Winter Model Discussion 18Z 5/2/13 onwards.

[SMU]

Is that no way or norway

A mixed bag this morning- UKMO the best for sustainabilty- ECm reverted back to previous nights 00z with the block being pushed aside-

GFS - didnt even look.

If we are to get anything prolonged we must focus on the western & SW part of norway- this has been the area including feb 12 where we struggled to get any higher heights.

S

[Glacier Point]

Meantime for the products that demonstrate the highest level of skill past day 8, the theme remains very consistent despite the inter-run variability of the operationals. If anything, the drum is beginning to beat louder.

Day 10 GEFS H5 mean anomaly:

The ridge in the Atlantic is developing day by day as the circulation becomes increasingly amplified. The troughing over Europe well ensconsed (and colder than normal temperatures) whilst +ve heights persist over Scandinavia.

At some point, the mid Atantic ridge will assume dominance and direct the flow from the NW / N rather than the east. Then two options on the table I think.. another pulse of energy from the residiual pv which would focus the ridge on Scandinavia, or a heights rising further NW.

Either way, looking below average, and the longer this goes on, the more we sleepwalk into a below average winter.

[TEITS]

Finally im not sure I agree with the snowfall risk areas you have highlighted. At this stage I feel Ireland/Wales/SW England are more likely to see rain than snow with the risk of snow being further E than you have highlighted. The reason being is I feel the ECM & latest Fax charts are wrong and we shall see a slight shift E in the morning. The GFS on the other hand is far to E with the pattern.

Unfortunately the shift E has occured this morning. Still I wouldn't be too concerned at this stage because the scatter in the ensembles has returned after relatively good agreement on the 18Z.

http://cdn.nwstatic.co.uk/ensimages/ens.20130206/00/t850Cambridgeshire.png

Really is incredible to have this amount of scatter this early. This illustrates how uncertain the outlook is for this weekend and beyond with regards to details..

My opinion hasn't really changed from yesterday. If we do see a brief mild spell next week it won't last as I feel even colder weather is on its way. Check out this SLP mean from Iceland. Probably the best I have seen all winter.

http://cdn.nwstatic.co.uk/ensimages/ens.20130206/00/prmslReyjavic.png

[CWT2012]

Typical

ECM teases us for days, GFS on a parallel universe, GFS falls into line with what ECM shows and soon as it happens ECM backtracks.

[Jason M]

Anyone know what the DAM values would be for the meto charts? In the absence of the 850s it's awkward to know whether meto is cold enough. I suspect it is, but that's an educated guess.

Jason

[snowmadchrisuk]

To be fair, his spelling is better than most on this forum

Ok well everything aside , his view is obviously a weak Atlantic with HLB becoming established to our North . For this to happen it will obviously depend on what the Models decide to do with the energy left over from these Short Waves forming off the Eastern United States. Why the PV looks so week and looks to be heading towards the Pole , We will obviously always be in with a chance of things going our way .. Would like to see Deep Cold establish in the next 10 days though as it is like a ticking time bomb , first week of Feb has already gone , and although Snow chances won't always diminish , Settled Snow and Ice Day chances will be getting less likely in the next 20 days or so. In the short term looking for Westward corrections of that Low on Sunday as this could provide lying Snow that might hang around for a bit with colder air tucking in behind.

[Ryan Dutch Weatherman]

Glacier point .You did make a good point with the ensembles from GFS.

But look the BOM model , its great run.

A block , a NE wind , end a POLAR low is sinking from the north towards the UK.

This you can print it out en hang it at your living room.

[phil nw.]

The general consensus from the 00z is to track the weekends diving low across the UK which pretty much is where mean outputs have modeled it for a few runs now so no real surprise on this.

I would still expect snow for quite a large area unless that low goes further east but of course from this range it`s always a bit of a punt.

Although the cold air will suffer some modification with the flow from the continent lower dew points will compensate somewhat especially more central and eastern areas.

Overall the pattern will continue to ebb and flow between the heights to the NE and the Atlantic energy trying to break it down.

