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Model Output Discussion 19th January 2014-18z onwards.


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It looks like the end of next weekend is when we may have chance of a wider snow event, that low spinning down on Sunday is bringing cold uppers, and plenty of moisture. 

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I remember steve murr mentioning a couple of days ago that we could see some snowfall with the front coming in later tonight and tomorrow!!he said something like there were -2 and -3 uppers with a southerly drift or sumin could potentially be enough for a bit of snow!!just wondering if that is still the case?

 

I doubt it , the Block has slowed the front , and the Warm core get's in first, end of the week looks better cause the Colder air is closer to the East . 

 

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Pennine / Peak Areas should do well from this:

 

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Not overly convinced by the 06Z - It pretty much follows the 00Z, so we have some consistency at least. Albeit i don't see much in the way of corrections West ?

 

Lots more cold pooling into more Southern parts of Europe on this run, compared to the 00Z.

 

00Z:

 

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06Z

 

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-5 850's also moving in from the west a lot quicker than the 00Z.

 

Small potential SE UK for snow:

 

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Not a bad run so far.

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I doubt it , the Block has slowed the front , and the Warm core get's in first, end of the week looks better cause the Colder air is closer to the East . 

 

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am sure that 0 degree 850 line doesn't get as far east on the ukmo!!well we can only hope!!
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A very snow westerly on the 6z! it's not often the coldest uppers attack the UK from the Atlantic is it! Another possible outcome and one i'd gladly take. Still to early to order my winter tyres, travelling up to Aviemore on the 1st February Posted Image

Edited by Liam J
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am sure that 0 degree 850 line doesn't get as far east on the ukmo!!well we can only hope!!

Will have to see , but it slows the front down so much , the PPN doesn't get to the East until Wednesday afternoon, by which time uppers may be Cooler , and if the PPn get's heavier as it comes up against the block , the East may see something with elevation ... One for us to keep an eye on ... 

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I remember steve murr mentioning a couple of days ago that we could see some snowfall with the front coming in later tonight and tomorrow!!he said something like there were -2 and -3 uppers with a southerly drift or sumin could potentially be enough for a bit of snow!!just wondering if that is still the case?

 

Only Scottish Mountains, Highlands on the NAE and Euro4 - too much mixing out of any cold air as southerly winds strengthen with arrival of rain.

 

Better prospects later in the week, as cold air moves in from the E via Scandi high while Atlantic fronts push in from the west, hill snow likely but maybe some surprise low-level falls in the north and west too?

 

Looking at the models this morning potential pattern change in the medium range over our part of the world IMO appears to be at the mercy of the following (potential) sequence of events showing:

 

1. Low rapidly deepens over the Atlantic Sat/Sun as deep cold trough moves SE from Greenland and low also falls in the left exit of strong jet streak, resulting in deep low to the NW of the UK next Sunday.

 

2. Upper trough continues to extend SE across UK towards Europe, but pushing strong jet streak, that helped deepen the low, southwards away from the low, so the deep low slowly fills over Nern UK.

 

3. Then the uncertainties begin, does the low over Nern Britain continue SE into Europe and co-incide with amplification upstream to allow pressure to build over the top to allow an E or NE flow as per 00z GFS, or does the low become absorbed by low pressure moving in from the Atlantic, as renewed energy pushes in from the west as per 06z GFS/00z ECM?

 

Not an easy call with regards to point 3, looking at the 00z GEFS.

Edited by Nick F
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06 GFS fails to bring the Iceland/Faroes LP southeastward in the same way the 00 run did, meaning an end result closer to what ECM was going for at T+192hrs and

eventually leading to a return of the milder Atlantic.

 

Still plenty more chopping and changing of evolution expected post T+120hrs, but overall this remains very finely balanced indeed, with cold no more likely to win out than mild...and visa versa.

 

If ever there were a case of the all to frequently used term 'more runs needed' then then this is it....so, more runs needed.

 

06 GFS

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00 ECM

 

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Edited by shedhead
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A very snow westerly on the 6z! it's not often the coldest uppers attack the UK from the Atlantic is it! Another possible outcome and one i'd gladly take. Still to early to order my winter tyres, travelling up to Aviemore on the 1st February Posted Image

 

Yes, if can't get the easterly, maybe cold westerlies - which won't be everyone's cup of tea, though would bring quite a bit of snow to northern areas.

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Well Well Well, the 06Z is a stonker of a run towards the end in particular.

 

Battleground Situation:

 

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Potential right there for some favourable areas re snow.

 

The cold wins out from the W/NW of all places:

 

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The above is a very nice chart, expecially for Scotland and the North West of England.

