Watching The Channel Low

[Roger J Smith]

This is going about as expected, the warm advection phase of the storm is rapidly ending, if you already have snow it will probably continue to the end of the event and reach 15-30 cms in some parts of the inland southwest ... if you're in the zone north of London with rain and 1-2 C expect it to turn to heavy wet snow by about midnight and start to settle, amounts will vary with elevation and urban effect but could be 3-7 cms. Places like London, coastal East Anglia, Kent and Sussex, southern Hampshire, will likely stay in rain to near the end of the event although temps will fall off sharply from near 10 C to near 2 C, then it may be snowing by morning but probably not sticking much.

Further north it seems to be mix and match depending on elevation and how close you are to the somewhat warmer North Sea, but eventually I think all rain north of TEITS-land will turn to snow, the thicknesses everywhere are about to take a tumble, and the usual parameters can be tossed out the window because of the snow you had on the ground when the event started (in a general sense, not necessarily snow on the ground where you are). The rain-snow thickness divide normally used in the UK needs to be revised upwards to more like the values seen in Nova Scotia or New Brunswick, and that can be as high as 534 dam. Reason is, usually you are in the deep maritime layers that are artificially warmed in the lowest 500 metres, but now you're in a mixed maritime and continental layer thanks to your snow cover. This will continue until the snow all melts ... and then you have to factor in that the North Sea is probably colder than recent winters by a degree or two.

This is why cold winters are on such a knife edge in the British Isles, they tend to self-perpetuate once they get going, turning marginal situations back to snowfall and feeding back in the form of colder overnight lows in clear weather, etc. If this storm had come along in Feb 2008 I suspect it would be raining and 3 C in Brum rather than sleeting or snowing and 0.5 C. Makes a big difference having regional snow cover when a marginal event like this begins.

[mettalfabrik]

those winds coming west ,still snowing like the devil here

==================================================

ICAO : EGHQ

Station Name :Newquay

Location : N/A

Elevation : N/A

Time : 9 / 21:50Z

Temperature : 3.0°C / 37.4°F

Dew Point : 2.0°C / 35.6°F

RH : 93%

Wind : N (360 degrees) at 30 mi/h, 46 mi/h gusts

Visibility : > 10000m

Pressure : 982.1 mb

Sky Condition : Broken clouds at 900ft, Overcast at 1500ft

Weather : Rain

Wind Chill : -3.9°C / 25.0°F

==================================================

Edited February 9, 2009 by blackdown

[Bristawl Si]

This is going about as expected, the warm advection phase of the storm is rapidly ending, if you already have snow it will probably continue to the end of the event and reach 15-30 cms in some parts of the inland southwest ... if you're in the zone north of London with rain and 1-2 C expect it to turn to heavy wet snow by about midnight and start to settle, amounts will vary with elevation and urban effect but could be 3-7 cms. Places like London, coastal East Anglia, Kent and Sussex, southern Hampshire, will likely stay in rain to near the end of the event although temps will fall off sharply from near 10 C to near 2 C, then it may be snowing by morning but probably not sticking much.

Further north it seems to be mix and match depending on elevation and how close you are to the somewhat warmer North Sea, but eventually I think all rain north of TEITS-land will turn to snow, the thicknesses everywhere are about to take a tumble, and the usual parameters can be tossed out the window because of the snow you had on the ground when the event started (in a general sense, not necessarily snow on the ground where you are). The rain-snow thickness divide normally used in the UK needs to be revised upwards to more like the values seen in Nova Scotia or New Brunswick, and that can be as high as 534 dam. Reason is, usually you are in the deep maritime layers that are artificially warmed in the lowest 500 metres, but now you're in a mixed maritime and continental layer thanks to your snow cover. This will continue until the snow all melts ... and then you have to factor in that the North Sea is probably colder than recent winters by a degree or two.

This is why cold winters are on such a knife edge in the British Isles, they tend to self-perpetuate once they get going, turning marginal situations back to snowfall and feeding back in the form of colder overnight lows in clear weather, etc. If this storm had come along in Feb 2008 I suspect it would be raining and 3 C in Brum rather than sleeting or snowing and 0.5 C. Makes a big difference having regional snow cover when a marginal event like this begins.