Inevitably with the UK on the boundary any slight shift east or west in the modelling will change the further outlook and continue to keep us on our toes.

i think what we can deduce from the ensembles is there is no early route to mild

That cold block to the NE still around at day 8 on the mean outputs and with the jet still on a NW-SE axis further opportunities of slider lows.

Edited February 6, 2013 by phil nw.

[Ryan Dutch Weatherman]

Btw EC Moyenne is better than the oper.

I told you.Again end again.

Moyenne means ensemble 00z.

[Gibby]

Good morning. Here is the report from the 00z output from GFS, UKMO, GEM and ECM for today Wednesday February 6th 2013.

All models show an agreed outlook for the next 4-5 days taking us through the weekend. The cold Northerly flow extending down through the UK as I type will continue through the day with the mix of rain and hill snow affecting the South clearing away South by lunchtime. As pressure builds from the NW the strength of the wind will decrease and clearing skies after dark will lead to a sharp frost away from Eastern Coasts where wintry showers will continue unabated for today and tonight. Tomorrow sees an area of cloud from an occlusion move into the cold air from the West with cloudy weather developing with rain and hill snow moving in from the West, more extensive snow likely over the North. Through Friday the occlusion weakens in situ with rain and snow dying out leaving a rather cold and non-descript few days with light winds and cold air sitting over the UK, though Saturday could be rather brighter with some sunshine. Then through Sunday a trough moves in from the West forming a depression along it as it dives SE over the UK with a period of potentially heavy rain and more importantly snow in the East as it runs into the cold air.

GFS then absorbs the main energy from the system South of the UK taking the rain and snow away with it leaving the UK under cold and cloudy weather on Tuesday with a gentle thaw of any lying snow especially in the North. By midweek the Atlantic makes inroads into the UK with a trough staggering East through the UK with rain preceded by a little snow in the East. From then on through to the end of the run GFS shows a much more Atlantic based pattern though not mild with further chilly winds and potential for snow developing towards the end of the run again as the block ever present to the NE strengthens again and realigns itself favourably for cold to the UK.

The GFS Ensembles show a rather cold couple of weeks to come with the 850 values averaging lower than normal for February. The operational above did spend some of the time as being one of the milder options from the pack with the Control Run particularly chilly later on. Some precipitation is to be found through the run especially in the middle of the run as it becomes a little less cold briefly.

The Jet Stream continues to flow in a Southward direction down over the UK into Southern Europe. As far as Europe is concerned the main thrust of the flow remains over well Southern latitudes throughout the reliable time this morning. Over the Atlantic the flow weakens for a time at the weekend and breaks up somewhat before repositioning somewhat further South than recently but still moving across the UK this time more from the West.

UKMO for midnight on Tuesday shows Low pressure moving away from the UK into Europe with a slack Easterly flow over all of Britain. High pressure stretches across from Northern Europe to Eastern Greenland. It would be cold with rain and snow from Monday petering out over the South to leave a cold, cloudy and raw day with some wintry showers near Eastern coasts.

GEM shows a much slacker pattern behind the Low at the weekend with rain and snow quick to depart the South on Monday. It then shows a second Low moving SE with some rain and sleet before the Atlantic begins to push the High pressure block East and gain supremacy over the UK by the end of its output.

ECM is more akin to UKMO at Day 6 moving forward to bring a new round of energy in from the West by soon after midweek, this time with more success as the parent Low holds over the North of the UK with strong winds with rain or showers with snow on hills towards the end of the run.

In Summary the cold spell still holds good this morning. All models support at least a week of cold weather with the longer term models experimenting with breaking the block to the NE down in the middle of next week. In the meantime there is ample opportunity for snowfall for many whether it's from stalling fronts towards the end of this week or the more meaningful thrust of energy SE at the end of the weekend. Thereafter, there are signs that the block will be pushed back East to allow the Atlantic to make its way over to the East of the UK with it's milder weather, though at this range this is very tentatively shown currently and is suspect to change over the coming days. With regards to snowfall as mentioned all areas are at risk of some but East and North looks best positioned and as is always the case in these situations the axis and position of the Low in it's movement SE at the weekend has little margin for error for more Southern and Western areas with cold rain a distinct possibility if the axis shifts slightly further East. This will be firmed up on over the coming days.

