Model Output Discussion:

[swfc]

Think the low over scan has lost its bearings.bit flabby looking with slack winds here

[cold snap]

Think the low over scan has lost its bearings.bit flabby looking with slack winds here

I like the North Easterly tilt on this.This done great for Dublin in January,its a good run

[January Snowstorm]

Not too keen on the Icelandic high slipping South over us, a trend that ECM also had

Would give a very dry cold spell, which is not really what we want.

Overall though still very good

[I remember Atlantic 252]

yeah Ian 12Z was way better, this too flabby and high pressure dominated, not sure about dull though, more cold and frosty

[cold snap]

I prefer the GFS 12Z to be honest, which had plenty more action and battleground scenarios. This would be just cold, cloudy and dull for most.

Ian i was thinking the same

Upgrade on cold temps

Downgrade on PPN

But we know the rule .get cold in first,then worry.

I enjoy your posts Ian

[Optimus Prime]

This would be just cold, cloudy and dull for most.

That's the exact opposite of what I see. Cold clear and then very cold with snow showers in the east and perhaps in the SE.

Edited February 3, 2010 by Optimus Prime

[Bobby]

I prefer the GFS 12Z to be honest, which had plenty more action and battleground scenarios. This would be just cold, cloudy and dull for most.

Me too. Very cold but not much action.

[BLAST FROM THE PAST]

Thanks guys, some fair criticism and also praise welcomed.

There is a clear instance of a teleconnective change influencing our thinking over the last 48 hrs.

There shouldn't be criticism especially if folk are not paying for your services and that this is done on a non professional stage. Indeed highlight incorrect portions and query why one thinks the forecast went wrong and where improvements can be made...but not criticism especially when it is usually strongest from those that offer no forecast at all. Quite frustrating when methoda re totally dismissed even though accuracy is pretty good standard.

BFTP

[LomondSnowstorm]

I prefer the GFS 12Z to be honest, which had plenty more action and battleground scenarios. This would be just cold, cloudy and dull for most.

Since when did -10 uppers give anything like those conditions?? http://cirrus.netweather.tv/gfsimages/gfs.20100203/18/150/h850t850eu.png

Sunny, perhaps quite a few showers in eastern and southeastern parts, but not dull at all.

[January Snowstorm]

A messy synoptic picture, far from what we saw in early Jan.

The jury is still out & has a toppler look about it.

Certainly no yellows over Greenland this run

[Bristawl Si]

I prefer the GFS 12Z to be honest, which had plenty more action and battleground scenarios. This would be just cold, cloudy and dull for most.

Agreed.

Not exactly a 'classic' late 70s/early 80s scenario - model runs earlier this eve defo more preferable. But you know, and most on here know, the models will take a few days to 'settle' so to speak. It will take to at least Saturday/Sunday before we can be confident of the weather for next week.

[swfc]

Strange looking run this after 96 hrs.Possible but looks slightly flat and elongated the high.low pressure either side and kind of a know mans land.All to play for tho given yesterdays output.

[Geordiesnow]

I prefer the GFS 12Z to be honest, which had plenty more action and battleground scenarios. This would be just cold, cloudy and dull for most.

I would normally associate uppers of -10 with sunshine and showers type of set up. I suppose the only problem on this run might be, how inland would those showers get but that is just nit picking. I can't see a cloudy dull easterly on this run.

Not too keen on the Icelandic high slipping South over us, a trend that ECM also had

Would give a very dry cold spell, which is not really what we want.

Overall though still very good

ECM shows a good little spell of sunshine and snow showers for quite alot of areas before the high topple over us. I can't believe your worrying over some trend which is far away that it will probably change. I'm more concerned about that shortwave in the short term and how it may affect our chances of an easterly.

[johnholmes]

forgive me folks and mods but I really have to reply to this part of a post from TEITS this evening- he posted

Personally its too early to be saying well done because after recent model performance my confidence is very low which is why im awaiting tomorrows runs. However I will give credit to others even if their posts aren't as technical as GPSS. Worth taking this into account John and not be blinded by technical posts because sometimes basic methods prove reliable!

I do take every angle into account TEITS, nor do I believe I am 'blinded by technical posts' be that me posting about short term probabilities or longer term. I did spend 20+ years before and after computer models were in operational use, doing just that, assessing and using basic meteorology. Indeed if you follow the occasional blog I do at T+24 or less then basic meteorology is often what I use not model output.

At the end of the day TEITS the best output is, as I often post, the man-machine mix. That is why outputs from UK Met and NOAA, as some, including Ian Fergusson, will testify, are USUALLY far superior to the model alone.

The performance, to date, of the winter prediction by GP is quite first class in my view. The crunch of course comes when he does next winter's forecast. If he gets two out of two largely correct then he can be justly very pleased. I'd be happy to get just the one right at that distance-hence my praise which you seem to feel is unjustified?

Edited February 3, 2010 by johnholmes

[Optimus Prime]

Anyway, it's only the 18z and the general theme of height rises directly to the North is maintained.

Exactly the same setup to January 2003 that gave us a slack flow and 10cm of snow. Then clear and very cold. it most certainly wouldn't be dull though! An easterly with uppers around -5c tend to be dull.

As you say though a good trend for some height rises to the north. With the easterly shown I don't think it would be sustained too long until high pressure moves southwards.

Any rate I define severe frost and cold days as quite exciting. Probably makes me boring but not greedy.

Edited February 3, 2010 by Optimus Prime

[Snowyowl9]

This run will give record amount of sunshine severe frosts and some snow to start.

And a battle ground snow held in the atlantic.

http://91.121.93.17/pics/Rtavn2401.png

And we would be looking at a very cold winter overall.

