Model output discussion 02/02/20

[PiscesStar]

6 minutes ago, Dennis said:

there is some from the strat to help a little 

What on earth is that please 

[Dennis]

Just now, Snowfish2 said:

What on earth is that please 

its the Polarvortex (tornado)  

 

[jules216]

46 minutes ago, Steve Murr said:

The EPS show a breakaway cluster day 10 onwards which is pretty much last chance saloon for Winter proper-

We would bees to see this trend develop & become a lot more consistent over the next 4-5 days to be really interested....

I would agree this is make or break weather we can achieve cold enough temperatures and snow that will not melt in daytime temperatures. Specially for areas below 400m. asl. For what its worth the control run does warrant some support which is always nice to see. It would still be quite a stretch for cold to reach at least East of UK. 

[PiscesStar]

41 minutes ago, Dennis said:

its the Polarvortex (tornado)  

 

Thanks. Is that a favourable chart for cold? 

[Methuselah]

Next Tuesday fare looks 'interesting': great should it snow, utterly bleurgh, should it not. Much like this winter really: a pentwyr o cachu. Pardon my Welsh!

    

[Jeremy Shockey]

GFS 6z @ 144

GFS 6z @ 144

Wed 12th looking very windy and very cold with uppers that will deliver some snow to many in the North and West ( and perhaps others down South too if this upgrades ) . 

 

Edited February 6, 2020 by Jeremy Shockey

[mb018538]

2 hours ago, IDO said:

Those expecting much snow other than from the favoured elevation and Scotland are going to need further upgrades. I would say Derbyshire south unlikely as per these chart graphics, though hills and mountains in Wales should see some:

So for those in the south.,SW SE and Midlands maybe hail, more likely cold rain. With the wind chill should feel very seasonal though.

As for the ECM D10, wary as usual. The GEFS have a couple of members vaguely similar, but ATM an outlier solution and the GFS op seems a fair rep of the mean. A UK height anomaly looking a sensible call though how it manifests is not consistent in the GEFS yet.

As for FI the GEFS have pulled back from a weaker tPV and it looks like it will still be the boss till the end of February. Maybe a signal for heights close to the UK but ATM FI is not too instructive though no sign of HLB'ing trending.

The MJO into phase 6 to 7 won't show in the charts for another few days with average lag so the predicted post-D10 pattern is more to do with the underlying atmospheric pattern:

If the MJO moves into phase 7 it will be nearly 4-weeks away so not sure how helpful that will be? That is assuming the underlying westerly cycle does not mute that signal and that any strat-trop coupling supersedes it as a driver. 

Saturday-Friday should be interesting at the very least weather wise with some snow around for Scotland and Wales and mountain life in England. 

I suspect that GFS MJO plot is completely wrong..



Here's the ECM one. Looks a lot more realistic to me.

[IDO]

Better 06z if you are not keen on the euro high, most of us, with the Pacific wave forcing different again, so the tPV main vortex stronger -v- euro heights pushing the jet further south than the 0z:

06z>  0z> 

Bearing in mind the boring FI from the 0z, maybe a better journey for cold though still westerly based and with the uppers sourced from a less cold travel. So by D10 big differences for the UK:

06z  0z> 

With the upstream variables changes like these are quite possible, but need further runs to see how likely. Sadly, northern blocking remains a tough task with either pattern.

[feb1991blizzard]

1 hour ago, Steve Murr said:

The EPS show a breakaway cluster day 10 onwards which is pretty much last chance saloon for Winter proper-

We would bees to see this trend develop & become a lot more consistent over the next 4-5 days to be really interested....

Well i cant see it but i would be buzzing if it did

[mb018538]

ECM OP probably best fits cluster 4 at day 10:



One of the smaller and less likely outcomes, unsurprisingly.

Beyond that, it potentially looks very mild by day 12-15 with a strong SW flow the most favoured outcome:

[weirpig]

Back to square one.  Only very briefly warmer uppers then back to the cold westerlies

Edited February 6, 2020 by weirpig

[weirpig]

GFS in summary    if you like next week weather then you are in luck.  Groundhog day  has the storm to our north is repeated a few times  resulting in stormy wet( and in some places wintry)  Weather   certainly no mild on offer.  

