Model Output Discussion

[Lewis]

What are you basing that on?

One run?

Ah come on for gawds sake,we've all been round long enough not to be doing that or making flawed conclusions from one run of one nwp...

Hi Tristrame,

I'm not basing it on one run, and it's not a conclusion, infact far from it. I post my thoughts on each seperate output per model run. How many runs have we had now showing the position of the HP more or less right over us, and also the easterly delayed and pushed further and further back. Have you had a look at how many warm sectors are floating about now. Where the precipitation will be mainly confined to the East and SE, it will be marginal most of the time with warm sectors all over the place.

*edit -

So i don't confuse people, when i mention warm sectors and also warmer 850's i'm relating to the reliable time frame *upto 72 hours*, with it changing a lot in reliable time frame, later on down the line becomes less certain, and un-clear.

Edited February 7, 2010 by Storm Force Lewis

[john mac]

Isnt it amazing how people find something to complain about when were starring down the barrell of a long lasting cold spell, the model outputs this afternoon are looking in on good form, as ever some places will get more snow than others and i want to reiterate one thing that is imperitive so moaners listen up.

YOU HAVE TO GET THE COLD AIR IN PLACE BEFORE YOU CAN GET SNOW!!!.

This is slowly happening right now, and anyone trying to forecast snow past a couple of days out is mis-leading themselves.

Once the cold is here the snow will come sometimes with little warning.

So sit back relax and enjoy the ride

[Iceni]

Yes they're in the full extra subscription, but there are a selection out to 96 hours in the free datacentre:

http://www.netweathe...=nwdcskew;sess=

Seen the diagrams and totally blanked… then followed the help link to John's guide. Seems I've got some learning curve ahead of me (Everest size ) but great stuff John thank you.

[January Snowstorm]

Constant slight downgrades now for about the last 36 hrs

Downgrades in that there will be little if any ppn around.

In fact with clear sunny weather at times it will feel positively Springlike in sunshine.

Yes frosty nights, but anything worthwhile being pushed further and further back, all the while we move gradually out of "Proper Winter" and more towards the drip drip of Spring snowfall

Edited February 7, 2010 by January Snowstorm

[Tristrame]

yeah it was me-- this is a definite slow burner- I will try & get one of those special long posts up later this eve-

Lewis- 850's getting warmer- their getting colder mate- the mean was only ever down to -10c-

Now we have -13c on tap-

http://www.wetterzentrale.de/pics/Rmgfs1262.gif

S

Yup and anyway-people are forgetting the cold surface air feed will eventually advect westwards too.

This takes a little bit longer than the 850's and is more usefull-less warmer air for the precip to fall down through and ergo less fear of 850's rising a few degree's if they do.

People-look East.

Look where the 0c isotherm is on the continent and up in Scandiland.

It's at sealevel right over to Holland even now and REMEMBER that means it's unlikely to go above zero there,it's not showing that it is likely to be several degree's below zero on the continent and it will be...

This is a sustained feed folks,a sustained feed.

People that are dissing it and worried they won't see snow at some stage in the next fortnight are frankly wrong.

So chin up.

Relax and take it as it comes.

Edited February 7, 2010 by Tristrame

[SMU]

GFS ensemble MEAN V the 06z is a nice upgrade- especially in the 90-150 arena-

-12c just off the coast in the mean & the -10/-11c isotherm present across England from 90 onwards-

Also the key 3 low pressures for sustained cold & possible heavy snow down the line are getting in place at 150-

more on this later-

S

Edited February 7, 2010 by Steve Murr

[Lewis]

Isnt it amazing how people find something to complain about when were starring down the barrell of a long lasting cold spell, the model outputs this afternoon are looking in on good form, as ever some places will get more snow than others and i want to reiterate one thing that is imperitive so moaners listen up.

YOU HAVE TO GET THE COLD AIR IN PLACE BEFORE YOU CAN GET SNOW!!!.

This is slowly happening right now, and anyone trying to forecast snow past a couple of days out is mis-leading themselves.

Once the cold is here the snow will come sometimes with little warning.

So sit back relax and enjoy the ride

Hey john,

I don't think there is many complaining, just a little dissapointed with the outputs/models. I would rather have dry cold weather than the Atlantic breaking through with temps of 9-11c, but when the models are showing dream land scenario's, plenty of snow/precipitation about, for it only closer to the hugely anticipated timeframe to be downgraded, it can have a negative affect on people.

I also agree with your theory of get the cold in first then think of the snow, that's what we want to do. But you do have to remember if your stuck under a HP the chance's of getting precipitation on a wide-scale is very very low, although i have seen weirder things

[johnholmes]

Seen the diagrams and totally blanked… then followed the help link to John's guide. Seems I've got some learning curve ahead of me (Everest size ) but great stuff John thank you.

pm me any time and I'll try to help-that goes for anyone thinking of starting to look at the skew-t tutorial.

There are some problems with one or two of the diagrams, I'll try again and get them sorted this week.

