Model Output Discussion

[FENDER.]

"Arctic Hurricanes" ?! You scaremongerer you! LOL You should know better!

Polar Lows are associated with a distinct "hook" or "comma" feature but not an eye surely!!!!

And of course Polar Lows are usually much smaller features than the depression puzzling the models currently.

smich

And of course die out quickly when they make landfall

[mountain shadow]

I like the look of that 120hr Fax chart as it looks to be dragging in some of that cold air from the south east from over france. Could be quite interesting over the south east corner of the country . Looks like pressure rising to the north east too on that chart. Possible easterly setting up later next week .

Looking at that Fax chart in isolation should have me very excited. A low pressure system in sub 528 dam air, with an occluded front over my house.Unfortunately, with all the other factors involved it will be heavy rain, sleet at best.

[Snowyowl9]

To see a low move north to south is certainly something that doesn`t happen very often,east to west it can happen.

And for it to be west of us is even more rare.

http://www.wzkarten3.de/pics/brack3.gif

http://www.wzkarten3.de/pics/brack4.gif

http://www.wzkarten.de/pics/Rtavn1201.png

http://www.wzkarten.de/pics/Rtavn1381.png

A low coming from south to north is more likely to happen.

[londonsnow]

great 18z. fascinating winter, and lots of potential over the next week or two

[nick sussex]

"Arctic Hurricanes" ?! You scaremongerer you! LOL You should know better!

Polar Lows are associated with a distinct "hook" or "comma" feature but not an eye surely!!!!

And of course Polar Lows are usually much smaller features than the depression puzzling the models currently.

smich

Heres a great link and yes it shows an eye! I think thats why they're also called Arctic Hurricanes, it does seem an over the top way of describing them but its true.

http://images.google.co.uk/imgres?imgurl=http://nsidc.org/arcticmet/images/patterns/polarlow_small.jpg&imgrefurl=http://nsidc.org/arcticmet/patterns/polar_low.html&usg=__uXpYAvlNDEGn-GAbIHAmDgLLveY=&h=463&w=480&sz=39&hl=fr&start=1&itbs=1&tbnid=HOM8XvosG6LAMM:&tbnh=124&tbnw=129&prev=/images%3Fq%3Dpolar%2Blow%26gbv%3D2%26hl%3Dfr

[Liam J]

gfs 18z is an upgrade imo, whether its the right evolution its to early to say but if the models can agree with the one shown tonight we would be looking down the barrel of a snowy spell, also gfs showing some very low minimum temps -10c over scotland and -7c northern england next week with ppn all over the country and well within sub 528 dam, uppers -5/-6c right side of marginal for most.

next 24 hours or so we should start to see the outcome and how the models expect it to develop.

[billy]

Looking at that Fax chart in isolation should have me very excited. A low pressure system in sub 528 dam air, with an occluded front over my house.Unfortunately, with all the other factors involved it will be heavy rain, sleet at best.

You may be right ms . I guess we will have to wait until saturdays 12z runs to get a good idea on how this will pan out. Exciting charts though it has to be said.

[kent]

Polar lows can be extremely snowy and aggressive however their size is anything between 100 to 500 miles and are usually short lived affairs from 12 to 36 hours but id like one over the south coast to dwarf the measly 1cm so far this year.

[FENDER.]

M/O having none of it though, 5c and rain for the midlands next Monday

[londonsnow]

Heres a great link and yes it shows an eye! I think thats why they're also called Arctic Hurricanes, it does seem an over the top way of describing them but its true.

http://images.google.co.uk/imgres?imgurl=http://nsidc.org/arcticmet/images/patterns/polarlow_small.jpg&imgrefurl=http://nsidc.org/arcticmet/patterns/polar_low.html&usg=__uXpYAvlNDEGn-GAbIHAmDgLLveY=&h=463&w=480&sz=39&hl=fr&start=1&itbs=1&tbnid=HOM8XvosG6LAMM:&tbnh=124&tbnw=129&prev=/images%3Fq%3Dpolar%2Blow%26gbv%3D2%26hl%3Dfr

great imagery there nick, almost a bit "the day after tomorrow".

