Jump to content
Snow?
Local
Radar
Cold?
IGNORED

General Model Output Discussion Thursday December 24Th:


Methuselah

Recommended Posts

Still some big differences between the GFs/ECM in the long term, though they are both now in decent agreement about a Iceland block rather then a Greenland block, at least at first. However given how the set-up evolved last time and how favourable conditions are, I'd imagine it would eventually evolve just like the ECM suggests.

The GFS still powers up the Candian vortex which makes things that little bit more prone to failing to link up, whilsat the ECM goes for the Scandi vortex, which of course is going to be a very good set-up for the UK.

Anyway we have good agreement indeed for a cold NE general flow and a -ve NAO to develop again...then to what extent this all happens is whats somewhat up in the air.

As for the battleground, I wouldn't get too excited about it, I think swilliam makes a very good point and I suspect whislst there will be some northern edge snowfall its not going to be all that impressive, esp where the milder air is present from now on....whilst that does leave us somewhat on the 28-29th we still don't really have quite cold enough conditions...its all far too marginal to call, though no doubt it could give someone snow but far to early yet.

Its a hard one to call really Kold we need a sustained -NAO with the block over Iceland,we don't want the northern arm kicking into life,as you say its where the more dominant vortex sets up,we want it to be Northern

Scandy,we dont want the dominant vortex to spill out of Canada as that will most likely prevent the HP near Iceland from retrogressing to Greenland which is want we need for a sustained cold spell,the updated meto 15 dayer seems to suggest the balance is in our favour at the moment,fingers crossed this continues!

Link to comment
Share on other sites

Posted
  • Location: Pencoed, South Wales.
  • Location: Pencoed, South Wales.

Lol, I live just north of the M4 in Cardiff and on many occasions you would drive up the A470 from Cardiff go under the M4 and soon as you go under the M4 bridge it would be snow and on the other side rain so in personal expierence its a good boundary.

I've been critical in the past but it certainly can work that way. That said the Vale does seem to do better than Bridgend, both of which are southerly of the M4. The Brynglas tunnels appear to divide weather systems as well!

Link to comment
Share on other sites

Posted
  • Location: Cheddington, Buckinghamshire
  • Weather Preferences: Winter: Cold & Snowy, Summer: Just not hot
  • Location: Cheddington, Buckinghamshire

No the Met O is definately going with the ECM. The UKMO at +144 wouldn't bring a risk of snow for the Midlands/Wales but the ECM would.

If some members are getting confused by this let me explain.

The track of the LP system next week is all important as to whether you see frontal snowfall or rain. However once the LP system moves E everyone would be experiencing colder weather. If you want to know whether it will rain or snow then the first thing you need to look for is are you on the N side of the LP. Look at the chart below from the ECM.

http://www.meteociel...M0-144.GIF?23-0

Now if that verified what would happen is N of the M4 rain would turn to snow in Wales, Midlands and W parts of E Anglia. As the LP moves E the risk of snow would move S & E so other areas would see rain turning to snow.

Use that above link as a guide for future models runs and you won't go wrong.

I agree with you fully TEITS, let me explain why I thought what I did. The Met Office released an "update" at about 1040 which seemed identical to yesterday's, so I was commenting on that. But it is obvious that it wasn't actually an update, and the new one seems very promising indeed.

Link to comment
Share on other sites

Posted
  • Location: ipswich <east near the a14> east weather watch
  • Location: ipswich <east near the a14> east weather watch

Fantastic model output all around from a cold perspective with things getting interesting again as early as Monday for some areas. I cannot believe this thread is so quiet considering the quality of the charts!

all i can say roll next week if the models are right, ps i think all the males are with HQ doing the shoppng get the turkey all geting HQ presents!!!

Edited by tinybill
Link to comment
Share on other sites

Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

Last post as I need to prepare for tomorrow.

The ensembles say it all really. Note the rise in pressure over Iceland and the drop in pressure over Madrid/Paris.

http://charts.netweather.tv/ensimages/ens.20091224/06/prmslMadrid.png

http://charts.netweather.tv/ensimages/ens.20091224/06/prmslParis.png

http://charts.netweather.tv/ensimages/ens.20091224/06/prmslReyjavic.png

Im fairly confident of this S,ly tracking LP although still uncertain about the track. Beyond and to be honest I would prefer to concentrate on this LP.