[Blizzard_of_Oz]

yeah it was me-- this is a definite slow burner- I will try & get one of those special long posts up later this eve-

Lewis- 850's getting warmer- their getting colder mate- the mean was only ever down to -10c-

Now we have -13c on tap-

http://www.wetterzen...s/Rmgfs1262.gif

S

Thanks Steve you were very confident earlier aswell as you can see. This was posted on Tuesday I think well done, I wish some of the more unexperienced on here would learn from you.

• Cumulonimbus

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Posted Yesterday, 18:23

http://www.wetterzen...cs/Recm1201.gif

Game set & match Cold-

Widespread snow in the NE at day 5 & heavy snow stalling out in the South & SW on the same day-

Feb 1996 redux morphing into Jan 85-

[Geordiesnow]

UKMO is better than the GFS this evening, it keeps a nice easterly flow going thus, more shower activity and showers would get inland especially in Southern areas.

It will be interesting if the models downgrade the cold pool for the end of the week, although i suppose subtle changes here and there will mean a shift of where the cold pool actually ends up.

The GFS FI charts are quite laughable and always seem to offer the coldest possible set up, may aswell enjoy them though because you won't see the same chart in the next run even if the FI is a cold one.

[johnholmes]

I've done a pdf for the Yorks regional thread based on Doncaster skew-t output on the 12z data. It is probably reasonably accurate for many parts of eastern England, in terms of what the skew-t shows. No guarantee of the subsequent forecast!

[Optimus Prime]

It's FI city on here this evening.

Not a lot of change since I last looked yesterday. Progressively cold as the week goes on with snow risk and the heavier stuff towards the east.

[Jamie.]

Isnt it amazing how people find something to complain about when were starring down the barrell of a long lasting cold spell, the model outputs this afternoon are looking in on good form, as ever some places will get more snow than others and i want to reiterate one thing that is imperitive so moaners listen up.

YOU HAVE TO GET THE COLD AIR IN PLACE BEFORE YOU CAN GET SNOW!!!.

This is slowly happening right now, and anyone trying to forecast snow past a couple of days out is mis-leading themselves.

Once the cold is here the snow will come sometimes with little warning.

So sit back relax and enjoy the ride

Yep, that's my thoughts!

We just need the cold air in first as with that over us we can get snow from LP's off the Atlantic in a breakdown at least.

[SMU]

http://91.121.94.83/modeles/gens/run/gens-4-1-204.png?12

as per comments RE : the locations of the low pressures- this is the BEST case scenario- this only comes once in a lifetime for many-

S

[Duane S.]

Chin up everyone. This cold spell was never progged to arrive with a bang, bar a few very progressive and unrealistic forecasts. Patience will be required. BUT... nothing has really changed. Tomorrow is the 8th, this was ALWAYS (roughly) the earliest date that the cold was going to start to filter in. Lo and behold and so it will be. To those in Bristol the west who are now saying the charts are not bringing what they promised a couple of weeks ago, the cold has to get there from the East (or North) first. If you don't like it, move somewhere beyond the Meridian There is no sign of any downgrades (in the broad sense). Some are, rather sadly, spending their Sunday afternoon trawling the charts looking for spoilers to wave in front of people's faces but there simply are none.

The AO has dropped highly negative and will remain so for a while yet to come. The NAO is slowly but surely dropping down. The MJO couldn't be better placed at slowing down in phase 7 and forcast to head to phase 8. The GFS runs have been excellent, the UKMET is a big improvement. The high cannot sink (other than a small amount initially) due to the energy to the south of us and looks likely to retrogress in about a week's time leaving us open to further cold and a greater chance of PPN. Add to that the unknown factor (in terms of when/how much it will propogate into the tropsphere) of the recent SSW and what we have is a heck of a lot of potential right in front of our noses.

[Iceberg]

I remember having a discussion with a couple of people on here a few days ago about max temps this week, then the models where showing temps of 4 or 5C on wednesday and then colder on thursday....I could be mistaken but that is what they are showing now isn't it.

Also re precip, a slight chance tomorrow and then a trough/wave wed/thurs has been there for a few days, other than that it's always been showers in the east, spreading inland when a streamer develops ?.

Steve has covered the extend and lowness of the 850's nicely, so for the life of me I can't see a downgrade or a put back in sight.

If your realistic in the first place the models are showing alot of consistance (and high pressure being alittle bit higher or lower at T140 is allowed and still counts as the models being consistance, they arn't exact reproductions ! ).

[john mac]

Hey john,

I don't think there is many complaining, just a little dissapointed with the outputs/models. I would rather have dry cold weather than the Atlantic breaking through with temps of 9-11c, but when the models are showing dream land scenario's, plenty of snow/precipitation about, for it only closer to the hugely anticipated timeframe to be downgraded, it can have a negative affect on people.

I also agree with your theory of get the cold in first then think of the snow, that's what we want to do. But you do have to remember if your stuck under a HP the chance's of getting precipitation on a wide-scale is very very low, although i have seen weirder things

But we all no that 99 times out of 100 that anything in FI changes as it gets into the reliable timeframe, especially with these cold set ups, snow wevents very often come down to nowcasting. Take for example in the last cold spell. The monday before christmas a snow event was predicted to hit southern england, the snow was only predicted to get as far eat as berkshire (anything east of that would be rain) without warning it started to snow in my area and we ended up with over 3 inches. What im saing is dont worry too much about the fine details to early because they will change. We're getting the cold the snow will follow.

