The well advertised turn to not only colder but brighter weather is now moving in to make way for a bright and largely beautiful Saturday across much of the UK and Ireland, however you may want to grab a jacket before heading out the door. That north breeze will make it feel nippy out there. Don’t be surprised to see a SNOW shower along the North Sea coast where winds will be strongest, a covering is possible, especially over higher ground but low levels could see it too.

The ‘active’ pattern continues as winds return to a stiff westerly Sunday as the next system pushes in, however this is only part of a bigger story evolving as the air, albeit is westerly Sunday into Monday, the origin of this air is off Greenland and so, while tomorrow is chilly with highs between 1-5C UK-wide, this is nothing compared to the bite in the air Monday following the initial wind and rain from the low. The backlash flow will be bitter.

Here’s the latest ECMWF 500mb heights Sat through Monday

Saturday

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As you can see, we’ve got the classic blocking high to the west, low to the east and a nice cold north wind tomorrow with high pressure bringing excellent conditions.

Sunday

By Sunday the next system spreads wind and rain in but you’ll notice those isobars squeezing together, so expect strong to gale-force winds out of the west, perhaps severe along the coast. The noteworthy aspect is the brief push of mild up into the UK but following, is a a real Greenland-style slap in the face.

Monday

Check out those tightly packed isobars but even more interesting is the very sharp demarkation between relatively mild air on the underside while, very closeby and on the north side of the jet, frigid air is flowing eastbound into the UK, once thios low crosses the UK, a renewed trough gets carved out and boy, will it not be cold. Look out for snow on the backside. It really depends on how much moisture is available once that colder air sweeps in.

Here’s the ECMWF for Tuesday through Friday

Tuesday

Wow! Just look at those thickness values dropping down over the UK as the low heads out into the North Sea. I wouldn’t be surprised if we get a snowstorm out of this with very low wind chills and air temperatures at or below freezing for many parts of the UK even during daylight hours.

Wednesday

By the time we get to Wednesday, the air is likely to be very cold and there could well be a decent snowcover, especially over eastern areas but what may be interesting is how cold it may get Wednesday night into Thursday, if like, tomorrow we manage to get a high build down to accompany the northerly flow which sets up once again. Keep in mind that while the air tomorrow will be much colder than anything seen this past week, it’s what the Sun-Mon low is bringing in, that may set the stage for some bitterly cold days and nights from mid week on towards next weekend.

Thursday

Thursday should be much the same, cold northerly flow which reinforces very cold air already firmly in place. High pressure should keep skies mainly sunny but this means freezing daytime highs, bitterly cold nights under starry skies.

By Friday, while still cold, the ECMWF appears to try and work the ridge towards the UK but th flow remains northerly but what’s interesting is that the period between 168-240 hours, the trough remains firmly entrenched over Europe with the mean ridge to our west, so a very cold, north flow keeps on blowing.

Could It Snow Sunday?

The GFS does show snow for a large part of the UK by as early as Sunday. Whether this is somewhat overdone, I am unsure but I would say that we shouldn’t underestimate the amount of cold air this system will pull in especially when you see the very steep thickness seperation within the jet stream. This is racing across the North Atlantic so fast (remember the tigh isobars indicating a faster flow), that it has much less time to moderate!

Sunday (48 hrs)

Tuesday 78 hrs

To summerize. Tomorrow is a mere wake-up call to a much bigger deal coming next week. The Atlantic low which pushes across Ireland and the UK Sun-Mon will open the door to a very cold week ahead and this believe it or not may beat anything we have seen all winter. The difference between this upcoming cold spell and the one we just had is that this is cleaner or should I say clearer with high pressure involved. Sunnier skies by day and starry skies by night mean, colder!

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