North West Regional Discussion 3 June 2020 onwards

[The Northern Ramper]

Fingers crossed we are posting a lot in here in 7-14 days time.

[I Cumbria Marra I]

16 hours ago, Weather-history said:

Who remembers 10 years ago tonight? The snow arrives that Friday evening and it snowed into the earlier hours. A memorable evening.

 

 

I remember being very dissapointed that night, very localised falls up here, only 1cm here but about 5cm only 8 miles north at sea level, the showers were no where near as intense and prolonged as in the south of the region.

[damianslaw]

2 hours ago, I Cumbria Marra I said:

I remember being very dissapointed that night, very localised falls up here, only 1cm here but about 5cm only 8 miles north at sea level, the showers were no where near as intense and prolonged as in the south of the region.

As mentioned, I was not here that evening, but at near freezing by 5pm certainly was cold enough for snow. My memories may be wrong but thought there was a NEflow then, hence snow showers in NE Eng, yet the bbc forecast suggests some sort of trough feature moved in from the west. I know there was heavy snow on the 20th here, but not sure much snow fell between the 17th-19th here. Will have to check the synoptical charts again.

[A Face like Thunder]

Yellow weather warning now in force for rain in the NW region, valid until tomorrow morning. Wet here in the south of the region today, but not unduly so. Problem seems to be accumulation of water which has made it extremely boggy underfoot, with much standing water in evidence. 

[cheshire snow]

Well the Met office update has changed for the better starting to come on board.I am now starting to believe we could be in for something special need to get those charts down to 96hr mark though then we may be able to talk

C.S

[Joe Snow]

I’m hopeful for cold prospects post Xmas and I think we definitely stand a good chance of a cold spell during January but those in the model thread seem to be chasing the pot of gold at the end of the rainbow at the moment. Fingers crossed but caution required. 

[A Face like Thunder]

What a gorgeous day and mild as well, a big change after some of the Saturday dross we've had recently.

[dodge]

I'd be happy to wake up to a frosty start on Christmas Day and temps not getting much about 4/5 during the day with plenty of dry sunny spells.  That will do me after the mild, wet and dreary weather we've had of previous years.  Hopefully something more wintery as we go into January.

Edited December 19, 2020 by dodge

[I Cumbria Marra I]

On 18/12/2020 at 13:42, damianslaw said:

As mentioned, I was not here that evening, but at near freezing by 5pm certainly was cold enough for snow. My memories may be wrong but thought there was a NEflow then, hence snow showers in NE Eng, yet the bbc forecast suggests some sort of trough feature moved in from the west. I know there was heavy snow on the 20th here, but not sure much snow fell between the 17th-19th here. Will have to check the synoptical charts again.

Yeh im sure the wind turned to a light WNW and the irish sea just came alive especially further south, can remember someone from St helens reporting thundersnow and very big accumulations, it was hectic in the NW regional thread that night

[Iceaxecrampon]

Holker - Newby Bridge - Bracing on the Morecambe Bay Coastline.

[itsnowjoke]

Trying to get in the mood but Boris has just ruined my day

[Rain Lady]

A bright morning, but weather turned and we had a flthy wet dark afternoon.  Matches the UK's miserable mood.

Our second wettest year by 9am this morning.   Been lots of rain since then. More details tomorrow.

[damianslaw]

A better day than anticipated, there was a heavy shower mid afternoon, but otherwise just a few shortlived showers and some welcome sunny breaks at times. Became cooler in the afternoon after a very mild start.

Outlook thankfully looks much more promising, hopefully plenty of sunny spells and blue skies to cast aside the gloom, and a welcome return to frost, which we have not had much of at all this season so far. 

Still too early to call but Christmas Eve could be a lovely crisp winter's day, long time since we had a such a Christmas Eve, 2010 last one, but nowhere near as cold as then. I'd be happy to wake up to a frost, and have it lingering in sheltered spots all day with a max of say 4 degrees. Not to much to ask for is it?

[Joe Bloggs]

Morning all

Just had a look at the 06z GFS and it’s the most promising synoptic setup for snow in NW England since Dec 2009/2010 I suspect. 
 

