This was the first GFS chart for 6pm on Christmas Day, so let’s track the model roller coaster and how the chance of a White Christmas rises and falls in the lead up to the big day.

Worth noting that very often the lift served season here in Scotland gets going between Christmas and New Year!





Edited 2 times. Last edit at 20.23hrs Thu 14 Dec 23 by winterhighland.

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Here’s Thu 14th 06z run:





Edited 1 times. Last edit at 20.25hrs Thu 14 Dec 23 by winterhighland.

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Here’s the 12z run take on it!





Edited 1 times. Last edit at 20.29hrs Thu 14 Dec 23 by winterhighland.

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Don’t look now!





Edited 1 times. Last edit at 01.19hrs Fri 15 Dec 23 by winterhighland.

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The pendulum swings back towards cold, with -7 to -8°c 850hpa temperatures over the Central Highlands for 6pm on Christmas Day, but with a risk of Severe Southerly Gales for the hills moving in from the West.





Edited 1 times. Last edit at 18.53hrs Sat 16 Dec 23 by winterhighland.

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So on recent runs we start Christmas Day in cold air, but a deepening area of low pressure is attempting to swing a warm sector towards us. On the 06z GFS this gets down to a sub 940mb low out in the Atlantic!



At 6pm on the big day, the 06z set of GFS ensembles show a spread of 13.1°c in the various ensemble runs, while the Met Office's MOGREPS doesn't quite reach 6pm on Christmas Day yet - it will on Monday, it reaches a peak spread of 17.1°c during Christmas Eve.

A general pattern of thaw / freeze cycling, with very mild warm sectors sweeping in looks to be the direction of travel so what happens on Christmas Day will all be down to the timing of specific frontal systems. The huge spread from MOGREPS on Christmas Eve underlining that relatively small changes in the synoptic setup and timing could have a huge impact in the actual Christmas Day weather!



Edited 2 times. Last edit at 14.35hrs Sun 17 Dec 23 by winterhighland.

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This evening’s GFS has us in colder air for 6pm on Christmas Day, there remains a big spread in scenarios. The GFS ensembles has a 12.1°c spread at 6pm on the 25th while the Met Office MOGREPS has 10.4°c of spread. Earlier on Christmas Eve the MOGREPS spread gets up to 14°c.

Here’s the 6pm GFS chart:



Of note to the previous post’s chart is is the lack of the deep and deepening low pressure to the West of Iceland. Maybe the volcano scared it away!



Edited 2 times. Last edit at 23.47hrs Mon 18 Dec 23 by winterhighland.

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This is the latest 6pm Christmas Day chart from the GFS operational showing 850hpa temperatures, we do seem to be moving towards a much slacker pressure gradient by Christmas Evening than off late at least!



The 2m temperature is subzero in parts of the Highlands away from immediate coastal areas, and a possible onshore breeze from the Moray Firth could give snow showers in places and possibly a trough nudging into the West Highlands bringing a wintry mix to low levels and snow with a bit of height / inland.

However, by Christmas Eve both the GFS ensembles and MOGREPS have around 15 to 16°c spread in scenarios. Even at T+ 72hours there is significant uncertainty over temperature for Highland Scotland with a 12.4°c spread on MOGREPS for the Central Highlands.




Edited 1 times. Last edit at 19.36hrs Tue 19 Dec 23 by winterhighland.

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The 18z GFS run is rolling out and we’re in cooler air by 6pm on Christmas Day, and some areas of Northern Scotland are in with a shout of a White Christmas. However how things develop for the ski areas over the coming week remains in the balance. At just T+30 hours there is a 7°c spread in the GFS ensembles for the Central Highlands, we could see 15-20cm of snow at the Lecht and rain at CairnGorm, it’s that sharp a divide!





Edited 2 times. Last edit at 22.13hrs Thu 21 Dec 23 by winterhighland.

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Merry Christmas - the big day is here and here’s what the GFS 18z run has for 24 hours out!


^Colder 850hpa temps moving into Northern Scotland.

Looking at dew points, which suggest if there’s precipitation there’s going to be a white Christmas for parts of Northern Scotland, with at covering possible with a bit of height or inland.



Finally the precipitation chart and the hatched area is projected snowfall!





Edited 1 times. Last edit at 00.51hrs Mon 25 Dec 23 by winterhighland.

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