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Model output discussion - 16th Nov onwards

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ECM1-192.GIF?16-12

it was not a surprise to see everything shifted a little east best model gefs but mostly all see heights pull away or sit located over the uk before slipping away south allow the atlantic onslaught in.

 

very close but no cigar.

 

mostly the north and the east effected by any wintry weather although still not bad for nov but the model that was very good at showing a more realistic outcome and does not seem to get over excited about heights and Greenland is the ukmo model.

 

this model is the best if you rather not be disappointed with an actual outcome.

UW144-21.GIF?16-06

 

best chart gefs

gens-0-1-126.png

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graphe3_0000_290_7___.gif

 

 

A quick look at the short ensembles for my neck of the woods from this mornings GEFS show that the 0Z was one of the coldest for upper 850s. The OP shows it possibly being cold enough for snow at lower levels (-7/-8C) whereas the mean is around -6c which would only support snow over the hills especially off the still warm North Sea. Still time for upgrades/downgrades and will be waiting for the weekend to be within the hi res NMM range to firm up on details.

Edited by vizzy2004

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On this ECM run its Saturday which is the coldest day with winds coming in from the north east

 

ECU0-120.GIF?16-12ECU1-120.GIF?16-12

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Just a quick overview of the models and it looks as though further Low Pressyre systems in the Atlantic will be on a rampage to spit out further spells of wet and windy weather for places, more so for Northern UK, on a Westerly or South-Westerly flow. The South seeing the best of the mildest and driest conditions between the bands of wet weather, although some continued troublesome rain for Northern areas, especially with some of the flooding. Then, towards Friday, the ridging from the Canada area will try to poke its way into the Atlantic and help force Lows to drop down Southwards or South-Eastwards to the East of the UK into mainland Europe pulling in a cold flow from the North/North-West. Northern areas will first see the effect of the colder weather (mid/late Thursday and into Friday) and then by the weekend, there is the possibility of places, especially those on higher ground, to see some spells of rain, sleet and snow as disturbances track down from the North or North-West over the UK on the Eastern flank of the Atlantic ridge. Whoever gets to see wintry weather is not fully decided and could be the case of nowcasting on the day itself. But some amusing treats for the cold weather enthusiasts to look forward to.

After that, and the models offer various solutions from flattening the Atlantic ridge (but some which still show amplification upstream which could aid further chilly outbreaks from the North-West or North) to toppling the Atlantic ridge over the UK and/or towards Scandinavia. So some undecided outcomes as you would probably expect at the 7 to 10 day range (though I wouldn't be too surprised if the latter scenario occurs. Have seen experiences a bit like this in the past where a cold Northerly outbreak becomes followed by mid-latitude blocking. Not a certainty, though).

(Red Line's 40 second model summaries ltd).

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The first cold snap of the autumn is on the way with Arctic air flooding south during friday with scotland becoming much colder with strengthening Northerly winds and wintry showers on friday and then further south for the weekend, saturday looks the most wintry day across the uk and yes, some areas will have snow showers, especially exposed coastal / hilly areas and all of us will have widespread frosts so it will feel like winter this coming weekend despite it still being late autumn. Both the Gfs and Ecm 00z show a good strong dig of arctic (522 dam) air covering much of the uk on saturday. Looking further ahead, the gfs 00z shows a spell of chilly cyclonic conditions next week with polar maritime incursions even further ahead with the jet generally aligned nw / se. :cold:  :)

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Yes Karl, Not really any change this morning for the weekend. A very cold Northerly shot continues to show for Saturday/Sunday and into Monday, As -7/8/9 850's push well South over the UK. And as usual in these cold dry Northerly set-ups it's Coastal regions that will be more effected by snow showers, Into next week by Wed a cool N/W Pm flow takes hold, So certainly not back to the balmy highs we have endured over the past Month, More average for the time of year from a more seasonal flow.

