Model Output - General Discussion

[Paul]

A fresh general model discussion thread...

We now have three threads available for model discussion:

Technical Discussion

General Discussion

Chat and Moods

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http://forum.netweather.tv/topic/58023-winter-topics-please-read/

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http://www.netweather.tv/index.cgi?action=nwdc;sess=

Please stay on topic and ensure you are posting into the relevant thread for the tone/content of your post!

[AtlanticFlamethrower]

Am absolutely shaking in shock here at the charts particularly the ECM which now has to be considered the winner, anyone under the age of about 35 is going to see a snowfest they have never seen in their lifetime with chronic drifts and several feet of lying snow, most of the north will have 3-4ft of lying snow with 20-30ft drifts by this time next weekend when the ECM comes off, not so good down here but even I am quite confident of 4 or 5 inches

This event from Thursday onwards is goiing to absolutely bring the country to its knees and is reliable timeframe now.

I am 31 and have never seen anything like this

Unfortunately that forecast finds no support with the 06z GFS which shows a washout. This is going to be a Battle of the Models that will decide which of the GFS or ECM is going to influence us more over winter...

I wouldn't look ahead at the charts past three or four days - Friday the charts were still predicting -10C for Tuesday. Now we have -3C

[Lewis]

Unfortunately that forecast finds no support with the 06z GFS which shows a washout. This is going to be a Battle of the Models that will decide which of the GFS or ECM is going to influence us more over winter...

I wouldn't look ahead at the charts past three or four days - Friday the charts were still predicting -10C for Tuesday. Now we have -3C

That's incorrect, i thought i would correct you.

The charts was showing -5 to -6 850's as the HP moved, there was a warmer sector that got pushed away as the easterly moved in introducing colder 850's

lewis

[Harsh Climate]

I cant believe howw different the ecmwf and ukmo are to gfs at 120h

ecmwf

http://www.wetterzentrale.de/pics/Recm1201.gif

ukmo

http://www.wetterzentrale.de/pics/Rukm1201.gif

gfs

http://www.wetterzentrale.de/pics/Rtavn1201.png.

Normally Id go with the ecmwf n ukmo, but the ecmwf has been all over the place recently and the gfs has been fairly consistant, with ukmo staying middle of the road. But within 120h thats where the gfs usually comes into its fortay and its much harder for things to turn more favourably in this time frame than is to go wrong.

I think think the models are starting to come to a conclusion with the generall theme being, wed/thu easterly narrowly misses us, perhaps having enough of a prescence to deliver wintery showers to eastern areas and maybe a little sleet/snoow to the south east. The second step I expect is for a northerly of some sort to set up with scattered snow showers(sat to sun) to the north sea coasts with northern/eastern scotland perhaps seeing some accumulations. Then after that I think it will be a case of scattered disturbances bringing the risk of rain/sleet/snow, with snow confined to high ground or scotland (mon to wed). Then the final stage of this cold spell will probably be a breakdown to milder conditions with transitional snowfalls in most areas (with snow perhaps staying on the highest hills and mountains, as the greeny high receeds further north west, with the uk losing its influence.

I fancy the ecmwf and ukmo to follow the gfs later as thats where all the signs are pointing, but if im wrong things have to change now, the next couple of gfs runs must start to follow the ecmwf n ukmo, with those respective models staying strong. If the ecmwf gets this wrong and starts to backtrack, seriouse questions must be asked about its performance it it will have been a dire one and vice versa for the gfs in its supposidly high accuracy range.

Im not groaning at what I think will happen, just pointing it out. Nether the less the weather is still going to be very interesting and much better to what were used to but cant see this being a classic. If this cold spell doesnt produce too much if it could just hang on through christmas without breaaking down, on the other spectrum will be a great sign/start for the rest of winter.

Edited December 13, 2009 by Jed Bickerdike

[John Snow]

Unfortunately that forecast finds no support with the 06z GFS which shows a washout. This is going to be a Battle of the Models that will decide which of the GFS or ECM is going to influence us more over winter...

I wouldn't look ahead at the charts past three or four days - Friday the charts were still predicting -10C for Tuesday. Now we have -3C

ECM has to be considered the reliable one now though in this timeframe, GFS I think by 18z will be firmly in line with the mammoth blizzards of the ECM

[SMU]

Unfortunately that forecast finds no support with the 06z GFS which shows a washout. This is going to be a Battle of the Models that will decide which of the GFS or ECM is going to influence us more over winter...