Roger, your posts are absolutely superb IMO. Just right for us relative novices and not too technical. Thanks.

[patrickshere]

This is going about as expected, the warm advection phase of the storm is rapidly ending, if you already have snow it will probably continue to the end of the event and reach 15-30 cms in some parts of the inland southwest ... if you're in the zone north of London with rain and 1-2 C expect it to turn to heavy wet snow by about midnight and start to settle, amounts will vary with elevation and urban effect but could be 3-7 cms. Places like London, coastal East Anglia, Kent and Sussex, southern Hampshire, will likely stay in rain to near the end of the event although temps will fall off sharply from near 10 C to near 2 C, then it may be snowing by morning but probably not sticking much.

Further north it seems to be mix and match depending on elevation and how close you are to the somewhat warmer North Sea, but eventually I think all rain north of TEITS-land will turn to snow, the thicknesses everywhere are about to take a tumble, and the usual parameters can be tossed out the window because of the snow you had on the ground when the event started (in a general sense, not necessarily snow on the ground where you are). The rain-snow thickness divide normally used in the UK needs to be revised upwards to more like the values seen in Nova Scotia or New Brunswick, and that can be as high as 534 dam. Reason is, usually you are in the deep maritime layers that are artificially warmed in the lowest 500 metres, but now you're in a mixed maritime and continental layer thanks to your snow cover. This will continue until the snow all melts ... and then you have to factor in that the North Sea is probably colder than recent winters by a degree or two.

This is why cold winters are on such a knife edge in the British Isles, they tend to self-perpetuate once they get going, turning marginal situations back to snowfall and feeding back in the form of colder overnight lows in clear weather, etc. If this storm had come along in Feb 2008 I suspect it would be raining and 3 C in Brum rather than sleeting or snowing and 0.5 C. Makes a big difference having regional snow cover when a marginal event like this begins.

Something I've found amazing is that we still have 3-5cm of snow on the grass in the garden, even though it's been raining today. Killed most of the snow cover, but I'm amazed we still have any. Still hope for us here by the sounds of things then, which is good. Will be interesting to open the curtains in the am. Not going to stay up and watch I don't think!

[frozencanals]

Hi Folks

Just had a text from my wife in our house in the Charente, very windy at the moment, lost all power to our part of the village, going to be an interesting night in France...

Cheers

FC

[mettalfabrik]

Roger, your posts are absolutely superb IMO. Just right for us relative novices and not too technical. Thanks

totally concur with that bristle boy spot on

still major flooding incidents ongoing here ,albiet in a near blizzard

Edited February 9, 2009 by blackdown

[john w]

Cant agree more regarding warnings Nick....will be some localised flooding I think.

Exactly what will fall here is difficult to tell though i dont expect anything other than rain. Butt we may be marginal with some sleet and snow by the end.

[Fitzwis]

Check the following station and ship reports, paying particular attention to the third one down:

http://www.ndbc.noaa.gov/rss/ndbc_obs_sear...&lon=5.600W

Worrying for those of us in the Channel Islands and Northern France...

Edited February 9, 2009 by Fitzwis

[kaz]

hi im on call again tonight so might be called out .. can someone tell me if conditions here are going to get better.? or is this the calm before the storm.. sorry i know its a pain in de bum when people ask but i need to know in case i have to go out. No snow no winds just lt drizzel thanks for any help

kaz x

[chapmanslade]

Winds now reaching 133km/h on the French coats and 85km/h widely inland

[mettalfabrik]

Check the following station and ship reports, paying particular attention to the third one down:

http://www.ndbc.noaa.gov/rss/ndbc_obs_sear...&lon=5.600W

Worrying for those of us in the Channel Islands and Northern France...

