My Winter Ode- 2005/2006

[snowmadchrisuk]

Well theweather outlooks christmas forecast doesnt look very promising. Abit of a difference to net-weathers.

Latest developments suggest the possibility of milder weather for much of the second half of December. This may well mean the UK is under a south westerly flow on Christmas day, with showers of rain in the west and drier conditions further east.

For these reasons we have downgraded the chance of a White Xmas from our initial forecast which was issued on the 25th September. So at the moment a green Christmas is looking more likely.

Probabilities

Northern areas of the UK are considered to have a 15% to 25% chance of snow at Christmas.

Southern areas of the UK are considered to have a 5% to 15% chance of snow at Christmas.

This forecast will be updated regularly between now and Christmas.

Issued 25/09/2005

[West is Best]

A terrific, momentous, post Steve. It's taken me two days to digest

One observation ... I'm sure you're right that an easterly set-up is not per se the harbinger of snow, except to east coast areas. But in my memory from childhood it was always the battle between cold to the east and mild to the west that brought the heavy snowfalls. If Russia and the European mainland got properly cold, and we got into an easterly feed situation, it was when the fronts advanced from the west that the fun really began. And the key there was the track of those low pressure systems. Sometimes they crossed the Midlands, bringing snow to the far north and mild to the south. But sometimes we got a channel low, or near enough, and that produced substantial falls. Furthermore, I seem to remember when that happend the easterlies often reasserted themselves, not least because to the north of the system is of course an easterly (anti-clockwise) feed.

What still worries me about today's conditions, quite aside from the general increase in temperatures, is that we seem to be missing this vital ingredient. We have low pressures crossing a good 200 miles further north and we never seem to be in a genuine battleground of mild and cold such as would produce lots of the white stuff. We're left clutching at northerly incursions as our only source.

Edited October 8, 2005 by West is Best

[Methuselah]

In recent years, we have often had heavy snow showers giving fairly big accumulations but I don't think we have had real frontal snowfall here since 1996.

Sometimes the showers have been helped by troughs though.

<{POST_SNAPBACK}>

I think the 'nearest' thing we had to frontal snow, was about six hours' of feezing rain (at c. -3C) last November. It's not quite the same though, is it??

[PersianPaladin]

Good God, Steve!

I almost had a mental orgasm after reading that post...

It's just so interesting and rich with fascinating info and concise facts, that is truly the best post i have come across.

You should be on the forecast-team.

[SMU]

A terrific, momentous, post Steve. It's taken me two days to digest 

One observation ... I'm sure you're right that an easterly set-up is not per se the harbinger of snow, except to east coast areas. But in my memory from childhood it was always the battle between cold to the east and mild to the west that brought the heavy snowfalls. If Russia and the European mainland got properly cold, and we got into an easterly feed situation, it was when the fronts advanced from the west that the fun really began. And the key there was the track of those low pressure systems. Sometimes they crossed the Midlands, bringing snow to the far north and mild to the south. But sometimes we got a channel low, or near enough, and that produced substantial falls. Furthermore, I seem to remember when that happend the easterlies often reasserted themselves, not least because to the north of the system is of course an easterly (anti-clockwise) feed.

<{POST_SNAPBACK}>

Hi WIB-

Yes- good post there commenting on these conditions-

These conditions are well a thing of the past- and the key im afraid is the Greenland high again-

99% of the time with a Scandi or Siberian high ( Without an influential GH)-the initial burst of Easterlies brings the snow flurries to the East & South-East - but after a couple of days have passed the jet stream that has been pushed away westwards begins to creep eastwards again and will run a continuous line SW/NE across the atlantic-

As the Siberain high slowly retreats east or worst still southwards again so the Easterlies subside and veer South easterly and even Southerly-

Ususally when this hapens the cold hasnt become embedded across the Country and a warm front will approach from the west- run up the western side of the country and snow -well usually a hour or two before quickly replaced by rain....

This is often a precursor then of 2 weeks of Bartlett high territory....

Then bring on the Greenland high Scenario.....

This is the 'perfect' conditions you refer to- and emphasised by years like 63/79-

You have the easterlies, backed up by a greenland high Birfercating the jet stream in the Atlantic sending one arm through the pole and the southern arm slowly on a Southern track across the track-

this then gives the weakness to the jet that is required for the Lp to run towards the South-west and stay to the south or even better Stall......

The Winds stay South Easterly and mild air is never allowed to creep into the Uk-

As the Greenland High exerts itself again- so the low will swing away into the near continent and we are often followed by another peiod of Easterlies, as well as looking to the North east for the Next trough to develop and push South, South West through the block-

Rare as rocking horse... these days- it just doesnt happen because of the lack of the Greenland high...

Can this year be different...

S

Edited October 8, 2005 by Steve Murr

[Thundery wintry showers]

My impression of easterly weather, from scrutiny of past charts, backs up what Steve is saying. The failed easterlies of Decembers 1997 and 2002 represent pretty good examples.

As well as the Atlantic lows stalling against the cold air situations, it often seems that easterlies which are entirely reliant upon a Scandinavian High tend to be south-easterly in nature (i.e. short track over the North Sea) and the air tends to be highly stable, producing little snow.

