I am becoming increasingly optimistic and excited about the end of December, beginning of January period as the models keep showing what all winter lovers want to see, a -NAO/AO with blocking highs over both Alaska and Greenland which hook up resulting in twin negatives underneath.

IMAGE CREDIT: William Smith

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Up till now we’ve seen a COLD Atlantic pattern with mean flow coming in from the northwest. 2 days of mild AHEAD of the front is followed by 3 or 4 cold days on the backside with plenty of snow showers piling in. Those snow showers have been impressive over Highland Scotland with a snow depth of 15cm built up at Aviemore. Even the higher parts of LOWLAND Scotland have seen a few days on light snow cover and let’s not forget parts of England, Wales, Northern Ireland and Ireland. That’s with a firmly positive NAO/AO but get that index negative, look out!

This week looks to be a ‘less extreme’ version of last week. Cold start with high pressure then in comes the next low and it’s warming west winds mid week only to be followed by more cold northwest winds accompanied by snow showers to end the week.

This setup looks to continue all the way to Christmas Day but by then, I recon we’re seeing the northward build of heights over the Atlantic which slows down the westward warm-cold train and eventually the cold takes over as the Atlantic shuts down. That’s me going by the models which have become consistent with this outcome.

I’ve always pegged January and February for the worst of winter and going by what I’m seeing, I’m becoming increasingly confident that December will turn out near to slightly below average with a below average January and February for not just Ireland and the UK but near continent also including Denmark and SW Scandinavia.

Will There Be A White Christmas?

The ECMWF shows this surface setup for Christmas Day. Snow showers possible in the North.

GFS is warmer but is followed by the same scenario as the ECMWF a day later (Boxing Day)

Boxing Day

The jury is still very much out!

While we all want a White Christmas, my attention is really more on the period between Christmas and New Year as Hogmanay looks more likely to be white and cold as the blocking to the northwest may be much more established.

Here’s the GFS 500mb 7-day mean 500mb height anomalies for this week and next. Notice the difference between the front running 7 days with milder westerly flow and next week which shows the strong positive building northward to our west!

Here’s the broader view. Note exactly where that high pressure core is situated! This would support a deeper trough for western Europe, more similar to what it has over the US.

GFS ensemble day 7-14

slightly more amplified day 9-16

EPS control day 7-14 is similar to the GFS only it has the positive further east over the Atlantic with less amplification but it’s got the same overall picture.

Looking at the broader picture we see the block core over the same place, perhaps extending further into Canada.

The above charts are going right to the analog based on the ENSO index next 30 days! Via Michael Ventrice.

Check out the 700mb CFSv2 forecast for January and February!

The dots are joining. If this doesn’t come off, I will be amazed!

See video for more.

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Tags: arctic oscillation, north atlantic oscillation, polar stratosphere, snow, stratospheric warming, UK Snow, uk winter, White Christmas