[cooling climate]

Blocking to the north pushing further south and east on the 18z GFS run which

will continue on future runs I think.

The 18z run looks very snowy for many areas but thats a long way off yet and

if I am right about the blocking then I think everything will be surpressed further.

I am still of the opinion that a colder pattern will develop than what is being shown.

Edited February 11, 2010 by cooling climate

[SP1986]

A messy type synoptic situation on the way, generally calm but wet at times with rain, sleet and snow. Nothing much more than that really.

It is a borderline situation for snow, some place will get snow, some places will get rain.

I'm still a bit miffed over the GFS temperature predictions which I think apart from one or two instances have handles cold temperatures very poorly indeed. The GFS definitely has a habit of progging the temperature too low. Last night it was right however many more times it has been wrong.

[k19]

The models show a deep low, but mild air, surely, anything will be extremely marginal? i also see it further west, surely thats bad, as the low ill move anti clockwise drawing in air from the atlantic? correct me if im wrong

Bbc now going for heavy snow for my location on tuesday.

[J10]

An interesting 18HZ run again, perhaps not quite as snowy generally as the 12Hz but still promising. A marginal event certainly but some snow is possible at different times in many parts even to low ground. Going by the 18Hz run certainty not snow all the way for low ground but taking South Wales as an example, looking very good on Wednesday/Thursday. But this is a fluid situation, if the charts end up further east then it could be less marginal,further west no event at all.

This is a very interesting event synoptically, even if turns out a damp squib.

A messy type synoptic situation on the way, generally calm but wet at times with rain, sleet and snow. Nothing much more than that really.

It is a borderline situation for snow, some place will get snow, some places will get rain.

I'm still a bit miffed over the GFS temperature predictions which I think apart from one or two instances have handles cold temperatures very poorly indeed. The GFS definitely has a habit of progging the temperature too low. Last night it was right however many more times it has been wrong.

That's the whole fun of this, predicting where the rain will fall, and where the snow will fall. As for GFS it tend to over do temps for coastal areas, especially over night, the forecast was for 0c, and the actual temp was -4c.

[nick sussex]

great imagery there nick, almost a bit "the day after tomorrow".

Yes can you imagine the bbc forecaster saying an Arctic Hurricane is about to hit Scotland! that would cause mass panic. Often you need to see a decent length northerly to see those, really unless you're in the north or ne you rarely see them as they die out quickly once they make landfall.

Edited February 11, 2010 by nick sussex

[robert]

I think a lot of people are underestimating the models and what they show and the 18z is a good example. Very unstable yes, but very significant amounts of snow for large parts of the country in a near time frame and beyond!

It could get very dangerous out there!

[kent]

Yes can you imagine the bbc forecaster saying an Arctic Hurricane is about to hit Scotland! that would cause mass panic. Often you need to see a decent length northerly to see those, really unless you're in the north or ne you rarely see them as they die out quickly once they make landfall.

Absolutely correct, polar lows are sometimes called arctic lows when they can be very aggressive but tend to dissipate very quickly when they hit landfall.

Edit. I meant sometimes called arctic hurricanes.

[londonsnow]

Yes can you imagine the bbc forecaster saying an Arctic Hurricane is about to hit Scotland! that would cause mass panic. Often you need to see a decent length northerly to see those, really unless you're in the north or ne you rarely see them as they die out quickly once they make landfall.

yes an arctic hurricane headline on the bbc forecast summary would cause media mayhem! the daily express would run out of pages. seriously though, i'm very interested in how this low pans out. height will always be a factor, but this, i think, is winter's last bellowing shout

Edited February 11, 2010 by londonsnow

[SP1986]

I think a lot of people are underestimating the models and what they show and the 18z is a good example. Very unstable yes, but very significant amounts of snow for large parts of the country in a near time frame and beyond!

