Model output discussion - here comes the beast!

[CK1981]

11 minutes ago, jam said:

There really are some drama queens on this forum.. should be ashamed of comments like this

Comments on the GEFS trending mild? Not sure that’s ‘drama’, just stating what is now showing, which is a milder trend. Whether we like it or not, that’s what it’s showing and this is the MOD thread. I’ve been steadfast in my opinion this low will move south, but it’s not looking good now.

[sn0wman]

12 minutes ago, Bristle boy said:

"Epic spell"

Used far too frequently by the less knowledgeable on here over last few days.

#learningpoint

Absolutely ridiculous comment.

Upper air temperatures as low as -17°C are modelled to move over parts of the UK by Wednesday. The return period for an event like this is around 1 in 20 years. If that doesn't reach the criteria of an "epic spell", then I don't know what does.

Anyway, back to the models. For anyone that hasn't heard of it before, the ManUniCast model (http://manunicast.seaes.manchester.ac.uk/) is pretty good at picking up short-term convective precipitation. Here's what it's showing for Monday at 8am:

Definite signs of a Thames streamer setting up here, as well as quite a few sea-effect showers setting up along the entire east coast of the UK. Considering that the main action for most will be on Tuesday and Wednesday, this is encouraging.

[ukpaul]

1 hour ago, BlackburnChris said:

Northern England alot Colder ... Mean stays around -5

Still scope to keep a lot of the country in colder uppers for a while longer and a slight improvement in pushing colder air down from the north on the 18z. Two thngs to look for, this week’s system not pushing as quickly or as far west as currently modelled and the second low remaining undeveloped and further south and west, delaying its intrusion.

GEFS ptb 7 is one of a few members doing that, with good results. GIF below.

 

[JBMWeatherForever]

So the models are now showing an end to the Exceptionally cold spell by the end of the week for much of the UK. Well we will see won't we. I certainly wouldn't bet too much on it happening, not yet anyway. If anything I think what this means is rather than a two week spell of exceptional cold with bouts of snow showers from the east, we now have the real prospect of lows from the south actually reaching the uk rather than staying to the south over France, and although the South may see some less cold air for at least a time, the new synoptics look to me like a cocktail for "Snowmagedon". Is the effect of the, by then, entrenched severe cold air being factored in by the models? I don't think so!  They nearly always don't factor this in until near term. We know that the eventual outcome is unlikely to be as shown tonight, with many factors still to be calculated by the models before the final outcome is accurately predicted. Next week is not a normal situation, and we all know how the models react to something which is far from the norm. I for one think that the end result is going to be EPIC, at the end of an EPIC week ! So I therefore hope that everyone has an EPIC nights sleep!  On a final note, it seems that those that were last to except the upcoming severe cold spell was actually on its way, seem all to ready to except its demise and seem to be all to quickly convinced of this !  Lots of snow to come under the bridge I think before the outcome for the end of the week is finally known.    

[SLEETY]

excited for end of week,either a big blizzard in the SW as the low stalls or it moves along the English channel and produces a big blizzard along the whole of the S,or it fails to make it and dives into France.

the models are way off with the track at the moment ,look at the archives when we have bitterly cold Siberian air over the UK and low pressure attempting to move up from the sw or s it doesn't just crash into the UK and push away the cold air so fast as is being shown.expect major snowfall somewhere or misses S completely 

Cold air is dense and heavy,hard to push it away 

 ,exciting times anyway before we know what's going to happen end of week with heavy falls of snow for some,with drifting and great sliding conditions,can't wait now,here we go Siberian beast is here  very soon,can you believe it's happening folks after years chasing the  Great Siberian High it's turning up in a few  hours

[Daniel*]

With the modest range we’re looking at don’t bother with GEFS the superior resolution of OPs should pick up a change first if it does that it. My eyes widened when I had a look at the SSTs the S North Sea and Thames Estuary is particularly ‘toasty’ relative to the norm. If some parts of SE England are not buried it’s time to find a new hobby!

Edited February 25, 2018 by Daniel*

[SLEETY]

9 minutes ago, Daniel* said:

With the modest range we’re looking at don’t bother with GEFS the superior resolution of OPs should pick up a change first if it does that it. My eyes widened when I had a look at the SSTs the S North Sea and Thames Estuary is particularly ‘toasty’ relative to the norm. If some parts of SE England are not buried it’s time to find a new hobby!

 the lake effect snow hasn't been picked up  by the high res models yet would expect Jan 87 totals along the e and se coasts  talking feet of snow not inches !,and many inland places joining in the fun as the strong and bitterly cold E wind increases through the week

Edited February 25, 2018 by SLEETY

[Interitus]

23 minutes ago, JBMWeatherForever said:

Is the effect of the, by then, entrenched severe cold air being factored in by the models? I don't think so!  They nearly always don't factor this in until near term

Of course the models can account for cold air - they wouldn't be able to forecast changes to milder conditions elsewhere in the world either - and the cold itself is not a barrier to milder Atlantic air, southerly plumes of air as happening concurrently with this easterly, seem to penetrate the deep cold inversion of the Arctic with increasing regularity. Surface temperatures at the North Pole are expected to reach above freezing this week.

The thing in this case is that the cold is not at the moment forecast to be accompanied by blocking by any of the models for this time next week - the storm tracks and subsequent temperatures may be open to question but as it stands no block means incursion of low pressure is inevitable.

[pureasthedriven]

1 hour ago, meh said:

For those who want the snow to survive for the one weekend (which surely isn't asking too much, is it?)  the GFS 18z is not a concern.  What is a concern is the UKMO and now the latest shift in the ECM run set.