 

Moving on we get full blow -5C's across the UK, the chance for snow just about anywhere:

 

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As we move on into February, the cold is still around and snow could fall anywhere again:

 

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Overall a fantastic set of charts from the 06Z after a quite shaky start, and finally a possible end showing to the drab of wet and mildish weather. Certainly nothing Zonal or remotely mild being offered in the charts at the moment from 4-5 days onwards.

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06 GFS fails to bring the Iceland/Faroes LP southeastward in the same way the 00 run did, meaning an end result closer to what ECM was going for at T+192hrs and

eventually leading to a return of the milder Atlantic.

 

 

 Not necessarily a mild Atlantic for long if the 06z were to come off post t+228. Though such cold zonality churned out by models at that range tends to be downgraded nearer the time

Edited by Nick F
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 Not necessarily a mild Atlantic for long if the 06z were to come off post t+228.

I said 'milder' Nick not mild, which when compared with what could still potentially move in from the east was the correct word to use. Re post T+228hrs who knows? Ever T+120hrs is very much up in the air.

 

Looking at the 00z London ENS it was clear the Op was very much on the colder side post T+120hrs...all the 06 appears to have done is corrected somewhat closer to the mean, which is where i think it will sit when it's ENS become available.

 

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Edited by shedhead
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short point but the extended ecm ens continue a trend to retrogress the azores high which would allow the general sinking of the PFJ further to our west. a general sinking of the whole pattern would be good news as it takes the warm sectors with it.

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We don't get the separation of upstream energy and this is a problem, if you're not going to get this you need the pattern further west to compensate for that.

 

Overall though a positive GFS 06hrs run for coldies and the lower resolution will always try and bring the pattern east and remove any blocking. 

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I said 'milder' Nick not mild, which when compared with what could still potentially move in from the east was the correct word to use. Re post T+228hrs who knows? Ever T+120hrs is very much up in the air.

 

Looking at the 00z London ENS it was clear the Op was very much on the colder side post T+120hrs...all the 06 appears to have done is corrected somewhat closer to the mean, which is where i think it will sit when it's ENS become available.

 

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But your post inferred milder air in the sense of "no" cold. But that's not true, those charts, if verified, could bring a fair bit of snow to some areas.

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Looking at the ECM De Bilt ensembles you can see the trend there an increase in colder members around the 24th this is in relation to that trough disruption which brings some colder air into that region, after a dip in cold members as the powerful low moves east and then an increase again:

 

post-1206-0-32581900-1390216868_thumb.pn

 

I especially like those members that bring a max temp over there of between -8 and -10c!

 

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The repeated undercutting low scenario can be great for snow lovers but it is also high risk. It only takes 1 low to approach on the wrong path and the Atlantic gets back in. Still lots of flip floping from the models. I'm still not convinced we have seen the end of the drama. It could look like game over again this evening and then back to undercuting lows and a scandi high tommorow,  Compared to what we have had so far this winter I will take the risk of the atlantic getting back in though . Lets hope for at least 1 dumping before the sun gets stronger in Mid Feb.  

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The control run is looking great at T192, as are many Ens, still keeping hold of the easterly that was shown by the GFS in the 0Z.

 

 

Yes I count 9 at 192 hours that look very good, it all looks down to how far North the Azores ridge can stretch and whether or not the Atlantic energy can become separated. 

 

heres one of the better peturbs :

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but we could also end up with this :

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The repeated undercutting low scenario can be great for snow lovers but it is also high risk. It only takes 1 low to approach on the wrong path and the Atlantic gets back in. Still lots of flip floping from the models. I'm still not convinced we have seen the end of the drama. It could look like game over again this evening and then back to undercuting lows and a scandi high tommorow, Compared to what we have had so far this winter I will take the risk of the atlantic getting back in though . Lets hope for at least 1 dumping before the sun gets stronger in Mid Feb.

Read in article the other week that the lag in temps for winter is the 21st Jan, from there on the Northern Hemisphere doesnt get any colder, know that wasnt your point about Feb Tim, just a little interest to add :) Edited by Nicholas B
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Read in article the other week that the lag in temps for winter is the 21st Jan, from there on the Northern Hemisphere doesnt get any colder, know that wasnt your point about Feb Tim, just a little interest to add Posted Image

February can be a lot colder than February in my opinion.  Yes technically the sun is higher than it was on 21st December and throughout January, but that doesn't mean that much especially when you consider that most years, December and January can be some of the mildest months of the winter.

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Read in article the other week that the lag in temps for winter is the 21st Jan, from there on the Northern Hemisphere doesnt get any colder, know that wasnt your point about Feb Tim, just a little interest to add :)

Very much subject to regional variance and timing in the NH.....think back to last March, many places in the UK a lot colder than Jan or Feb, tho hemispheric ally you could be right
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