Winter Model Discussion - The Hunt For Cold -12z 14/12/12

[John Badrick]

Trouble is John we do look at the bigger picture; the bigger picture is looking at ALL models, ALL ensembles and ALL available maps and graphs..... and at the moment they ALL look shocking!

that's My point the models, ensembles etc are only worth looking at short term, average December weather for 5 days maybe( not sure why people keep using the word shocking!! To me this is normal winter weather, shocking weather would be 20 degrees + or 20 degrees below) I refuse to take anything the models, ensembles say after 5 days as gospel. Paul T the bigger picture can change in an instant, a little change here and there can result in a big change all together

[Paul T]

Tell you what, here's a thought: I'll negotiate to get permission to show some recent post-hoc products on here if possible, such as the frontal position/shortwave spaghetti plots; MSLP dalmatian plots etc as it would seem a pertinent posting on this thread to help illustrate the sort of vast MRF suite available to folks at Exeter from EC when they prepare their analyses (of course they also regularly employ ARPEGE for these, too.... never seen it cited on this thread, strangely, but maybe it's not on public web access I guess?)

I think that would be a fantastic idea; my old man used to work for the met and I believe that you guys have access to some fantastic bits and bobs that some on here don't seem to appreciate.

Since moving to Bristol last year, one of the unexpected benefits was having yourself doing our local weather forecasts. Good work, Ian.

[minus 9]

Wait till the mornings runs big changes a foot. Ian fergie i love you. Ps two bottles of wine is not good when ..........................?

[SMU]

the biggest feature of the models in the mid term isnt sadly cold, but the growing signal for strong + VE heights over Spain & western France-

If that continues then no matter what blocking there is to the NE - that will wipe out any cold.

S

[Panayiotis]

the biggest feature of the models in the mid term isnt sadly cold, but the growing signal for strong + VE heights over Spain & western France-

If that continues then no matter what blocking there is to the NE - that will wipe out any cold.

S

Ye I suspect the NOA will increase, if the models are to be believed!

[Gibby]

Just to be clear, I normally agree with gibby's posts but tonight I don't because we have had some positive runs for cold to return, last nights ecm, this mornings ecm and to a lesser extent tonights ecm, also the ukmo and occasionally from the gfs, I think most on here will agree that the outcome next week is a long way from being resolved one way or the other, cold cannot be ruled out which gibby seems to have done rather dismissively.

Just to be clear, I normally agree with gibby's posts but tonight I don't because we have had some positive runs for cold to return, last nights ecm, this mornings ecm and to a lesser extent tonights ecm, also the ukmo and occasionally from the gfs, I think most on here will agree that the outcome next week is a long way from being resolved one way or the other, cold cannot be ruled out which gibby seems to have done rather dismissively.

I stand by what I wrote earlier. Yes there was some sway back towards a return to cold last night as we looked into next week. Through the 00z and tonight's 12z that trend has been somewhat reversed with hardly an endorsement for it from the GFS Ensembles either hence why I gave a rather pessimistic approach to my earlier summary. Bear in mind I only commentate on what the charts show and the weather experienced at that time, not what might happen in the future which is why I have mentioned nothing about cold from UKMO as it is speculative outside the time frame. When compiling them I am mindful of what previous runs have shown and its on this basis I form my end summary with my own slant of where things might lead. Probably the most important part of them is the Ensemble report which despite some people's criticism is still a good indicator of trends and as of the 12zs there is no definitive trend towards much in the way of cold, in fact imo rather the reverse.

I will not be able to do a morning report tomorrow but will be back rather belatedly for the 12zs.

Edited December 14, 2012 by Gibby

[swfc]

Spot on gibby . Unbiased and informative as ever

[bluearmy]

the biggest feature of the models in the mid term isnt sadly cold, but the growing signal for strong + VE heights over Spain & western France-

If that continues then no matter what blocking there is to the NE - that will wipe out any cold.

S

i did notice naefs removing that anomoly on the 12z run steve. not much else to take from the run mind you !!

[Zenarcher]

Update on Saturday's wet and windy weather can be found here http://forum.netweat...00#entry2447995

As for the models interesting to see the ECM and UKMO showing something similar at 144 hours and GFS appears to be on its own,

144 hours,

ECM

UKMO

GFS

ECM and UKMO offer better heights to our North, weaker Atlantic low also the low trying to enter the Atlantic is being delayed slightly thanks to high pressure surrounding it.

