Next week is looking potentially very wintry with very cold air
sweeping across the country on strong W-NW winds. By Thu/Fri both the
ECMWF and GFS models have 1000-500mb thicknesses below 520dam as far
south as the Midlands in what would very probably be a very showery
airstream. There's potential for substantial snowfall over western and
northern areas, especially over high ground. It's still a fair way off
but certainly one to keep an eye on if you are planning any travelling.
My wife, for one, is due to travel from Buckinghamshire to Tideswell on
Friday next week. It might not be too clever!

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
https://peakdistrictweather.org
Twitter: @TideswellWeathr

On 09/01/2018 11:42, Norman Lynagh wrote:
Next week is looking potentially very wintry with very cold air
sweeping across the country on strong W-NW winds. By Thu/Fri both the
ECMWF and GFS models have 1000-500mb thicknesses below 520dam as far
south as the Midlands in what would very probably be a very showery
airstream. There's potential for substantial snowfall over western and
northern areas, especially over high ground. It's still a fair way off
but certainly one to keep an eye on if you are planning any travelling.
My wife, for one, is due to travel from Buckinghamshire to Tideswell on
Friday next week. It might not be too clever!


I make storminess minimum values, as distinct from winteriness, for
this month around 21 Jan 2018 is 50, 25 Jan is 60 , 28 Jan is 56, so
peak around 25 Jan. Currently the 3 component value of 55
Around Storm Brian a value of 68 and Dylan a value of 62.

Based on this paper , Julian Orford
"Storminess and surges in the South
Western Approaches of the eastern North
Atlantic: The synoptic climatology ... "
Compairing the same 3 pairs of patches of the NOAA North Atlantic for
historic major storms their then current and previous month data, giving
a weighting to their relative importance and scaling to 100 as a nominal
peak value
SST Anomaly "predictor" for storm systems coming into UK airspace
3 digit numbers are the 2017 day-number (days from 00:00, 01 jan 2017),
this exploration starting at 12 October 2017, day-number starting again
in 2018
October
285, 43
289, 73
292, 66 : 292, (NHC) Hurricane Ophelia
296, 58 :294, Storm Brian
299, 68
303,58
November
306, 45
310, 49
313, 55 : 312, TS Rina
317, 47 : 314, putative NHC TD/TS 20, dissipated before UK
320, 36
324, 45
327, 48
331, 51
334, 58
December
338, 54: 341 , Storm Caroline affecting Scotlland
341, 58 : 344, no named storm but 90mph gusts in the English Channel
with a 971mB low
345, 42
348, 34
352, 59( no named storm, very localised force 9 westerlies for Ireland
on 14 Dec)
355, 38,
The prior month component suggesting a stormy January 2018, considering
that component is negative currently
359, 35
362,62, Storm Dylan 30-31 Dec 2017

2018

1, 43, ,Storm Eleanor 02-03 Jan 2018
4,44
Processing the previous month ,selected pair of areas, as if next month
for the principal component p/p value, so if the other components are
non negative, then the minimum 3 component combined pointer value out of
100 for the next month
Most recent of 08 Jan 2018
8,51, p/p 55

On 09/01/2018 14:35, N_Cook wrote:
I make storminess minimum values, as distinct from winteriness, for
this month around 21 Jan 2018 is 50, 25 Jan is 60 , 28 Jan is 56, so
peak around 25 Jan. Currently the 3 component value of 55
Around Storm Brian a value of 68 and Dylan a value of 62.

Storminess pointer up to 57, for the next week or so, from today's NOAA
SST anomoly output

On Tuesday, 9 January 2018 11:42:19 UTC, Norman Lynagh wrote:
Next week is looking potentially very wintry with very cold air
sweeping across the country on strong W-NW winds. By Thu/Fri both the
ECMWF and GFS models have 1000-500mb thicknesses below 520dam as far
south as the Midlands in what would very probably be a very showery
airstream. There's potential for substantial snowfall over western and
northern areas, especially over high ground. It's still a fair way off
but certainly one to keep an eye on if you are planning any travelling.
My wife, for one, is due to travel from Buckinghamshire to Tideswell on
Friday next week. It might not be too clever!

How rare is snow from cold NWlies? I suspect up north - especially on hills up north it's a good source of snowfall, but in the SE? Would be intrigued to understand coldness from NWlies and how this has changed in frequency over time. May have to dig out some climate data and have a look as I typically associate a cold NWly in SE with dry, chilly and if you're very lucky the remnants of a shower through the Cheshire Gap.

