Greenland High vs Scandinavian High or Both

[Gibby]

While everyone over on the Model Output discussion thread constantly seek out a Greeny High or a Scandinavian High pressure block it would be interesting to discuss how members here perceive these two Winter factors and the odds they give of delivering cold and snowy weather to the UK. FWIW here's my feelings.

 

Greenland High While these are a welcome factor for those seeking cold across the UK they are not a definitive guarantee on their own that cold weather will affect us. What they do support is a greater chance of an icy Northerly blast and for that reason those living near Northern and Western and Eastern coastal counties will welcome these as they often produce heavy convective snow showers drawn down over the open Waters to the North and NW. However, for many mainland inland locations snow is rare with gin clear cold and crisp weather with frost and ice more of an issue rather than snow. However, even to achieve these conditions synoptics elsewhere have to be favourable. For example a Northerly may well be displaced too far West over the Atlantic Ocean if pressure stays high over SE Europe keeping the UK in a milder and wetter SW regime despite Greenland High pressure so because of this it is no guarantee of cold over the UK and other complications filtering down from the NW has also known to  be a problem in the past.

 

Scandinavian High This High is often more loved by folk who live in Southern and Eastern areas as I believe it offers the best chance of severe Winter weather down here while the North and particularly the NW benefit by shelter from the prevailing east or NE winds this system delivers to the UK giving milder benign conditions there. This High pressure feature can beome very intense especially in later Winter months and early Spring and often delivers the goods in the form of sub zero conditions and snow showers close to eastern coasts most likely in February and March. Occasionally warm air drifting North from the Med can give rise to more substantial snowfall across the South and East as it engages the cold European air. Lastly but probably the best scenario of all is when Low pressure to the SW comes up against this cold block of air and gives rise to the well known but rarely experienced Channel Low scenario delivering blizzards and disruptive snowfall to Southern and SW Britain in particular. Of course where there is prolonged snow there is mild air not far away and this is how many Scandinavian High's lose their influence across the UK with the inevitable snow turning to rain event coming up from the SW we often here in this pattern..

 

Both. When both High's link across Scandinavia through Icleand to Greenland this often gives Northern Europe it's coldest and most sustained chance of little change over a long period of time. While the weather over the UK is greater influenced by the Scandinavian portion of this High the Jet Stream is pushed well South of the UK with Low pressure areas giving Iberia, Spain and the Med in general it's worse Winter weather conditions while we can be locked into cold and icy conditions with snow showers near the East Coast. The ususal type of breakdown from this scenario is dependant on which portion of the High pressure belt gives way first with the usual scenario being for mild air to cross the UK from the SW should the Scandinavian portion decline while a period of Northerly winds backing West under a toppling ridge scenario most likely occurs if the Greenland end declines. Of course this is a broad brush treatment of most likely events but as we all know the weather is far more complicated than that.

 

Conclusion  It depends on where you live as to which I feel delivers the best snow chance results for the UK with the North fairing best from a Greenland block while the South and East of England and Wales have a better chance of fairing better from snow from a Scandinavian block with it's bitter East winds and snow showers and the illustrious rare chance of that 'Channel Low' we all love down here.

[damianslaw]

I would say Greenland Highs, always a chance of polar lows developing in the flow, and low pressure more generally from the NW, second half of December 2010 was a great Greenland high.

 

The best case scenario for all is a combo of both.

[sundog]

A greenland high rather then a scandi one for my location.

 

Ive been let down time and time again by scandi highs due to my location. They can look great on paper but for me the reality is it usually ends up that my location is just that bit just too far west to get the proper cold in,when it comes to scandi highs i really need a true beast from the east. I mean Jan 2013 for example the cold stopped dead over around wales it couldnt make the final journey over the irish sea,so bloody frustrating.

 

But as Damianslaw says above a combination is best for all.

[J10]

For Wales, a Greenland High is far better as this has delivered many moderate snowfalls here over the past decade or so. But not so good for cold as they are often "topplers"

 

Being greedy having both is better.

 

For outright cold a Scandinavian high is better, but they are often dry this far west [1991 an obvious exception]

 

A problem for Scandi High is they can give colder weather to Europe never quite make it to the UK and leave the UK at the end of the line of Atlantic depressions never quite making it part the meridian and this pattern can get stuck for weeks.,

[Guest]

Well I is down at Watford, give me a Scandi/Siber High, the type where we can get a max of -5C, then if we can get a low coming up the Channel, giving a slightly south of east air flow to give the Thames streamer a chance of depositing some of that white stuff a little to the north of London, then that would be perfict.

[Weather-history]

Greenland high for me.

The problem with the Scandi high is that unless there is a cold pool to the east to advect westwards, they are bobbins.

Look at the December 2002 easterly

The December 1997 easterly was really poor, didn't even get below zero once in Manchester during that period.

[Lettucing Gutted]

It is indeed a very complicated picture, Gibby.  Some of our classic winter months have the Scandinavian High waxing and waning all month.  February 1956 is a classic example.  This month had a Greenland High all month along with a Scandi High but the Scandinavian High kept waxing and waning.  However because the main westerly Jetstream was always on a southerly track from the eastern U.S, across the North Atlantic and into southern Europe with the Greenland High always remaining strong, the cold lasted the whole month as Northerly and Easterly winds repeatedly alternated with each other.

Edited December 24, 2014 by Craig Evans

[cheeky_monkey]

All of the coldest winters have both at different times and premier league winters have all 3..that is too say at some point a Greenland high...a Scandinavian high and a link up of both...look at 1947 as a classic example where all 3 scenarios happened..1963 and 1979 had Greenland highs and Scandinavian highs at differing times that produced cold and snow.