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phil nw.

Model Output Discussion 4th Dec.2013-12z onwards.

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That was a(nother) wonderful post from Old Met Man - a simply expressed summary in laypersons terms we can all understand, and his obvious experience underpins it so wellPosted Image

Thank you Tamara, that's much appreciated.

Let's see what later runs today come up with.

OMM

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I think people need to be realistic here - the outlook is unsettled and predominantly mild.  December CET is likley to be in the very mild or mild category.  Not saying there will not be transient periods of polar martime or polar martiime returning air but for most of lowland Britain that does not produce significant wintriness.

 

Here in the south, the last few days have actually been cold so we will notice the ramp up in temperatures.

 

http://www.meteociel.fr/cartes_obs/gens_display.php?x=306&y=141&run=0&ville=Londres&runpara=0&type=3&ext=1

 

http://www.bbc.co.uk/weather/2643743

 

Milder than average for London for the foreseeable future.

Edited by mulzy

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I think people need to be realistic here - the outlook is unsettled and predominantly mild.  December CET is likley to be in the very mild or mild category.  Not saying there will not be trasnient periods of polar martime or polar martiime returning air but for most of lowland Britain that does not produce significant wintriness.

 

Here in the south, the last few days have actually been cold so we will notice the ramp up in temperatures.

 

http://www.meteociel.fr/cartes_obs/gens_display.php?x=306&y=141&run=0&ville=Londres&runpara=0&type=3&ext=1

 

http://www.bbc.co.uk/weather/2643743

 

Milder than average for London for the foreseeable future.

Agree 100% Mulzy, the ENS show a classic zonal unsettled and mild picture especially for the south

 

Posted Image

 

The very far end of FI does show some hints of a change which may or may not lead to an improvement for cold prospects.

 

Posted Image

Some vortex disruption showing but very tentative.

Edited by Purga

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Agree with those non cold biased posts, a rapidly undulating temperature graph for the rest of December indicative of very unsettled weather - often warm sector for the south and middle, briefly rather cold after cold fronts pass through but successive warm fronts never far away

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If we are not going to get blocking then I would prefer cold zonalality infact some of the best snowfall in December have being throught these cold shots . December 16th 2011 was great here heavy snow all day about 2-3 inches fell . Then there's the famous white Christmas of 2004 when all of a sudden we had a Polar nw wind through the cheshire gap that brought the only white Christmas since I was born. In my opinion these are better charts than the dross that was showing last week atleast with this pattern there can be a few surprises thrown in.

Edited by Paul
Why the need to have a go at people?

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A fair amount of biase in a number of posts showing this morning.

To get the 'actual' prediction by the models, or at least the Extra version of GFS, simply go to the play through on Extra of msl and Td, one can then see how often the isobars are from south of west, or westerly, how often low Td values show up and how often higher values show on the whole 384h. 

One or two do suggest what the model at 00z showed, a fairly mobile and unsettled spell with high pressure not the main player. It may be right it may be wrong only time will tell but new folk do try this rather than scratching your head wondering which of our posters is showing what is the most likely outcome. If you don't have Extra, why not treat yourself to an Xmas present, Paul will be delighted to send Santa to you. Failing that then the basic model outputs can still show you exactly what the model(s) are predicting. Go to our Guides section, plenty of help there.

oh and of course ask questions there will always be someone who can answer your query, don't like that then pm whoever you feel able to trust. All of us love talking about the weather.

well put John, I do that with the UK charts when I'm creating my week ahead video, run through the UK sl pressure and the 1000-500 thickness just to get a theme of the week

 

looking at the atlantic charts gives you a bigger view for a longer time frame. Always remembering that being in Scotland biases your view of the forecast (and realistic hopes) against say hopes for SE England

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Hopefully that dartboard low ECM has will be less so or less of a hit, as its FI it may well get shifted and watered down a tad

 

Nasty

 

Posted Image

 

 

BFTP

 

Indeed!

 

Very nasty conditions shown from that with peak gusts of 90-100kts (100 knots is 115mph) up the Bristol Channel - certainly hope this is a one off run for anyone in those areas with the flow aligned perfectly (not sure thats an appropriate word in the circumstances) to allow a funnelling effect.

 

But so far no support from elsewhere so lets hope it does one come the 12z.

 

ECM this morning bringing the low closer to the NW of Scotland too for the weekend:

 

Posted Image

 

Disturbed just about sums it up, with indicated gusts once again up to the 90-100kts category on the 0z for a short time Sunday evening in the far North-West. 

