General Model Output Discussion

[casparjack]

If it (CET Average) is still below -1.1C on the 21st, it may happen. Now we need someone like Mr Data to tell us when the last sub zero month was.

As for the models, we have an interesting weekend in store in the Eastern counties, that wind will be bitter, as for the North, I'd like to see how low we go in Scotland as the clouds clear away -23C anyone?

EDIT:

Jay Wynne on BBC just saying no respite for 10-15 days, so 16th -21st before a break? He's been reading GP's and BFTP's analysis

The last sub zero month was Feb 1986 (-1.1c), the last sub zero Jan was 1979 (-0.4c). Jan 1963 was -2.1c, so a bit to go for that!

[sebastiaan1973]

My link

excellent ENS

[bluearmy]

http://www.cpc.ncep.noaa.gov/products/predictions/814day/814day.03.gif

the jet gets closer to the south than for a while. this really is high stakes stuff. the risk of the atlantic winning is obviously greater (could be a blip as per xmas to new year) - however, the rewards of the channel lows is a tempting stake seeing as by then, most if us will be approaching our third week of snowcover!!

[shuggee]

Come on folks - there is a thread with the mysterious title of January CET to discuss exactly that.

[Ian Fergusson]

If it (CET Average) is still below -1.1C on the 21st, it may happen. Now we need someone like Mr Data to tell us when the last sub zero month was.

As for the models, we have an interesting weekend in store in the Eastern counties, that wind will be bitter, as for the North, I'd like to see how low we go in Scotland as the clouds clear away -23C anyone?

EDIT:

Jay Wynne on BBC just saying no respite for 10-15 days, so 16th -21st before a break? He's been reading GP's and BFTP's analysis

No, Jay is rightly sticking with our latest UKMO (longer) medium range briefing from the Exeter folks, in which over the past two days they've hinted at consistently present but nonethless low confidence signal of a milder SW/S incursion and/or breakdown developing towards the end of the next 10-15 day prognosis, but until then, it must be stressed, it's an ever-entrenched cold set-up with far higher PROB.

Edited January 6, 2010 by Ian Fergusson

[swilliam]

My link

excellent ENS

Also in the extended ensemble. There is still the step in some members at Jan 16th - but this has been put back a day from yesterday - always a good sign. Control run looks good.

[Bobby]

Latest ECM ensembles = freezing with a renewed easterly brewing up mid Month. No sign of breakdown there.

http://www.knmi.nl/exp/pluim/Data/PLUIM_06260_NWT.png

No end in sight.

[Ben_Cambs]

Intresting what GFS 18z will do tonight. Over the past week it has been playing catch up with the other models and like the post above mine other models such as ECM continue with the cold with no breakdown in sight.

[NorthNorfolkWeather]

No, Jay is rightly sticking with our latest UKMO (longer) medium range briefing from the Exeter folks, in which over the past two days they've hinted at consistently present but nonethless low confidence signal of a milder SW/S incursion and/or breakdown developing towards the end of the next 10-15 day prognosis, but until then, it must be stressed, it's an ever-entrenched cold set-up with far higher PROB.

Thanks Ian,

I was joking

With the models showing what they are at the moment, are there any estimates for drifting, especially in Eastern Areas?

From the attached chart I would expect sustained winds between 20-25mph with gusts perhaps up to 40mph, so drifting could become a problem. Wholey dependent on how much snow falls.

[BLAST FROM THE PAST]

UKMO 96-- streamer............

S

Steve

I have posted in SE thread to expect quick time big upgrades to snowfall for Sat/Sun. It always was the case in similar set ups gone by and it will be the same this time IMO....I suspect you agree.

BFTP

[yamkin]

If it (CET Average) is still below -1.1C on the 21st, it may happen. Now we need someone like Mr Data to tell us when the last sub zero month was.

As for the models, we have an interesting weekend in store in the Eastern counties, that wind will be bitter, as for the North, I'd like to see how low we go in Scotland as the clouds clear away -23C anyone?

EDIT:

I'm going with the ECM & UKMO for a longer colder period.

Jay Wynne on BBC just saying no respite for 10-15 days, so 16th -21st before a break? He's been reading GP's and BFTP's analysis

Peter Cockroft from BBC London Weather said tonight that the piece of ice he held from one of the Trafalgar Square fountain will not melt until February.

Piers Corbyn who predicted a very cold winter months ago said that February will also be cold with a few mild interludes.

Edited January 6, 2010 by yamkin

[cyclonic happiness]

Thanks Ian,

I was joking

With the models showing what they are at the moment, are there any estimates for drifting, especially in Eastern Areas?

