Watching The Channel Low

[Mondy]

Dropped 5mb in an hour:

http://meteocentre.com/analyse/map.php?hou...en&map=AtlN

[johnholmes]

please not the French buoy at 47.5N 08.5W is reporting correct pressure but NOT the rate of change.

It is wrong

pressure is 1008.0mb but it NOT falling at 15.4mb per 3 hours as it suggests!

[snowking]

Latest FAX out

Pretty much the same track as the GFS, however the feed of air is far more continental and from slightly further north than the GFS

http://www.meteociel.fr/ukmo/fax/fax36s.gif

It could be little details like that through the next 24 hours that makes the difference

SK

[johnholmes]

the 12z Fax position is exactly as predicted yesterday, depth and position

Edited February 8, 2009 by johnholmes

[Mondy]

Forecasters nightmare this one.

[Upgrade]

Forecasters nightmare this one.

Blizzards in City Centres according to the BBC.............

[Totoro]

I would just like to say that a few years ago a similar situation arose,a Channel Low was forecast dire warnings were given out ie dont travel,take a hot drink and a shovel if you do type of thing and the south of england awoke to dry pavements the low slid off at the last minute into France,all that i am asking is could it possibly happen again or is the setup now close enough to treat as near gospel,You see ,only the other daythere was a siuation where this part of the world was expecting rain as per the forecast and for a short while thats what we got then due to unforecast frontal movement we had snow for many hours.

Just out of interest,does anyone remember the non event date regarding my opening remarks?

I remember something very similar happening sometime in the early 80s. The difference that time was that it wasn't a borderline situation as we have now - the event that I remember was due to come over some VERY cold air which had been established over the UK for about a week after a big blizzard a week earlier. There was also plenty of very cold continental air which would have been dragged in, so maintaining heavy, lying snow for all of England and south Wales.

Going off at a tangent slightly, this time things are different - if the low takes the 'predicted' track (whichever one that may be - take your pick!) then the air over us isn't THAT cold and the continent isn't THAT cold either, hence the marginality of the situation. There's more to it than that of course (plus less cold air wrapped up in the channel low) but that'll do for now.

Blizzards in City Centres according to the BBC.............

Any particular city centres? As things are right now, they may as well draw straws.

[Albion Snowman]

It certainly looks marginal from many different directions. I think its a watch and wait thing now.

[Andy_Calafell_Sheffield]

Would this be one of the scenario's where snow could fall, even with 850's of only -3, due to the sheer intensity of the precipitation?

This event is looking very marginal, however I do feel that the BBC are being a little optimistic. It looks by the end of the precipitation that it may turn to snow but the ground may already be too wet for any signifcant accumulations.

It also could be a possiblity that any extra little bit of altitude could make all the difference. If I were to stick my head out, I would expect snow from about the wash northwards with at least 200-250m altitude?

Are those reasonable predicitions are even still a little too optimisitc for snow lovers?

Edited February 8, 2009 by Andy_Calafell_Sheffield

[snowking]

Im going to start doing this for a comparison, latest BBC forecast

Snowline generally north of the M4, will be interesting to see where it lies later on this evening from the BBC's perspective

SK

[Tim Bland]

Im going to start doing this for a comparison, latest BBC forecast

Snowline generally north of the M4, will be interesting to see where it lies later on this evening from the BBC's perspective

SK

Isn't the system going to pull away to the SE? This would mean rain turning to snow in East Anglia and the SE

[da_bish]

Does anyone have a serious idea of the timing for this event tomorrow? I have to attend a (for me) serious job interview, should be leaving London at around 1500hrs (3pm).

When is the likelihood of the ppn starting?

[snowking]

Isn't the system going to pull away to the SE? This would mean rain turning to snow in East Anglia and the SE

Whilst the system will eventually pull away eastwards, the pull of continental air is a bit more complex, and wraps itself around western areas first.....how quickly it spreads eastwards around the centre of the low is one of the many things thats baffling forecasters at present and will be crucial to the rain/snow boundary

However i would have thought there would be a spell of snow as it moves away eastwards for a number of areas, even if it doesnt turn to snow earlier on

SK

[Tim Bland]

Does anyone have a serious idea of the timing for this event tomorrow? I have to attend a (for me) serious job interview, should be leaving London at around 1500hrs (3pm).

When is the likelihood of the ppn starting?