Richard

On Tuesday, January 9, 2018 at 3:09:32 PM UTC, Richard Dixon wrote:
On Tuesday, 9 January 2018 11:42:19 UTC, Norman Lynagh wrote:
Next week is looking potentially very wintry with very cold air
sweeping across the country on strong W-NW winds. By Thu/Fri both the
ECMWF and GFS models have 1000-500mb thicknesses below 520dam as far
south as the Midlands in what would very probably be a very showery
airstream. There's potential for substantial snowfall over western and
northern areas, especially over high ground. It's still a fair way off
but certainly one to keep an eye on if you are planning any travelling.
My wife, for one, is due to travel from Buckinghamshire to Tideswell on
Friday next week. It might not be too clever!

How rare is snow from cold NWlies? I suspect up north - especially on hills up north it's a good source of snowfall, but in the SE? Would be intrigued to understand coldness from NWlies and how this has changed in frequency over time. May have to dig out some climate data and have a look as I typically associate a cold NWly in SE with dry, chilly and if you're very lucky the remnants of a shower through the Cheshire Gap.

Richard

That got me checking my records for the tip of Cornwall. We do get a number of days when showers briefly turning to snow in a N-WNW wind. Typically the temperature is around 5C or so between the showers, but drops close to freezing during. Much of southern England, of course, misses these showers, but there's plenty of warm sea to the NW of Cornwall.

Anyway, on the tip of Cornwall, since 1991, total days when snow
Fell Settled Ground Covered @ 09:00
N 20 7 3
NE 15 8 6
NW 11 6 1
E 6 3 2
SE 5 4 2
SW 2 1 1
W 2 0 0

NE winds are aligned with the peninsula, and hence the most common direction for a snow cover to stick around. Northerly winds tend to give our heaviest snow (on a 'dangler'), but the temperature soon (normally) rises considerably as soon as it stops.

In the old days (back in the '60s when I was but a lad) snow seemed much more common on a SE wind as fronts forced themselves in against a block. In fact we got a few blizzards. The last time that happened was way back in 1987 http://www.turnstone-cottage.co.uk/1987Snow.pdf

Significant snow here on a SE wind is clearly now largely a thing of the past.

Graham
Penzance

In message ,
Graham Easterling writes
Anyway, on the tip of Cornwall, since 1991, total days when snow
Fell Settled Ground Covered @ 09:00
N 20 7 3
NE 15 8 6
NW 11 6 1
E 6 3 2
SE 5 4 2
SW 2 1 1
W 2 0 0

Can one assume that the missing row would read:

S 0 0 0
--
John Hall "George the Third
Ought never to have occurred.
One can only wonder
At so grotesque a blunder." E.C.Bentley (1875-1956)

On Tuesday, January 9, 2018 at 4:38:13 PM UTC, John Hall wrote:
In message ,
Graham Easterling writes
Anyway, on the tip of Cornwall, since 1991, total days when snow
Fell Settled Ground Covered @ 09:00
N 20 7 3
NE 15 8 6
NW 11 6 1
E 6 3 2
SE 5 4 2
SW 2 1 1
W 2 0 0

Can one assume that the missing row would read:

S 0 0 0
--
John Hall "George the Third
Ought never to have occurred.
One can only wonder
At so grotesque a blunder." E.C.Bentley (1875-1956)

Yes, that's correct.

I've just checked the 2 days snow fell on a SW wind. On both days the pressure was low (982 & 992mb respectively) and there was also hail.

This is the synoptic chart for the last occasion http://old.wetterzentrale.de/archive...ka20090203.gif

The wind was obviously SW at the time of the observation (though the air mass was returning polar maritime) just before the onset of a northerly & associated dangler.

Graham
Penzance

Richard Dixon wrote:

On Tuesday, 9 January 2018 11:42:19 UTC, Norman Lynagh wrote:
Next week is looking potentially very wintry with very cold air
sweeping across the country on strong W-NW winds. By Thu/Fri both
the ECMWF and GFS models have 1000-500mb thicknesses below 520dam
as far south as the Midlands in what would very probably be a very
showery airstream. There's potential for substantial snowfall over
western and northern areas, especially over high ground. It's still
a fair way off but certainly one to keep an eye on if you are
planning any travelling. My wife, for one, is due to travel from
Buckinghamshire to Tideswell on Friday next week. It might not be
too clever!

How rare is snow from cold NWlies? I suspect up north - especially on
hills up north it's a good source of snowfall, but in the SE? Would
be intrigued to understand coldness from NWlies and how this has
changed in frequency over time. May have to dig out some climate data
and have a look as I typically associate a cold NWly in SE with dry,
chilly and if you're very lucky the remnants of a shower through the
Cheshire Gap.

