Model Output Discussion:

[Filski]

Still waiting and watching. It seems like every year we get dream charts and the cold is nailed on outside of 7days. Then the flipside comes and throws up the reverse until everyone throws their hands up and says anything beyond 72hrs is FI. At some point between the dream charts and 72hrs the true pattern is invariably shown and generally disappears as quickly. We generally have little way of knowing until the pattern actually starts and so far a bit can still change.

So at this point with people saying that there are few hurdles in the way I'm not getting my hopes up for more than a few frosty nights and clear days in Greenwich. We missed out on the best of the Jan spell so we'd deserve a turn now... but I'll hedge my bets until probably Sun before I unpack the toboggan for Greenwich park. Even then a Thames Streamer would give less than 6hrs notice!

Just on that note I hope the wobble occurred between last Fri and Tues and we're seeing the correct pattern now

Edited February 4, 2010 by Filski

[BLAST FROM THE PAST]

there we go folks- A FULL HOUSE of Easterlies- Aces over Kings.....

Thicknesses on the ECM 72 are down to 532 DAM in continental Air--- 3 days to the start...

Im on holiday for 10 days from Sat - 1 have planned a mon to friday break at centre parcs-

Where do i go- Suffolk, or Sherwood or Cumbria!!!!!!!!!!

YESSSSSSSSSS

S

Eleveden Forest first, then New Forest.

Well I seem to have every post removed thus far, maybe I'm not talking enough about the models that have taken upto t48/72 to pick up on the evolution that has been progged for some considerable time.

Like I said earlier before removal, UKMO, GFS, ECM ,GEM ALL ON BOARD....and about time. What is interesting is that more runs are showing channel lows as a feature. Although it may may not become as long lasting the 9-14 period will be very cold with some extreme 'feel' with very strong easterly/NE'ly winds and heavy snow.

BFTP

[BLAST FROM THE PAST]

Anyway, I don't know why the ECM doesn't sink from T144, clearly this juncture will be dependent on upstream signals which are not certain yet.

Most energy goes into southern arm and although there is a signal for the HP to sink a little towards the UK after the cold spell gets underway for a few days it will not be allowed to do so by southerly tracking jet....something which is a longterm feature and has been for about 2-3 years in the new cycle we have entered.

BFTP

[Ian Fergusson]

Even then a Thames Streamer would give less than 6hrs notice!

Hmmm - perhaps (Mods?) we need to start a short-range model thread to discuss and indeed demonstrate how the UKMO 1.5km modelling of convergence-focused ppn 'streamers' (I assume it's what you mean by 'streamers??') has been surprisingly good... and I can immediately recall - with far more than 6h forecast lead time - the Feb 2009 SW London snowfall event; Glastonbury 2009 T-storms; Dec. 2009 Bristol/S. Glos localised snowfall event and some more recent Kent/ S Downs snowfall events as prime examples where the high-res modelling of such effectively sub-regional forcing was pretty good..... but I do appreciate this thread is largely or wholly concerned with everything into the longer term modelling!

[Alex95]

I have to say that for anywhere near the North Sea this is looking like it could match the early January snow! I'm going to Center Parcs in Cumbria for the weekend, good job I get back on Monday, I'd be mad otherwise!

Generally I think by the end of Sunday it will be cold enough for some wintry showers in the East, but no snow. During Monday thickness values and 850s are reducing so that by the end of the day snow will begin to fall in the east. After that it becomes uncertain, but the chances are that the snow will continue in most places away from the NW. The main thing is the start of the colder weather is just 3-4 days away, so confidence is very high for colder weather.

Now the question we need to be asking is will it be a 2 day cold snap or a 7+ day one? At the moment the models are showing the latter. :lol:

[ribster]

Still waiting and watching. It seems like every year we get dream charts and the cold is nailed on outside of 7days. Then the flipside comes and throws up the reverse until everyone throws their hands up and says anything beyond 72hrs is FI. At some point between the dream charts and 72hrs the true pattern is invariably shown and generally disappears as quickly. We generally have little way of knowing until the pattern actually starts and so far a bit can still change.

I'm not sure that I agree with this, we have had dream charts this winter in my opinion that have verified. Not only that, the models have been playing around with something kicking off around or on the 8th Feb for about two weeks now, albeit they have dropped it at times and latched back on to it, on and off. Granted there is still time for another 'wobble', but that time is fast diminishing as things get interesting in about 3 days time....

Edited February 4, 2010 by ribster

[nick sussex]

Latest ECM De Bilt ensembles for the Netherlands are out, given the expected set up these are a good indication:

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

Very good support for the operational run with the control run following all the way through.

On a different note, it looks like the Baltic Sea will freeze over completely for the first time since the 80's , this link shows the northern hemisphere snow and ice cover upto yesterday.

http://www.rap.ucar.edu/weather/surface/snowAFnh.gif

[Cloud 10]

Tonights 12z ecm ensembles looking very good indeed for a cold spell.

edit. to slow as usual!