[Ryan Dutch Weatherman]

Hoy pandemonium , LOOK at this , look at this.

The battle over the UK saga continue s.

Now even the Chinese weather model is knocking on your door.

There will no strong atlantic , only glide lows.

[lord stratus]

Ok well everything aside , his view is obviously a weak Atlantic with HLB becoming established to our North . For this to happen it will obviously depend on what the Models decide to do with the energy left over from these Short Waves forming off the Eastern United States. Why the PV looks so week and looks to be heading towards the Pole , We will obviously always be in with a chance of things going our way .. Would like to see Deep Cold establish in the next 10 days though as it is like a ticking time bomb , first week of Feb has already gone , and although Snow chances won't always diminish , Settled Snow and Ice Day chances will be getting less likely in the next 20 days or so. In the short term looking for Westward corrections of that Low on Sunday as this could provide lying Snow that might hang around for a bit with colder air tucking in behind.

As you say a westward correction is required and is quite possible. Jan 18th snow had a south and west corrections up to that event which is generally what happens in these cases.

[Bristawl Si]

Interesting that posters seem to have forgotten/ignored Ian F's post from midnight which was indicating major snow issues for Sunday/monday and did highlight a more western/central bias.

Anyone think Meto will ignore this morning's runs or modify their thoughts from 9/10 hours ago instead?

[weather eater]

No model will be the winner, I have to say almost all of you miss the obvious, synoptic evolutions do not stand still, they do not hit a point in time and then verify for the next 4, 5 6 days whatever. For the models it’s a case of trying to make sense of a sum where the starting numbers keep changing, which is why we have the ensembles, but even with their help it’s difficult beyond a few days. Then you have to take into account the size of the UK, the models can look similar from run to run but small changes will make major changes to the weather we receive, like a shortwave 100miles further east. We can discuss until we are blue in the face but a synoptic evolution for 144hrs is going to change, simply put, the 144hr 00z ECM chart for Tuesday will not look like the actual chart come Tuesday, it may be similar or it could still change substantially but even a similar chart will mean substantially different weather for us.

And people are frequently being misguided on here, by being told trust X model and ignore Y because its rubbish, the GFS is not always playing catch up to the ECM, the truth is they are both trying to play catch up with events happening in real time, sometimes and in certain situations one is better than the other, the ECM we know verifies better than the GFS although the margins are not great and it is not verifying better all the time, it’s an average not an absolute. Without a doubt ignoring the one that doesn’t show what you want to see is a mistake, besides which the likelihood is that beyond 120hrs they will both be wrong for our tiny island, the best thing to do IMO, is except, that beyond 72hrs they are all, already slipping well behind the 8 ball.

Edited February 6, 2013 by weather eater

[fergieweather]

Interesting that posters seem to have forgotten/ignored Ian F's post from midnight which was indicating major snow issues for Sunday/monday and did highlight a more western/central bias.

Anyone think Meto will ignore this morning's runs or modify their thoughts from 9/10 hours ago instead?

They'll modify right to the wire, of course. Long way to go.

[Jason M]

Interesting that posters seem to have forgotten/ignored Ian F's post from midnight which was indicating major snow issues for Sunday/monday and did highlight a more western/central bias.

Anyone think Meto will ignore this morning's runs or modify their thoughts from 9/10 hours ago instead?

They certainly won't ignore this mornings runs. Ian also made the valid point that the GFS is rubbish line that has taken hold on here in recent days is itself rubbish.

Can't imagine they will change their guidence this morning though as there was much uncertainty last night and that remains the case this morning. It will be interesting to see where the ECM opp falls within its ensembles this morning.

If this evenings runs trend away from a snow event again then i reckon METOs concern will drop away pretty sharply given the timeframes.

Only my take on things and tbh my guess is no better or worse than anyone elses.