I wouldn't look ahead at the charts past three or four days - Friday the charts were still predicting -10C for Tuesday. Now we have -3C

Where do do you get your information from??-- because none of your last 2 posts bear any reality-

So we have -3 for Tuesday>???? - the South East was the only place progged with -10C & that was the extreme corner- with that in mind this is your 06z -

http://www.wetterzentrale.de/pics/Rmgfs572.gif

-8c...... Slightly different you your comments-

You also mentioned washout...?- Perhaps you would like to explain the washout theory with these -9c dewpoints for the end of the week?

http://www.wetterzentrale.de/pics/Rmgfs1328.gif

If your going to post something- dont come on here & bait people - especially perhaps the newer people who are a little less knowledgable than some-

S

Edited December 13, 2009 by Steve Murr

[Nick L]

I wouldn't look ahead at the charts past three or four days - Friday the charts were still predicting -10C for Tuesday. Now we have -3C

The thing is though, they were never predicting -10c on Friday...

Friday 06z

http://charts.netweather.tv/gfsimages/gfs.20091211/06/96/h850t850eu.png

Sunday 06z

http://charts.netweather.tv/gfsimages/gfs.20091213/06/45/h850t850eu.png

Not THAT much change, at least not as much as you suggest.

[Lewis]

Where do do you get your information from??-- because none of your last 2 posts bear any reality-

So we have -3 for Tuesday>???? - the South East was the only place progged with -10C & that was the extreme corner- with that in mind this is your 06z -

http://www.wetterzentrale.de/pics/Rmgfs572.gif

-8c...... Slightly different you your comments-

You also mentioned washout...?- Perhaps you would like to explain the washout theory with these -9c dewpoints for the end of the week?

http://www.wetterzentrale.de/pics/Rmgfs1328.gif

If your going to post something- dont come on here & bait people - espeically perhaps the newer people who are a little less knowledgable than some-

S

Indeed Steve he is clearly wrong...

I save charts,

Although it does show this, IN FI on past models, but never in reliable time frame, so his comment should just be ignored, don't take the bait steve, your better than that.

Only models showing that was clearly in FI;

[kold weather]

The pattern differences between the UKMO GFS and the ECM are really very subtle indeed, as I said in the other thread the GFS and the UKMO aren't that far away until the high states to sink, with the UKMO taking a good deal longer.

The 12z runs will be very interesting in this respect to see what model backs down, you don't usually come into 72hrs without some sort of decent agreement but this is a set-up where even 30-50 miles differences make a very big impact on our actual weather.

As for the longer range, its quite far out yet and I'd have thought that the Greenland block won;t just weaken into nothing over 24hrs like some of the GFS ensembles are keen on. Equally the ECM maybe overdoing the blocks staying power, at this stage its very hard to call.

My personal views would be for something close to the 0z ECM but with a more active Atlantic as well trying to push into the SW.

[AtlanticFlamethrower]

The thing is though, they were never predicting -10c on Friday...

Friday 06z

http://charts.netweather.tv/gfsimages/gfs.20091211/06/96/h850t850eu.png

Sunday 06z

http://charts.netweather.tv/gfsimages/gfs.20091213/06/45/h850t850eu.png

Not THAT much change, at least not as much as you suggest.

Thanks for posting those charts. I interpret them differently. In the Friday chart all of England gets -10C. Today's chart barely any of England does and I'd wager another 4 downgrades and the bit on the east coast will be gone too - I think the model simply doesn't handle SSTAs in the North Sea and so keeps on having to revise down the cold.

Secondly in the Friday chart the isobars were tighter giving us a faster flow. A faster flow is more important when you have a warm North Sea because a quickly moving airmass has less time to warm up than a slow moving one.

[nick sussex]

Afternoon all

It really says something about the current model output when theres so much to discuss and its within 168hrs and not some distant scenario that never verifies!

Overall the general pattern remains the same today but again the detail is incredibly difficult to pin down, the model divergence continues and this isn't really a surprise given the synoptics. In terms of the upstream pattern still uncertainty in the discussions over at NOAA:

LARGE MODEL DIFFERENCES BECOME EVIDENT ESPECIALLY BY DAY 5 AND

BEYOND IN REGARD TO THE LOCATION OF THE SLOW MOVING CLOSED

CIRCULATION...AND THE RESULTING PATTERN OVER THE EASTERN HALF OF

THE NATION.

Of course anything that effects the eastern US will impact downstream in western europe. But its nice to be talking about model differences that impact on the depth of cold and snow and not one showing cold and the others mild. So its strong agreement on cold for the outlook but a big question mark on amounts of snow and how cold the upper air will be.

Regarding the further outlook the ecm looks like prolonging the cold spell whereas the gfs wants to bring this to an end before Xmas, on the face of it looking at the mean height comparisons there really is decent agreement between the ecm and gfs 00hrs runs in terms of the general pattern.

http://www.meteo.psu.edu/~gadomski/ECMWF_0z/hgtcomp.html

There are however smallish but important differences on how far west the block edges and how troughing over europe interacts with low pressure to the south. Preferably you want to see the block remain far enough east and extend far enough south to reduce the interaction between low pressure heading south and low pressure likely in the sw approaches. Again its a fine line between snowy success and cold and dry.