From the attached chart I would expect sustained winds between 20-25mph with gusts perhaps up to 40mph, so drifting could become a problem. Wholey dependent on how much snow falls.

That, i think, is the only thing missing from this winter to be ranked "a classic winter cold spell", the lack of blizzards.

Sunday may, if the easterly survives downgrades/changes, may just be the blizzard factor that so far has been missing.

[Shirelord]

No, Jay is rightly sticking with our latest UKMO (longer) medium range briefing from the Exeter folks, in which over the past two days they've hinted at consistently present but nonethless low confidence signal of a milder SW/S incursion and/or breakdown developing towards the end of the next 10-15 day prognosis, but until then, it must be stressed, it's an ever-entrenched cold set-up with far higher PROB.

What sort of synoptic output is it showing? The ECM has (bar today) consistently indicated renewed retrogression to the GIN sea area, is that something at is consistent with the UKMO 10-15 day outlook or is there more of an easterly component?

[TEITS]

Latest ECM ensembles = freezing with a renewed easterly brewing up mid Month. No sign of breakdown there.

http://www.knmi.nl/exp/pluim/Data/PLUIM_06260_NWT.png

No end in sight.

Excellent set of ensembles.

Coming back to the whether this cold spell will break down is very uncertain. However I reckon your better off looking at the archives of 1963, 47 than using the GFS. The problem with the GFS in these situations is once beyond +180 the model will do its very best to break down any blocking and bring a return of the Atlantic.

My view is we're simply locked into this pattern. As we have experienced spells of being locked in mild SW,lys in previous winters the reverse is true now. The difference is a cold airmass is very difficult to shift and the GFS in F.I will be too progressive in every respect.

If this cold spell continued for the rest of January I wouldn't be at all surprised.

[summer blizzard]

Personally, i think that people may be dissapointed with the lack of snow for most of the working week, next week.

This is because while cold, the flow looks too stable to generate much shower activity away from East Anglia and south east England and then the flow picks up too much of a southerly component to generate any real shower activity at all.

The exemption to this looks to be Monday-Wednesday next week as a low pressure system approaches the Channel from the south west, and as usual the GFS and ECWMF are at war, the GFS bringing the low pressure faster and much further south, while the ECWMF brings the system much further north and practically has the system stalling.

The system in question, does not actually form for another 96 hours and approaches from west of Portugal, so while marginal dewpoints may be an issue in the south, the thermal gradiant should result in some impressive intensities and as much some impressive totals should the ECWMF have the correct idea.

[NorthNorfolkWeather]

I've attached a couple of FAX charts, one of them has a feature that I don't know what it is, the other has the 528 DAM line surprisingly far north.

The feature I don't know is the warm front with the white semcircles rather than black a la normal warm front. Could someone explain that to me.

The other chart. the T120 actually has the 528 DAM line bisecting the country East west. Isn't this likely to bring more marginal conditions to the South ?

[BLAST FROM THE PAST]

We could be finally beginning to see the models settling on the beginning of the end. More agreement to settle the High somewhere over Scandi which leads to an Atlantic attack.

Obviously this could lead to some serious snowfall but from past experience from these set-ups, in terms of the Atlantic coming back in, if the first one doesn't get you the second one probably will.

Agree with this, I have been posting this for days and PMing folk. Attack from the SW from 14-20 with second LP breaking the cold block but snowfest for SW and Southern UK then it moves north on second attack. Less cold for the final third of Jan...and that is very much very likely IMO BUT NOT until 20 - 22. Potential reload towards end of the month into early Feb.

BFTP

Edited January 6, 2010 by BLAST FROM THE PAST

[Shirelord]

Personally, i think that people may be dissapointed with the lack of snow for most of the working week, next week.

This is because while cold, the flow looks too stable to generate much shower activity away from East Anglia and south east England and then the flow picks up too much of a southerly component to generate any real shower activity at all.

The exemption to this looks to be Monday-Wednesday next week as a low pressure system approaches the Channel from the south west, and as usual the GFS and ECWMF are at war, the GFS bringing the low pressure faster and much further south, while the ECWMF brings the system much further north and practically has the system stalling.

The system in question, does not actually form for another 96 hours and approaches from west of Portugal, so while marginal dewpoints may be an issue in the south, the thermal gradiant should result in some impressive intensities and as much some impressive totals should the ECWMF have the correct idea.

I think it's quite early to be calling a dry week, T+96 only takes us to the end of the weekend and the ECM is showing a "raging" easterly. You only have to look at the Country Tracks forecast last Sunday to see how much can change within the 72-96 hour period (reviewing the forecast for yesterday and today).