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Edited by Polar Maritime
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UKMO this morning has us in a chilly north to north westerly flow for the weekend with wintry showers possible right down to the south on high ground in the north they could get down to some fairly low levels at times

 

UW120-21.GIF?16-06UW144-21.GIF?16-06

Edited by Summer Sun
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The ECM 00z det. seems to struggle with resolving whether the polar vortex lobe over Scandinavia will remain the dominant player beyond the weekend or bow down to lower heights trying to re-establish to our NW.

 

The GFS 00z det. is all for the Scandi PV holding strong with Atlantic storm systems being drawn into it, affecting the UK from the northwest. Cold at times but mobile, with conditions conducive to snow only fleeting for many parts - typically longest lasting across the northeast. You could call it 'cold zonality', a phrase that has come up quite a few times in the past couple of winters.

 

 

The GEFS outlook for Global AAM continues to confound, suggesting a step change into a more La-Nina like configuration with an orbit in negative territory: gfsgwo_1.png

 

So it's no wonder the charts beyond day 10 are looking rather different to the classic El Nino early winter pattern of a polar vortex near or over Greenland and the Azores High extended into Europe, the flow of weather tending to vary between WNW and SW.

 

An often NW to sometimes N flow is the last thing climatology had long-range forecasters thinking of to end Nov and start Dec, but what can you do eh? I have my own long range product to worry about, which is at risk in the same way, though it is one stressed as being a 'guide' and is full of caveats so that eases the pressure somewhat.

 

 

From a cold/snow seeker's perspective, there are also problems relating to the way in which a negative AAM state promotes stratospheric warming in the wrong places (last winter being a prime example). Essentially we're at risk of trying to get what we can out of amplified mid-Atlantic ridges early in the season, only to be faced with a polar vortex displaced to Canada/Greenland later on with few prospects for much in the way of cold and snowy weather.

 

On the other hand, we could be seeing signs of a transitory 'El Nino Modoki' (Central Pacific El Nino) type state, which is even more promising than the standard El Nino pathway. I could say more, but Tamara's been doing a lot of thinking about this and I don't want to take any more away from her next post  :wink:

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We have a 10 C plus drop in temperature in the mountains by Saturday. Will be a bit of a shock after one of the warmest Novembers on record so far !. We expect the cold front when it arrives to produce the first snowfall of the season  mainly in the Northern Alps. Later in the weekend and into early next week, trough disruption on the front will leave a cut off circulation in the region, especially where the uppers are coldest with induced cyclonic circulation. It is during this period that the prospect of more substantial snowfall  will occur. It will not be until approx. 36 hours before the event that our fine mesh models will be able to substantiate the amount of snow with height.

We expect after the initial weekend cold spell that heights will rise to the SW and remain blocked over Western Siberia. Low circulation over Scandinavia with a fairly pronounced upper trough into Central /Eastern Europe to persist a bit longer. We do not expect major height rises/ Euro block to pursue. Regarding the UK, its a bit less certain but the feeling is still to look for disturbances in the flow  from Iceland, whether on the cold or milder side.

 C

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Much better GFS this morning, everything further west, longer draw from the North and some periods of moisture that may produce snow at all levels just about anywhere.  Not sure on the technicalities of snow falling and lying, but if these fronts cross overnight, with around -7/8c uppers I thing a few surprises may be in store next weekend.

Edited by Ali1977
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Much better GFS this morning, everything further west, longer draw from the North and some periods of moisture that may produce snow at all levels just about anywhere.  Not sure on the technicalities of snow falling and lying, but if these fronts cross overnight, with around -7/8c uppers I thing a few surprises may be in store next weekend.

 

Yes a much better 6z with a straighter northerly with kinks in the isobars suggesting a higher chance of the white stuff in places.

 

gfs-0-144.png?6

gfs-1-144.png?6

 

I would of thought with those 850s combined with the overnight period would mean any precip would likely to fall as snow to all levels.

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Current state of play for Saturday from the models,

 

ECH1-144.GIF

 

UN144-21.GIF

 

gfsnh-0-126.png

 

gemnh-0-132.png

 

JN144-21.GIF

 

Now to my eyes at least I can't see even two of them who have the blocking in the Atlantic. Perhaps the ECM & GEM are the closest? Until we get some sort of cross-model consensus the 'model pendulum' is going to keep swinging and it's probably pointless trying to decide if and where might see snow this weekend.