For the timebeing regarding the shortwave later in the week amounts of snow are up in the air, in terms of convective snowfall, this again difficult till the models can agree on the strength and severity of the easterly flow, so i would stay well clear of the gfs precip charts, these IMO are not accurate and particularly useless in dealing with Lake Effect type snow.

So overall today alot to be optimistic about if you like the cold and snow.

[pyrotech]

fully agree Steve, glad you posted them dew points they are fantastic and i had not seen them. Really looking very positive right now.

one worry i have is gFS paralll as some say it consistant and accurate, but even that still shows a cold spell with some snow for just about everyone.

gut feeling only for me is UKMO at this range for closest to actual. ECM would be amazing.

Great kick off for winter

[Iceberg]

I agree with all the comments re the breakdown, it will be put back, also about the 06Z moving towards the ECM, the 06Z did have the highest pressure out of the Ensemble for Friday in the south( the man was 8mb lower), so I would expect it to move more towards the ECM at 12Z.

I would also expect ECM and METO to move a bit closer towards GFS at the 12Z range.

Todays 12Z will be pretty key, tomorrows 00Z will the the major decider IMO re Thursday and the low.

[kold weather]

Yep Iceberg I agree with you, the next 2 sets of runs for the models will be very key, (3 for the GFS) I think we will have a much better idea about Thursday and what will happen with regards to the easterly airflow.

A easterly would be snowier, the ESE of the GFS would likely to be colder given the fact it won't be going over the higher SST's of the North Sea. I also suspect the 12z GFS will move towards the ECM a little more. I'm just hoping it decides to keep lengthening the time the upper high is strong, seems to have the upper high weakening consistantly at 168hrs over the last few days without it really moving forward much which probably suggests it is a little over progressive at the moment.

[MP-R]

So overall today alot to be optimistic about if you like the cold and snow.

Well that's what I was thinking. It now seems that the really cold air doesn't want to play ball this week but may arrive in the form off a more NNE or direct N flow the week after, commencing Dec 21st. As an amateur, I know not to believe charts more than five days ahead of time fully but these really do show some good cold for the week after, a nice sign that the cold would continue, and hopefully onwards into Christmas.

Friday 18th:

http://www.wetterzentrale.de/pics/Rtavn1201.html

Sunday 20th:

http://www.wetterzentrale.de/pics/Rtavn1681.html

Tuesday 22nd:

http://www.wetterzentrale.de/pics/Rtavn2161.html

Look at the blues and dark blues on this one!

Hope this is more contributing than the opinionated one-liners.

[PB22]

Thanks for posting those charts. I interpret them differently. In the Friday chart all of England gets -10C. Today's chart barely any of England does and I'd wager another 4 downgrades and the bit on the east coast will be gone too - I think the model simply doesn't handle SSTAs in the North Sea and so keeps on having to revise down the cold.

With all due respect, please stop misleading people. You are not helping those trying to learn and understand. That Friday charts shows no -10C 850hPa air over England.

In any case, the 06Z GFS ensembles have upgraded for the short term:

http://www.wzkarten.de/pics/MT8_London_ens.png

http://www.wzkarten.de/pics/MT8_Manchester_ens.png

http://www.wzkarten.de/pics/MT8_Aberdeen_ens.png

http://www.wzkarten.de/pics/MT8_Dublin_ens.png

[Harsh Climate]

You can tell, because on the graphics it shows less speckles far between, when there bunched/grouped it illustrates more snow.

I do agree with you though, it all rests on future models, i don't know what they are looking at. Probably the ECM and not the GFS. BBC/METO have confidence in the euro's.

Why don't we lol ?

lewis

Super. My gut feeling says the 12z ukmo n ecmwf will follow the gfs as I just cant see the gfs backing down in its normally so solid timeframe. But a gfs backdown would be an upgrade of epic proportions!

[AtlanticFlamethrower]

Where do do you get your information from??-- because none of your last 2 posts bear any reality-

So we have -3 for Tuesday>???? - the South East was the only place progged with -10C & that was the extreme corner- with that in mind this is your 06z -

http://www.wetterzentrale.de/pics/Rmgfs572.gif

-8c...... Slightly different you your comments-

You also mentioned washout...?- Perhaps you would like to explain the washout theory with these -9c dewpoints for the end of the week?

http://www.wetterzentrale.de/pics/Rmgfs1328.gif

If your going to post something- dont come on here & bait people - especially perhaps the newer people who are a little less knowledgable than some-

S

The trend on the GFS has so far been to downgrade temperatures. If you take the GFS output and add on some downgrades in temperatures of the sort we have seen since Friday (see my above post where I defended this view) the event is not nailed on.

