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Paul

Cold hunt - models and chat

Paul

Please ensure that the majority of your posts in this thread are model related - a theme of model discussion needs to run throughout.
Some off topic chat and reactions are ok, but please use other, more relevant threads for entirely off-topic chat (such as snow reports, met office forecasts and general chat/moans about the weather or this winter).

For more no banter and just model discussion please head to the new focused model thread - this is also a great place to post (or cross post) your longer model summaries or thoughts around the models.

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2 minutes ago, kold weather said:

The thing people have got to remember is that there is no 'physics' reason why we couldn't see an equally dramatic change that we saw with regards to the shift from easterly to the set-up originally forecasted (though the truth ended up slightly closer to the easterly than expected!)

 

Indeed mate. Remember back in Feb 2005 when at one stage the models were predicting the dreaded Euro HP which actually reversed into a whooping Greenland HP.

Normally we always expect downgrades when it comes to cold spells but sometimes the reverse happens and as you say there is no meterological reason why this cannot happen. I can see why the Met O have continued with their extended outlook.

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10 minutes ago, Froze were the Days said:

Don't believe the 06z...usually throws up different trends, again I wonder what it's verification is like compared to the 0z and 12z...it does look a better trend though and one we'd like to see but I have my doubts.

A tad bizzare..(your post).. both classic wave patterns emerging in delayed responce-to strat/trop happenings..

The mods were bound to have a massive jump to what is likely to become..ie mirror opposite..

And now highly likely to note all forcings..

And feb then sets up a both our most notable winter month...

And 1 that many have craved!!..

And this 6z run could look very tame in just a short time!

 

gfsnh-0-252.png

Edited by tight isobar

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Possible northerly incoming on Day 16!🤣

image.thumb.png.0172e524f7a2e2758388639a9d219b3d.png

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1 hour ago, Frosty. said:

Nobody seems to want to talk about the mid / longer range but both the Ecm / Gefs mean indicate a return to normal / mildish from next week with the azores high ridging in close to the southwest and low heights to the northwest with a zonal pattern for the uk.

Some do and did. And sadly, I think it may well be the form horse too, although colder interludes with wintry showers behind the rain bands are undoubtedly possible. Before then, much cold to talk about, if no Beasts From The East there's always Brexit to fall back on.

Edited by gottolovethisweather

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34 minutes ago, TEITS said:

Indeed mate. Remember back in Feb 2005 when at one stage the models were predicting the dreaded Euro HP which actually reversed into a whooping Greenland HP.

Normally we always expect downgrades when it comes to cold spells but sometimes the reverse happens and as you say there is no meterological reason why this cannot happen. I can see why the Met O have continued with their extended outlook.

Yes and I can't see the Met changing their outlook either as there are no strong signals for anything just yet. I know certain folk look for trends in the ens but that has proven useless time and time again.

The movement of the Siberian high is notoriously difficult to predict, particularly on the northern fringes around the Kara strait locale. Historically, if we can get pressure to build into that territory it is a precursor to a cold shot into Europe. If there is more support for pressure building around Kara and into Svalbard in the next few runs things could get very interesting indeed. Let's not forget the Kettley high saga back in Feb 2001!  

Edited by Altostratus

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The GFS Control highlights the high entropy as we head into next week:

gens-0-1-168.thumb.png.eded1b6fef869480c4884bde5c36a631.png

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17 minutes ago, Nick F said:

People moaning that the SSW will do diddly squat for our cold prospects, well, as mentioned above yesterday, the Siberian high appears to be a product of the SSW reversal down into the trop, and it certainly seems to be spreading its tentacles our way by day 10, though the Atlantic trough scuppering it reaching all the way on 06z. Could be some interesting medium range model watching coming up over next few days.

240.thumb.png.443f01605098cb2944a84b37907f4b16.png

True enough. It's a fallacy to say that the SSW has not affected out weather: it has, just not in the way that some of us were forecasting and others were hoping.  

We head into to February with a weak PV at a time when we would normally start to see more blocked scenarios increase in likelihood anyway. As @TEITSsays, there's no reason why we cannot see a swing to cold in the medium range, especially given we don't have a very organised PV centered over the Arctic.

This is not to say that one run or another will verify and we will see widespread freezing weather because of it; but, the setup does not seem to favour a long term (i.e. 10 days plus) pattern of mild W to SW flow. 

We may end up with some more slider scenarios, or we may end up with a more prolonged cold spell, but I do not think that we are looking at a prolonged above average period of weather before the end of winter. I would be surprised if the upcoming snow this week is the last we see before next winter.

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06z GFS para appears further south with ppn band northern extent than 06z GFS op for 00z Friday (T+66)

PARA

GFSPARAUK06_66_4.thumb.png.4bceb5d29f852a560107e96d5715e9c1.png

OP

GFSOPUK06_66_4.thumb.png.4b96c3bbfb387472c20d64a56f59b427.png

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The GEFS at T180 highlight the shift in the model, for next week, a few more runs needed for trend and consistency, better nether the less:

gens_panel_bxl9.png

 

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51 minutes ago, Ed Stone said:

06Z not at all bad. Backs up Those Who Cannot Be Named...?:cold:

image.thumb.png.0976b7cc641c58f50f14900eb1dca240.png

Who's that Pete could it be VOLDERMET..!!

