North West Regional Discussion Feb 2021 onwards

[Joe Bloggs]

7 minutes ago, Kasim Awan said:

Ok folks here is my current assessment for tonight and Monday.

Vorticity (convection) is building now, and will continue to build overnight. It will remain highest over Lincolnshire, South Yorkshire and South Derbyshire which are currently favoured for high totals of 10-20cm. Locally 25cm can't be ruled out in the vicinity of this area, say Chesterfield or south Sheffield area.

I am expecting moderate scattered showers further north into the Peak District, East Manchester, East Cheshire, East Cumbria and further north into "central" and West Yorkshire. Here, a covering of up to 5cm is possible by the morning, especially above 200 metres. The instability will wave northwards during the morning so I can see an area of more organized converge move into north Sheffield, Glossop, East Manchester area (more of us in this forum) through Monday, and potentially Monday evening as the streamer further south reduces in it's convective potential. This will result in more convection further north due to convective laws, and subsequently more snow showers late Monday into early Tuesday for Halifax, Huddersfield, Manchester. This is unlikely to be as intense as the streamer further south, the Humber > Chesterfield > Ashbourne one, however will be enough to produce a 2-5cm covering  and in places 10cm >200m in the East.

This pattern, I expect, will be quite repetitive through Monday and even Monday evening. So I can see further big accumulations in "the south", - relative to us, and relatively short lived heavy showers further north., before a switch to more northerly convection through Monday.

As a prognosis of streamer activity, uncertainty here is relatively high so I expect this to "go wrong" in some regard, for example the switch further north may occur earlier on, or the two streamers may exist in tandem

In terms of western progression, fortunately wind speed and instability is ample to allow showers to climb over the Pennines now. Lighter yes but enough for accumulation. So in general a dusting to 2cm locally west of the M6 > east of the M6 1-5cm, east of the 100 metre contour in the East Manchester region > 2-8cm, and 5-15cm over and on the Eastern flank of the Pennines even to low levels.

@MancRM95 There my friend is your explanation!

Cheers Kasim, brilliant post as always. 

[Thunder Snow]

Whens the wind due to strengthen there just not making it over the hills

[Kasim Awan]

4 minutes ago, Had Worse said:

Does that mean we get double portions Kasim?

We potentially get the lighter edge of one streamer (tonight and early MON), then a direct hit from a moderate streamer later Monday. So probably slightly less than Chesterfied, Ashbourne etc. The exiting thing is, other options are still available, this is just a most likely solution in my opinion.

Worth also noticing that, given the streamers remain weak, there will still be significant convection between them. If they do become very strong, they will likely uptake all the available instability between the streamers.

Atm I'd favour moderate intensity streamers, meaning there will still be some energy between them for showers. This is where the Arpege is a bit wrong.

[Backtrack]

They are making it over the hills. They’re dying around the welsh border. It’s a good sign if we can get any beefier PPN crossing. FWIW- showers are losing intensity over Manchester and then reintensifying over the lower ground. 
 

For those saying there’s PPN on the radar but it’s not failing. One of two things:

 

anaprop (radar signals that are false)

super low DP’s. Air is super dry. That’s why it’s not falling to the group. It’s drying up mid-fall. 

[Had Worse]

Just now, Kasim Awan said:

We potentially get the lighter edge of one streamer (tonight and early MON), then a direct hit from a moderate streamer later Monday. So probably slightly less than Chesterfied, Ashbourne etc. The exiting thing is, other options are still available, this is just a most likely solution in my opinion.

Worth also noticing that, given the streamers remain weak, there will still be significant convection between them. If they do become very strong, they will likely uptake all the available instability between the streamers.

Atm I'd favour moderate intensity streamers, meaning there will still be some energy between them for showers. This is where the Arpege is a bit wrong.

I was joking mate, I was referring to the double post you did further up.

[Kasim Awan]

This is a perfectly evolving textbook easterly. Not a brutal one like 2010 or 2018, from a meteorological perspective just as interesting.

The start > light ppn in clusters, like we're seeing over Lincolnshire right now.

After 12-24 hours > heavier showers like Scotland has right now

This is clear to see. On the radar last night Eastern Scotland looked exactly like Lincs does now. Now the instability has come to lift there, the shower composition has evolved from snizzle to heavier stuff.

[Kasim Awan]

2 minutes ago, Had Worse said:

I was joking mate, I was referring to the double post you did further up.

Haha, and I thought you were referring us getting hit from both streamers.

[Joe Bloggs]

Just saw Sara Blizzard’s ramp.

Snow streamers galore. A bit different to Jo Blythe the other night. 

[Joe Bloggs]

4 minutes ago, Kasim Awan said:

This is a perfectly evolving textbook easterly. Not a brutal one like 2010 or 2018, from a meteorological perspective just as interesting.

The start > light ppn in clusters, like we're seeing over Lincolnshire right now.

After 12-24 hours > heavier showers like Scotland has right now

This is clear to see. On the radar last night Eastern Scotland looked exactly like Lincs does now. Now the instability has come to lift there, the shower composition has evolved from snizzle to heavier stuff.