[/quote

jeez 80 knots

latest metar Caen

==================================================

ICAO : LFRK

Station Name : Caen/Carpiquet(A

Location : 49-10N 000-27W

Elevation : 67m

Time : 9 / 22:00Z

Temperature : 11.0°C / 51.8°F

Dew Point : 7.0°C / 44.6°F

RH : 76%

Wind : SSW (210 degrees) at 33 mi/h, 54 mi/h gusts

Visibility :

Pressure : 981.0 mb

Sky Condition : Broken clouds at 3000ft, Broken clouds at 3700ft

Weather :

Wind Chill : N/A

==================================================

[acbrixton]

Fascinating to see the steep temperature gradients for the south east at 9pm:

Herstmonceaux [south Sussex]: 9.8c

Gatwick: 8.7c (up from 3.8c at 8pm)

Kenley [outer south London/surrey border]: 6.6c (up from 3.3c at 8pm)

London Weather Centre: 3.9c

Heathrow: 3.5c (falling slightly)

Northolt [north west London suburbs]: 3.0c

Stanstead: 2c

High Wycombe: 1.1c

Luton 0c

regards

ACB

[frozencanals]

Wow that is one hell of a difference over a relatively small area...

Cheers

FC

[Polar Continental]

Heavy snow currenty, the change over from rain began around an hour ago, if this continues then a few cm's by morning, currently 0.5c, dew point 0.2c.

Paul

[Roger J Smith]

Thanks in general (including PMs) ... Kaz, you are definitely going to see much stronger wind and sleet turning to snow in your area, the low centre is about to move far enough east in the Channel to bring your region into the strong NNE winds now starting to blow further to your west. It will come on fairly quickly, like old age (sadly) ...

Ship report 100 kms southwest of Brest is saying 80 knots from 120 (ESE), I suspect, in fact I know, that these reports are probably reversed in direction under the stress of trying to navigate whatever vessel that is through the hurricane force winds, so read it as WNW 80 knots (sustained) and draw your own conclusions for the Channel Islands in four hours time.

Otherwise the very strong winds appear to be WSW 60-90 mph across a large swath of France from around Nantes and Le Mans up to Paris, it won't get that bad in the Channel but probably will be pretty windy by 0300 around the Dover Straits, would suggest SW 40-70 mph for a brief time, don't think this will touch any part of Kent but you never know for sure, the low centre is shown crawling along the south coast from midnight to 0300 then east into Belgium.

It's fun to have some winter weather for a change, isn't it?

Just one other thing, this is more for novices than seasoned weather watchers, but this low will have quite an extensive calm centre like a sort of hurricane eye (but it's not as tightly wound as a hurricane), anything inside the 980 mb contour if you're watching meteociel.fr pressure unfold, should remain under 20 knots. This may extend onto land, so we don't want to keep reading from people along the south coast "I thought it was supposed to be very windy" because it will be, just wait for the centre to go past. Then it will suck in air from the north at a rapid rate to replace all that air that is going up into the atmosphere over Paris and over that way. But at some point in the next few hours, people in the IOW and Sussex coast will be seeing a sharp drop in windspeed, maybe almost calm for an hour or two, then it will haul around to NNW and back to NNE picking up to 35-60 mph. The low tide around 0700 could see the water pushed unusually far out from the south coast harbours as a result. But the Wash and some other parts of the east coast could have a very high tide around 0100-0200 tonight with the strengthening NE wind.

[Snowyowl9]

I imagine the snow has a high water content though, and combine this with strong winds - it could bring powerlines down!!

Tell me about it.

I was just saying on the other thread our bushes are getting weighed down already and theres only maybe an inch could be more actualy,sticking to trees like anything even in the wind,no wind just here.

Snow is heavier now and temps have dropped abit more 0.2c/0.3c still this will be heavy snow,not dry snow thats for sure.

Something I've found amazing is that we still have 3-5cm of snow on the grass in the garden, even though it's been raining today. Killed most of the snow cover, but I'm amazed we still have any.

Today is not your normal type of day,there was a light cold east wind so thawing is much slower,that happened in early february 1986 but it thawed less than today,but there was 3 inches more.

Edited February 9, 2009 by Snowyowl9

[frozencanals]

Roger

I can confirm the strong winds are further south than Nantes, power is out South of La Rochelle and even in my own village near Cognac

It is going to be a stormy night in NW France, stange how the French Meteo did not issue any warnings until later this morning.

