General Model Output Discussion

[rmc1987]

Just slightly off topic...

As a learner, I'm on the understanding that the Jet Stream is staying well south? Which is good if we don't want mild south westerlies! The same goes for summer if you want decent sunny weather, no? Now I fear it'll decide to show up during the summer months!! If I recall it spent some time round here the summer gone? Maybe a pattern is emerging and we can look forward to colder winters and cooler wetter summers!

Edited January 10, 2010 by rmc1987

[Thundery wintry showers]

The jet stream staying well south is double-edged at best in the summer if it's warm sunny weather you're after- it will often bring a lot of frontal rain to southern areas while in the north it will be mainly dry but often on the cool side, and cloudy near the east coast.

In the last three summers the jet tended to track right across the British Isles so it ended up very wet everywhere, although in 2009 the jet was less strong than in 2007 and 2008 and hence most eastern parts had a higher emphasis on convective rather than frontal rainfall, and slightly above average sunshine despite above average rainfall.

For warm sunny weather in summer, one major setup has the jet being deflected to the north via a strong ridge of high pressure from the Azores extending over to Britain, although it is often cloudy on the northern flank of such a high. The other has high pressure centred over and to the east of Britain and low pressure tending to stall out in the Atlantic, which usually means hot sunshine and occasional thundery outbreaks due to the frequent southerly winds that result.

[rmc1987]

Thanks TWS ;-)

[swilliam]

I was looking at the ECMWF ensembles on Meteociel, I know they are the De Bilt ones, but look at the temperatures being forecasted by both the Operational and the control run. Clearly some uncertainty with many of the ensembles going somewhat milder, but clearly no certainty in the end to the cold weather.

http://www.knmi.nl/e...agse/index.html

There seem to be a lot more mild solutions compared to the last few days though.

[PubliusEnigma]

oddly enough-what has to be guarded against now-is to go too far in the less cold direction.

All forecasters need to take stock-look at what is ACTUALLY happening both on the surface and in the upper air-and from some distance from the UK shores, all round-what is happening-have the models got a good hold on that. The 12z input should address any problems from early on so hopefully the 12z output from GFS/Extra and UK Met/NAE should pick up on anything. Also any forecaster will also be looking back at basic forecasting.

So interesting to see what the output shows for the next 24-48 hours later this afternoon.

John, what do you make of the latest warning from the MO for the South West warning of up to 30cm of snow in the

South West on Tuedsay. No mention to say this is limited to high ground. Surely the last of the salt will be spread

to avoid traffic chaos. Then if it rains, all that salt will be simply washed away. Not looking good either way.

[johnholmes]

I have no comment to make-I'll wait until I see the latest model outputs. I remain of the view that this week is a forecasters nightmare and I'm pleased not be any part of it!

No human forecaster can predict what the detail might be for Tuesday so one has to rely on the models and that forecasters interpretation of what h/she sees.

[tinybill]

I have no comment to make-I'll wait until I see the latest model outputs. I remain of the view that this week is a forecasters nightmare and I'm pleased not be any part of it!

No human forecaster can predict what the detail might be for Tuesday so one has to rely on the models and that forecasters interpretation of what h/she sees.

john do sky get there weather some were else miles diff to what BBC are saying????

[Methuselah]

I have no comment to make-I'll wait until I see the latest model outputs. I remain of the view that this week is a forecasters nightmare and I'm pleased not be any part of it!

No human forecaster can predict what the detail might be for Tuesday so one has to rely on the models and that forecasters interpretation of what h/she sees.

Absolutely right, John. It's all so 'marginal' just now...It's a mare. Even for us armchair meteorologists!!!

[R.P. McMurphy]

At least there is no "mild" weather being shown on any charts. Albeit the -16.5C won't be here again for a while, but it will still be cold with maximum temps of around 2C in my opinion, possibly 4C down south. But that's no where near mild, so I'm just glad about that, it's good we keep the cold weather with us, it's what winters all about.... An it's only early January so we have a couple of months yet to repeat what we just had. Woo hoo, NO Mild at all.