It could get very dangerous out there!

Underestimating the models, I think not.. personally I think we overestimate them.

As for significant amount of snow for large parts of the country, there's nothing on the models that really back that up, add the further complications of the models being particularly shaky recently.

[karyo]

As we come closer to next week, things are looking more and more marginal! I won't be surprised to just get rain when the event arrives, with snow essentially on high ground! Good for the Pennines I suppose!

However, the good news are that the models have nothing mild to offer on the further outlook. Also, GPs post was just what I wanted to read! Plenty of cold/below average weather on offer for the end of winter and the start of spring!

Karyo

[johnholmes]

I'm still a bit miffed over the GFS temperature predictions which I think apart from one or two instances have handles cold temperatures very poorly indeed. The GFS definitely has a habit of progging the temperature too low. Last night it was right however many more times it has been wrong.

Stephen you really have a bee in your bonnet about this and I'm not sure why?

Do you compare it to the the UK Met progs now available on Wx Online? How does it compare to that?

Have you yet done any actual data comparison-your nearest station to what GFS shows?

or using the Extra data, more detail and comparing that?

Or using NMM and comparing that?

You really should be showing a more scientific approach if you don't mind me saying so.

A polar low is different from a normal low formed north of the polar front. A polar low is formed generally in an unstable northerly flow when the upper atmosphere is generally below -35, these aren't well forecast further out than 24hrs. Interestingly they're also called Arctic Hurricanes as they often have an eye in the centre!

The low the models are currently forecasting actually forms near Iceland, the deeper this becomes the more likely we'll see milder air sucked into its circulation and a larger milder sector.

correct Nick-it has none of the polar low characteristics whatever

[ScottSnow]

yes an arctic hurricane headline on the bbc forecast summary would cause media mayhem! the daily express would run out of pages. seriously though, i'm very interested in how this low pans out. height will always be a factor, but this, i think, is winter's last bellowing shout

It's only mid feb lol, cold weather can pack a punch well into April.

As for the models with high pressure forecast to remain high to our north the potential is there for a cold pattern to last some time and with no really mild air reaching here since mid December I wouldn't be suprised for it to remain below average until early March. I'd imagine you would have to be lucky to see lying snow at low levels next week, certainly in the early part but if the cold becomes entrenched this could change.

[johnholmes]

Well the Met O Fax charts are interesting if only for the confusion.

As I posted earlier this evening to get where they were, and are now, predicting the low to be 1200z 16 Feb requires the low to do a sharp right hand turn from its predicted position at 1200z 14 Feb. To me its too sharp a turn and I would expect it to end up rather further east than their current 1200z 16 Feb prediction. But stranger things have happened so its actual position at that time/date will be very interesting to see.

[J10]

Well the Met O Fax charts are interesting if only for the confusion.

As I posted earlier this evening to get where they were, and are now, predicting the low to be 1200z 16 Feb requires the low to do a sharp right hand turn from its predicted position at 1200z 14 Feb. To me its too sharp a turn and I would expect it to end up rather further east than their current 1200z 16 Feb prediction. But stranger things have happened so its actual position at that time/date will be very interesting to see.

When was the last time we had such a major retrogression event like this.

[joespontiac]

Just been looking at this site as it gives data for my area plus backs it up with gfs (i think) imagery. http://wxweb.meteostar.com/sample/sample_C.shtml?text=EGGW

Interestingly at t150 there seems to be a channel low developing. http://wxweb.meteostar.com/leads_images/Models/GFS/ERP/CP/large/surface/2010021118_ERP_GFS_SFC_SLP_THK_PRECIP_WINDS_150.gif

before that though, things maybe marginal for Tuesday onwards but there is the suggestion of a continual line of showers coming off the Atlantic hitting the south and south east. I there is not too much warm air dragged round this low, im sure there will be quite a large amount of snow....

Edited February 11, 2010 by joespontiac