Cheers

FC

[chapmanslade]

Roger

I can confirm the strong winds are further south than Nantes, power is out South of La Rochelle and even in my own village near Cognac

It is going to be a stormy night in NW France, stange how the French Meteo did not issue any warnings until later this morning.

Cheers

FC

142km/h on the coast now to the N of La Rochelle which is 76 knots

[kaz]

Thanks in general (including PMs) ... Kaz, you are definitely going to see much stronger wind and sleet turning to snow in your area, the low centre is about to move far enough east in the Channel to bring your region into the strong NNE winds now starting to blow further to your west. It will come on fairly quickly, like old age (sadly) ...

Ship report 100 kms southwest of Brest is saying 80 knots from 120 (ESE), I suspect, in fact I know, that these reports are probably reversed in direction under the stress of trying to navigate whatever vessel that is through the hurricane force winds, so read it as WNW 80 knots (sustained) and draw your own conclusions for the Channel Islands in four hours time.

Otherwise the very strong winds appear to be WSW 60-90 mph across a large swath of France from around Nantes and Le Mans up to Paris, it won't get that bad in the Channel but probably will be pretty windy by 0300 around the Dover Straits, would suggest SW 40-70 mph for a brief time, don't think this will touch any part of Kent but you never know for sure, the low centre is shown crawling along the south coast from midnight to 0300 then east into Belgium.

It's fun to have some winter weather for a change, isn't it?

Just one other thing, this is more for novices than seasoned weather watchers, but this low will have quite an extensive calm centre like a sort of hurricane eye (but it's not as tightly wound as a hurricane), anything inside the 980 mb contour if you're watching meteociel.fr pressure unfold, should remain under 20 knots. This may extend onto land, so we don't want to keep reading from people along the south coast "I thought it was supposed to be very windy" because it will be, just wait for the centre to go past. Then it will suck in air from the north at a rapid rate to replace all that air that is going up into the atmosphere over Paris and over that way. But at some point in the next few hours, people in the IOW and Sussex coast will be seeing a sharp drop in windspeed, maybe almost calm for an hour or two, then it will haul around to NNW and back to NNE picking up to 35-60 mph. The low tide around 0700 could see the water pushed unusually far out from the south coast harbours as a result. But the Wash and some other parts of the east coast could have a very high tide around 0100-0200 tonight with the strengthening NE wind.

Wow thanks roger you should be a teacher think i have learn more form you in the last few days than all the yrs on here have to say snow is defo not my thing as we never norm get any so never get the practice :lol: ..

I agree with the hurricane type eye because that is exactly how it feels.. It does also feel like something is going to go boom here very soon it has been scarcely quiet here so far.. Now i know where the low is .. Still cant believe i lost it feel such a twit, how can someone loose a massive low system .. Me thats who.

thanks again hun take care

Kaz x

[Nights King]

Could you explain the current situation regarding where ppn is going ect and how long it may last because i thought we were expecting heavy to blizzard like falls but all i see in somerset so far is light to sometimes moderate snow and a blustery wind.

[chapmanslade]

Could you explain the current situation regarding where ppn is going ect and how long it may last because i thought we were expecting heavy to blizzard like falls but all i see in somerset so far is light to sometimes moderate snow and a blustery wind.

Roger's post 401 tells you all you need to know above

[mettalfabrik]

its doing its thing down this end of somerset,i can tell you

[Fitzwis]

Positively barmy outside at the mo...temperature currently reading 8.4C with a 17kt southerly wind...eerie... gonna see if I can last the other side of midnight...

[frozencanals]

That really is eerie Fitzwis, judging by what is going on all around you

The wife says the winds are still getting stronger where she is near Cognac in France...

Cheers

FC

[Fitzwis]

That really is eerie Fitzwis, judging by what is going on all around you

The wife says the winds are still getting stronger where she is near Cognac in France...

Cheers

FC

Just trying to find Cognac on the google map ...the fact that we have had a deluge of rain here all day today will make it so much easier for the expected storm to topple trees...just glad most peeps will be tucked up in bed at the time it is expected to hit...