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phil nw.

Model Output Discussions 06z 04/11/16

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 Lots of discussion about the longer and medium charts, but this shorter term chart out to 102 hours catches my eye. Just look at the steep gradient change in 850mb level temps between the coast of Blighty and NE France. Ripe for Quasi- stationary front over SE England for a while next week. Much of mainland Europe in the warm upper flow and British Isles holding its own cold sector. Pressure rises over Scotland will become the main feature later next week. Interesting short term charts to ponder. We here in the Alps getting bucket loads of wet snow as the boundary of the warm air mass and colder air mass mix today. Freezing level 1600m  and only -1c at 2200m, so holding a lot of moisture.

 C

ARPOPUK00_102_2.png

Edited by carinthian

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the extended eps offer a little light in the post day 10 period. I don't expect any scandi trough to be fed from the Siberian vortex ( as looked possible on the past couple ECM ops courtesy of the Arctic ridge and consequentially deeply low -AO ) but  the result of the relaxation of our mid lat ridge and backing west of the trough fed from the train of systems running across the top. That doesn't promise anything of note for the uk away from the usual suspects in the ne. 

thereafter, broadly the same message as recent runs but any really wintry signature doesn't seem to become estblished and I susect we would be looking at lee northerlies as further lows run nw/se around a mean high to our west. relying on these to run into the troughing far enough south to keep the uk on the polar side of the jet .  The last two eps have lessened my wintry enthusiasm a tad but as ian pointed out yesterday evening, the parallel ens was more encouraging. 

One possible consequence of the detachment of the Siberian vortex and sceuro trough is the potential for a ridge to establish early dec to our north/ne which would be more interesting with cold over e Europe. This was something that didn't appear feasible on previous output. 

Edited by bluearmy

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1 minute ago, fergieweather said:

Given that we have TMin ENS spread by morning of Dec 2nd ranging from +10C to -11C (!!), I think we can reasonably emphasise the uncertainty....!  Indeed even early next week, there's a raft of issues to resolve including threat (yet tbc) of significant snow in the W Country and Wales >ca 200m. 

21c is quite some spread, tricky long range forecasting by the sounds of it. Is the threat (possible) of snow from the low pressure swinging in on Monday?

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I will say the extended GEFS 00z mean is increasingly bullish regarding scandi trough influence for the uk beyond the settled spell, more so than yesterday..so we could be in for a colder more unsettled period beyond the high.

21_288_500mb.png

21_336_500mb.png

21_360_500mb.png

Edited by Frosty.

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7 minutes ago, fergieweather said:

Given that we have TMin ENS spread by morning of Dec 2nd ranging from +10C to -11C (!!), I think we can reasonably emphasise the uncertainty....!  Indeed even early next week, there's a raft of issues to resolve including threat (yet tbc) of significant snow in the W Country and Wales >ca 200m. 

The last sentence sounds very interesting Ian! The first part does not suprise me , we are for sure going to see a settled spell medium term but im becoming a bit concerned that despite all the positive comments about the strat/ zonal winds etc we dont appear to be seeing any sort of retrograde signal, in fact theNWP seems to be going on the opposite direction this morning! 

Edited by northwestsnow

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2 minutes ago, fergieweather said:

Disagree. If anything, the clustering for HP to NW and cyclonicity to our E with colder outcomes has strengthened in 00z EPS by early Dec.

 

2 minutes ago, fergieweather said:

Disagree. If anything, the clustering for HP to NW and cyclonicity to our E with colder outcomes has strengthened in 00z EPS by early Dec.

Im very happy that you disagree!! :D tbh my comments were based on the Gfs/Ecm ops, thanks Ian...:)

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Even with tonights low there are still slight differences with the models!some have it deeper and some a lot shallower!!this at just 18 hours out aswell!!wonder if there could be a few snowy surprises by tomorrow morning!

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Well the storm is coming and a follow up to boot from a very low latitude.  Very interesting weather ahead in near term with possibly some surprises. Fergie confirms that possibility.