For Manchester in particular, a slack, WNW’ly flow with a solid Greenland block is one of our best setups for snow streamers - we can say that from experience.

The biggest risk at the moment is that despite the stunning synoptics - the air is simply not cold enough. This would be a huge upset, especially as the charts have a real Dec 2009 look about them at the moment which provided convective lying snow in Manchester City centre. 

I know uppers aren’t everything but here at 40m ASL in South Manchester I’d prefer 850s closer to -10C than -5C. The flow looks too warm currently. 
 

Interesting times ahead. If you’re at elevation I’d maybe start getting excited. 

[iand61]

1 minute ago, Joe Bloggs said:

Morning all

Just had a look at the 06z GFS and it’s the most promising synoptic setup for snow in NW England since Dec 2009/2010 I suspect. 
 

For Manchester in particular, a slack, WNW’ly flow with a solid Greenland block is one of our best setups for snow streamers - we can say that from experience.

The biggest risk at the moment is that despite the stunning synoptics - the air is simply not cold enough. This would be a huge upset, especially as the charts have a real Dec 2009 look about them at the moment which provided convective lying snow in Manchester City centre. 

I know uppers aren’t everything but here at 40m ASL in South Manchester I’d prefer 850s closer to -10C than -5C. The flow looks too warm currently. 
 

Interesting times ahead. If you’re at elevation I’d maybe start getting excited. 

I am probably high enough but it looks a bit marginal even for here.

On the tops of the Pennines, possibly a different story

[Joe Bloggs]

8 minutes ago, iand61 said:

I am probably high enough but it looks a bit marginal even for here.

On the tops of the Pennines, possibly a different story

Yes for convective snow off a warm Irish Sea we need to see the uppers a bit lower than currently forecast. 
 

If you look at the archive charts from December 2009 we had an initial push of genuine Arctic air, approaching -10C at 850 hPa which really helped things along.

It would be a huge blow if all we get is rain from such a brilliant setup. 
 

Either way it’s looking interesting and there are plenty of times for upgrades and downgrades to the fine details. 

[Joe Bloggs]

FWIW, all these setups gave convective, Irish Sea lying snow to lowland South Manchester

https://www.wetterzentrale.de/maps/archive/2015/cfsr/CFSR_1_2015012906_1.png

https://www.wetterzentrale.de/maps/archive/2015/cfsr/CFSR_1_2015012906_2.png

https://www.wetterzentrale.de/maps/archive/2019/cfsr/CFSR_1_2019013006_1.png

https://www.wetterzentrale.de/maps/archive/2019/cfsr/CFSR_1_2019013006_2.png

https://www.wetterzentrale.de/maps/archive/2004/cfsr/CFSR_1_2004122518_1.png

https://www.wetterzentrale.de/maps/archive/2004/cfsr/CFSR_1_2004122518_2.png

Purely for comparison purposes! 
 

We need uppers -7C or lower IMO. 
 

 

 

[Joe Bloggs]

Of course us Mancunians all remember the “big once in a lifetime” snow event of Jan 2010. 
 

https://www.wetterzentrale.de/maps/archive/2010/cfsr/CFSR_1_2010010500_1.png

https://www.wetterzentrale.de/maps/archive/2010/cfsr/CFSR_1_2010010500_2.png

Surprisingly modest uppers but of course we had deeply entrenched surface cold back then.

Basically with the upcoming spell I’d feel much better if 850s were around -7C or -8C. With a strong Greenland ridge and a slack westerly that gives much more of the region a chance at the white stuff, otherwise it’s a hills only affair. 

 

[HafrenLMP1]

1 hour ago, iand61 said:

I am probably high enough but it looks a bit marginal even for here.

On the tops of the Pennines, possibly a different story

 

Whenever I see the 'm' word, I immediately resign myself to disappointment.......

[Rush2019]

Disappointment is when a bit of frost becomes marginal. 