TBH honest i would be glad to see a bit of sunshine for a couple of days as it has been in short supply this winter.

[Weathizard]

http://91.121.94.83/...-4-1-204.png?12

as per comments RE : the locations of the low pressures- this is the BEST case scenario- this only comes once in a lifetime for many-

S

Hi Steve, just wondering if you could further your post, if this was to happen what would it bring ect?

Only if you have the time obviously.

[Lewis]

But we all no that 99 times out of 100 that anything in FI changes as it gets into the reliable timeframe, especially with these cold set ups, snow wevents very often come down to nowcasting. Take for example in the last cold spell. The monday before christmas a snow event was predicted to hit southern england, the snow was only predicted to get as far eat as berkshire (anything east of that would be rain) without warning it started to snow in my area and we ended up with over 3 inches. What im saing is dont worry too much about the fine details to early because they will change. We're getting the cold the snow will follow.

TBH honest i would be glad to see a bit of sunshine for a couple of days as it has been in short supply this winter.

Good post mate, you made some very good points.

Although the pressure is going to be so high thanks to the High Pressure, and friday too me is FI, and that will change also as we come closer, so really in terms of unexpected events, i cannot see it with this kind of setup, other than a trough heading south thats clearly being shown on all the charts over the past 24-48 hours. I won't forecast/predict friday tbh when the easterly is expected to affect us, that is of course if it does.

lewis

[Sawel]

Looking at the latest verification statistics, it is becoming clear that the UKMO is breathing down the neck of the ECM for best verifying model at +120 and +144 hours. There isn't much in it, especially at +120 hours, with the ECM on 911.31 and the UKMO on 904.11.

http://www.emc.ncep.noaa.gov/gmb/STATS/html/acz5.html

http://www.emc.ncep.noaa.gov/gmb/STATS/html/acz6.html

The GFS has not verified better than the UKMO at +120 hrs for 14 days in a row and counting. At 144 hrs it has not verified better for 11 days in a row and counting.

People talk about the "big 3" but these stats show that right now it's the big 2 with the GFS well behind scrapping it out with the GEM for 3rd best verifying model.

Edited February 7, 2010 by Sawel

[john mac]

Good post mate, you made some very good points.

Although the pressure is going to be so high thanks to the High Pressure, and friday too me is FI, and that will change also as we come closer, so really in terms of unexpected events, i cannot see it with this kind of setup, other than a trough heading south thats clearly being shown on all the charts over the past 24-48 hours. I won't forecast/predict friday tbh when the easterly is expected to affect us, that is of course if it does.

lewis

Still plenty of time for the high to shift furthur north and then its game on for you, i think we are in good shape for some snow especially if a thames steamer can develop like last feb. Got over 8inches from that event.

[cooling climate]

I can certainly understand some posts on here this afternoon in regard to the GFS

operational run but that is all it is one run best to wait for the ensembles to come out.

I think the operational is over doing the lows and energy to the north and by the time

we get to t72 onwards the UKMO looks the more likely to me.

It should be interesting to see which way the ECM will trend tonight as this morning

it was showing better heights to the northwest and a stronger easterly airflow.

The outlook though is definitely one of cold perhaps turning very cold later in the week

with an increasing risk of snow as we go through the week.

Longterm outlook... cold to very cold with snow at times almost anywhere.

[Iceni]

I think that's a fair assessment. Minor changes in terms of where the High is could make for significant differences in terms of PPN. But beyond that it does look very good for a prolonged cold spell, it's difficult to see how the Atlantic can breakthru at the moment. Things can change quickly of course, this time last week the ECM showed the potential for 17C today !

This loop of the Atlantic coming up against the brick wall of the Scandi high off the west coast of Ireland is a pretty graphic depiction of the situation.

http://www.sat24.com/Region.aspx?country=eu&sat=ir&type=loop

[TEITS]

Short post from me.

Excellent NAE with tomorrow now showing more snow than rain compared to previous NAE runs.

http://expert.weatheronline.co.uk/daten/proficharts/en/nae/2010/02/07/basis12/ukuk/prty/10020812_0712.gif

UKMO is an upgrade compared to the 0Z. The GEM is very nice also. Im eagerly awaiting the ECM though.

http://91.121.94.83/modeles/gem/run/gem-0-120.png

Medium-long range looks fantastic based on the GEFS mean. I can't believe some are complaining because synoptically speaking its bloodyfantastic!

http://91.121.94.83/modeles/gens/run/gens-21-1-192.png?12

[PubliusEnigma]

http://91.121.94.83/modeles/gens/run/gens-4-1-204.png?12

as per comments RE : the locations of the low pressures- this is the BEST case scenario- this only comes once in a lifetime for many-

S

Twice in a lifetime .. It happened on 31st December 1979 or was it 1978, one of the two anyway, perhaps there is

someway of finding that chart, as that brought about 10 inches of snow to the south overnight.