Longer term. I think we will be on cold side of the average line but no arctic or HLB lock out in Dec like 2010, not on the cards for me but a fairly wintry month in parts as I remain with the PV displacement being the main talking point which brings with it HP and LPs being in interesting positions to allow potential pretty wintry episodes.   Recent weather type and what is ahead moved forward into Dec heightens wintry potential and it isn't bad for mid Nov as we have seen and could see early next week.....lots imo to look forward to.  

 

BFTP

Edited by BLAST FROM THE PAST

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13 minutes ago, fergieweather said:

Disagree. If anything, the clustering for HP to NW and cyclonicity to our E with colder outcomes has strengthened in 00z EPS by early Dec.

Let's hope there is at least a hint of that in today's MO update..would be welcome:D

At least the latest GEFS has strengthened the scandi trough signal again.

Edited by Frosty.

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Snapshots' @192hrs..via ecm/gfs/gem/jma.

Just to highlight although similar at these juncture s' placement of high cell with have massive ramifications' around and beyond time frames. 

So much more to be resolved' and so much resolve' needs eyeing...given its an open book atm...but one well worth waiting for the 'climax' of the story! 

ECM1-192-3.gif

gem-0-192.png

J192-21-1.gif

gfs-0-192.png

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1 minute ago, Frosty. said:

Let's hope there is at least a hint of that in today's MO update..would be welcome:D

there was yesterday Karl - possible unsettled came with mention of sleet or snow rather than rain. 

the scandi trough solution is so solid in the ens over the past week (and before that on the weeklies) that anything else would be a surprise. where we sit in between the main features and what surface conditions ensue is the question. 

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15 minutes ago, bluearmy said:

there was yesterday Karl - possible unsettled came with mention of sleet or snow rather than rain.

Hi BA

That isnt quite what I meant, with height rises to the NW and increasing scandi trough influence I would expect to read the words cold Northerly showery flow but what I read yesterday, reading between the lines was for a southerly tracking jet with a mix of mild and rather cold.

 

Edited by Frosty.

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18 minutes ago, fergieweather said:

The issues Sun into Mon are especially tricky. UKV generated a plastering of snow even at lower elevations across W'rn parts of the W Country (incl adjacent Bristol Channel/M5 corridor up into Wales and SW Midlands) but considered overdone. However 00z EC gives quite a few cm in pretty much same areas, but that model automatically settles all solid phase ppn. MOGREPS currently disinterested. Jury out....

Mogreps - is that model seeing things develop broadly in line with the eps ian? 

Not had much of a mention recently and always important to have it on the same page.

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A thought on the mid-range ... Just remember that we've seen a lot of failed UK Highs in the last few years (more than 50% imo). They normally get shifted slightly between T192 and T120. So I'm not getting too hung up on exactly where the cold/mild bits are going beyond about Friday.

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19 minutes ago, bluearmy said:

Mogreps - is that model seeing things develop broadly in line with the eps ian? 

Not had much of a mention recently and always important to have it on the same page.

It offers a broad swathe of possible tracks into Monday and this spread is likely one reason for the lack of strong signal re snow probabilities. 

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5 minutes ago, fergieweather said:

It offers a broad swathe of possible tracks into Monday and this spread is likely one reason for the lack of strong signal re snow probabilities. 

Just wondering what the MOGREPS signal is into the medium range wrt positioning of high towards NW of us.

Edited by feb1991blizzard

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Bar very specific micro details it does appear within the 10 day period the volatility has now gone so we have a good view of the macro Atlantic sector NH pattern. The three main models at D10:

ECM1-240.gifgem-0-240.pnggfs-0-234.png

Mix and match of those should not be far off the D10 pattern.

Looking at the D16 GEM and GEFS mean for our quadrant and similar profile:

gens-21-1-384 (1).pnggens-21-1-384.png

Probably more to do with default algorithms than what will happen so best to leave D10+ to resolve over the next 2-5 days model runs.

 

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Looks like the gfs 06 run is going to be a cracker towards the end.

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Powerhouse Northerly in-bound on the latest GFS run.

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Gfs6z is more like it, we finally see an op with the retrograde signal in the Atlantic!! :D

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