[bennytes]

http://www.rte.ie/news/2010/0110/tracker.html

just thought you boys + girls might want to know that an iceberg has been spotted just off Ireland for the first time in 40 years.

it's at 14:58

Edited January 10, 2010 by bennytes

[Methuselah]

At least there is no "mild" weather being shown on any charts. Albeit the -16.5C won't be here again for a while, but it will still be cold with maximum temps of around 2C in my opinion, possibly 4C down south. But that's no where near mild, so I'm just glad about that, it's good we keep the cold weather with us, it's what winters all about.... An it's only early January so we have a couple of months yet to repeat what we just had. Woo hoo, NO Mild at all.

Hiya 'Glennis'!! :lol: Good to see you back, mate!! Guessing from the models, I agree - nothing all that mild, for some time to come!

[Thundery wintry showers]

Difficult to pin down at this stage due to tremendous uncertainty over front positioning, but the GFS 12Z run has a front move slowly eastwards during Tuesday/Wednesday, failing to introduce particularly mild air, and potentially bringing some light-moderate snowfall to the central strip of the British Isles.

[Eugene]

http://www.wetterzentrale.de/pics/Rtavn8417.png

Any slushy snow will refreeze at night.

[R.P. McMurphy]

Hiya 'Glennis'!! :lol: Good to see you back, mate!! Guessing from the models, I agree - nothing all that mild, for some time to come!

Hello Peter good to see a familiar face! It's good to be back xD! It's been one hell of a cold spell, just glad to see the models

not pushing any mild air in. Got a feeling it will be a classic 80's style winter, and it's about time!

[Supercell]

Hello Peter good to see a familiar face! It's good to be back xD! It's been one hell of a cold spell, just glad to see the models

not pushing any mild air in. Got a feeling it will be a classic 80's style winter, and it's about time!

Welcome back, Glenn.

Tues / Weds looks better. The frontal PPN comes through (almost quasi-stationary), without the really mild uppers we've seen on previous runs. The west country has favourable conditions for a mainly snow event.

[Liam J]

looks like staying on the cool side, but not the very cold of late. why does the gfs continue to show widespread snowfall for later tonight, when temps in most places have risen to 3 or 4c far higher than predicted

[Matty M]

Contrast between UKM at T60 and GFS at T60 is very large

UKM much colder and potentially snowier.

UKM

GFS

[rich1]

milder air again fails to make much headway on this run

hopefully may be some clearer spells at night, which would be handy in holding existing snowcover

[R.P. McMurphy]

Welcome back, Glenn.

Tues / Weds looks better. The frontal PPN comes through (almost quasi-stationary), without the really mild uppers we've seen on previous runs. The west country has favourable conditions for a mainly snow event.

Hello Supercell! Another familiar face. Yes the models look quite interesting for Tuesday and Wednesday. I expected what happened today in regards of temps and snow. I jus can't believe the BBC and MetO forecasts for Sunday, absolute shocker. I don't even know where they got it from, but definatly excited about next weeks prospects.

[chionomaniac]

Watch this cold spell just evolve into another one. The average milder interlude won't make it and the Easterly will return. The block is being reinforced on the GFS at T+120. As I said yesterday any milder segment will get squeezed at both ends.

[Methuselah]

Hello Peter good to see a familiar face! It's good to be back xD! It's been one hell of a cold spell, just glad to see the models

not pushing any mild air in. Got a feeling it will be a classic 80's style winter, and it's about time!

It's fascinating, isn't it? After umpteen years' of Modern Winter crap, we've a real 1960s-style battelground?

[Craigers]

Watch this cold spell just evolve into another one. The average milder interlude won't make it and the Easterly will return. The block is being reinforced on the GFS at T+120. As I said yesterday any milder segment will get squeezed at both ends.

if this is an ongoing trend then i must say you will be correct! just hoping is the key now

[Matty M]

UKM more keen to bring in more Atlantic influence eventually.

But it must be said model accuracy is appalling at the moment.

The huge differences of that low approaching the SW around T48 have still a long way to go to be resolved. Amazing stuff.

[nick sussex]

A bit of a dilemma for cold and snow lovers this evening with the UKMO delivering quite a snow event before less cold air gets in and with a less cold outlook going forward, compared to the GFS which has less of a snow event but a better chance of the cold staying a while longer.

Quite amazing differences at such a short range.

[snowlight robbery]

Just for information as I live on the extreme South Coast of Dorset,temperature through the whole day has hovered around 1.8-1.9 deg,an area where normally temperatures would rise more quickly than others.