General Winter Discussion

[swebby]

I think what Steve was referring to with a 4 wave pattern is that there are four Rossby waves in the PFJ, which produces a stable jet flow - potentially for quite a while, and this implies that our current synoptics stay locked in because the jet doesn't flatten and break through the Mid-Atlantic block.

That's my understanding anyway, I'm sure someone more knowlegable can correct me if it's all wrong!

Splendid - thanks for the response Evo. I was begining to guess it was something along the lines of a standing wave pattern from what i could tease out of google but this makes things clear. It has also helped to clarify to me what meridonal/zonal/rossby terms are, which i was a bit fuzzy about, thanks. Do these waves tend to move west to east around the hemisphere or can they stay locked on a longitude until the jet then flattens out?

[cj114]

Bit glad really. Christmas shopping on Ski's was not my idea of fun anyway.

[Snow Queen one]

I want mild mid dec cause i will be in Florida and don't want snow whilst i am away as knowing my luck it will melt the day i come back and i will miss out.

[Bl!zzard]

It would be nice to see significant snowfall in my area (Bristol). In the previous years we have had hardly anything, maybe a random day with 2 or 3 cms.

[Stoxs]

hey EVO do more explainations you are top dollar i understood all of what you were saying and it all made sense in good old plain english .the trouble with alot of the forcasters on here is they understand what thet are saying but dummies like me ain`t got a clue!!

bye the way scoubies are better

well done

[roberthines]

Its looks good for us in county durham for snow from 6pm thursday till late friday.Bring on the snow.

So do u think the northeast uk will get snow during thursday.With the stats ive read im still new to it all.

[paul tall]

LOL, at Damien "I reckon I'm OWED 9 years of snowmen"...........quality.

[dinger]

I can't wait to build my first snowman. I estimate I am owed some 9 years of snowmen, and I intend to show a finger up to Mother Nature and botched winter forecasts by building every single one of them!

Get yourself plenty of gloves mate. You'll be building a helluva lot of snowmen

P.S Really enjoyed your posts

Colin

[Damien]

LOL, at Damien "I reckon I'm OWED 9 years of snowmen"...........quality.

I am being serious. Frankly I have a good mind to march down to my old school and begin with the winter of 1997/98 in Year 9, but that would be sheer lunacy and I probably be escorted off the premises (and with damn good reason too). So I will have to find some other means of having fun instead. Who knows, maybe snowball fights outside of banks, town squares, etc..

I can still go sleighing in a big field though. Everyone does that - like in the video to "Last Christmas" by Wham! It is possible for older people to behave like youngsters in the snow.

Edited November 21, 2005 by Damien

[LaoisWeather]

It is possible for older people to behave like children in the snow.

Skiing anyone?

[Damien]

Skiing anyone?

Too upper class.

I always found skiing on TV largely boring anyway. Give me a summer full of F1 and stuff anytime.

Edited November 21, 2005 by Damien

[Damien]

Absolutely. I dont know how you guys faired in Jan 87 in essex but in Kent we had some spectacular hoar frosts for days before the 'big event' and we all know what happened from 12th onwards.

I was thinking the exact same thing. Days of frost then the snows come and for not just one day....fingers crossed

I should just get this off my chest before I go, but January 1987 where I live AFAIK was absolute rubbish.

I just seem to remember really big snowflakes but that could have been anything really. No significant cold spell during this period AFAICR - and we normally fare very well from easterlies.

Edited November 21, 2005 by Damien

[Stratos Ferric]

Splendid - thanks for the response Evo. I was begining to guess it was something along the lines of a standing wave pattern from what i could tease out of google but this makes things clear. It has also helped to clarify to me what meridonal/zonal/rossby terms are, which i was a bit fuzzy about, thanks. Do these waves tend to move west to east around the hemisphere or can they stay locked on a longitude until the jet then flattens out?

Evo's done a very good job with his explanation. The jet is usually deemed to be stable when it has between 3-5 long waves. These tend to be low amplitude, and with less variation in core speed than when the jet becomes unstable and starts to move more latitudinally. This variation in speed is important because it is the acceleration and decelration in the jet that drives the development of surface systems. When the jet speeds up it literally sucks air upwards, causing air masses to come together at the surface (i.e. fronts) and with rising air, if spin is induced, a depression develops. For an anticyclone, the jet is slowing down, causing a pile up of air aloft which then has to sink, so causing a characteristic surface HP. With a low amplitude jet surface systems tend to move quickly, hecne the mobile weather (e.g. a couple of weeks back). With a high amplitude we start to get blocks forming - see this week.

What causes a breakdown? Typically an increase in energy in the flow, though subtle changes in location of the jet can be critical as well. Hence why, this week, we really won't start to be sure of how the cold flow at the end of the week will turn out at the surface until, say, early Wednesday.

[swebby]

What causes a breakdown? Typically an increase in energy in the flow, though subtle changes in location of the jet can be critical as well. Hence why, this week, we really won't start to be sure of how the cold flow at the end of the week will turn out at the surface until, say, early Wednesday.

