Zakos

Best looking Ensembles i have seen for my area (central/eastern England) since last year. Most of 18z ensembles show a fairly significant cold blast. I do think some are being a little pessismtic about next week. During the autumn euro high, some would post about a northerly at 380 hours, and people would rightly say they are wrong to do so. But the GFS and ECM both are showing the -potential- for of low level snow in the midlands next week in the high res output, consistently, and with good back up from their ensembles. Not saying its a certainty whatsoever, just pointing out that it a realistic possibility.

Well if its broken then so is the ECM, because the ECM also backs the GFS up to 192 hours in terms of general theme.

I don't think anyone here is saying were going to experience Greenland blocking on par to last year next week. But a brief Northerly does look quite likely at the at the end of next week at this stage. Little indication of an extreme deep freeze next week, Little indication of mild weather. Polar maritime dominance, each blast increasing in length and severity, with perhaps a northerly at the end of next week, is the most likely outcome IMO. That is not my hopecast, that is just what the GFS and ECM have consistently been showing. Snow over Scotland is almost certain.Whether it snows to low levels in the south is up for debate, But if you take today's ECM and GFS runs, it looks quite probable that there will be some, and with a bit of luck, there could widespread snowfall, but this is out of the reliable time frame.

A cold PV is not necessarily terrible for cold, just as a warm PV does not necessarily does not necessarily bring strong and prolonged cold? Am I right in saying that?

AO to go negative? .... http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index_ensm.shtml

Yes it may not happen, but it's far ,far more likely to than any outputs we have seen throughout autumn, we're cold was in FI only. It may not be in the reliable, but it is still in the high res output that's better than anything we have seen this autumn IMO. Also, how can the 6z Be more likely than the 12z to verify?

GFS 12z is a significant upgrade as I said it would be. I respect people's view point, and I'm far from certain, but something like the GFS 12z Is what I would expect not the 06z. Oh and to the person who asked where I live, it's Wellingborough, 93 meters above seal level. Im on my iPhone do can't put it on my profile yet sorry.

I see. Well I still think the operational is milder than most of the ensembles. If this milder scenario for Monday is still there on the 12z, then I will put my hands up and say yep I was wrong. But IMO the 12z will be an upgrade on the 06z.

. It is in my area http://hw.nwstatic.co.uk/ensimages/ens.20111201/06/t850Northamptonshire.png I apologise I should have looked at more ensembles not just my area.

Ensembles are out. GFS operational clear mild outlier for england, with no support. Vast majority of ensembles go below -5 (briefly) on Monday. As i predicted. What happens after that, is quite a mess, ensembles are in disagreement.

. Yes I am aware of this. Im just saying it's very likely it will be. Well know for sure in half an hour.

Mild outlier...

I doubt I will see any accumulating snow in my area (Central England) from this initial blast. However,I do expect to see some snow flurries, or at least sleet on Monday Night Something similar to this - http://hw.nwstatic.co.uk/gfsimages/gfs.20111130/12/129/prectypeuktopo.png Whether a more severe cold reload occurs, is out of the reliable time frame, but looking quite likely if you take the last two GFS runs.

GFS has downgraded the chance of snow to low levels in the south, although sleet at least is still quite likely. It has also downgraded the severity of cold in the initial cold snap. However, in doing so, has significantly upgraded the possibility of following cold blasts, which at this stage seem quite potent. The GFS Ensembles (00z) are also indicating at continual reloading cold blasts. Interesting times ahead, things are slowly improving from a cold perspective now that dreaded euro high is gone!

A massive upgrade to the snow potential next Monday, but, a downgrade slightly for the severity of cold. The GFS keeps showing slightly different outcomes, but every single run today and yesterday has gone for at least some sort of significant (although perhaps brief) cold spell Now the ECM has backed it up, I cant see this not happening now. Whether Central England actually gets low-level snow remains to be seen, but according to the 18z and 12z, quite likely it would seem.

Thank you for your reply Yes, I noticed there has been a slight downgrade from the GFS. Agreed there is little scope for long lasting cold spells. Anything is better than the dreaded euro high earlier. There was no way that was going to deliver anything except inversion cold. At the very least some exciting weather these next few days! And with any luck, I and many others may see a bit of snow...

Still out of what many would say is the reliable time frame,but nonetheless the first time I have had heavy snow non-Fi forecast for my area (Central England) this year. The fact that this is being consistently forecast by the GFS is also encouraging. I now agree with what many have been saying - Last December "Spoiled" Cold lovers. Yes, with a cold PV were not going to get a prolonged cold spell on par with last year until at least the new years. But, this doesn't mean we cant get a few decent cold snaps, We can get these with a cold PV can we not? Although I am a cold lover, I am really happy with just falling snow even if it only settles for a few hours. I dont need a 30 cold spell like last year to appease me, A few 3 day cold spells with a few days of lying snow is enough for me! Well until the New Years that is...

I was expecting the GFS to downgrade the snow potential for the early december cold snap, but, it has instead increased it. Very interesting. ECM also upgrading the snow potential. It's stil out of the reliable time frame, but I hope this upgrade trend continues. I think has a realistic chance of veryfing IMO,but I won't get my hopes up unless the cold spell has not dissapeared by tomorrows 18z...

http://hw.nwstatic.co.uk/ensimages/ens.20111125/12/t850Northamptonshire.png. B. Biggest mild outlier I have ever seen from the GFS operational. Absolutely no support in any way, shape, or form. Its laughable

For temperature anomalies, use this animation (GFS) http://policlimate.com/weather/current/gfs_t2m_anom_eur_f.html

In all fairness, the charts are fairly misleading as they show negative anomalies in blue, and positive anomalies in red, easy mistake to make IMO, as this what you would expect with a temperature anomaly chart.

The GFS has been toying with a cold spell these last few days in FI. And now, finally, there is a forecast for a significant cold spell outside of FI. Im not saying its going to be this severe, or even if it will occur, as it is still out of the reliable time frame. But, this is the best GFS run we have had in terms of cold since last winter IMO. Im very confident of some kind of cold spell as we enter December, even if it is just a fairly brief northerly toppler.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif After being positive for a lengthy time, all forecast ensembles go for a for a fairly sharp drop in AO. The disagreement between the ensembles begins as to whether the AO becomes positive again quickly, or continues its decline to become negative. I shall be watching this closely the next few days.

. Do you have a link to the NAEFS Models? I agree, the GFS is showing blocking in the Atlantic in FI frequently. Whether this brings cold weather, or even occurs is anybodies guess, but the signal is there. Im thinking the cold will start around the beginning of December, maybe a bit later. I can see why people are writing off any cold this November, and writing off a repeat of December 2010. But how anyone can say there won't be any widespread snow before now and new years is beyond me. Not to offend I just don't understand.

I disagree. There are many worse scenarios we could be in now, Bartlett, Atlantic dominated etc... If the Atlantic was dominating, or there was a strong PV over Greenland, I would be far more worried. And I agree with BTFP its the least likely scenario.