Edited February 6, 2020 by weirpig

[nick sussex]

After the initial PM flow the GFS reforms the PV to the north and shows no interest at all in the ECM trend .

The GFS 06 hrs run was flatter upstream than the earlier 00hrs run .

Putting aside what happens post PM flow , there is quite a lot of uncertainty upstream with shortwave energy which impacts the amplitude of the Newfoundland low .

And this then of course impacts events downstream .

 

[Banbury]

Low after low after low after ………………….according to the GFS6z

[Methuselah]

Just to show the difference between subsequent runs:

00Z:   06Z: 

00Z:  06Z:  

The difference in sea-level weather would be stark; though, synoptically, that difference reduces to a matter of emphasis and no more...And is, to be sure, nowt worth hyperventilating over!

Edited February 6, 2020 by General Cluster

[feb1991blizzard]

2 minutes ago, Banbury said:

Low after low after low after ………………….according to the GFS6z

With some snow though as well - of course it wont verify like that at that range though admittedly.

[weirpig]

Ensembles 6z   Huge scatter in the mid to long term as one would expect  Gfs op  on the cold side  but  quite a few runs continue with the cold uppers      

[frosty ground]

Lightning strike risk according to the warnings for Monday/Tuesday.

Looking at the flow I think this risk will be more widespread. 

[nick sussex]

The upcoming PM flow will be a good test to see how much snow that can produce .

Ordinarily in the UK you need colder 850s to produce more wider interest unless you have embedded cold and frontal precip , something we see when low pressure moves in from the sw engaging a flow off the continent .

The plus column for the expected set up .

Time of year , colder sea temps than earlier in the winter . Strong flow which helps to lessen that moderation . The freezing level is quite low so any snow has less time to melt as it falls . You’re also likely to find colder downdrafts so esp in heavy precip that lowers the freezing level .

The negative is the 850 value itself  , and conditions are likely to be marginal away from higher ground . The strength of the flow will stop nights from getting particularly cold so you’re going to need that elevation to preserve any snow .

What happens after the initial PM flow seems less certain today because of the divergence in solutions . 

The placement of the reformed PV is the point of contention rather than whether that happens.

So the three possibilities today .

Either to the west so milder with a sw flow in general . More to the north of the UK as in the GFS 06 hrs run and then the wildcard and currently the long shot the ECM view of digging this much further west and more amplified .

What we don’t see is the PV reforming further east which would have been better for coldies .

Even if the ECM was correct you’d still need some further westwards corrections and more energy heading se .

 

 

Edited February 6, 2020 by nick sussex

[feb1991blizzard]

The only downside of the stronger flow though is that sometimes stronger winds actually kill the convection.

[mb018538]

As expected - the 6z Op was a HUGE unsettled outlier in the ensemble pack:




Still looking good to dry out and and settle down somewhat towards the last 10 days of winter.

[The Northern Ramper]

3 hours ago, Snowfish2 said:

What on earth is that please 

Well technically it’s not on the earth.

[nick sussex]

1 minute ago, feb1991blizzard said:

The only downside of the stronger flow though is that sometimes stronger winds actually kill the convection.

I can’t see that being an issue . The flow is very unstable. And of course the strength will drive any showers well inland . Nearer the time we’re likely to see some troughs showing up enhancing the showers .

[feb1991blizzard]

4 minutes ago, nick sussex said:

I can’t see that being an issue . The flow is very unstable. And of course the strength will drive any showers well inland . Nearer the time we’re likely to see some troughs showing up enhancing the showers .

Yes true - the aforementioned problem is usually more prevalent with an Easterly rather than a WNW flow, the late Feb 2018 Easterly would have delivered me an even bigger dumping if the isobars were less tightly packed IMO.

Mind you its not that unstable.

Edited February 6, 2020 by feb1991blizzard

[The Northern Ramper]

1 hour ago, Banbury said:

Low after low after low after ………………….according to the GFS6z

Low after snow after low after snow ?