I agree - I’ve enjoyed watching this evolve! 

[damianslaw]

Sara Blizzard on BBC news (great surname!), said first time she had heard of snow streamers in her 22 years of forecasting - where has she been for 22 years? Take it she means she has never had to use the word streamer in any forecast, but anyone with an interest in meteorology should have heard of the term you would think.

Looks like a streamer will develop to affect possibly SE parts of the region - looks more of a Humber to S Derbyshire affair.

Further north could see showers band together in lines through tomorrow. As ever a day of radar watching.

Today though has been very underwhelming, the flurries representing the never ending adverts you used to have to watch before the film started on the cinema screen!

Edited February 7, 2021 by damianslaw

[Joe Bloggs]

Just before going to bed I realise I now have some heavy snow symbols for tomorrow morning on the MetO app. Good to have it on side. Night all. 

[Frosty the Snowman]

7 minutes ago, damianslaw said:

Sara Blizzard on BBC news (great surname!), said first time she had heard of snow streamers in her 22 years of forecasting - where has she been for 22 years? Take it she means she has never had to use the word streamer in any forecast, but anyone with an interest in meteorology should have heard of the term you would think.

Looks like a streamer will develop to affect possibly SE parts of the region - looks more of a Humber to S Derbyshire affair.

Further north could see showers band together in lines through tomorrow. As ever a day of radar watching.

Today though has been very underwhelming, the flurries representing the never ending adverts you used to have to watch before the film started on the cinema screen!

She's a weather presenter rather than a meteorologist at least going by her wiki and Twitter (the ones who are both tend to be quite prissy about making the point they are both).

 

Pretty sure they used to just call them 'bands of showers' on telly.

[Backtrack]

The problem we have though. Yes it’s bitterly cold. But it only feels bitterly cold. 
 

Any snow will be melting as much of the region is around 1-3C. Regardless of that low DP, it’s gonna struggle. Concerning. 

[Kasim Awan]

21 minutes ago, raul_sbd said:

Can you represent that graphically on a map @Kasim Awan? Accumulation is quite clear but the streamer distribution/timing bit confusing or complicated lol

I am going to shy away from doing this. Only because streamers are so mobile that the map may just not verify. Key areas are south Derbyshire, South Yorkshire and Lincolnshire for the initial streamer, with showers further north giving 2-5cm east and 0.5 to 2cm west of the Pennines. Then, a northwards shift in the streamer on Monday evening towards Glossop, 5-10cm over and to the east and 2-5cm west of the Pennines is a best guess. These may be slight overestimations to the west of the Pennines.

 

[raul_sbd]

1 minute ago, Kasim Awan said:

I am going to shy away from doing this. Only because streamers are so mobile that the map may just not verify. Key areas are south Derbyshire, South Yorkshire and Lincolnshire for the initial streamer, with showers further north giving 2-5cm east and 0.5 to 2cm west of the Pennines. Then, a northwards shift in the streamer on Monday evening towards Glossop, 5-10cm over and to the east and 2-5cm west of the Pennines is a best guess. These may be slight overestimations to the west of the Pennines.

 

That’s not need of a map with such a clear explanation!! Whatever it brings tomorrow and the rest of the week still exciting times, weather science at its best!! Thanks pal

[raul_sbd]

6 minutes ago, Joe Bloggs said:

Just before going to bed I realise I now have some heavy snow symbols for tomorrow morning on the MetO app. Good to have it on side. Night all. 

I will drive up to withington as not showing in area - shows on a streamer how much differences can be 2 miles north or sth of a streamer! Good luck everyone

[itsnowjoke]

25 minutes ago, Joe Bloggs said:

Just saw Sara Blizzard’s ramp.

Snow streamers galore. A bit different to Jo Blythe the other night. 

Latter name

[Had Worse]

Night all, Snowy dreams.

[Spah1]

Going bed. Looked at every chart. Read what Kasim has written and I’m right, Easterlies are crap. 
 

(I’ll still be grabbing the phone at 6am to check the radar)

[Cheshire Freeze]

15 minutes ago, Spah1 said:

Going bed. Looked at every chart. Read what Kasim has written and I’m right, Easterlies are crap. 
 

(I’ll still be grabbing the phone at 6am to check the radar)

It’s the hope that kills ya

[Frost HoIIow]

Interesting developments north of the Humber. But can't see it getting here for a while so am going to call it a night. Good luck all

[Kasim Awan]

9 minutes ago, CreweCold said:

It’s the hope that kills ya

It's because Chorley has a very high hill run to the East. Winter hill directly ENE. This is not great from an orographic perspective. Still, if streamers align 1-3cm is just about possible. Whereas 2-8cm in streamers that far west in somewhere like Bolton.

[Frosty the Snowman]

Another complete let down then, really thought I'd have seen some real snow by now rather than dandruff. 

 

Up early tomorrow to see if outs falling overnight then, Easterlies are dung. 

[jam2010]

Dandruff falling, wind is pretty wild. We have been over light blue ppn for ages with nothing falling, must be a good sign when something is actually falling from the sky. 

[snowdrifter]

Never mind...!