I don't know why they have to run the GFS 4 times a day to 384h:  maybe it's an attempt to buy love and attention by compensating for the lack of quality with excess quantity.  What's a pro forecaster meant to do, publish a new in-depth analysis every 6 hours?  It's an overload of information that muddies the waters rather than making them clearer. 

Anyway FWIW, the JMA + GEM ensemble means still have promise out to a week on Tuesday for much of the country.  I don't expect a shift in tone from the MetO just yet.

If the snow survives one weekend, rather than just wrecking the drive to work then vanishing Friday night, I'll be happy.

I think this echoes my current thoughts and hopes really well.

Exeter’s most recent update (within the last hour) is excellent. Standing firm and all to play for - and this after the EC 12 and 18 GFS and GEFS. Interesting. 

[The Eagle]

So....I take it ICON is once again the darling model?

 

[ZK099]

4 minutes ago, The Eagle said:

So....I take it ICON is once again the darling model?

 

Picked up on the easterly first to be fair... 

Edited February 25, 2018 by ZK099

[essexweather]

The low slightly further South and West on the 00Z at the T+144.

Brighton for example has a air temperature 5C lower on this run than the previous for Friday evening at 6PM.

Hopefully the ECM brings the low a touch further South - a trend which I believe will continue over the next few days keeping a large proportion of the UK in the colder uppers.

EDIT: Great UKMO for the short range period, higher snowfall totals for the East and South-East.

Edited February 25, 2018 by essexweather

[high ground birmingham]

I think the northward progression of the low into the U.K. is highly likely. The reason I say this is that the models have firmed up on the cold flow turning from an ENE flow to a ESE giving encouragement to the system to move up.

however, I do say a little perspective is needed in here. Remember 10 Dec 2017? there was an almost 50-75 miles correction south within a few hours of the event. What was Manchester/Liverpool’s loss was N/E London’s gain. This could and probably will happen here.

 

Edited February 25, 2018 by Paul

[SLEETY]

models slowly working out the track of the low,still wrong at the moment,snow hitting the SW moving across to other Southern counties before dying away South or not making it far enough Northwards ,before heading S and bitter weather returning.met going with that scenario too.

[essexweather]

While it's too early to say the cold is winning this battle... wait for the ensembles... no where in the UK ends up with postive 850s on the operational out to T+180 which is a big difference from the 18Z from yesterday evening.

Going to be a interesting couple of days to see how this pans out. Something doesn't sit right with me when you flick between T+72hr and T+144hr - the cold pool just disappears which isn't normal in a Easterly scenario. Blocking normally puts up a bigger fight than this.

[SLEETY]

really think it's going to end up with an historic blizzard somewhere end of the working week,before retreating S.gfs always wants to push away dense cold air too fast ,known failure inits program,algorithm or whatever it uses 

Edited February 25, 2018 by SLEETY

[Flash bang flash bang etc]

Not sure which region our area comes under (SW or SE?) but i’m hoping the Thames plays it’s part in driving the mid-week snow further inland to reach central areas, and does a nice big dump on us.

I have a lot of driving (potentially) during the coming week, so it’s particularly interesting watching the evolution of this one

[Mr Frost]

Good Morning all!

Once again I am loving the charts this morning - splendid to see the incoming cold spell still intact and looking as cold and severe as ever! (Just look at the uppers - mind blowing! 

UKMO charts below for 48 hours away (Just take that in - 48 HOURS AWAY!)  to 144 - short term to medium they are simply incredible for the UK (Scotland, England, Northern Ireland and Wales) and Ireland. Snow will be piling up for Eastern parts from North to South and more widespread heavy snow showers will be affecting pretty much anywhere with locally significant accumulations! (not the rust variety @Great Plum)

At the end of this run Scotland and parts of Northern/North East England are still in the freezer! You also have the much discussed  low moving up from the South which is going to dump some incredible amounts of snowfall for some very lucky people. (for how long who knows but I would be very excited if I was in it’s path!)  (check out the forecasts on the Metoffice website/APP for London, Cardiff, Dublin and Belfast for Friday...chose capitals to make it easier )

It really is going to be a very exciting and sleepless week ahead for people who enjoy this type of weather. (looking forward to browsing all the regionals to see pictures/reports - about bloody time some of you get to enjoy/see snowfall again!) 

Have a fantastic Sunday! 

 

Edited February 25, 2018 by Mr Frost

[swfc]

Slight but subtle changes this morning on the mo.exeter forecast also excellent. Low pressure looks via iberia will push northwards but small increments slipping it southwards may gradually get to the stage where the south ends up very snowy and the rest stay in a very active snow shower regime. Lots to get threw with the usual caveats. 

[chris55]

The end of this week could well produce the biggest blizzard parts of the country have seen for many many years.

Lots of modelling yet to come on track/details but could be memorable  

UKMO looks to pull the low back west under the high, keeping the cold continental air flow for most :0

Edited February 25, 2018 by chris55

[Scandinavian High.]

The gem keeps low to south heavy snow for the south future north you easterly flow heavy snow showers ..

[radiohead]

ECM 120. Looks like heavy snow  for southern Ireland, Wales and inland areas of SW England at this time. Huge snowfall potential for some areas.

[Mr Frost]

ECM 48 hours to 120! What else can we say? It’s just unbelievable to see these charts so close and not downgrading! 

Perfect Winter/Spring charts! 

 

 

 

Edited February 25, 2018 by Mr Frost

[Gustywind]

UKMO brings a 24 hour snow event before mild moves in, again with the front swinging out west of the U.K. at T144.

Edited February 25, 2018 by Gustywind

[SLEETY]

not buying the Ecm idea of the low pushing in as fast as that at t120 at all, and pushing the bitter air away, its way too progressive,tends to do that when it doesn't know what to do,I've noticed in this model