Thanks for another year's imput, Dave. Have yourself a good one, mate!! :good::good::good:

Link to comment
Share on other sites

Posted
  • Location: Liphook
  • Location: Liphook

Its a hard one to call really Kold we need a sustained -NAO with the block over Iceland,we don't want the northern arm kicking into life,as you say its where the more dominant vortex sets up,we want it to be Northern

Scandy,we dont want the dominant vortex to spill out of Canada as that will most likely prevent the HP near Iceland from retrogressing to Greenland which is want we need for a sustained cold spell,the updated meto 15 dayer seems to suggest the balance is in our favour at the moment,fingers crossed this continues!

I suspect even if the PV were to set-up stronger on the Candian side its still not that potent really and we still have a split PV which means there is always going to be the real risk of a Greenland high punching up through the gap so to speak, but even if we weren't to get the full works as long as we keep that split there should still be some sort of ridiging going up through the gap IMO...its just a matter of where everything sets up for the UK, but there is a real risk for once of the UK getting a very prolonged cold spell...indeed I suppose it would be true to say that its just another phase of the cold spell we have now, given the north never loses the cold...

Link to comment
Share on other sites

Posted
  • Location: Churchdown, Gloucester
  • Location: Churchdown, Gloucester

I must I am not to optimistic about the setup for 29/12 as winds are going to be drawn from the near continent rather than well to the east. I suspect the coldest areas will be too dry and the wettest areas will be very marginal. May be I have just been here too many times before, however I said the same in Jan 82 and we had more snow than I have seen at anytime in my backyard and followed by very low temps

Link to comment
Share on other sites

Posted
  • Location: Leigh On Sea - Essex & Tornado Alley
  • Location: Leigh On Sea - Essex & Tornado Alley

And the point you make rbw about Jan'82 is an Interesting one IMO.

This Winter has been an almost Mirror of Nov/Dec 1981 and looks like contineing like Jan'82 did as well.

Nov 1981 was exceptionally stormy after a dryish Autumn, On 21st November 1981 (105) Tornadoes touched down across the UK and we got battered by Low after Low Pressure, then the freeze up began on the 10th December 1981 and continued until about the 20th, meaning not a technical White Xmas although Snow was on the ground in most places in the Uk.

Nov 2009 was one of the wettest on record in the Uk, Low Pressure systems and Mild winds for almost all the month with around 7 Reported Tornadoes. The GFS Picked up on 2nd December (Which was incredible btw at such long range) a cold NE Signal to start on the 17th and the "Real" Cold started on the 17th December!!

What happened in January 1982 after that Infamous Dec'81 is looking very similar to what the Models are showing for the end of Dec and start of January.

As Ian Brown said earlier this might just be the winter that we all remember.

Have a great Xmas wont be around much after tonight until 28th Dec so have a good one everyone!

Paul S

Link to comment
Share on other sites

Posted
  • Location: Home near Sellindge, 80m/250feet, 5miles from Coast
  • Weather Preferences: Severe Storms and Snow
  • Location: Home near Sellindge, 80m/250feet, 5miles from Coast

I see people getting excited or saying it's a good winter have had a good snowfall already but here , terrible.... The models do look good into next week , with a more north east element to the wind

but if its anything like the last bit this would've been the biggest slap in the face so far this winter.

Just this once i'd like to open my front door(side of the bungalow) and see the ground completely white but thats not happened for the last two years

Link to comment
Share on other sites

Posted
  • Location: Tunbridge Wells, Kent
  • Location: Tunbridge Wells, Kent

I see people getting excited or saying it's a good winter have had a good snowfall already but here , terrible.... The models do look good into next week , with a more north east element to the wind

but if its anything like the last bit this would've been the biggest slap in the face so far this winter.

Just this once i'd like to open my front door(side of the bungalow) and see the ground completely white but thats not happened for the last two years

Unlucky for you with the cold snap, but apart from December 1981 which was a truly exceptional event, this cold spell sits well alongside anything else pre-christmas in the last 20-30 years. The good thing about an early cold snap, whether it delivers for the individual or not is that it is now in the bank. I suspect for some areas even if it doesn't snow again this season it will be above average in terms of days with snow at 9am (i have my 7th in a row today and it will be 8 or 9 before it all melts).

Already another cold spell or snap is looking likely by the turn of the year. All in all much preferable to scraping around looking for northerly topplers in FI in mid february, as has been the case all too often in recent years gone by.

Link to comment
Share on other sites

Posted
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield
  • Weather Preferences: Any Extreme
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield

It's beginning to look like we're going to have a Winter for once. Although all the major action is reserved for FI then deep FI the trend does seem to be for average to well below average.

