSEMBLE MEAN PATTERN FOR DAYS 6-7. MANUAL PROGS ENHANCED THE COLD

HIGH SURFACE PRES FROM THE 00Z/11 GEFS MEAN OVER THE ERN CONUS FOR

THU/FOR DAYS 6-7.

Interesting here as its not often NOAA go totally with one operational run especially the UKMO. If you're looking for an extended cold spell the safest route here is the high doesnt edge too far westwards, its a difficult call here, if we're lucky we'll have a direct hit from a probable northerly if not low pressure will head south too far west. If this happens then you need this to clear well to the south to allow colder air back in.

Edited December 11, 2009 by nick sussex

[Jan_Bromley]

in relation to the models i kind of thought we maybe looking at the wrong side of December for any real snow to occur however it can only get better

from here on in

Hi glasgow,

That is exactly why the models are so interesting at the moment. It is early in the season really to get these kind of synoptics. The minima of the sun is at it's lowest, and should any decent cold arrive, it would be snow fest time.

reards

Jan

[stewfox]

Talking about the AO, at last we see the projected drop in values take place. Today's update...

http://www.cpc.ncep....ndex_ensm.shtml

Interesting to note that in 5 days time not one member goes for anything above -4 This has been on the cards for a while and I really believe this is affecting the chart's behaviour.

I don't really want to set up a new thread in the learning zone and think this counts re model output ?

-4

Is that a 10 day average ?

Stats suggest nothing like that before

http://www.cpc.noaa....ent.ascii.table

Just learning so if mods thinks it should be in the learner area happy to set up a thread there.

[Thundery wintry showers]

I don't blame them to be honest- except for the one-off wobble at 00Z a couple of days ago the UKMO has been the most consistent model, even out to T+144 which has traditionally been its Achilles heel.

[glasgow-guy]

I don't blame them to be honest- except for the one-off wobble at 00Z a couple of days ago the UKMO has been the most consistent model, even out to T+144 which has traditionally been its Achilles heel.

consistent yes realistic perhaps not. not many of those wonderful charts looks to be likely to occur in the time frame set in the models perhaps the trend is there though and that's the important thing to focus on

[Frosty.]

Yes I think that was to be expected today, as the meto update is pretty much what the latest outputs are showing, GFS overcooked the strength of cold on many of it's outputs. Just hope in the longterm we can get a better setup.

At least it's a better set up than it could have been after that poor ECM yesterday, I was happy to see the upcoming pattern was still fairly intact and the cold blast from the north could upgrade for the end of next week hopefully.

[karyo]

Interesting here as its not often NOAA go totally with one operational run especially the UKMO. If you're looking for an extended cold spell the safest route here is the high doesnt edge too far westwards, its a difficult call here, if we're lucky we'll have a direct hit from a probable northerly if not low pressure will head south too far west. If this happens then you need this to clear well to the south to allow colder air back in.

Thanks for the update Nick. It is interesting (see embolded text)but on the other hand, the 0z UKMO is the least promising for next week's easterly!

Karyo

[glasgow-guy]

At least it's a better set up than it could have been after that poor ECM yesterday, I was happy to see the upcoming pattern was still fairly intact and the cold blast from the north could upgrade for the end of next week hopefully.

i think many have said that before "all eyes north" and maybe the most reliable source of cold snowy weather for all the UK

[Geordiesnow]

Has it really become that bad that we are going now to concentrate on the Northerly that may occur?

I said that it probably will take until this afternoon/tomorrow morning model runs on what may happen and that probably has not changed. I just hope the 06Z is not a trend of what might happen regarding the easterly.

[Iceberg]

The models have always said that it will be Wed night into Thursday for the real cold to arrive.

Before that they have always said that Mon/Tues will bring a spell of cold, with increasingly wintry precip for the east, se and central southern england.

Wed has always been a transistion day so milder(but still cold ! ).

When I say Always I mean for the last 48 hrs or so.

I've actually been very impressed at how the models have generally modelled next week quite consistantly.

The only real variable has been the amount of snow on thurs/fri, the penetration of a short wave low pressure system thurs/fri and the how cold the uppers will be thurs/fri.

But all of the above is very small detail for a global model 1 week out !.

Just to add there has been a bit of variability re mon/tues as to how cold the uppers will be and the extent of precip but not much considering.

At least not yet.

[mountain shadow]

No offence

ps where is 'Cardiff'

Is Arctic oscillation (AO) still predicted to be in very –ve terrorty.

I did ask in the previous thread.

I suppose we don't have data re AO and 1947,1963 etc

I'm looking at the wider trends, rather then all this 'will it snow in my back yard' or why is he/she interested in his/her local weather. Most of the 'Pros' on here publish world wide data

http://www.wetterzentrale.de/archive/ra/1963/Rrea00119630101.gif

Well I just took a random chart from January 1963 and the AO doesn't look positive to me with a strong PV to the north, however the Uk is still cold.

You shouldn't look at one teleconnection for the answer, they all need to be looked at and a forecast arrived. The AO is important in that it shows cold air spilling out of the Arctic however that is no guarantee it will knock on our doors, we need a -NAO to help deliver that as the above chart shows.

[nick sussex]

Thanks for the update Nick. It is interesting (see embolded text)but on the other hand, the 0z UKMO is the least promising for next week's easterly!

Karyo

Hi Karyo well they're only using it upto day 5 so that still leaves the gefs ensemble mean to take over after this, its at this point that the ukmo looks a bit halfhearted. I think the main interest for me is seeing what the models do with that next low heading south, preferably we want this to head towards the low countries this will then as it clears pull the flow in from the ne although this is well into the later timeframe. This looks like the next rollercoaster!

[glasgow-guy]

Has it really become that bad that we are going now to concentrate on the Northerly that may occur?

I said that it probably will take until this afternoon/tomorrow morning model runs on what may happen and that probably has not changed. I just hope the 06Z is not a trend of what might happen regarding the easterly.

no of course not but if it likely to occur its going to be talked about and is a northerly all that bad for December anyway? the easterly has not been abandoned

well not yet anyway perhaps if this evenings outputs are still wobbling then a northerly will be quickly picked up.

[mountain shadow]

Hope i didn't jink anything by posting a chart from 1963...