For us here in western Europe, we’re entering a classic benign pattern with a calm end to the cold spell as ridging warms the mid and upper layers. The warming arrives across the northern Republic, N Ireland and Scotland initially with damp weather while still beneath the cold air, England remains cold again tomorrow but eventually the warming transfers down the surface and we’re back to around average across all parts by Wednesday.

While high pressure continues to build into the UK, so a reinforcing shot of arctic air descends over Scandinavia all the way to Italy bringing a shot of cold and snow. The cold and likely the snow too, should expand over central and eastern parts of the continent this week as low pressure develops at the base of the cold trough. Look for additional heavy snow across the Alps and likely over much of Germany in the next 7 days.

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This somewhat quieter and reserved pattern we’re entering is no surprise as I had forecasted a relaxation of any late November cold with the NAO/AO flipping back positive. Indeed the AO appears to be returning to a strongly positive state which should help build the cold over the pole once again while the NAO looks to go more neutral. That suggests a return to a more zonal or west to east flow but it appears we sit right along the boundary between mild and rather cold air, so although you may think a west-east flow would be mild, it of course depends upon where you sit beneath that flow and it looks like we swing between mild and cold over the next couple of weeks.

I’ve stated since all the way back to August that the first half of December could remain relatively mild and that looks increasingly likely. However, I want you to watch what’s going on in other parts of the hemisphere because this can provide insight as to what we might expect further down the road.

I believe the next spell of -NAO/AO will be the real deal and although there’s no real suggestion of any real locked down cold pattern in the west over the next 15-20 days, one must look out as we’re seeing a tremendously cold end to the month across the eastern half of North America. That cold looks to keep charging from Alaska to Georgia over the next couple of weeks and perhaps once their pattern moderates, one must look towards Europe. Of course the feedback of ocean to atmosphere becomes more crucial as we enter December and the overall atmosphere enters a more winter-like state.

Once we see major cold developing in the upper atmosphere, so the response of the ocean heat content becomes more apparent. Since early October we have witnessed 3 -NAO episodes and three cold troughs into Europe. Each time a trough has come south, so we’ve see the trough and ridge go further and further west. The ridge will head for the warmest SST;s while the trough heads for the wettest soils and coolest SST’s. Well the UK soils are wet and waters surrounding the UK are cooling. If you look at the current global SST anomalies, you’ll notice the warmest waters in the North Atlantic are now centred over the Davis Straits.

Let’s just wait and see what happens with the next -NAO/AO which I suspect will return sometime mid-December.

Here’s the latest ECMWF surface charts through this week and note the ridge largely dominates the UK with weak systems riding the northern periphery across NI and Scotland, better weather is to be had over England and Wales.

Below is the chart for tomorrow and you can see the ridge continuing to build in but notice the lower thicknesses nearer the centre while milder air makes it to the surface along the northern edge where WSW winds are fresher and able to erode the cold, dense air.

Tuesday, Wednesday and even Thursday shall see largely settled conditions with bright or sunny spells and milder air over England and Wales but by Friday a stronger Icelandic low should drop a cold front south over the UK and eventually the western mainland of Europe bringing chillier, wetter and windier weather which somewhat deflates the ridge.

Notice by Saturday that the same system drops into the trough already established from Norway to Italy, this system drops south to the east of the UK pushing the ridge further out into the Atlantic. This setup provides a cold, unsettled northerly flow with plenty of damp, blustery conditions from Ireland through Denmark into Germany with some snow in places.

Once that system drops into the base of the trough, look for more heavy, flooding rain, gales and mountain snow over southern Europe while the ridge tries to once again rebuild into the UK.

Here are the latest NAO/AO ensembles from the GFS and you can see the largely neutral NAO which supports a more west-east upper pattern next week with the AO returning to a strong positive state. This is good because it once again gives the arctic a chance to reload once again.

Here’s the ECMWF 500mb and 850 temps and notice the flattening of the upper flow but there’s a fine line between mild and cold.

192 hrs

By 240 hrs we flirt between the two contrasting air masses.

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Tags: arctic oscillation, europe cold, europe weather, ice, long range forecast, north atlantic oscillation, snow, uk weather, UK Winter Forecast