Jason

Edit just seen Ians post That was quick!

Edited February 6, 2013 by Jason M

[snowmadchrisuk]

Interesting that posters seem to have forgotten/ignored Ian F's post from midnight which was indicating major snow issues for Sunday/monday and did highlight a more western/central bias.

Anyone think Meto will ignore this morning's runs or modify their thoughts from 9/10 hours ago instead?

Ian's views were as of Mo Greps , chief forecaster and operational data as of last night , this can obviously change at that range , Were still 114-120 hours away even now .. If it slides over the Center of the country from the NW , the fact is it will likely be associated with a large Warm sector and we will have to wait for this to get mixed out when it hit's the channel and wings swing East... if of course it goes West and slips SE over Cornwall the Cold air will remain in place and Colder air will quickly be forced in from the East. We have obviously had an Eastward correction so far this morning which is not good news for our area , but at this range things can easily swing back the other way .. Ill post some charts in the regional thread after the 6z is out .

Edited February 6, 2013 by snowmadchrisuk

[chicken soup]

Glacier point .You did make a good point with the ensembles from GFS.

But look the BOM model , its great run.

A block , a NE wind , end a POLAR low is sinking from the north towards the UK.

This you can print it out en hang it at your living room.

. Whats the chances of this actually happening, I dont think ive ever experienced a polar low.

[Simonl]

Hoy pandemonium , LOOK at this , look at this.

The battle over the UK saga continue s.

Now even the Chinese weather model is knocking on your door.

There will no strong atlantic , only glide lows.

This guy is fun.....That chart is awesome I do agree Sir lol!

[snowmadchrisuk]

. Whats the chances of this actually happening, I dont think ive ever experienced a polar low.

Let's not get into this again , It is not in technical terms a Polar low , for more Information on polar lows see here http://en.wikipedia.org/wiki/Polar_low

However there is a Low coming down from the North on the Chart he refers to .

Edited February 6, 2013 by snowmadchrisuk

[egret]

Hoy pandemonium , LOOK at this , look at this.

The battle over the UK saga continue s.

Now even the Chinese weather model is knocking on your door.

There will no strong atlantic , only glide lows.

Apologies but i cannot resist this - that chart for me reads like 'Strong blockings and long stockings' LoL

Thanks for your input Ryan - we appreciate your perspective from the other side of the Nordsee! Keep up your your good work.

[Ryan Dutch Weatherman]

Let's not get into this again , It is not in technical terms a Polar low , for more Information on polar lows see here http://en.wikipedia.org/wiki/Polar_low

Howver there is a Low coming down from the North on the Chart he refers to .

Yes you are right in technical term is that not a PL.

[I remember Atlantic 252]

Slightly of topic this but does anyone know when we last had a polar low.

maybe 26th into 27th Feb 04

[Stu_London]

What staggers me is that in a couple of weeks, months or years at least 30% of the regular contributors to this thread will be singing the praises of the ECM and how it superbly handled the Feb 2013 cold snap. What rubbish - I don't even buy that it's been that consistent. Last Thursday or Friday when IanF posted that MOGREPS was showing potential frontal snow for this weekend, the ECM was just bringing an easterly. UKMO showed the slider first and the ECM jumped all over it. It's difficult to rate a model that you can't see but it seems that MOGREPS was the only one that got near to the likely pattern early on. Perhaps Ian might let us know if it has been consistent after the initial early view of this weekend

[The watcher]

Glacier point .You did make a good point with the ensembles from GFS.

But look the BOM model , its great run.

A block , a NE wind , end a POLAR low is sinking from the north towards the UK.

This you can print it out en hang it at your living room.

Glacier Point was pretty much agreeing that an Atlantic block of some kind looks good. No need to hang anything anywhere.

In regards to the Eastward shift of things overnight, I wouldn't be surprised to see another shift East with the days runs bringing just a marginal fare for those in the East of the UK. Problem is, if they haven't perfected the slider interest, beyond that isn't really going to be "reliable" as it usually is. Could be a dumping on the cards, could be more snow in my fridge.