[damianslaw]

As ever with snow prospects when it comes to the UK it's always a tricky proposition speculating where snow may fall and lie. Lots of factors come to play:

-Thicknesses (generally sub 528 dam air is required but not always)

-Dewpoints - most critical factor 0 or below is required

-Uppers - less critical, it can snow with uppers as high as -1, -2 degrees, provided surface temperatures are low

-intensity of precipitation, the heavier it is the more evaporative cooling takes place, reason for rain to snow and events 

-Lapse rates, drier continental air generally more conducive for snow than maritime air

-Windflow and strength, slack airstreams are better, less mixing of cold and warm layers

-frontal and trough features, showery airstreams less conducive for snowfall, than frontal and trough situations

-time of day, nightime more optimal time for snow and early morning less solar heating

-proximity to sea, coastal locations influenced by sea temps, further inland less so greater chance of snow

-altitude, this is where evaporative cooling comes into play, there are 4 heights/boundaries that tend to demarcate conditions, 100m, 200m, 400m, 600m. These tend to be the boundaries at least here where the snowline often is. The higher you are the greater chance of snow.

Too many variables, and always a nowcasting situation. 

NW airflows are notoriously individual, I've known rain showers from NW airstreams and impressive uppers, as low as -8 degrees, likewise we've had heavy snowfalls from NW airflows with uppers as high as -1 or -2 degrees.

Whatever, if current synoptics verify, I'm expecting the lakeland fells at least to have a good white mantle on them in the run up to the New Year.

[dodge]

2 hours ago, Joe Bloggs said:

Yes for convective snow off a warm Irish Sea we need to see the uppers a bit lower than currently forecast. 
 

If you look at the archive charts from December 2009 we had an initial push of genuine Arctic air, approaching -10C at 850 hPa which really helped things along.

It would be a huge blow if all we get is rain from such a brilliant setup. 
 

Either way it’s looking interesting and there are plenty of times for upgrades and downgrades to the fine details. 

Aye just looking back through my Gallery there was a fluffy footfall white dumping of snow between 20-22nd Dec 2009...and more of the same Dec into Jan 2010.  We were sure spoilt during those years.  Get the uppers right and NNW is the best for precipitation here.  Easterly bone-chilling cold but tends to be a bit dryer this side of the Pens.

 

 

 

[Had Worse]

I'm afraid I have to report sleet in the rain thats currently falling. 

[damianslaw]

Here in central, south lakeland, our best snowfalls come from frontal systems moving into cold surface air, a light SE flow ahead and we tend to receive more snow than any other parts of the regions.

NW airflows can be hit and miss, as we are sheltered from Galloway land mass, southern parts do better. NW airflows wrapped around low heights to our east and bending to a WSW or SW are very good as well though, think Dec 2009 when we had thundersnow and showers coming in from the SW off Morecambe Bay our own snow making machine.

Frontal features from the east can deliver surprisingly but these are rare, such as  Jan 1996, fronts from the north tend to fizzle out by the time they reach here.

Frontal features from the south also very good when cold air clings on, these are also rare, and often herald arrival of milder air, they usually stall to our south and south west and not make it here, instead we are left frigid cold still..

We have an added advantage the tall heights of the central fells, which help to lower temperatures and aid evaporative cooling, many a time places in west Cumbria have rain or sleet and once you hit the central lakes divide, it is all snow to the east, we just sneak into the snowy side of the boundary, helped by a bit of height and proximity to the fells, go just a few miles south again and its rain close to Morecambe Bay. We have a unique geography probably the most complex part of England to predict the weather.

Edited December 20, 2020 by damianslaw

[Joe Bloggs]

^^^^^

You are right that all NW flows are individual and these things are unpredictable. However we do see a few patterns repeating time and time again...

- a very strong NW’ly wind = increased chance of hail/graupel showers with limited streamer potential. 

- NNW’ly flow, Merseyside/Wirral best placed

NW’ly - South Cheshire/Crewe, genuine Cheshire gap effect 

WNW’ly - South Manchester/Stockport/Peak District 

W’ly - Larger areas of the NW

Then on the rarer occasions when we get a very cold WSW’ly more northern parts of the region are primed for showers. 
 

Of course we need some decent cold air in place too - the parameters for snow are very complex and as you say aren’t limited to 850’s.

Interesting times.