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12z Model discussion - rain, sleet or snow?


Paul

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Nick F did you move to tunbridge wells recently - i never noticed you lived there before. During holidays i live 10 mins away.

Back to the weather, Ive just taken a look at the AO forecast for the first time in a while, and i can say im overwhelmed. Its a fairly good indicator of whether we have any chance of prolonged blocking and wintry condiditons here in the longer term, and right now its looking like theres quite a bit of disagreement, but most of the ensemble members are actually going to take it positive. Four or five, including two outliers which have it plunging negative, show it staying negative with the beginning of negative plunge at the extent of the forecast. The rest of the 11 ensembles members though have it rising steadily towards a positive state by mid month, including one horrible, but unlikely outlier, which rockets positive. Here it is:

http://www.cpc.noaa.gov/products/precip/CW...ex/ao.sprd2.gif

Overwhelmed? Underwhelmed surely? Positive AO tends to promote warm and wet conditions in our neck of the woods... interestingly the NAO is trending negative in the long term, which is a good thingh.

Not that I ascribe much accuracy to the long term NAO/AO forecasts :D

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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
Nick F did you move to tunbridge wells recently - i never noticed you lived there before. During holidays i live 10 mins away.

Back to the weather, Ive just taken a look at the AO forecast for the first time in a while, and i can say im overwhelmed. Its a fairly good indicator of whether we have any chance of prolonged blocking and wintry condiditons here in the longer term, and right now its looking like theres quite a bit of disagreement, but most of the ensemble members are actually going to take it positive. Four or five, including two outliers which have it plunging negative, show it staying negative with the beginning of negative plunge at the extent of the forecast. The rest of the 11 ensembles members though have it rising steadily towards a positive state by mid month, including one horrible, but unlikely outlier, which rockets positive. Here it is:

http://www.cpc.noaa.gov/products/precip/CW...ex/ao.sprd2.gif

Personally, i would back the members which take the AO more negative, you can see that from November to January, the AO pulsed more and more positive, and is now pulsing more and more negative, i would expect this to carry on with a very low pulse around mid month and the most negative pulse around the beggining of March.

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Posted
  • Location: Bristol, England
  • Location: Bristol, England

Brief summary of the 12Z GFS:

Significant snow Wedesday night into Thursday.

Mainly dry on Friday, after a bitterly cold night especially where any snow fell.

More significant snow likely Friday night into Saturday which is a major new development.

Sunday - ????

A stunning run from the 12Z!

Edited by Thundersquall
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Posted
  • Location: Castle Howard, North Yorkshire
  • Location: Castle Howard, North Yorkshire
Posted
  • Location: Co Dublin, Ireland
  • Location: Co Dublin, Ireland
Updated t+36 and t+48 faxes, marginal South of the occlusion for snow by 12z Thurs, though as I said earlier it's hard to say how much mixing of milder air and higher dps there'll be South of M4, Midlands, Wales looking good though:

post-1052-1170784473_thumb.png post-1052-1170784482_thumb.png

Really good or bad charts depending on your location. South Coast certainly not looking good for snow but really anywhere north of the M4 still at risk. Great for Ireland and Northern England though with the 528 DAM line firmly imbedded and the UKMO temp chart would suggest Wales in a great posistion there. Our own met office has just said moderate acumulations for us.

Edited by Darkman
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Posted
  • Location: Bristol, England
  • Location: Bristol, England
Really good or bad charts depending on your location. South Coast certainly not looking good for snow but really anywhere north of the M4 still at risk. Great for Ireland and Northern England though with the 528 DAM line firmly imbedded and the UKMO temp chart would suggest Wales in a great posistion there. Our own met office has just said moderate acumulations for us.

I'm only at most 2.5 miles south of the M4, so it's very much in the balance for me here in Bristol.

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Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire

The +48,+60,+72 are now out.

http://cirrus.netweather.tv/fax/PPVI89.png

http://cirrus.netweather.tv/fax/PPVJ89.png

http://cirrus.netweather.tv/fax/PPVK89.png

Not much to add following my snow map. What I will say is note how the occluded front becomes almost stationary, also note how on the +72 how the 528 dam moves S and IMO if there is any precip left on this front those areas S of the front that have seen snow turn to rain could well see this turn back to snow as a colder NE,lys moves in as the LP centre tracks E. By this stage though I don't expect much precip left on the front expect this to be more an area of cloud. Somone though could see large snowfall totals from this front and the favoured areas continue to be those that are on my map.

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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
The +48,+60,+72 are now out.

http://cirrus.netweather.tv/fax/PPVI89.png

http://cirrus.netweather.tv/fax/PPVJ89.png

http://cirrus.netweather.tv/fax/PPVK89.png

Not much to add following my snow map. What I will say is note how the occluded front becomes almost stationary, also note how on the +72 how the 528 dam moves S and IMO if there is any precip left on this front those areas S of the front that have seen snow turn to rain could well see this turn back to snow as a colder NE,lys moves in as the LP centre tracks E. By this stage though I don't expect much precip left on the front expect this to be more an area of cloud. Somone though could see large snowfall totals from this front and the favoured areas continue to be those that are on my map.