Edited February 4, 2010 by Cloud 10

[West Sussex Kate]

Hmmm - perhaps (Mods?) we need to start a short-range model thread to discuss and indeed demonstrate how the UKMO 1.5km modelling of convergence-focused ppn 'streamers' (I assume it's what you mean by 'streamers??') has been surprisingly good... and I can immediately recall - with far more than 6h forecast lead time - the Feb 2009 SW London snowfall event; Glastonbury 2009 T-storms; Dec. 2009 Bristol/S. Glos localised snowfall event and some more recent Kent/ S Downs snowfall events as prime examples where the high-res modelling of such effectively sub-regional forcing was pretty good..... but I do appreciate this thread is largely or wholly concerned with everything into the longer term modelling!

I agree about a short-range model thread....it always seems once we get 'in' the bad weather, we are usually looking ahead to the next big thing/change. It would be helpful to have something which would be a place to focus on the short-term.

Edited February 4, 2010 by Westsussex1

[Filski]

Hmmm - perhaps (Mods?) we need to start a short-range model thread to discuss and indeed demonstrate how the UKMO 1.5km modelling of convergence-focused ppn 'streamers' (I assume it's what you mean by 'streamers??') has been surprisingly good... and I can immediately recall - with far more than 6h forecast lead time - the Feb 2009 SW London snowfall event; Glastonbury 2009 T-storms; Dec. 2009 Bristol/S. Glos localised snowfall event and some more recent Kent/ S Downs snowfall events as prime examples where the high-res modelling of such effectively sub-regional forcing was pretty good..... but I do appreciate this thread is largely or wholly concerned with everything into the longer term modelling!

To be fair you are mostly correct. However a streamer coming off the estuary can deliver in extremely localised areas depending on winds at the time. A few weeks ago it looked good for south London on the models inside of 24hrs but ended up only 10's km south (cue yamkin). If there is any sort of feature in the channel it could mean north, south or central areas miss out or get hit depending on about 15' variation in wind direction. Feb 09 was well predicted but the one before that... (a Sun in Oct 08?) was strictly a case of waking up to see a dusting outside and 15cm in the park an hour later. At the moment it's not possible to talk about snow in any area, except in very generalised terms... yet.

To be honest I don't know how you lot deal with it. I've learnt more from lurking in here in 4 yrs than in all the time in Oz watching weather.

[snowblizzard]

Good model agreement for some type of continental flow next week

However, when looking at the temperatures across Central Europe and Scandinavia it's plain to see that it has warmed-up considerably during the past few days.

http://www.wzkarten3.de/pics/Reurmett.gif

Where will any really deep cold come from now?

Edited February 4, 2010 by snowblizzard

[Cheese Rice]

GFs looks great, would probably be on par with the December cold spell and the January cold spell for England and wales (probably not Scotland). I don't think the main emphasis on the precipitation will be in the south east, it is pretty un-common for just the South East to get snow from an easterly and no where else, sometimes this happens but more often than not the bulk of Eastern England experiences snow. If anything the main risks looks to be for North East England and Yorkshire, yes South East England will get snow but the main risk looks to be northern and eastern areas. Anywhere on in the east will be at risk though.

[KTtom]

On a different note, it looks like the Baltic Sea will freeze over completely for the first time since the 80's , this link shows the northern hemisphere snow and ice cover upto yesterday.

http://www.rap.ucar.edu/weather/surface/snowAFnh.gif

Great chart on first glance, then suddenly you get a heavy heart and long to live in Greece!

BTW, Has Greenland and Iceland linked up recently??

Edited February 4, 2010 by KTtom

[ITSY]

Latest ECM De Bilt ensembles for the Netherlands are out, given the expected set up these are a good indication:

http://www.knmi.nl/e...M_06260_NWT.png

Very good support for the operational run with the control run following all the way through.

On a different note, it looks like the Baltic Sea will freeze over completely for the first time since the 80's , this link shows the northern hemisphere snow and ice cover upto yesterday.

http://www.rap.ucar....ce/snowAFnh.gif

WOW! that northern hempisphere chart is absolutely incredible to look at.

Other than Portugal, Spain, central/eastern France and England/Wales, virtully every country is snowed under. lets hope it returns to our shores next week.

[Nick L]

Why when the threat of snow does this site always flatter to deceive regarding snow potential for your own area. For example trawling the other sites for encouragement Metcheck states absoluteley no snow for my location in Poole for the next 14 days. Weather outlook suggests the same. Even the BBC give temperatures of 5 degrees plus for next Tuesday. Incidentally the symbols never come to fruition on here and I would suggest its not the models that are over progressive but this site itself. We will see.

The Netweather forecasts are based on the GFS runs.

I think the forecasts need to make this clearer.

[damianslaw]

Upstream signals support strong heights over the mid north atlantic into Greenland with energy in the jet being transferred into the southerly arm, so I am not surprised to see the models toying with the idea of showing channel lows next week.

