Model output discussion - the beast arrives

[Mike Poole]

I think the 12s today are going to be quite  important.  ICON edging in very cold air, here at T54,  looks a bit colder than recent runs to me - and a bit like a dragon incoming!

Here's the low at at T72

 

Edited February 26, 2018 by Mike Poole

[The Eagle]

Northern extent of snowfall Friday on Icon. It pulls away south and weakens to nothing after.

 

Edited February 26, 2018 by The Eagle

[pages]

3 minutes ago, Mike Poole said:

I think the 12s today are going to be quite  important.  ICON edging in very cold air, here at T54,  looks a bit colder than recent runs to me.

Looks like the low is going to be a bit further south on this run, here at T72

6z here at same time for comparison.

 

 

we have seen many  a predicted cold spell disappear on the models at just 48hr in the past this may be the one time we see the opposite the icon is really showing that retrogression to happen slower putting more pressure on the low as I posted before a lot more energy go south east  at t-30 if that retrogression slows down any more this low is going to go under and keep South Easterly feed. something to watch on next couple of runs.

[Tony47]

Re the definition of a polar low, I searched and found a back copy of my 'Weather' magazine and the article states: "A polar low has been defined (Met Office 1964) as a 'fairly small-scale cyclone or trough (sometimes the surface isobars show only a very minor ripple) embedded in a deep cold current which has recently left northerly latitudes.'"

Make of that what you will but it would seem to suggest that the trough showing up to our north-east has been too clearly defined to be a true polar low.

[Mark Neal.]

ICON not as far north with the system again. Starting to see models not get as far North. Block in place/Cold air in place playing its part>?

 

Edited February 26, 2018 by Mark N

[Weathizard]

Low a little bit further west at t90

 

Looks like more pressure is being put on the low by higher pressure to our n/NE

Edited February 26, 2018 by Weathizard

[Mike Poole]

ICON more elongated at T99 edging towards holding the cold

UKMO edging the same way at T96

Edited February 26, 2018 by Mike Poole

[SMU]

IKON straight easterly by 105 & -10c uppers heading back SW

[Singularity]

  

ICON with a variation from the 06z but within the same general theme; the trough elongating along the Channel.

 

I like how taking the LP so far S and W negates most of the mixing out of the continental air, which is able to quickly tuck back in across the S.

Will GFS play ball I wonder? Seems like the models have initially gone more east, then gone more disrupted, then picked up a more W track and undone the disruption, but are now at last exploring a combination of more west and disrupted. 

Well, apart from UKMO which has kept exploring that combo for most of the time. Kudos to that model if it does turn out to be along the right lines.

 

[Weathizard]

ICON at day 5 1/2, so close to retaining the cold for the entire country, massive change compared to its morning run with much more forcing on the lows... perhaps this isn't over yet?

[Dominic Carey]

4 minutes ago, Mike Poole said:

ICON more elongated at T99 edging towards holding the cold

What does this mean in terms of cold?

[bradymk]

GFS also better so far. Slightly Colder than previous run for Wednesday and now at +72 we have a slightly stronger Greenland high and the approaching low further south west than previous run too.

[pages]

1 minute ago, pages said:

we have seen many  a predicted cold spell disappear on the models at just 48hr in the past this may be the one time we see the opposite the icon is really showing that retrogression to happen slower putting more pressure on the low as I posted before a lot more energy go south east  at t-30 if that retrogression slows down any more this low is going to go under and keep South Easterly feed. something to watch on next couple of runs.

look at much further East that high Pressure is on the 12z if it changes by same amount again on next couple of runs it will be around Iceland and we will still be in an easterly.

12z

6z

 

and look how those early changes leave us at t-132  no point going any further as models are really struggling with the speed at retrogression and position of vortex within 24hr there are difference of a couple of hundred miles.