If anything this spell has taught us that huge events can crop up at 24 hours notice, like the NAE on Monday.

[snowingtequila]

Personally, i think that people may be dissapointed with the lack of snow for most of the working week, next week.

This is because while cold, the flow looks too stable to generate much shower activity away from East Anglia and south east England and then the flow picks up too much of a southerly component to generate any real shower activity at all.

The exemption to this looks to be Monday-Wednesday next week as a low pressure system approaches the Channel from the south west, and as usual the GFS and ECWMF are at war, the GFS bringing the low pressure faster and much further south, while the ECWMF brings the system much further north and practically has the system stalling.

The system in question, does not actually form for another 96 hours and approaches from west of Portugal, so while marginal dewpoints may be an issue in the south, the thermal gradiant should result in some impressive intensities and as much some impressive totals should the ECWMF have the correct idea.

isn't monday to wednesday the majority of the working week!? Not the exemption. I really don't think we can make any predictions on dry or wet based on the models as we have seen this last week with predictions by many for a dry cold spell.

[Timmytour]

Peter Cockroft from BBC London Weather said tonight that the piece of ice he held from one of the Trafalgar Square fountain will not melt until February.

Piers Corbyn who predicted a very cold winter months ago said that February will also be cold with a few mild interludes.

I've seen Cockroft's quote elsewhere. Of course he's guessing that as no model as far as I'm aware actually shows that far ahead, but it could be a fair guess based on the reluctance of previous entrenched cold air masses to shift easily. Very much reminds me of 81/82 this. I don't know if the source of the cold is the same, but that was a winter where snow in early Dec lasted till a mild spell between Christmas and New Year and then came back to stay well into Feb.

As for Piers Corbyn.... I think he might well have declared that every single one of the last twenty winters were going to be cold...bless him he has to be right once in a while with that consistency of forecasting The funny thing with him is that you rarely hear about his predictions until after a major event such as this when he comes along and tells you he predicted it!

[beng]

http://www.meteo.psu.edu/~gadomski/ECMWF_12z/hgtcomp.html

The ECM mean pressure anomaly chart is interesting and shows a Scandi block still in place on the 16th - looks to be an omega type block too - which in my experience have a habit of retrogressing; if that was to happen, then that would lock the cold in even longer.

[Duane S.]

We could be finally beginning to see the models settling on the beginning of the end. More agreement to settle the High somewhere over Scandi which leads to an Atlantic attack.

Obviously this could lead to some serious snowfall but from past experience from these set-ups, in terms of the Atlantic coming back in, if the first one doesn't get you the second one probably will.

I agree with both paragraphs. Although I still feel we may have one more reload before things return a bit closer to normal. It is still up in the air but I think things will be a lot clearer come Sunday.

[weather eater]

I've attached a couple of FAX charts, one of them has a feature that I don't know what it is, the other has the 528 DAM line surprisingly far north.

The feature I don't know is the warm front with the white semcircles rather than black a la normal warm front. Could someone explain that to me.

The other chart. the T120 actually has the 528 DAM line bisecting the country East west. Isn't this likely to bring more marginal conditions to the South ?

Hi NNW

I think you will find that the 528 DAM line loops around the UK in the first instance, leaving us on the right side of it.

Edited January 6, 2010 by weather eater

[johnholmes]

http://www.meteo.psu...2z/hgtcomp.html

The ECM mean pressure anomaly chart is interesting and shows a Scandi block still in place on the 16th - looks to be an omega type block too - which in my experience have a habit of retrogressing; if that was to happen, then that would lock the cold in even longer.

not really beng as the eastern upper trough is almost under the ridge, it needs to be east of the centre of gravity of the ridge for it to be a true omega pattern.

One thing that the model keeps showing at times is not too dissimilar to just prior to Christmas.

That is almost an omega block in the northern half with a more mobile W'ly flow south of it.

[bluearmy]

http://www.meteo.psu.edu/~gadomski/ECMWF_12z/hgtcomp.html

The ECM mean pressure anomaly chart is interesting and shows a Scandi block still in place on the 16th - looks to be an omega type block too - which in my experience have a habit of retrogressing; if that was to happen, then that would lock the cold in even longer.

i've asked this question many times ben and never had a definitive answer. to me, that output is purely representative of the op run. i have looked at it on runs when the op is clearly an outlier and yet it still reflects the op output. nowhere on the page does it mention the word ensemble. if i am right, i think that too much is made of these charts. we pretty well know what they are going to show if we've looked at the operational runs. at T168/T240, we should be looking at ens means, not operational ones.