Model Output Discussion - Spring Has Sprung

[Lukesluckybunch]

1 minute ago, legritter said:

Down a bit cheers

Same here legritter!

[andymusic]

gfs 18z steady as she goes - snow for mid wales north and mid/north midlands north

[Nick123]

 andymusic think thats gonna be the track -surprisingly as they professionals are/have been saying all along

[blizzard81]

 Nick123 It's neither brave or foolish. Dramatic words for something that just isn't dramatic. You are misconstruing my comment by making it look like I somehow 'disrespect' the professionals. Way off the mark - The gist of my post is the fact that the professionals can only work from the latest data they have at their disposal. So, say at any given time when they record their forecast, the next set of model suites are already rolling. If the ones rolling turn out to be a significant change from previous suites then their present forecast is already out of date. Yes, the suites may revert back again but the fact remains, they are always playing catch up. That's not a criticism as there's absolutely no way of combating that - unless they invent a time machine. 

Edited February 5 by blizzard81

[Harveyslugger]

 andymusic gfs 18z has no snow for mid Wales?

[andymusic]

 Nick123 yep - exactly where meto's warnings are progged for

[Lukesluckybunch]

Looks a slightly better wrap around here!

[andymusic]

 Harveyslugger

[Allseasons-Si]

Actually the 18z has the low a bit squashed(rugby ball than bowling ball) hence the snowline is further south than the 12z...

still some ironing to be resolved just yet me thinks.

 

[WYorksWeather]

Starting with the short range outlook for Thursday - just trying to understand where the possibilities are.

The peak of the spread of colder 850hPa temperatures, based on UKV, looks to be on Wednesday evening, and for dew points, Wednesday afternoon.

We have marginal snow possibilities down as far south as East Anglia and West Wales, but the main possibility continues to be around a line from the Humber northwards.

Unfortunately, the issue is that by the time the main band of precipitation comes in, from around 3am Thursday onwards, conditions rapidly become less favourable.

By Friday morning, snow chances to low levels will be very limited away from Scotland and far northern England.

Based on this output, I'd expect that for most lowland areas away from Scotland, we're looking at a snow to rain event at best. The worst case is probably a sleet to rain event. Of course, if you have a decent amount of altitude, say 200m or more, then you may well have better chances.

For the medium term output, we see a colder than average spell lasting until around the 15th going by the mean, but much less pronounced in the south, to the point that it barely even qualifies at all. Once we get beyond the 15th, there's really not much of a signal. Early spring is a possibility, as is continued winter. I don't think we're close enough to that point yet to say anything with confidence.

Longer range models may vary, but CFSv2 is also backing up EC46 in predicting a colder second half of February.

All I would say is that the later we go into February and especially into March, the stronger any negative anomalies will need to be in order to deliver a cold and snowy spell. Below average by a degree or two will not be enough. I'd really like to see a very strong signal for temperature, not just the look of the synoptics.

And of course, we've been chasing a major cold spell around the corner at days 10-14 or beyond for a while. So far, in my northern England location, so not even as snow-deprived as some southern locations, I've had about a centimetre of slush that lasted about 12 hours in early December, and a cold spell in mid-January which lasted about seven days and produced some hard frosts, but zero snow.

I would also note that the long-range models have also moved the goalposts. Originally the whole of February was looking very blocked. Now the blocking looks more likely for mid-month onwards. Not saying it won't happen, but any further pushing back, say to the beginning of March, would mean we'd need an almighty cold anomaly to deliver.

We maybe have one more go at it after this week, or at most two if a very significant cold spell were to be indicated at the turn of the month. I continue to watch with interest for the next couple of weeks, except that I'll cut that short and go for an early spring if we see that in the models before then, or extend it if a BFTE repeat looks possible.

[Mcconnor8]

 Allseasons-Si Snowline is further North on Thursday though I think 

[Nick123]

 blizzard81 fair enough but your wording made it come across like you were suggesting we are in a better place to make a forecast than the pros and that will never be true. 

 andymusic look at scandy... so jealous 

[Allseasons-Si]

Meanwhile,...the eps control,...go on son...

[bradymk]

 Mcconnor8

It’s just as much about the shape of this incoming low as it is how north / south it is.

Although it appeared further north early on, its a better shape than GFS 12z. The better shape will likely keep snow / cold in the Midlands & north for longer and also improve chances of any colder feed following.

It’s not what we quite want on the 18z GFS, but better anyway.

Could be a good (even if transient) event Thursday for central third of UK and Ireland.

Current sweet spot maybe inland North Wales at the moment?

Edited February 5 by bradymk

[Lukesluckybunch]

3 minutes ago, bradymk said:

Current sweet spot maybe inland North Wales at the moment?

Current sweet spot is northern England..going by the 18z

[Mcconnor8]

 Lukesluckybunch

Yep, maybe transient snow to rain prior to this in Wales and Central England but probably brief.

[Lukesluckybunch]

18z really bad run again!

[frosty ground]

 Lukesluckybunch

anything you wish to add to that? 

[Lukesluckybunch]

Just now, frosty ground said:

anything you wish to add to that? 

It's a real mess at 162..and the Azores high wants too come in..from were we was couple days ago..it's not good

[Lukesluckybunch]

5 minutes ago, frosty ground said:

anything you wish to add to that? 

Do you like this run then?

[Spah1]

 Ali1977 Why do we need it to go South? 

[Johnp]

 Lukesluckybunch It’s the worst run of the day.

 Spah1 Because by moving north, the low is wafting mild air up across us and Europe. 

[Lukesluckybunch]

2 minutes ago, Johnp said:

Lukesluckybunch It’s the worst run of the day.

Yes john long fetch southwesterlies at day 8!!..there is literally no cold air about at this point!

Edited February 5 by Lukesluckybunch
Adding

[frosty ground]

Lot of differences in that run but yeah worst run of the day. 

[Kasim Awan]

A textbook strengthening of the Iberian high and warm upper air plume on the GFS18Z.