Edited February 3, 2010 by Snowyowl9

[SMU]

I don't agree, heights are fairly low but the flow is very slack, light wintry PPN around Eastern coasts but nothing to get excited about. Anyway, it's only the 18z and the general theme of height rises directly to the North is maintained.

LOL --- That post is misguided- light wintry PPN-

try heavy Snow showers moving westwards - This run favours the NE, East & all of the South-

In terms of this evolution is there a month that can compare- yes Jan 1985 but only partially-

January 1985 very cold (0.8C CET) with frequent snow in the first three weeks. There was heavy snowfall in Kent on the 5th (25 cm of snow around Ramsgate and Margate), with maxima of -4C. The 7th was a cold day, with temperatures beneath freezing over much of the country; -16 at Jubilee Corner (Kent) on the morning of the 8th. As the cold air retreated temporarily to the continent, temperatures rose for a while, but the cold soon returned with a vengeance around the 13th. Some very low maxima on the 16th, which was one of the coldest days of the century in parts of southern Britain: -6C at Brighton and in Kent on the 16th and Shrewsbury and Wittering on the 17th. 20cms of snow over much of the south. Thaw from the 19th, preceded by a blizzard over the Highlands. There was a minimum of -19C on the 25th, rising to only -9, and a minimum of -22.4 at Aviemore on the 27th, and -23C at Braemar.

Jan 5th 1985 had the identical flow from the 18z for ONE DAY-

http://www.wetterzentrale.de/archive/ra/1985/Rrea00119850105.gif

The 18z proggs the same flow for 3/4 days in -13c air-

So by that token you could quite easily see 30/40cm of convective snow in the East & SE AT least-

but we are talking sematics... lets get the flow first- Also how many people were moaning in December about how dry the last cold spell was going to be then places like reading ended up with 40cms-

S

Edited February 3, 2010 by Steve Murr

[nick sussex]

Well another GFS run survived which given the last week is good going! Preferably I'd like to see that Icelandic shortwave weakened much more quickly,i just don't like shortwaves which serve no purpose but to be a nuisance! I still prefer the ECM output as it gives a bit more margin for error but overall a good evening in the model output.

[snowdrifter]

won't know snow situations until nearer the time as usual!

Agreed! back in early Jan I made an unthinking post about not just wanting merely cold but snow, and was rightly reminded that we needed the cold in place first. Now, I'm in a v unfavourable area for snow compared to some, but days after that post we had a brilliant snowfall and the most wintry week since we moved here 9 years ago. All to play for. Tomorrow's a big day - I so want the models to share the same easterly songsheet.

Edited February 3, 2010 by snowdrifter

[ScottSnow]

Well the 18z maintains model agreement and height rises to our north with an easterly setting in.

After the uncertainty of the past few days I'm certainly not going to get excited yet, however if we do get the cold air/synoptics in place I think the cold may last some time, just my own hunch going off previous cold spells this winter. Just hope the models hold up after the reversals of the past week.

As for snow, the cold spells of Dec and Jan have shown that once the cold air is in place then snowfall can occur almost anywhere and really can only be forecast at very short range. Some of the best spells of snowfall here weren't forecast and it just reitterates the fact that once cold air is in place then oppurtunities will arise.

[BLAST FROM THE PAST]

but we are talking sematics... lets get the flow first- Also how many people were moaning in December about how dry the last cold spell was going to be then places like reading ended up with 40cms-

S

How many were 'bigging up' the death knell of cold and mild has won out..just 2 days ago!!!!! Some folk won't look beyond the end of their noses!!!

I agree that there will be periods of heavy snow for the SE and NE mainly but as LPs travel across the channel that could produce some sparks.

Lovely 18z run, but too delayed initially. 12z ecm IMO is on the money

BFTP

Edited February 3, 2010 by BLAST FROM THE PAST

[Guest North Sea Snow Convection]

I'm really surprised at some of the comments to the 18z. It is a brilliant output I think I would very very gratefully bank that now if it was offered with its guarantee

Especially after all the ups and downs of recent days surely the most important thing was to keep the continuity going of the trend for the easterly to come in, rather than fretting already about IMBY snow details. And that is before we can officially confirm that all this is (everything crossed) going to actually happen. These same people yesterday would be complaining about the threat of mild south westerlies and 12c temps with drizzle streamers coming in off the atlantic over the Torbay beach ice cream kiosk!

Edited February 3, 2010 by North Sea Snow Convection

[Cloud 10]

The above 3 charts are from the 18z at 144 hrs.

The 3rd chart is the precipitation chart but is way underdoing the amount of convection that would occur over the north sea given the air pressure and 850 temperature values of the first 2 charts.

This seems to happen often with gfs,but it does normally upgrade the ppn as it gets closer to the event.

[Bottesford]

Perhaps lets stick to discussing the models from now on maybe? Just an idea to stop your posts being deleted!

[johnholmes]

Its nothing to do with point scoring, if it was an inexperienced member then yes, treat them a bit gently, but lets be honest - an experienced member, ex forecaster should know better....

S

As to the models then the input from Ian F and the data available from NOAA as well as the overall output that we see from UK Met all support the view of cold not mild getting the upper hand by early next week. I also agree with GP's view that it is probably not going to be anywhere near as long lasting as the previous spell but then it would take something pretty unusual to repeat that if we are honest-so a minimum of 3-4 days and a maximum of about a week perhaps a shade over.

BUT the actual outcome is certainly not set in stone which the posts from UK Met that Ian drops in make very clear.

Edited February 3, 2010 by johnholmes