Model Output Discussion - Spring Has Sprung

[Jordan S]

The Icon is certainly an interesting update this morning for Thursday/Fridays low and subsequent high migration into next weekend and beyond, that last night Gfs seems very unlikely. 

I wouldn’t take the snow or the Icon output for the weekend into next week too literally as it could be quite dry at times, the model overview exaggerates the snow to some extent to what the model is truly showing but does show potential wintry precipitation, the air certainly likely to be cold enough for snow for especially central/northern areas with any precipitation about. And clearly a milder outcome isn’t likely at all still atm.

Edited February 5 by Jordan S

[Lukesluckybunch]

5 minutes ago, SLEETY said:

what's makes you think gfs is correct anyway, top of the ensemble runs other models have the low further south etc. 

Nick does have a point though sleety..the gefs also were not interested in the southward shift!

[Dennis]

 

[nick sussex]

Clearly the UKMO have low confidence in their output even though that’s two runs in a row with the more elongated low set up further south.

They have modified today’s T84 hrs fax chart .

So we should bear that in mind . There remains a lot of uncertainty.

 

[Anthony Burden]

 Nick F Hi yes the Met Office extended has been stating the dry northerly air flow for some time,in regards to snow this weekend I’m sure some parts of the UK will get a considerable amount.

[nick sussex]

 Lukesluckybunch

I think because of the Euros the GFS is an outlier solution but we do need it to make a move on the 06 hrs run . 

[AO-]

Mind the scatter at day 5-6 (already) for here. More members going for the UKMO variant? Seems cold next week, but no ice days in the forecast as of yet. 

 

Edited February 5 by AO-

[MKN]

 nick sussex  nick sussex In marginal situations similar to this the GFS has been out on its own numerous times and ended up being on the money. For that reason unless it comes on board soon I wouldn't be holding out for much if you live further south. 

[Snowyowl9]

GFS has certainly gone off one..Caught countryfile weather last night not seen that before they should GFS..

Anyway a slider low is whats mostly shown on all the other models..

Ukmo is definately my favourite of course..ECM would still bring snow just about in the although cold surface undercut would help..

Comparing 0z run to 0z run not much has changed really..

[nick sussex]

 MKN

The complications around the low aren’t just how far north or south it tracks . The models also differ in the structure of the low , as in one main system or a splitting of that into a complex low pressure . 

[Dennis]

just a comment : one day GFS is super , another day bad and suddenly EC takes over after first bad and suddenly good

i think sometimes : its just how they drinked their coffee (just joking)

[SLEETY]

Gfs is worse in the verification stats over the other two, remember that as well, when thinking the gfs has the correct pattern. . 

[Purga]

GFS is a diabolical mildfest this morning enthralled by U Barty but at least the Op is counter to the main ENS runs.

It's not without support and the Control also is in scheister mode towards the end.

Good that ECMWF have read the script at least this morning with UKMO not half bad.

   

To be fair, there is a lot of uncertaintity regarding the positioning of the incoming LP, especially in the north of the IK, which can make all the difference. As seen by the spread chart.

 

[Lukesluckybunch]

ICON rolling out..let's see the behaviour of the low..

[Nick F]

 nick sussex Agree, quite a complex low pressure system moving in from the Atlantic later this week. 00z GFS perhaps looking the least likely to handle well the various low centres that develop and disappear within the low pressure system.

Differences between EC and GFS on baroclinic development around the southern side of the parent low moving in from the southwest across the Bay of Biscay. A strong jet streak moving E and NE underneath the parent low, EC shows wave developing over the Bay of Biscay which forms a low that moves NE across SE England early Friday. GFS doesn't have this low, but this low is quite pivotal in elongating the low pressure system and pulling the parent low east away with it and not allowing it to drift north over Ireland like GFS and Arpege do.

 

[Lukesluckybunch]

ICON bringing the snow risk further south by Friday..!no real change with the low Thursday..takes it through central England..

Edited February 5 by Lukesluckybunch
Adding

[Ice Day]

23 minutes ago, Nick F said:

GFS doesn't have this low, but this low is quite pivotal in elongating the low pressure system and pulling the parent low east away with it and not allowing it to drift north over Ireland like GFS and Arpege do.

This is the key bit that takes place around 96-120hrs.  Looking at the Icon (6z), ECM, UKMO, GEM & GFS at 120hrs

    

The GFS is the only model that has the low to the west of mainland UK. Now maybe the GFS has it right, but it's highly unlikely. Assuming it's wrong, being outperformed by the ICON at relatively short range is not its finest moment!

Let's see if the 6z starts it's usual incremental move back towards the others?

[AO-]

 Lukesluckybunch

Risk/chance of wintry showers in Saturday is high on Icon. After the snow on Thursday/Friday in the Midlands, the wintry showers might head more South. 

[IDO]

 AO-

The ICON is not seeing much snow  up to D5:

By D5 the precipitation has petered out. Usual suspects, Scotland and hills and mountains in the north, the best chances.

[Daniel*]

Some of you folks confuse me the EPS strengthens the cold signal growing optimism of colder E’ly flows into next week.

[nick sussex]

So far the GFS 06 hrs run shows no sign of u-turning .

[Eskimo]

GFS sticking with its guns - snow to rain for northern areas. Perhaps temporary accumulations over hills. 

Edited February 5 by Eskimo

[Battleground Snow]

 nick sussex

One is going to have blink by the 12z runs,

We will be down to 78 hours by then, extreme difference at short range.

 

[IDO]

 nick sussex Yes! I am not saying it is right, but it is more consistent than the EC, which changes every run.

Transient snow to rain in England:

[Lukesluckybunch]

That low is just sitting there...southwest of ireland!pulling up milder air!!