IMO you will only see rain in London and Oxfordshire until early hours of Tues morning when it will turn to Snow. Only problems around London will be on Tues morning unless flodding becomes an issue

[Timmytour]

Whilst the system will eventually pull away eastwards, the pull of continental air is a bit more complex, and wraps itself around western areas first.....how quickly it spreads eastwards around the centre of the low is one of the many things thats baffling forecasters at present and will be crucial to the rain/snow boundary

However i would have thought there would be a spell of snow as it moves away eastwards for a number of areas, even if it doesnt turn to snow earlier on

SK

In addition, by the time it does eventually turn to snow for the SE, if at all, the heaviest of the precipitation will long be gone I suspect

[phil nw.]

so as the fronts moving north surely that dosnt diminish out snow event does it?? the area of snow the bbc showed from th m4 corridor surely gives us room to move north anyway???? im dont think it will all change to be honest, ones are so took in by every thread , i remain very confident myself, comments welcome

Hi Shawn,

I am less confident of a complete snow only event now.

I posted earlier before i saw the low positioned further North on the 12z runs,which would mean the Midlands in less cold uppers than before.

The best thing we can expect now is rain then some wet snow before it clears away tues. am.

Subject to a change of track of course.

[da_bish]

Many thanks for your answer. Confirmed my initial thoughts, but doubts set in!

Well used to floods here!

[Lynxus]

Im going to start doing this for a comparison, latest BBC forecast

Snowline generally north of the M4, will be interesting to see where it lies later on this evening from the BBC's perspective

SK

HAHA omg, only if!

Tbh if the wind was coming more from the NE like some are suggesting then this could happen, but im really not holding my breath, With such strange winds predicted from the low, I thin the warmer air would win?

[Stratos Ferric]

It certainly looks marginal from many different directions. I think its a watch and wait thing now.

Possibly the most sensible post on here. Something will happen, across quite a wide area.

Best guess currently is south of a line from about the Wash to the Mersey, with snow most likely north of the Thames - Severn, but as others have noted, there have been many times in recent years when late developing systems have missed their projected track by a fair margin, usually south rather than north I think in more recent years. As last week, +/- 100 miles, which is very little in the great scheme of things, might make all the difference on the ground.

[Snowyowl9]

How bad is it likely to be on Dartmoor? We have had about a foot of lying snow for 3 days now, although it has decreased a bit today, is the wind going to be the dominant feature or should we be expecting problems from the snow/rain?

As you`ve got a foot of snow that`ll start drifting before the ppn comes in unless it`s damp,although the wind might dry it out.

If it rains or sleet even wet snow there will be no blizzards.

I think Wales is going to get hit severly by this.

I think our snow now will have a frozen top as there was sleet/light drizzle falling so snow falling on a frozen snow surface will blow off better than anything and NE-ly gales,hope it`s relatively powdery,although november 1996 gave a blizzard with marginal uppers.

http://91.121.93.17/pics/Rtavn362.png

http://www.wetterzentrale.de/archive/ra/19...00119961120.gif

http://www.wetterzentrale.de/archive/ra/19...00219961120.gif

http://www2.wetter3.de/Animation_12_UTC/36_30.gif

[FENDER.]

Hi Shawn,

I am less confident of a complete snow only event now.

I posted earlier before i saw the low positioned further North on the 12z runs,which would mean the Midlands in less cold uppers than before.

The best thing we can expect now is rain then some wet snow before it clears away tues. am.

Subject to a change of track of course.

Depends what part of the midlands. The midlands is too big a region to lump it all together for an event like this. Remember the midlands runs from Oxford in the south way up to Stoke and beyond in the north, from the Welsh border in the West to Lincs in the east. North of Birmingham stills looks OK to me, Certainly, North Staffs/ Derbyshire. and anywhere with a bit height, must have a chance.

[J10]

Meteociel snow charts show snow over much of Wales with snow from around 9pm onwards, with some with heavy precipitation likely, evaporational cooling may come into play and with temps forecast to be around 1c above freezing this cold make a big difference come tomorrow.

However the Midlands and the higher hills in inland Wales could perhaps have snow for much of the time.

as SF says, 50-100 miles could make all the difference and that is still possible going by the events of the past week.

[Cal2]

ECMWF Icelandic version

18hrs mon

00hrs tues

[snowking]

Latest BBC update

SK

[Nick L]

Latest BBC update

SK

Thanks for that snowking. Exactly the same map just a different forecaster! Will be interesting to see how they change their tune. Keep them coming!