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Yes a much better 6z with a straighter northerly with kinks in the isobars suggesting a higher chance of the white stuff in places.

 

gfs-0-144.png?6

gfs-1-144.png?6

 

I would of thought with those 850s combined with the overnight period would mean any precip would likely to fall as snow to all levels.

 

If it played out like that then snow would certainly be the case (I think -8 uppers are the required for low levels in the south) - the timing, as I said in the other thread, being very helpful in this case. The GFS 06Z is certainly wavering back towards a more showery spell than the 00Z which leant more in the anticyclonic direction. I await further runs for more consistency. :)

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FI into account, however the NH PV is split in 2, not quite set up to deliever Europe any cold but V interesting all the same....I wonder if the METOs models have picked up any other signals for december that may not have been showing themselves last week.  I can't post pictures but are we seeing signs of an SSW event, defo some warming up on this Run in FI.

 

This FI looks like that Siberian High that is growing at a rate of knots could possible lean to a beast.....just saying!!!!

Edited by Ali1977

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Now I know it's FI and all that but who'd have expected to see a chart like this for this November, what with a near record El Nino et all....

 

gfsnh-0-312.png?6

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We should all remember that this weekend is a bonus as it is still Autumn.  looking at the bigger picture things are looking encouraging for earlyt winter.  A persitent Siberian high and regular splits in the Votex look like providing pleanty more opportunities for cold & snowy spells into December :)

 

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We should all remember that this weekend is a bonus as it is still Autumn.  looking at the bigger picture things are looking encouraging for earlyt winter.  A persitent Siberian high and regular splits in the Votex look like providing pleanty more opportunities for cold & snowy spells into December :)

 

attachicon.gifGFS06Z.png

I think this Siberian HP will play a major role this winter, even if to start with to just stop a westerly train going right through Scandi and encourage a trough there bringing a flow from N quadrant to regularly vist the UK shores.  eg situations like that are approaching this weekend.

I am very encouraged by the signs

 

 

BFTP

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The 06z data isn't available yet, but the 00z snow charts show some fairly widespread snow across Scotland, albeit not overly heavy for most, maybe even a dusting for the west and east of England and Wales

 

144-780UK.GIF?16-0

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Now I know it's FI and all that but who'd have expected to see a chart like this for this November, what with a near record El Nino et all....

 

gfsnh-0-312.png?6

Yes I agree this is of interest, because although FI of course remains very unpredictable, in recent years the GFS has not been too far from the macro-scale picture - in 2013/14, there was virtually nil splitting of the tropospheric vortex in FI and it was proved right, and in 2014/15 there were very few carrots being dangled by Arctic Highs at T300+, and that too was broadly correct. 2012/13 though, the vortex was all over the place in FI, and although the fine details were often wrong at long range, they did correlate with a decent amount of cold spells.

 

So although the chart for 29th November is unlikely to look exactly like this, the recent form of the GFS suggests that there must be potential for the tropospheric vortex to do interesting things, at least in the short-term.

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I think this Siberian HP will play a major role this winter, even if to start with to just stop a westerly train going right through Scandi and encourage a trough there bringing a flow from N quadrant to regularly vist the UK shores.  eg situations like that are approaching this weekend.

I am very encouraged by the signs

 

 

BFTP

As tony posted the other night, unprecedented times may be upon us, given the background signals.

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Would never have thought we'd be seeing charts such as the hemispheric pattern in GFS 6z FI a week or two ago...pretty remarkable turn around, especially considering the signals we were getting at beginning of November. Good to see that some more seasonal temperatures are finally on the way and it would seem plenty of further opportunities for something colder down the line.

Edited by bradythemole
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GFS snow charts showing a fairly big upgrade on the 06z just covering for the Ski resorts hopefully after a slow start - 00z run on the right

 

126-780UK.GIF?16-6132-780UK.GIF?16-0

144-780UK.GIF?16-6150-780UK.GIF?16-0

Edited by Summer Sun
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