 

[Mike Poole]

Yep, further south at T72 on GFS too

[warrenb]

The shift ties in quite nicely with the new weather warning for the SE for Friday of possible deep snow

[SMU]

UKMO 96-

It looks like a total turn around back to cold as most expected

Looking for snow moving west out of low countries 96>120

@CK1981

 

Edited February 26, 2018 by Steve Murr

[Weathizard]

Just now, pages said:

look at much further East that high Pressure is on the 12z if it changes by same amount again on next couple of runs it will be around Iceland and we will still be in an easterly.

12z

6z

 

and look how those early changes leave us at t-132  no point going any further as models are really struggling with the speed at retrogression and position of vortex within 24hr there are difference of a couple of hundred miles.

 

Indeed, I had previously lost hope I won't lie but the retaining of some heights to our N at day 4 are absolutely crucial as it doesn't allow that low pressure to just barrel up from the south.

This along with the hEights increasing to our NW and less of the dreaded East based NAO have given me some real hope now.. lets see

[Paul_1978]

3 minutes ago, Dominic Carey said:

What does this mean in terms of cold?

Would suggest to me that the snow line would be further south (not good for those Midlands northwards), but with the advantage that we hold onto the cold for longer (instead of it becoming less cold), and as such more favourable options on the table after the weekend if you are of the cold persuasion?

[Mike Poole]

2 minutes ago, Dominic Carey said:

What does this mean in terms of cold?

It may mean extension of the cold period country wide, possibly at the expense of a massive blizzard for the south and south west, if this is a new trend.

[Summer Sun]

Major upgrade from ICON 12z

[johnholmes]

13 minutes ago, Tony47 said:

Re the definition of a polar low, I searched and found a back copy of my 'Weather' magazine and the article states: "A polar low has been defined (Met Office 1964) as a 'fairly small-scale cyclone or trough (sometimes the surface isobars show only a very minor ripple) embedded in a deep cold current which has recently left northerly latitudes.'"

Make of that what you will but it would seem to suggest that the trough showing up to our north-east has been too clearly defined to be a true polar low.

I think you will find there has been a lot more research done on this since 1964 Tony. Not sure if myself would class it as a polar low but Google and there are a good many articles by meteorologists and research scientists about it. Anyway anyone under/close by its track should get a decent fall of snow over the next 24-48 hours.

good luck folks.

[BleakMidwinter]

26 minutes ago, Mike Poole said:

I think the 12s today are going to be quite  important.  ICON edging in very cold air, here at T54,  looks a bit colder than recent runs to me - and a bit like a dragon incoming!

Here's the low at at T72

 

 

Strewth! It's the Eastern Wolf itself, jaws agape, saliva drooling, ready to gobble up our little island...! :o

[Dominic Carey]

4 minutes ago, Paul_1978 said:

Would suggest to me that the snow line would be further south (not good for those Midlands northwards), but with the advantage that we hold onto the cold for longer (instead of it becoming less cold), and as such more favourable options on the table after the weekend if you are of the cold persuasion?

Thanks this is good news then as I've been longing  for a decent cold spell for years 

[Singularity]

GFS still took the deep low further N and then had it move W toward the Azores low despite that one being further W... so pretty unconvincing there, but look how it has the disruption sending a shallow low east to pass S of the UK.

This brings the cold back down into the frontal system just as it moves NE - resulting in what at first glance appears to be an all-snow event even in the far S. Need to see higher-res to confirm though.

[pages]

Just now, Steve Murr said:

UKMO 96-

It looks like a total turn around back to cold as most expected

@CK1981

 

yep still not convinced  frontal snow will actually reach UK.

I still think it may head trough France looking at trend particularly the icon its showing  retrogression now occurring slower and slower run by run putting more pressure on low keeping further south and it gets very close at T-33 to phasing with some energy in the Med. if models continue to trend this way we will just keep  north easterly showers until the cold pool exhausts itself  thou Icon shows upper reloading to NE at t-180 but that fantasy land with big changes to high place meant in 24hr-36hr period