Not ruling out an ECM scenario which over the last couple of days has been, bar one or two runs, consistent in a fairly fast moving cold easterly. That's why this is a Battle of the Models.

[PB22]

Super. My gut feeling says the 12z ukmo n ecmwf will follow the gfs as I just cant see the gfs backing down in its normally so solid timeframe. But a gfs backdown would be an upgrade of epic proportions!

I can't see the two Euro's backing down at this stage of procedings. The GFS started to edge towards them in the early stages of the 06Z run, and I expect this to be continued in future runs. The Met Office clearly have faith in the Euro's, because they wouldn't be forecasting what just got broadcast. The GFS has backed down towards the Euro models more times than I can remember.

Why do you think the two Euro models will backtrack to the GFS?

[Nick L]

I wasn't misleading people. A poster I replied to on page one linked to a Friday chart which shows exactly what I recollected - a powerful easterly (-10C 850hpa all of England) for Tuesday. That it's not going to happen is a downgrade.

It never showed any -10c! The -10 line is well out into Eastern Europe, you are misleading people.

http://209.197.11.166/c9s4a5k3/cds/gfsimages/gfs.20091211/06/96/h850t850eu.png?dopvhost=charts.netweather.tv&doppl=0cb4ec154790309847c030c896053b8347c030e9&dopsig=fe57a864b984141eeb5c77a7adba7dca

[PB22]

I wasn't misleading people. A poster I replied to on page one linked to a Friday chart which shows exactly what I recollected - a powerful easterly (-10C 850hpa all of England) for Tuesday. That it's not going to happen is a downgrade.

You are misleading people.

Here is the chart: http://charts.netweather.tv/gfsimages/gfs.20091211/06/96/h850t850eu.png

Now where is the -10C 850hPa over all of England????

In any case, it hasn't happened yet so cannot be judged!

[Harsh Climate]

I can't see the two Euro's backing down at this stage of procedings. The GFS started to edge towards them in the early stages of the 06Z run, and I expect this to be continued in future runs. The Met Office clearly have faith in the Euro's, because they wouldn't be forecasting what just got broadcast. The GFS has backed down towards the Euro models more times than I can remember.

Why do you think the two Euro models will backtrack to the GFS?

The main reason is because the gfs has started to back track on itself over the last few days and know is well within its reliable timeframe. It would be very unusual for the gfs to give us such a big upgrade (suddenly giving us the type of easterly that ecm is offering wed-sat), especially when the model is renound for downgrading. Also the ecm has chopped and changed so rapidly within the last 5 days, I think its quite easy for it to quickly change again towards the gfs, a lot easier than it will be for the gfs to make a big u-turn.

I certainly hope Im wrong and the gfs follows the ecm this evening, but not sure it will happen

[AtlanticFlamethrower]

Okay, sorry, I thought the light blues were -10C. I mean -8C.

I restate my previous argument but with -8C (light blues) where I said -10C.

[Geordiesnow]

I can't see the two Euro's backing down at this stage of procedings. The GFS started to edge towards them in the early stages of the 06Z run, and I expect this to be continued in future runs. The Met Office clearly have faith in the Euro's, because they wouldn't be forecasting what just got broadcast. The GFS has backed down towards the Euro models more times than I can remember.

Why do you think the two Euro models will backtrack to the GFS?

The beeb always shows the UKMO charts no matter what, if we had the countryfile forecast for last nights UKMO, they probably won't show much in the way of snow graphics and probably would not even menturn the S word. Must also be noted that the forecaster did say snow amounts and where it will be is still up in the air.

I have to admit, i wish the GFS would of backed down by now. I did not see the 00Z run but i assume by the comments it was showing something similar to the 06Z. So until this model backs down towards the euro's then i'm not going to get too carried away. Also considering we had a 2v1 situation yesterday with the UKMO/GFS vs ECM so it can easily change back(hopefully not!).

However, this morning's output is certainly more encouraging regarding the strength of the easterly with the UKMO coming on board now. Hopefully we will get FULL agreement regarding how strong the easterly will be by the 12Z's. From what i read, the GFS 12Z is normally the best run out of all the GFS runs albeit it can be over progressive.

[SnOwFeSt]

I am perhaps hopecasting, but I think the GFS will move slowly toward the ECM output, as it seems to have done a little this morning.

The margins between an absolute pasting of snow and a much slacker (albeit still very cold) flow are tiny (about 100-200 miles), so I'm not expecting any firm consensus until Tuesday at the earliest.

However, if the GFS starts moving toward the ECM solution at 12z, it will be a step in the right direction.

I need to take a couple of days off the models (I tried yesterday, but was back online after about 4 hours!) - this model watching is starting to drive me crazy!!