 

The best hope for cold lovers is to go up to the scottish mountains with some PM and rPM shots increasingly modelled...just maybe leave it until after the weekend.

 

SK

Edited by snowking

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Met Office 10-15 day trend (issued daily), says " there is no evident signal for persistent and/or significant cold weather" so that does cover Christmas

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some of us are only talking about polar maritime incursions with occasional snow across higher ground, I don't think anyone has said we are looking at deep cold, it's fair to say it's a mixed bag of mild, average and rather cold, the colder incursions in general being further north.

Nice everyone agrees then

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There is hardly anything mild on the Gfs 00z op run outlook,

 

I think people need to be realistic here - the outlook is unsettled and predominantly mild.  December CET is likley to be in the very mild or mild category.  Not saying there will not be transient periods of polar martime or polar martiime returning air but for most of lowland Britain that does not produce significant wintriness.

 

 

 

Very confusing for newbies to get a general idea of what the models are showing with such conflicting ideas! 

 

I guess this is down to personal definition of what's mild and cold, personal bias, where you live, etc. 

 

From what I can see, over the next 10 days at least there will be mild spells for all, particularly the next few days, while Tm air is in place ahead of low pressure systems moving in from the Atlantic and spells of colder conditions at times when Pm airmasses move in the wake of low pressure systems passing E/NE close to or over the north of Britain. Given the alternating airmasses, UK overall it looks average for the time of year temp wise, though for southern Britain it may turn out milder than average. Certainly don't think it will be cold overall.

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We've added a few features to the site in the last 24 hours which I thought would be of interest as they're both model related..

 

The first is in the free datacentre, and is the ECMWF EPS ensembles:

http://www.netweather.tv/index.cgi?action=ecmens;sess=

 

The second is for Extra subscribers and is NMM based snowfall accumulation maps (not much use right now, but hopefully handy later in the winter!!)

http://www.netweather.tv/secure/cgi-bin/premium.pl?action=snow-accum;sess=

 

We've also added timestamps to our ensemble graphs recently (thanks to those who requested this)

http://www.netweather.tv/index.cgi?action=ensviewer;sess=

 

And finally, we've started the process of upgrading some of our charts to use more colours, and a more modern colour scale. We've also added 500mb anomaly maps to the GFS extra viewer

http://www.netweather.tv/secure/cgi-bin/premium.pl?action=gfs;sess=

 

Posted Imagegfs500.png

Posted Imagenatemps.png

 

More model related additions and updates are on the way over the next week or so too Posted Image

 

Hi Paul, will you be adding the t144 chart from UKMO at some point?

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Nice everyone agrees then

If only.Posted Image

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Met Office 10-15 day trend (issued daily), says " there is no evident signal for persistent and/or significant cold weather" so that does cover Christmas

I think we all have got that, 90% at least anyway?  Posted Image

 

BFTP

Edited by BLAST FROM THE PAST

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Met Office 10-15 day trend (issued daily), says " there is no evident signal for persistent and/or significant cold weather" so that does cover Christmas

Indeed Jo, but I'm sure most of us on here had figured that much out...Posted Image

 

As you have brought the MO and Christmas up, perhaps the best, least subjective guide is offered by their latest 6-15 day update.

 

UK Outlook for Monday 16 Dec 2013 to Wednesday 25 Dec 2013:

Through next week it should be windy across much of the UK. The most unsettled weather will be in the north and west, where there will be a continuing risk of heavy rain and severe gales. Across the south and east the rain should be less widespread and the winds lighter. It will be generally mild although some wintry showers are possible in the northwest, and there will be some overnight frosts. Through the weekend and into the following week there is still likely to be the risk of severe gales and heavy rain. It should still be mild across much of the UK although it may turn colder at times in the north, with wintry showers still possible. However, there will also be some sunshine in places.

Edited by shedhead

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Looking at the ext ecm ens this morning, shows a trough to the NW of the UK between days 10-15, which covers the festive period. Temperatures at the 5000ft level indicate below average conditions for the west, while the east &se see more in the way of average. Height &temp anomalies for ecm ensembles below for days 10-15.

Posted Image

Posted Image

the GFS 0z ens show surface temps to be slightly below/average towards the west, while the bulk of GB is slightly above at days 10-15.

Posted Image

a definite trend to cooler conditions nationwide as we progress to the New year, certainly the EC32 indicated this on Mondays update.

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There is a firm trend towards cooler conditions with the GFS again pushing everything further south. Even a shallow surface high appearing over Greenland now!