Link to comment
Share on other sites

Posted
  • Location: Weardale 300m asl
  • Weather Preferences: Snow
  • Location: Weardale 300m asl

Thanks TEITS.

Can't quite work out whether I'm N or S of the M4! :blush:

But either way it's going to be marginal for my location at first. From an IMBY point of view, I'd like the LP to be slightly further South.

Nice to see the METO update starting to turn the right way for next week....

From the west: Cornwall, Devon, Somerset, Dorset, Hampshire, West Sussex, East Sussex, Kent or draw a line from the Bristol Channel to the Thames Estuary.

Link to comment
Share on other sites

Posted
  • Location: Reading/New York/Chicago
  • Location: Reading/New York/Chicago

Following on from Daves post regarding the model data issues around Xmas/Boxing Day i agree with him, flight data that would normally come from many airlines will be much reduced, this is especially important regarding northern blocking as the much higher latitudes suffer from a lack of data anyway,

Not entirely true! Although the UK transport system halts for two days over Christmas, Transatlantic flights and other long haul flights continue much as normal. In fact, Christmas Eve/Day departures tend to be the cheapest to the US and beyond over this period!

Link to comment
Share on other sites

Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

Not entirely true! Although the UK transport system halts for two days over Christmas, Transatlantic flights and other long haul flights continue much as normal. In fact, Christmas Eve/Day departures tend to be the cheapest to the US and beyond over this period!

There are still fewer flights so any reduction will make a difference to the data the models have access to. The airlines always schedule less flights due to lack of demand, this is a fact and not something I made up. How much effect it has on the data we can only wait and see. I'm talking specifically for Xmas Day here and the early runs going into Boxing Day,after this things normally improve.

Edited by nick sussex
Link to comment
Share on other sites

Posted
  • Location: Reading/New York/Chicago
  • Location: Reading/New York/Chicago

There are still fewer flights so any reduction will make a difference to the data the models have access to. The airlines always schedule less flights due to lack of demand, this is a fact and not something I made up. How much effect it has on the data we can only wait and see. I'm talking specifically for Xmas Day here and the early runs going into Boxing Day,after this things normally improve.

There are still enough flights to provide the data; the reduction is very small. I was looking at flying on Christmas Day two years ago and found that exactly the same flights were available from Chicago to London as on any other day (just as an example).

To use your argument I could say that the data is less accurate than a few years ago anyway; most airlines have reduced flights during the recession so we have less data now than in 2005!

Link to comment
Share on other sites

Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

There are still enough flights to provide the data; the reduction is very small. I was looking at flying on Christmas Day two years ago and found that exactly the same flights were available from Chicago to London as on any other day (just as an example).

To use your argument I could say that the data is less accurate than a few years ago anyway; most airlines have reduced flights during the recession so we have less data now than in 2005!

It all depends on how complex the pattern is IMO as to how much the reduced data may effect the models, thankfully the reload to cold in terms of projected synoptics is not the most complex set up.

Link to comment
Share on other sites

Posted
  • Location: chellaston, derby
  • Weather Preferences: The Actual Weather ..... not fantasy.
  • Location: chellaston, derby

i agree with the simularity to 81-2, id also be very happy if the second half of that winter was repeated this winter too! :drinks:

i cannot remember the last time i had lying snow (albeit only a slight scattering) for 7 consecutive days, even if no more cold weather comes (which looks very unlikely, i expect the cold trend to continue) we have had some real wintry weather for once. us mildies have had more then our fair share of mild in recent years, i dont begrudge some wintry weather in winter.

Link to comment
Share on other sites

Posted
  • Location: STEVENAGE, HERTS (100M ASL)
  • Location: STEVENAGE, HERTS (100M ASL)

Not such a good run from 12z IMO. I can see allot of rain for the south and snow on the penines on Tues. I expect the next few frames will show this low pulling south and snow for all. After this I hope it will show a NE with snow showers for the usual spots.

Edited by Tim Bland
Link to comment
Share on other sites

Posted
  • Location: Madrid, Spain (Formerly Telford)
  • Location: Madrid, Spain (Formerly Telford)

Tuesday looks like an almighty snowstorm here in Telford, and considering you lot in the South East have had plenty of snow in the past week i think us Midlanders are entitled to it :)

Link to comment
Share on other sites

Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

IMO all systems go! shovel watch early warning for lucky people on the northern flank of the low. I suspect the gfs still has the low too far north and complicates things with that secondary feature but overall a great run so far.

Link to comment
Share on other sites

Guest
This topic is now closed to further replies.
×
×
  • Create New...