Some of the best charts that i have ever seen, based on those, i think that it is fair to say that west Yorkshire is back in the firing line!

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Posted
  • Location: Herefordshire
  • Location: Herefordshire
The +48,+60,+72 are now out.

http://cirrus.netweather.tv/fax/PPVI89.png

http://cirrus.netweather.tv/fax/PPVJ89.png

http://cirrus.netweather.tv/fax/PPVK89.png

Not much to add following my snow map. What I will say is note how the occluded front becomes almost stationary, also note how on the +72 how the 528 dam moves S and IMO if there is any precip left on this front those areas S of the front that have seen snow turn to rain could well see this turn back to snow as a colder NE,lys moves in as the LP centre tracks E. By this stage though I don't expect much precip left on the front expect this to be more an area of cloud. Somone though could see large snowfall totals from this front and the favoured areas continue to be those that are on my map.

Sorry TEITS, must have missed your map! Any chance of a re-post or possibly informing the more forgetful members where it was earlier posted?!? Being in Herefordshire, i am quietly confident of getting something from this......... FINGERS CROSSED for us ALL!!!

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Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire
I'm only at most 2.5 miles south of the M4, so it's very much in the balance for me here in Bristol.

Trouble is though saying the M4 is only a general guide because Bracknell is S of the M4 but because it is further E I would say they have a greater chance than yourself.

I hope im wrong but for your region because it is so marginal you would be better off looking at your temps/dewpoints before the precip arrives for a much better guide than the models could ever give you.

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Posted
  • Location: Liphook
  • Location: Liphook

Yep pretty much confirms what is expected Eye, though worth noting most of the precip appears to be on the southern side of that front, i think the northern edge will fizzle out as it gets deeper and deeper into the colder air.

Also you are right about the cold air starting to tuck in again behind the front, anywhere that is just on that frontal system will get a lot of snow, I really do think the higher extremes that have been mentioned would be quite likely, higher ground on the frontal line would quite possibly get 15-20cms from those fax charts and i think this will likely be the most noteable set-up since Jan 2004 on a countrywide scale anyway, which afterall did have a lot of snow over a large part of the country an dprobably the last country-wide set-up, though for the wes tit was ruined a little it has to be said.

Edited by kold weather
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Posted
  • Location: Canada
  • Location: Canada
Really good or bad charts depending on your location. South Coast certainly not looking good for snow but really anywhere north of the M4 still at risk. Great for Ireland and Northern England though with the 528 DAM line firmly imbedded and the UKMO temp chart would suggest Wales in a great posistion there. Our own met office has just said moderate acumulations for us.

Magical stuff darkman, This doesnt seem real.

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Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire
Sorry TEITS, must have missed your map! Any chance of a re-post or possibly informing the more forgetful members where it was earlier posted?!? Being in Herefordshire, i am quietly confident of getting something from this......... FINGERS CROSSED for us ALL!!!

Here we go.

Sorry about the arrows though my hands always shake all the time due to medication and I struggle to draw straight lines.

post-1766-1170785586_thumb.jpg

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Posted
  • Location: The Fens. 25 asl
  • Location: The Fens. 25 asl
Here we go.

Sorry about the arrows though my hands always shake all the time due to medication and I struggle to draw straight lines.

post-1766-1170785586_thumb.jpg

From your pic it looks good for our area, I am still a little unconvinced we will see a great deal in laying snow though?

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Posted
  • Location: Brighton (currently)
  • Location: Brighton (currently)
The +48,+60,+72 are now out.

http://cirrus.netweather.tv/fax/PPVI89.png

http://cirrus.netweather.tv/fax/PPVJ89.png

http://cirrus.netweather.tv/fax/PPVK89.png

Not much to add following my snow map. What I will say is note how the occluded front becomes almost stationary, also note how on the +72 how the 528 dam moves S and IMO if there is any precip left on this front those areas S of the front that have seen snow turn to rain could well see this turn back to snow as a colder NE,lys moves in as the LP centre tracks E. By this stage though I don't expect much precip left on the front expect this to be more an area of cloud. Somone though could see large snowfall totals from this front and the favoured areas continue to be those that are on my map.

It is brilliant news that as the low moves east is likely to track the cold air back in. As we know, not so long ago it was expected to turn milder.

Nevertheless, the UKMO doesn't look as promising for the weekend unlike the gfs which brings more snow.

Karyo

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Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire

I still think the fax charts are to far NORTH-

S

You know it's funny you say this Steve because I have this nagging doubt that even though my region is supposed to be in the ideal zone I can['t help but fear the area of snow won't even reach me and shall be further S. My instincts are telling me around 60miles further S.