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Indeed!

 

Very nasty conditions shown from that with peak gusts of 90-100kts (100 knots is 115mph) up the Bristol Channel - certainly hope this is a one off run for anyone in those areas with the flow aligned perfectly (not sure thats an appropriate word in the circumstances) to allow a funnelling effect.

 

But so far no support from elsewhere so lets hope it does one come the 12z.

 

ECM this morning bringing the low closer to the NW of Scotland too for the weekend:

 

Posted Image

 

Disturbed just about sums it up, with indicated gusts once again up to the 90-100kts category on the 0z for a short time Sunday evening in the far North-West. 

 

The best hope for cold lovers is to go up to the scottish mountains with some PM and rPM shots increasingly modelled...just maybe leave it until after the weekend.

 

SK

Yes, the trend that began a few days back to erode the influence of the High pressure most especially across SE UK is moving further up the gears with the latest ECM really ratcheting up these secondary lows that are forming on the boundary of the polar front jet as dense bitterly cold Canadian arctic air meets moist warm atlantic air and spawns some very intense cyclogenesis.

 

Hopefully, at a weeks distance the intensity and track of that low is adjusted to something much less ominous than suggested on the ECM - but the MSLP spreads make it easy to see the areas in which these rapidly deepening secondary lows might develop, and where in future outputs they may track

 

Posted Image

Posted Image

 

We should not expect much amplification within the 10 day period with the pattern very fast and flat, and therefore polar maritime incursions will be restricted further north and very temporary as one low replaces another. This isn't unusual at this time of year with a very deep polar vortex in situ over Greenland and NE Canada, but on the basis of how significantly cold it has been in parts of Canada and the US, then we should expect some deep lows to develop and then sent downstream across the atlantic towards the UK

 

Edit: The charts look a bit squashedPosted Image , but they open ok when clicked onPosted Image Posted Image

 

We can see from the EPS members ensemble maps that there is good agreement for a wave depression, which could possibly become a closed feature, tracking fairly well south across central UK in the first half of next week - so the unsettled breakdown in the south completed then by the looks of things

 

Posted Image

 

The ECM operational is quite an outlier on the London ensembles for wind speeds for day 7

 

http://www.weathercast.co.uk/meteo/eps/ensemble-ff-london.gif

Edited by Tamara תָּמָר

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Looking at the ext ecm ens this morning, shows a trough to the NW of the UK between days 10-15, which covers the festive period. Temperatures at the 5000ft level indicate below average conditions for the west, while the east &se see more in the way of average. Height &temp anomalies for ecm ensembles below for days 10-15.

Posted Image

Posted Image

the GFS 0z ens show surface temps to be slightly below/average towards the west, while the bulk of GB is slightly above at days 10-15.

Posted Image

a definite trend to cooler conditions nationwide as we progress to the New year, certainly the EC32 indicated this on Mondays update.

Good post...the standout thing for me here is just how anomolously warm Scandi looks set to be, particularly the southern half of Finland.  IF this verifies it's hard to see much lowland snow cover persisting south of the 65th parallel, with a steady thaw also likely across parts of NW Russia, especially if it rains heavily. What implications, if any this has for UK cold in the New Year remains to be seen.

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combine this with all the wind generated from all the sprouts being eaten and it's gonna get messy.

 

post-115-0-58894500-1386845912_thumb.png

Edited by No Balls Like Snow Balls

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We've added a few features to the site in the last 24 hours which I thought would be of interest as they're both model related..

 

The first is in the free datacentre, and is the ECMWF EPS ensembles:

http://www.netweather.tv/index.cgi?action=ecmens;sess=

 

 

Nice one Paul, a query though, in that first link I don't notice anything different from before? Should they not look like the equivalent GEFS ensembles or am I missing something?

 

On the models front, not that I ever pay much attention to the GFS 6z and for that matter leap on every run, but the 6z looked even more SW'rly driven zonal than before. I imagine it'll be an outlier and the afternoon suites will continue to pick up deep surface features with alternating PM and TM flows in the run up to Christmas. Regarding the confusion earlier, I think there was a little bit of posters quoting things from their patch, nothing wrong with that of course, but usually best to clarify the point to save any further confusion. Down in my patch, it is highly likely you can write the next seven days if not ten or more for anything wintry. Further North of Yorkshire (say from Frosty's location Northwards, this is more hope of wintriness on the odd isolated occasion.

 

Finally, it is like Christmas has arrived early with all these new netweather tools. Posted Image

Edited by gottolovethisweather

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