North West Regional Discussion 30 December 2020 onwards

[PennineMark]

Just for fun of course but couldn't help notice this snow accumulation map in the MAD thread. Look closely and isn't that a big fat zero over GM? Realise these things are not meant to be taken seriously at this range but there must be some reason the data put into the system produces a '0' in this location. 

[The Northern Ramper]

Foehn effect?

[Geordiesnow]

50 minutes ago, Snow free zone said:

I'd agree. Especially imby.  Now looking likely ppn will reach here, but with an e/se I'm struggling  to see significant  ppn amounts for here at least. 

 

The angle the front is coming in, I don't think there be any rain shadow affect in a honesty but at this stage, indications are Tuesday will be more wet than white sadly. 

Maybe still enough time for small changes which could make a difference but looking less and less likely. 

[WillinGlossop]

Xc weather update is having a laugh

[severe snowstorm]

13 minutes ago, PennineMark said:

Just for fun of course but couldn't help notice this snow accumulation map in the MAD thread. Look closely and isn't that a big fat zero over GM? Realise these things are not meant to be taken seriously at this range but there must be some reason the data put into the system produces a '0' in this location. 

Shadow effect due to SE flow?

[Day 10]

3 minutes ago, Geordiesnow said:

The angle the front is coming in, I don't think there be any rain shadow affect in a honesty but at this stage, indications are Tuesday will be more wet than white sadly. 

Maybe still enough time for small changes which could make a difference but looking less and less likely. 

[PennineMark]

6 minutes ago, Ramp said:

Foehn effect?

Possibly. Its the zero that gets me as its so definite. No even a mm or two at the very least to give some flexibility. Somebody doesn't like us

[alr1970]

45 minutes ago, PennineMark said:

Just for fun of course but couldn't help notice this snow accumulation map in the MAD thread. Look closely and isn't that a big fat zero over GM? Realise these things are not meant to be taken seriously at this range but there must be some reason the data put into the system produces a '0' in this location. 

It's a '6'. There are no zeroes anywhere else on the map. No snow gets no shading and no number at all.

[Joe Bloggs]

45 minutes ago, PennineMark said:

Just for fun of course but couldn't help notice this snow accumulation map in the MAD thread. Look closely and isn't that a big fat zero over GM? Realise these things are not meant to be taken seriously at this range but there must be some reason the data put into the system produces a '0' in this location. 

Some of the models pick up on a UHI for Greater Manchester which is sometimes over-exaggerated, I know that UKV does this at least. 

[Spah1]

How can it snow with positive uppers? 
 

I don’t understand

[russwirral]

Today we had a front coming in from the south west, but the wind was SE... so the precip was moving from south east to north west...

 

This could explain a rain shadow despite the front coming from rhe west

[Joe Bloggs]

10 minutes ago, Spah1 said:

How can it snow with positive uppers? 
 

I don’t understand

It can’t snow with positive uppers. Once the 0C isotherm passes over us then the precipitation will turn to ice pellets or rain. 
 

GFS has consistently shown it to sweep through the NW very early on Tuesday and the 12z is no exception , it’s at Morecambe Bay by 6am. 

Those of us saying Tuesday looks positive for snow are hoping that GFS will be wrong and everything will be corrected south - which is why posting links from xcweather and meteociel etc show little to no snow. Anything that uses data from GFS will show rain - the model has never really been on board for this. 
 

I think @Geordiesnow’s pessimism is fairly well placed - you just can’t ignore the GFS. If we are lucky though it will have this wrong. 

Edited January 30, 2021 by Joe Bloggs

[Spah1]

6 minutes ago, Joe Bloggs said:

It can’t snow with positive uppers. Once the 0C isotherm passes over us then the precipitation will turn to ice pellets or rain. 
 

GFS has consistently shown it to sweep through the NW very early on Tuesday and the 12z is no exception , it’s at Morecambe Bay by 6am. 

Those of us saying Tuesday looks positive for snow are hoping that GFS will be wrong and everything will be corrected south - which is why posting links from xcweather and meteociel etc show little to no snow. Anything that uses data from GFS will show rain - the model has never really been on board for this. 
 

I think @Geordiesnow’s pessimism is fairly well placed - you just can’t ignore the GFS. If we are lucky though it will have this wrong. 

Cheers

Just doesn’t look cold enough. 
 

really need a correction South by 50 miles

[Had Worse]

Glossop  upto Midday WRF 12z run

Edited January 30, 2021 by Had Worse

[Joe Bloggs]

As a very crude measure for Tuesday lunchtime the 0C 850 hPa isotherm shows the snow & ice pellet/rain boundary. 
ICON and ARPEGE are are by far the most favourable for snow. The others indicate a snow - to ice pellet/rain transition by lunchtime, especially in the south of the region. The latter scenario is probably favoured at this time, but could change.  Very very fine margins. 

ICON

GFS 

ECM

GEM 

ARPEGE

Edited January 30, 2021 by Joe Bloggs

[Joe Bloggs]

7 minutes ago, Spah1 said:

Cheers

Just doesn’t look cold enough. 
 

really need a correction South by 50 miles

Yes we definitely need southern corrections ! Not looking that likely in my view but we’ll see. 

[Day 10]

ECM is poor for tues.

[Spah1]

6 minutes ago, Had Worse said:

Glossop  upto Midday WRF 12z run

Wish I was in Glossop on Tuesday. 
 

I think it will snow in Chorley on Tuesday but turn slushy as the day goes on. 
 

Would love to live 300m up. 

[PennineMark]

23 minutes ago, alr1970 said:

It's a '6'. There are no zeroes anywhere else on the map. No snow gets no shading and no number at all.

That explains it, thanks. Looking at it again there are several zero looking sixes on that map . However, the point still stands that as is shown on this particular model, GM is an island of lower snow accumulation for all Foehn/snow shadow reasons. It is so difficult to get a perfect set up for snow locally.

[Spah1]

1 minute ago, Day 10 said:

ECM is poor for tues.

Why? 

[Alexis]

2 minutes ago, Spah1 said:

Why? 

[Had Worse]

3 minutes ago, Spah1 said:

Why? 

Day 10 is on the Wirral. its hard to get snow there.

[Day 10]

3 minutes ago, Spah1 said:

Why? 

Snow to rain a lot quicker, not on my laptop so don't have Fridays 12z for 6am tues. If you have it then compare with tonights.

[Geordiesnow]

8 minutes ago, Day 10 said:

Snow to rain a lot quicker, not on my laptop so don't have Fridays 12z for 6am tues. If you have it then compare with tonights.

Yep poor orientation of the low although at least the rain should clear on Tuesday so it might not be a washout but we ain't going to be making snowmen either!

[Had Worse]

Mr Del MOD 12z say no.