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Posted
  • Location: Kettering, Northamptonshire
  • Location: Kettering, Northamptonshire
Kold, would you include NW England in that. Still worried about marginal temps here, though BBC does give heavy snow warning for Blackpool. Best chance for a long time though.

Yes well it would be a very long time here. 1987 since we had real desent snow here

I think the models will begin to show more and more like a event which many that are under the age of 30 will not remember. As they say "wait a long time for a bus and 2 or 3 come along at once"

Peter

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You know it's funny you say this Steve because I have this nagging doubt that even though my region is supposed to be in the ideal zone I can['t help but fear the area of snow won't even reach me and shall be further S. My instincts are telling me around 60miles further S.

In My mind I have ALways had Oxford as the Sweet spot-

remember the forecasts in 96- had the front to London..... never made it...

s

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Posted
  • Location: Hull - North Humberside (or east yorks)
  • Location: Hull - North Humberside (or east yorks)

Looks good for me tonight in east riding of yorkshire.

This Evening and Tonight:

Wintry showers will continue to feed off the North Sea giving a covering of snow in many parts by morning, as much as 5cm to 10cm possible over the North York Moors. Widespread locally sharp frost away from immediate coast.

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .
You know it's funny you say this Steve because I have this nagging doubt that even though my region is supposed to be in the ideal zone I can['t help but fear the area of snow won't even reach me and shall be further S. My instincts are telling me around 60miles further S.

At this timeframe and given the volatile nature of the models theres bound to be some movement in the track of the low. Its really a lottery at present and anything could happen. I'm sure the bbc will still stress the uncertainty and may not call this until tomorrow. What a thriller! :doh:

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I know it's not completely model related - but I'm getting a flight from Heathrow at 1pm, should it be okay in getting there (from Aylesbury) and for planes taking off etc? I've been looking forward to this holiday for ages - looks like I'm going to miss the big snow event I've always wanted whilst away :(

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Posted
  • Location: Powys Mid Wales borders.
  • Location: Powys Mid Wales borders.
Your 200m asl is pretty handy though

Going to last March 12th it was a totally different set-up but we had 4 inches of snow as the winds started SE then turned to the S/SE and they were strong too and was absolutely bitterly cold on this day as the temp was 1.3c then it turned to freezing drizzle despite the temp above freezing drifting snow before the light drizzle come which happened in the 80s too sometimes.

This day was still bitter at 2.1c max with some hail rain/snow mix and still drifting at times in strong S/SE winds.

http://www.wetterzentrale.de/archive/2006/...00120060312.png

http://www.wetterzentrale.de/archive/2006/...00220060312.png

Then something I`ve only seen once before was it turned to freezing rain and it was heavy I was out in it later and my coat was freezing and the temp was getting lower the trees were creaking as you could here the ice on them as the wind was still strong it was getting worrying everything was ice :( and crunchy under foot until it stopped this night and got milder.

http://www.wetterzentrale.de/archive/2006/...00120060313.png

http://www.wetterzentrale.de/archive/2006/...00220060313.png

All in all a major event :(

This looks a better event/s to me up there with 1996 anyway

http://85.214.49.20/wz/pics/brack1a.gif

12z UKMO out

A track further south towards northern France please! lol!

Most other areas will see snow at some time and places further north are in in for an amazing time - as the 12z UKMO confirms! Very frustrating - but enjoy other people! :D

Tamara

The way it`s going it may track a little further south,if not you`ll have to come too the welsh hills too see some snow :D

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Going to last March 12th it was a totally different set-up but we had 4 inches of snow as the winds started SE then turned to the S/SE and they were strong too and was absolutely bitterly cold on this day as the temp was 1.3c then it turned to freezing drizzle despite the temp above freezing drifting snow before the light drizzle come which happened in the 80s too sometimes.

This day was still bitter at 2.1c max with some hail rain/snow mix and still drifting at times in strong S/SE winds.

http://www.wetterzentrale.de/archive/2006/...00120060312.png

http://www.wetterzentrale.de/archive/2006/...00220060312.png

Then something I`ve only seen once before was it turned to freezing rain and it was heavy I was out in it later and my coat was freezing and the temp was getting lower the trees were creaking as you could here the ice on them as the wind was still strong it was getting worrying everything was ice :D and crunchy under foot until it stopped this night and got milder.

http://www.wetterzentrale.de/archive/2006/...00120060313.png

http://www.wetterzentrale.de/archive/2006/...00220060313.png

All in all a major event :(

This looks a better event/s to me up there with 1996 anyway

http://85.214.49.20/wz/pics/brack1a.gif

The way it`s going it may track a little further south,if not you`ll have to come too the welsh hills too see some snow :D

Ah yes, I remember that It's looking good for us in Wales, for once.

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