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8 minutes ago, Nick F said:

Atlantic ingression seems to falter quite early on 06z GFS, early next week, with trough disruption Mon-Tues, and cold -5C and below air hanging around, so when Atlantic fronts come in, they could bring some snow, chiefly northern areas as per GFS.

Some very cold air lurking to the NE, so if we do get pressure to rise to the N and NE, which it increasingly looks like with time, as the Atlantic troughing wanes, then it could be fun and games 2nd half of Feb maybe. 

GFSOPEU06_183_2.thumb.png.301ea7438956ca9fe39977a1e0145db7.png

Your posts are restoring my faith big-time, keep it up. The good thing is you know what you're talking about as well, as netweather's prominent chief forecaster. My assumptions about next week were based around the Beeb 10-dayers and a few recent model runs but...... could the cold hang on instead of being pushed aside, I guess with full snow cover around in places, it may well win the day. Conversely, there are other respectable types on here calling for a very special February, so I'm equally mindful of that. Fascinating days ahead either way.

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Yes Nick F, that GFS para actually lines up very nicely with the ECM and the UKMO as well I have to say!

The GFS OP  still stubbornly further north than the others, and in all fairness quite a few ensembles from the GFs agree with it, probably similar levels as to what the ECM back its OP, around 80-85% roughly.

Got to think these size disagreements will slowly ease away over the next 24hrs, but I've got a sneaky feeling we may STILL be in this position come 00z tomorrow!

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just had a perusal of the Can't Forecast Sh** model...(or CFS for short) and it has a monster siberian block retrogressing into Scandi throughout a good chunk of February and March.....What could go wrong?......(Can't post charts as I'm too lazy)

Edited by beerandkebab
predictive text faux pas

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So summing up this mornings data, we have hlb devoloping, westerly winds incoming, a bit of snow, no snow, red warning snow, from a foot of snow to a cm of slush! Its gonna be north, its gonna be south, its gonna be west, its gonna be east. Tell you what guys if all of this comes off, it's gonna be one hell of a weather event, 🤔

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The Euro 4 at T48 hrs given its low set up looks like it would take things further south.

But confidence in any one solution isn’t great  because the models have really struggled with exactly where the low goes and I think we’ll have to wait till tomorrow before nailing down the detail .

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Well the GFS/GEFS 06z really highlights the huge sensitivity of next week's setup to small Atlantic pattern adjustments that I mentioned yesterday, though there's a big shift up N of the UK too which is intriguing as it doesn't appear to be a result of any troughs moving much differently; the heights just rise in-situ as if forced from above.

Today's update to the model MJO projections will be interesting - seeking an increase in eastward propagation to counter yesterday's decrease that had me starting to wonder if it was going to play nice.

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GFS 6z seems a lot better at keeping this cold'ish spell continuing on (i'm a londoner - I generally need colder).

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Nice cold T850s (-7 to -9) down the eastern side of England & Scotland, come Saturday evening:

image.thumb.png.531157bfda10802ce897a51e660f614e.png

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5 minutes ago, Singularity said:

Well the GFS/GEFS 06z really highlights the huge sensitivity of next week's setup to small Atlantic pattern adjustments that I mentioned yesterday, though there's a big shift up N of the UK too which is intriguing as it doesn't appear to be a result of any troughs moving much differently; the heights just rise in-situ as if forced from above.

Today's update to the model MJO projections will be interesting - seeking an increase in eastward propagation to counter yesterday's decrease that had me starting to wonder if it was going to play nice.

In modelling chaotic systems there are times when the modelling takes a huge adjustment to change the pattern . In weather terms this would be  the equivalent of a huge adjustment needed to move away from a mobile westerly pattern but there are times when the system is particularly chaotic and is extremely sensitive to adjustments that can have massive impacts.

It has been clear that the models have struggled beyond day 3 and is sensitive to small changes flipping between extremely cold and mild scenarios every few days with the major factor being the SSW downwelling and my hunch is that until the downwelling has fully played out then the models will continue to be chaotic and that there will be surprises at short notice and reading between the lines of the Met Offices reluctance to do away with its cold outlook, I do not feel it would be a mild surprise.

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06z ECM broadly the same again as the 00z run, I'd say the biggest change is a slight change in the orientation of the front, not that dissimilar to the GFSp but the LP is a touch further south.

Snow line is a touch north (especially in the west) compared to the 06z though like previous runs, there isn't a whole lot left of it by that point.

Main areas of snow again SE/E Wales and W.Midlands. Also quite a lot of snow for CS England, though this would be very marginal indeed and less secure than the 00z run due to that slight orientation difference. I will need to see what the higher resolution version shows with regards to dew points, etc.

S.ROI also hit hard again!

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