Whereas if pressure is high more generally to our north, with centres over Greenland and Scandinavia, then our continental air often arrives via more of an ENE'ly (longer track over the sea) bringing heavy snow showers. The easterly spells of Januarys 1982 and 1985 both had a prominent Greenland High, while that of 1987 saw the Scandinavian High extend as far west as Iceland bringing in the ENE'lys.

[J10]

I think the 'nearest' thing we had to frontal snow, was about six hours' of feezing rain (at c. -3C) last November. It's not quite the same though, is it??

<{POST_SNAPBACK}>

But you are in a much better position for snow than me.

[Rollo]

A terrific, momentous, post Steve. It's taken me two days to digest 

One observation ... I'm sure you're right that an easterly set-up is not per se the harbinger of snow, except to east coast areas. But in my memory from childhood it was always the battle between cold to the east and mild to the west that brought the heavy snowfalls. If Russia and the European mainland got properly cold, and we got into an easterly feed situation, it was when the fronts advanced from the west that the fun really began. And the key there was the track of those low pressure systems. Sometimes they crossed the Midlands, bringing snow to the far north and mild to the south. But sometimes we got a channel low, or near enough, and that produced substantial falls. Furthermore, I seem to remember when that happend the easterlies often reasserted themselves, not least because to the north of the system is of course an easterly (anti-clockwise) feed.

What still worries me about today's conditions, quite aside from the general increase in temperatures, is that we seem to be missing this vital ingredient. We have low pressures crossing a good 200 miles further north and we never seem to be in a genuine battleground of mild and cold such as would produce lots of the white stuff. We're left clutching at northerly incursions as our only source.

<{POST_SNAPBACK}>

I remember the situation quite clearly when a low formed over the Midlands and then moved slowly ESE into the near continent. Here in newcastle as the low approached light snow would start and gradually become heavier with at least moderate accumulations and then after several hours of precipitation the sky would clear from the North and the temperature which was usually around 1c during the snow would plummet,the joy of seeing the freshly fallen and well frozen snow twinkling like mad the following morning is still in my minds eye,however I cannot really remember the last time this happened-whether it is GW or not,it would be great to see it happen soon.

[Polar Continental]

The Greenland high

How can I put this- If i had a shopping list for producing snowfall this would be in CAPITALS at the top-!!!

The daddy, The boss,- The Single Most importartant factor in determining a decent Artic outbreak across the UK-

ALL SUSTAINED cold periods across the UK have involved a strong Core pressure across Greenland 'Steering' the Northern Arm of the jet stream up the western side-

An almost rarity in recent years- perhaps a forgotton entity- They are so rare ive trawled the archives looking for that 'Classic' Greenland high that ridges South, Holds then doesnt retreat or topple but goes onto repetativley force cold Northerlies & Easterlies over the Uk-

Ive found it- ( the reason that this is pertinent to our current Winters is the starting day is almost a 'modern' winter-)

So Day 1- Low pressure in the atlantic, Azores High in play and the polar front holding across Iceland- However the key here is the track of the second low pressure coming off the Eastern seaboard- Often people comment on the procession of low pressure systems running across the Atlantic in quick succession-Our Cold spell is on the cards already as the jet Stream is Bifercated across the South-western coast of Greenland-

7th Feb 1955

Day 2- That Low pressure is being forced south and the core pressure over Greenland drops to 1040 mb-

8th feb 1955

Day 3- And were under starters orders- Cold just starting to stream into Scotland-

9th Feb 1955

Day 4- Look at that lovely long fetch of Cold air all the way from the Fram straight/Svalbard-

10th Feb 1955

We then enter into a succession of Northerly & Easterly dominated days-

( PLUS LOOK HOW -VE the AO is on the chart below)

Day 5 Northerly-

11th Feb 1955

Day 6 North-Easterly

12 feb 1955

Day 7 North-Easterly

13 Feb 1955

Day 8 Northerly ( You may think this is the beginning of the end...)

14th Feb 1955

Day 9 North-Easterly

15th feb 1955

Day 10 Northerly- This chart shows a renewed burst around the GH- more is commented apon this scenario in the Freezing month section-

16th Feb 1955

Day 11-Northerly- Back to a great square one again-

17th Feb 1955

Day 13- Easterly

19th feb 1955

The cold weather lasted untill the 27th of feb thats 2 and a half weeks of cold from one strong greenland high ( backed up by a neg AO) the true Daddy-

Hi Steve, everyone,

Have been having another read of your ode; this part is one of the most fascinating to me, I just love looking through those charts of the Greenland high at its best.

Have been studying the Archive of 1955, you mention that incredible spell of northerlies lasted until 27th February, what’s interesting is even well in to March the pattern kept on repeating. By the 8th the cold was back, and didn’t give up there.

March 8th 1955

March 19th 1955

28th March 1955 (I'm still the daddy)

It would be a dream come true if we could just see that happen again.

Regards

Paul

Edited October 19, 2005 by Paul Carfoot