Richard

Cold NW'lies are a good source of snow for many parts of the country
but, as you say, the SE is an exception. In Tideswell, some of the
heaviest snowfalls I have seen in the 9 years that I have been here
have been in NW'lies. The airmass next week is forecast to be unusually
cold for a W-NW'ly. If it works out as forecast, and that's a very big
'if', there would almost certainly be a mass of showers streaming in
off the Atlantic on the strong wind and with the very low thickness
values these would be mostly of hail or snow. As I said, it's still a
long way off and well beyond the 5 days that I consider to be the
realistic limit for forecasting with any useful level of reliability.
Nevertheless, the models have been hinting at this development for a
few days. Interesting times ahead, perhaps.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
https://peakdistrictweather.org
Twitter: @TideswellWeathr

On 9 Jan 2018 15:51:22 GMT
"Norman Lynagh" wrote:

Richard Dixon wrote:

On Tuesday, 9 January 2018 11:42:19 UTC, Norman Lynagh wrote:
Next week is looking potentially very wintry with very cold air
sweeping across the country on strong W-NW winds. By Thu/Fri both
the ECMWF and GFS models have 1000-500mb thicknesses below 520dam
as far south as the Midlands in what would very probably be a very
showery airstream. There's potential for substantial snowfall over
western and northern areas, especially over high ground. It's still
a fair way off but certainly one to keep an eye on if you are
planning any travelling. My wife, for one, is due to travel from
Buckinghamshire to Tideswell on Friday next week. It might not be
too clever!

How rare is snow from cold NWlies? I suspect up north - especially on
hills up north it's a good source of snowfall, but in the SE? Would
be intrigued to understand coldness from NWlies and how this has
changed in frequency over time. May have to dig out some climate data
and have a look as I typically associate a cold NWly in SE with dry,
chilly and if you're very lucky the remnants of a shower through the
Cheshire Gap.

Richard

Cold NW'lies are a good source of snow for many parts of the country
but, as you say, the SE is an exception. In Tideswell, some of the
heaviest snowfalls I have seen in the 9 years that I have been here
have been in NW'lies. The airmass next week is forecast to be unusually
cold for a W-NW'ly. If it works out as forecast, and that's a very big
'if', there would almost certainly be a mass of showers streaming in
off the Atlantic on the strong wind and with the very low thickness
values these would be mostly of hail or snow. As I said, it's still a
long way off and well beyond the 5 days that I consider to be the
realistic limit for forecasting with any useful level of reliability.
Nevertheless, the models have been hinting at this development for a
few days. Interesting times ahead, perhaps.


NW is a good direction for Dartmoor. Been some very heavy snowfalls up here
over the years in cold Pm airmasses.

On Tuesday, January 9, 2018 at 5:15:56 PM UTC,
On 9 Jan 2018 15:51:22 GMT
"Norman Lynagh" wrote:

Richard Dixon wrote:

On Tuesday, 9 January 2018 11:42:19 UTC, Norman Lynagh wrote:
Next week is looking potentially very wintry with very cold air
sweeping across the country on strong W-NW winds. By Thu/Fri both
the ECMWF and GFS models have 1000-500mb thicknesses below 520dam
as far south as the Midlands in what would very probably be a very
showery airstream. There's potential for substantial snowfall over
western and northern areas, especially over high ground. It's still
a fair way off but certainly one to keep an eye on if you are
planning any travelling. My wife, for one, is due to travel from
Buckinghamshire to Tideswell on Friday next week. It might not be
too clever!

How rare is snow from cold NWlies? I suspect up north - especially on
hills up north it's a good source of snowfall, but in the SE? Would
be intrigued to understand coldness from NWlies and how this has
changed in frequency over time. May have to dig out some climate data
and have a look as I typically associate a cold NWly in SE with dry,
chilly and if you're very lucky the remnants of a shower through the
Cheshire Gap.

Richard

Cold NW'lies are a good source of snow for many parts of the country
but, as you say, the SE is an exception. In Tideswell, some of the
heaviest snowfalls I have seen in the 9 years that I have been here
have been in NW'lies. The airmass next week is forecast to be unusually
cold for a W-NW'ly. If it works out as forecast, and that's a very big
'if', there would almost certainly be a mass of showers streaming in
off the Atlantic on the strong wind and with the very low thickness
values these would be mostly of hail or snow. As I said, it's still a
long way off and well beyond the 5 days that I consider to be the
realistic limit for forecasting with any useful level of reliability.
Nevertheless, the models have been hinting at this development for a
few days. Interesting times ahead, perhaps.


NW is a good direction for Dartmoor. Been some very heavy snowfalls up here
over the years in cold Pm airmasses.
--------------------------------------------------------------------------------
The output looks a bit chilly compared with the 30yr average but not winter here in SW Devon at 83m asl.
I've just managed to get rid of that awful beast from the east which lasted a horrendous three days.
Hopefully it won't return.
NWesterlies sometime come with some nice deep convection.
Giving hail, graupel or sleet. I am often struggling to identify the difference between sleet and soft hail in my location. I appreciate sleet splatters, but sometimes I can see a soft centre in it. As if it has not made up its mind.

Does anyone else have soft centres?

http://www.wetterzentrale.de/show_di...12&lid=ENS&bw=

Len
Wembury, SW Devon coast
------------------------------------------------------------------------------