Edited December 14, 2012 by weathermaster

[TEITS]

the biggest feature of the models in the mid term isnt sadly cold, but the growing signal for strong + VE heights over Spain & western France-

If that continues then no matter what blocking there is to the NE - that will wipe out any cold.

S

Im not sure I agree with that.

Using the ensemble mean on both the ECM/GEFS and to me the period between Xmas and New Year looks dominated by rather cool or even cold W/NW,lys.

[Weathizard]

Going through the ENS at 240 there looks to be some pretty decent runs in there to be fair, not great but decent and I would say better than the 12? Lots bring in a northerly origin incursions

[TEITS]

Spot on gibby . Unbiased and informative as ever

I think you wlll most posts on this thread have been unblased but they have also highlighted the difference between the ECM/GFS. A biased view is members who dismiss the cold output i.e ECM 0Z and assume a very mild GFS 18Z will verify.

This bias is based on members previous years disappointments but that is flawed meterologically speaking.

[LomondSnowstorm]

Im not sure I agree with that.

Using the ensemble mean on both the ECM/GEFS and to me the period between Xmas and New Year looks dominated by rather cool or even cold W/NW,lys.

http://modeles.meteo...21-1-300.png?18

Similar to the GFS operational then (by this range at least, although it is much milder beforehand), which is what real cool/cold zonality looks like, rather than just a limpet trough:

The 12Z had a similar pattern too. I'm not entirely sold on this by any means though but it is a possibility and wouldn't necessarily lead to mild, unless heights built strongly over Europe.

Edited December 14, 2012 by LomondSnowstorm

[SMU]

Im not sure I agree with that.

Using the ensemble mean on both the ECM/GEFS and to me the period between Xmas and New Year looks dominated by rather cool or even cold W/NW,lys.

http://modeles.meteo...21-1-300.png?18

dave why post a MEAN chart from 13 days away.?- thats not the mid term- pretty pointless TBH- why dont you go the whole hog & present the 18z 16 day ens mean-

http://modeles.meteo...21-1-384.png?18 smoothed to climatology as expected-

try wave 1 at 96-

http://modeles.meteo...21-1-102.png?18

wave 2 trying to develop at 168

http://modeles.meteo...21-1-168.png?18

580 decameter high pushing north out of africa into spain-

S

Edited December 14, 2012 by Steve Murr

[Dean E]

In my opinion, The GFS has been tossing and turning so much in the past day or so. Believing anything after +144 seems crazy to me.

SM

[nick sussex]

Similar to the GFS operational then (by this range at least, although it is much milder beforehand), which is what real cool/cold zonality looks like, rather than just a limpet trough:

The 12Z had a similar pattern too. I'm not entirely sold on this by any means though but it is a possibility and wouldn't necessarily lead to mild, unless heights built strongly over Europe.

Unfortunately LS models have a bias at later stages to suggest a cooler type zonality with the PV that strong. We've seen this many times, cooler zonality eventually becomes milder as the models take the jet further north.

If a chart like that appears I'd book a trip to Canada or Lapland!

[Chris K]

Note: Please be aware i'm a complete amateur and will show how I am seeing things right now. If it's misleading or incorrect/inappropriate, advise me or mods can delete if really that terrible haha...

Anyway.....

Regarding the idea of looking at the "bigger picture"....

I would of thought with recent switch arounds, people might actually have listened and not get down when FI brings in mild SW'erly winds. How many times have people said it very quickly becomes more and more unlikely to verify as it shows after about 5 days(T+120)? Ok perhaps we might stay 'milder' in some sense towards Christmas, but from the GFS past couple of days, the trend is yet again evident of the PV migrating across towards Siberia. Look at the bigger picture... aka the Northern hemispshere. Just take note of how small we are there compared to the whole area. Tiny changes WILL affect us and influence what we get at the surface weatherwise. It really does all need to fall into place close to the day itself.

GFS 18z at T+0 as we stand tonight:

PV has begun/continues to shift but still looks quite energetic. I think whilst its moving the models are going to be a bit all over the place at times.

GFS 18z T+144 (this is now pretty much the furthest I take notice of after this week):

Look how the PV has moved across a bit more and seems to be weakening. Was there not suggestions that this may occur as we enter the latter third of December? Also, although not that substantial...AT THIS POINT heights are rising in Northern Greenland compared to tonight.

Today's ECMWF 12z @ T+144:

Again PV moving across...more energy than the GFS but still weaker than tonight. Heights again higher across Greenland - AT THIS POINT - not going into whether it will get blown away or start to stick right now.

