THIS ARTICLE MAY BE SUBJECT TO SOME MINOR CHANGES OVER THE NEXT DAY OR SO…

The (locked) cold pattern has broken… The return of the Atlantic is down to the MJO returning to phases 2, 3, 4 combined with the WPO, EPO going back positive. The southward discharge of arctic air out of Alaska, N Canada will enhance the south-displaced Atlantic jet stream helping flip the NAO neutral to positive.

The complication to the above however is the level of negative Arctic Oscillation.

So, with plenty of cold within the MID LATITUDES, an Atlantic pattern doesn’t necessarily mean mild as the run-up to Christmas will show (see below). The return of the Atlantic shall make for more fluidity of air mass movement and greater likelihood of changeability and back and forth swings with perhaps a lean more towards mild given a warmer-than-normal Atlantic.

The below MJO charts as per the GFS operational shows the eastward progression from favorable to unfavorable cold phases.

The below GFS ensemble shows what happens when these key drivers switch modes and as stated in my winter forecast, the Pacific will be key this year.

ECMWF

The above being said, the ECMWF suggests the rotation back into phases 6, 7 and 8 during the Christmas to New Year week so it could potentially be colder than the GFS suggests.

HOWEVER, while we are likely heading into a much more mobile, likely milder pattern as expected. There is a fascinating battle unfolding in the run-up to Christmas.

Based on the the latest model data available as of Wednesday 21 December, here is my analysis of the upcoming Christmas period.

We currently have an active WSW oriented Atlantic storm track with positioning of depressions over or just NW of Scotland during the Christmas Eve to Boxing Day period.

Exact track and speed of approaching lows remain uncertain and very much subject to change.

The latest run of the models point to a low pressure centre making an approach just NW of Scotland Christmas Eve. This suggests milder source air from the SW will be present over much of the UK with very low snow chances outside of the Scottish Highlands LATE CHRISTMAS EVE/1st HALF OF CHRISTMAS DAY before colder polar-maritime air arrives LATE CHRISTMAS DAY INTO BOXING DAY.

Little to no snow for bulk of England, Wales, Northern Ireland, Ireland and even Scotland Christmas Day but with chances increasing OVER HIGH GROUND late on the 25th and increasing chances during Boxing Day and particularly so on the 27th as colder air wraps in around the departing low.

LATEST GFS and ECMWF data…

GFS MSLP & 850mb temp

Snow cover midday Christmas Day

ECMWF MSLP & 850mb temps

Snow cover midday Christmas Day

Arpege

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GFS ensemble

Probability of falling snow midday Christmas Day

The Thursday video below is an updated version of the above!

While snow chances INCREASE late Christmas Day and Boxing Day across the NORTHERN half of the UK, so the mild shall return to even here as more lows pile in off the Atlantic.

The mean position looks to be to the WEST of the UK/Ireland so the southerly door remains open through most of next week.

Any cold will be fleeting and on the rear of these lows.

Also, with a pretty strong jet stream, some of these lows have the potential to become pretty deep and so as well as frequent spells of rain, wind could become a notable feature of the centres get close or indeed cross the UK or Ireland…

I shall have my January 2023 forecast available here on the website next week! Stay tuned!

FEATURED IMAGE CREDIT: Highland Weather

Tags: christmas 2022 outlook, christmas forecast, featured