I doubt heights will quickly topple over the country after the initial easterly burst. Watch development to the NE, the scandi trough wants to make an appearance... the easterly will transfer into a northerly as we see heights build strong to the NW, very similiar to what happened both in Dec and early Jan.

An easterly becoming north easterly then northerly/north westerly with chance of frontal snow at times in the SW as lower heights try to edge into the country, I doubt we will get into proper channel low territory or sustained easterly territory, very much a continuation of the synoptics we saw between mid dec-mid jan.. a much better scenario for sunshine and convection and that biting arctic air, as opposed to grey gloomy skies that an easterly from the near continent would deliver.

Of the models the ECM is most in line with what I expect to happen. Wouldn't it be great to see a polar low before winter is out.. the only thing missing so far from this winter, to get this we want heights to transfer strong to Greenland.

[shuggee]

MODEL OUTPUT DISCUSSION

[Snowyowl9]

Just noticed how much difference yesterday`s ECM to today`s it`s all pushing the atlantic further west.

Colder air comes in quicker more of an east flow instead of S/SE which was 2 days ago,more of a battle ground chart then.

http://91.121.93.17/pics/Recm961.gif

http://www.wzkarten.de/pics/Recm721.gif

[Lewis]

MODEL OUTPUT DISCUSSION

Shuggz i'm finding it hard to read that, can you PM me it in a bigger font size please lol

Anyhow, here's my take on things off my latest blog post;

-----------------------------

Good evening,

Welcome to my first blog post on my new NetWeather blog. I hope to give in-depth and non biast information with regards our weather.

As we can all see the forum is once again very busy with mixed signals of a cold snap on it's way for the start of the new working week. The models have some what struggled over the past 7 days, at one point showing a potent easterly setup then 24 hours later showing a mild south westerly dominated pattern.

The GFS "whom i take my hat off to" although showed mixed signals to start, soon backtracked and brought the East/North Easterly back on the outputs. It's certainly going to get a whole lot colder, while there is still some uncertainity to how cold it will be, and whether or not they will be lots of precipitation about "in the form of snow", we do have a fairly sound agreement accross the board with the GFS,UKMO,GEM,ECMWF models all showing a cold outbreak, although the latter model has it's own evolution, so it's 3/4 models with solid agreement for a bitter E/NE'rly, with the ECM going for a more gentle approach with HP close by.

I will base my current forecast with a mixture of all models, although more of a blend from the GFS and UKMO models.

The colder air will make it's way Westwards during overnight Sunday, with -5 to -7 upper 850's affecting coastal counties, the wind will be a NNE'rly, with some showers affecting coastal counties, although at first these will be mainly of a wintry mix as dew points are still rather high.

During Monday, the colder air really starts to digg in from a very cold continent, 500-1000 thickness levels are now sub 528, with snow showers already affecting coastal countines in the East. Day time temps of around 3-5 in the West, typically 1-3c elsewhere. The snow showers will affect Eastern areas, with Eastern parts of Scotland southwards to the Kent Coast line.

Showers will be heavier North of the Wash. With some accumulations possible, although wet bulb temps will be a little on the high side.

Overnight into Tuesday morning, heavy snow showers will continue, the stength of the wind will pick up with snow showers pushing well inland, showers becoming very heavy at times and merging together to give longer spells of snow.

Accumulations once again possible, especially for Eastern areas.

As we go into Wednesday it get's very interesting, with some significant snowfall possible for NE England, Yorkshire/Lincs coastline, EA, and later on into the day and over night SE England.

I won't go into anymore detail, as i'm already edging out of my comfort zone with forecasting, typically i refuse to forecast 4 days out.

I hope you enjoyed my first post :lol: I'll do an update tomorrow at the same time, and will continue to do so each day.

http://forum.netweather.tv/blog/236/entry-3966-cold-spell-incoming/

Favourite chart of the day;

[nick sussex]

Just noticed how much difference yesterday`s ECM to today`s it`s all pushing the atlantic further west.

Colder air comes in quicker more of an east flow instead of S/SE which was 2 days ago,more of a battle ground chart then.

http://91.121.93.17/pics/Recm961.gif

http://www.wzkarten.de/pics/Recm721.gif

Yes and if you look at the fax charts the new one for 72hrs and the old one for 84hrs you'll also see the pattern retrogressing.

[bluearmy]

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.html

the extended are colder and naturally, on the continent, colder=drier.

[Snowyowl9]

Yes and if you look at the fax charts the new one for 72hrs and the old one for 84hrs you'll also see the pattern retrogressing.

It certanly has.

Hows saturday looking,huge atlantic dartboard low going nowhere,thats changed too.

http://wzkarten.de/pics/brack1.gif

[I remember Atlantic 252]

cor quiet, middle of a snowy 18Z run! seems good at 96, no changes really

[Lewis]

Yep looks good, at first i thought it was showing a Northerly toppler, but i forgot about the retrogression lol.

[Weathizard]

Quiet is good, means there's no changes for the worse.