Thanks SF - And with that i turn to Mr Murr's teleconnections guide and suddenly i feel the need for a lie down.........................!

Seriously though, i feel many users are like me and would really benifit from a very simple layman's guide (with diagrams pls!?) as to what the jet stream(s) are (eg polar, ferrell cell explained) and how they function. I'm asking a lot perhaps, but a basic reference would be great.

Cheers

S

Edited November 21, 2005 by swebby

[Sevendust]

Thanks SF - And with that i turn to Mr Murr's teleconnections guide and suddenly i feel the need for a lie down.........................!

Seriously though, i feel many users are like me and would really benifit from a very simple layman's guide (with diagrams pls!?) as to what the jet stream(s) are (eg polar, ferrell cell explained) and how they function. I'm asking a lot perhaps, but a basic reference would be great.

Cheers

S

Agreed - although I have some knowledge of the subject,such an explanation in simple terms would help many IMO

[Optimus Prime]

Well the cold spell next week looks as if it's been upgraded some what. -5 to perhaps -8c HPA for the south. Smiler for the north, maybe down to -10c HPA;

http://www.wetterzentrale.de/wz/pics/Rtavn962.gif

Looks favourable for snow for even areas as far south as the south coast.

It generally stays unseasonably cold right to the end of November with Milder air pushed way out west (With the kind of Set-up Greenland looks mild) Although the milder air does try and push in.

It stays cold right the way into December with all the runs indicating at an Exceptionaly long cold spell. Never seen before recently, probably since February 1986 (With comparable number of below average days for southern england)

EDIT; Here's the FAX chart

http://www.wetterzentrale.de/wz/pics/brack4a.gif

Also, of very light northerly winds after Saturday may bring temperatures down, over northern Scotland over the snow fields possibly as low as -15c over night? Favourable for say Caingorm moutains.

Edited November 21, 2005 by Optimus Prime

[Polar Continental]

Morning everyone,

Well have just run through the 0z GFS, and it's game on from Thursday, the low pressure sweeps down from the north across the country bringing with cold arctic air and possibly snow to many areas. After that the GFS continues to project north-south zonality up to +T204, incredible.

Off to work now, lets hope the runs continue this theme, looking forward to this evenings discussions.

Regards

Paul

[Great Plum]

Some great postings on here - thanks all!

Have been trying to catch up with all of the weekend's news - looks like game on for most of the country...

Apparently we won't have a frost tonight though looking at the forecast on the local news - unusual because I live in a frost hollow and because the weather seems to be reamining cold - anyone got any explanations?

[Guest Mike W]

cloudy and windy could be one or both of the reasons.

[Guest nukleopatra]

Anyone noticed this in the close up forcast? Apparently the winter of 1946 in to 1947 gave us a particularly cold February. Buxton recorded 30 days of Frost during February. Were their more days in February in the 40's then?

Edited November 21, 2005 by nukleopatra

[Macey]

It stays cold right the way into December with all the runs indicating at an Exceptionaly long cold spell. Never seen before recently, probably since February 1986

i like this sentence

[swebby]

Anyone noticed this in the close up forcast? Apparently the winter of 1946 in to 1947 gave us a particularly cold February. Buxton recorded 30 days of Frost during February. Were their more days in February in the 40's then?

Not sure if it was a leap yera but could you technically double up on the 1st day of the month - i.e frost in the morning and a 2nd frost in the evening?

S

[Paul]

It was a test to see who reads it, well done you passed

[SMU]

Evo's done a very good job with his explanation. The jet is usually deemed to be stable when it has between 3-5 long waves. These tend to be low amplitude, and with less variation in core speed than when the jet becomes unstable and starts to move more latitudinally. This variation in speed is important because it is the acceleration and decelration in the jet that drives the development of surface systems. When the jet speeds up it literally sucks air upwards, causing air masses to come together at the surface (i.e. fronts) and with rising air, if spin is induced, a depression develops. For an anticyclone, the jet is slowing down, causing a pile up of air aloft which then has to sink, so causing a characteristic surface HP. With a low amplitude jet surface systems tend to move quickly, hecne the mobile weather (e.g. a couple of weeks back). With a high amplitude we start to get blocks forming - see this week.

What causes a breakdown? Typically an increase in energy in the flow, though subtle changes in location of the jet can be critical as well. Hence why, this week, we really won't start to be sure of how the cold flow at the end of the week will turn out at the surface until, say, early Wednesday.

And with the aforementioned section highlighted the pinnacle of a High Amplitude jet its the rare evolution of

A 4 WAVE PATTERN... ( the left one)

This basically ensures that Nothing changes fast....

S

Edited November 21, 2005 by Steve Murr

[Tucco]

I know people focus on low ground in these situations because most people live there. But some of us have use the high routes to get to work, and tiny minority live 400m>600m asl.

Snowfall looks possible at high levels for next week or so. Condtions in these areas could be severe, and could cause prolonged problems for transport at high levels.

Mark

Barnard Castle,Co Durham