Ayrshire Weather Blog - Beast from the East is on the way this weekend
This weekend will see an extremely cold spell of weather arrive across Ayrshire and i explain all about it in this blog.
Over the past week the weather has been coming in off the Atlantic bringing mild air, along with wet and windy conditions at times. Though fortunately we’ve avoided the worst of the Atlantic depressions, thanks to the strong jet stream being to the south of the UK across northern Spain and France – which has taken a few intense lows across France over the weekend.
One deep depression, named Leiv not Doris (as it didn’t affect the UK) brought some violent and damaging wind gusts across the central Atlantic coast of western France on Saturday morning, with a gust of 92 mph (148 k/h) on the coast to the west of Bordeaux. Another deep low, named Marcel, moves off the Bay of Biscay into France today, bringing damaging northwesterly winds gusting to 70-80mph with exposure across northern Spain and SW France.
Although we will see further wind and rain from another Atlantic frontal system moving through on Monday and Tuesday, high pressure is building stronger over Scandinavia in the meantime and from mid-week we start to see this large blocking high pressure system influence our weather from the east, bringing a much colder but drier flow from the east or southeast to end the week, through the weekend and perhaps into early next week.
Our weather is usually dominated by the Atlantic bringing the usual wet and windy winter weather but due to the Sudden Stratospheric Warming = SSW. This then leads to a set of rather complicated scenarios that push cold Air over the Uk from scandinavia and canada bringing snow and very cold weather with night lows of -9c in Rural parts of Ayrshire.
Sudden Stratospheric Warming = SSW explained below
There are 5 main layers within the atmosphere : troposphere, stratosphere, mesosphere, thermosphere, and the exosphere.
Cold air will try and likely win to flow into Europe , also West-Europe.
Extreme cold /deepfreeze will be in EurAsia coming days/weeks.
High Pressure above Scandi is animator of the east cold flow towards West-Europe.
It is strong 1045mb or 1050mb in its core, could be stubborn from nature.
Also it makes retrogression moves, which is highly unusual /rare.
Only by nice conditions at Polar Vortex Stratosphere weakening/SSW wave 1 or wave 2 it is favorable to do so. Wave 1 is Polar Vortex displacement.
Wave 2 is Polar Vortex split.
First some cold/frost and light snow local places in West-Europe, but chances for decent snow event in great parts of West-Europe will increases dramatic deeper into Feb month and possible March 2017 as well too. Splits from Polar Vortex at 30mb : those locations from the vortices which will be split for sure , favour Europe for cold and snow. And for sure EurAsia parts, or all parts of them.
Also many members GFS Ensemble showing up with a yellow Northpole High., was case in 18z run from Saturday 4 Feb 2017.
If that will be later verified too , it would be awesome.
Some signs at +240H for power transfer from Scandi to Greenland.
ECMWF,.model runs was suggestive for that.
Also in there and earlier runs , possibility of Polar Vortex split at 10mb , wich would be granted/declared as huge breakthrough.
United Kingdom and Ireland had as so far this winter a very pour performance, also in month Jan 2017 when rest of Europe or great parts of Europe had decent cold/freeze/frost and some snow.
Next weekend and beyond
Next weekend and beyond, growing uncertainty, as some recent models ensemble means suggest the block over Scandinavia may sink south a little, but if it does, we still keep a cold and dry southeasterly flow – so probably staying cold with below average temperatures, but mostly dry bar the odd snow flurry/shower near eastern coast.
However, there is potential, albeit low probability for now, that the Scandinavian blocking high may not sink and we may see another surge of deep cold air coming out west Russia towards NW Europe after the initial cold surge later this week. Particularly given the models may not be handling correctly changes to the upper patterns caused by the MJO. Such a second cold surge from the east next week could bring deep cold air, which would be more conducive to snowfall – but not showing in the models for now.
So we could be looking at the longest nationwide cold spell of the winter thus far starting from the middle of the week, though any snow, for now looks like and limited to more eastern areas with scattered flurries elsewhere.