So, we aren't exactly seeing any snow events reaching our shores by T+144 on these charts - I wasn't expecting to considering everything else affecting the outcome....but **FOR THIS FACTOR ALONE** the fact the PV is already on the move and seems to be weakening is something to take note of in my opinion. Will this bring us the snow everyone is craving? I don't think there is any way of knowing right now without speculation....because obviously many other factors will come into play and can either help or hinder our chances along the way. As people have been discussing tonight, a less cold/milder outlook seems favoured for now. I repeat...I know the PV's placement isn't the only factor in getting cold, snowy weather, but I think we will need to see in a few days time as to whether the PV's energy starts heading back to Greenland area and reinvigorating itself across the models runs as suggested in FI. This could obviously affect what happens at a later stage.

My point I'm trying to get across to people in this post really, is the need to look further than just the UK and its closer surroundings. I think this is why some are banging on about the 'bigger picture' which I agree with. Whether it shows mild or cold weather we can't really help that can we...its just a representation the computer models are throwing at us for the particular timeframes and it's down to you how you analyse them.

I love to see snow.. but realisticly, unless its showing within 2 days on the models, I've now realised not to get disbondent if it all goes pear-shaped - because everything really does need to be in our favour within T+48hrs,,,perhaps even less?

Again, I apologise if im barking up the wrong tree...still in the basic stages of learning.

Edited December 15, 2012 by Chris K

[bluearmy]

the ridges are associated with the zonal train of depressions. if the train ceases, so will the ridges. i just hope we are in the right place when the music stops.

[LomondSnowstorm]

Unfortunately LS models have a bias at later stages to suggest a cooler type zonality with the PV that strong. We've seen this many times, cooler zonality eventually becomes milder as the models take the jet further north.

If a chart like that appears I'd book a trip to Canada or Lapland!

Yes, well the GFS in FI throws up so many things that's it's hard to take any of it seriously! The GFS does tend to really overdo those lows though as well in FI, bringing often apocalyptic looking charts even into the lower part of the high res, and during the genuinely cool zonal and stormy period last December we frequently had charts with sub 930mb lows appearing. Anyway, for my own location at least I do take a bit of comfort from the ECM ensembles, many of which have the cold air sitting pretty close to the east of Scotland by +168 with an easterly based flow, many of them do look pretty transient but it's something at least.

[nick sussex]

Yes, well the GFS in FI throws up so many things that's it's hard to take any of it seriously! The GFS does tend to really overdo those lows though as well in FI, bringing often apocalyptic looking charts even into the lower part of the high res, and during the genuinely cool zonal and stormy period last December we frequently had charts with sub 930mb lows appearing. Anyway, for my own location at least I do take a bit of comfort from the ECM ensembles, many of which have the cold air sitting pretty close to the east of Scotland by +168 with an easterly based flow, many of them do look pretty transient but it's something at least.

Yes I think for your region as long as we don't see any further northwards trend re the jet then you've got a chance of some colder shots.

As for tonights GFS 18hrs run, it implodes within 96hrs with its view of the shortwave , things might not seem great but I certainly don't buy its view of things.

[TEITS]

dave why post a MEAN chart from 13 days away.?- thats not the mid term- pretty pointless TBH- why dont you go the whole hog & present the 18z 16 day ens mean-

S

Depends on your definition of mid term. I define mid term as 14 days and long term 30days.

Besides im still not ruling out what the ECM 0Z was showing this morning.

Reading your posts this evening I suspect someone has taken the jam out of your doughnut.

Looks like the ensembles support my view with the mean dropping below zero from the 23rd onwards.

http://cdn.nwstatic.co.uk/ensimages/ens.20121214/18/t850Aberdeenshire.png

This is not indicative of blow torch SW,lys but a cool/cold W/NW,ly.

Edited December 15, 2012 by THE EYE IN THE SKY

[Timmytour]

I'm an eternal optimist but, without the next two GFS runs giving us something to cling to, i think even Peter Gabriel and Kate Bush would give up on there being anything this side of the New Year

[Guest Kent-Weather]

Looks like the pub run ensembles have been well and truly having a Christmas party drink or 20!

[LomondSnowstorm]

Health advisory when viewing the GFS this morning: it's pretty damned hideous for cold lovers, following the 18Z in many respects.

[Blizzardof82]

Health advisory when viewing the GFS this morning: it's pretty damned hideous for cold lovers, following the 18Z in many respects.

Sat in work watching it roll out and it's grim reading, on the plus side anything from here can only get better