Cold Spell Looming? Not so much.

January 7, 2012

Weather Forecasts


If you’ve been reading the weather forums in the last few days you’ll see that some people are getting excited about the prospects of cold weather in the next couple of weeks, in fact, there’s been quite a lot of talk of a cold spell moving across the United Kingdom around the middle of the month, but let’s take a look at some of the computer models to see just how likely this is, we’ll start with the NAO and AO forecast charts

Whilst the AO is trending towards a more weak negative which would suggest a weakening of the Polar Vortex, the NAO is forecast to become generally neutral, which would suggest the stormy weather we’ve seen in the last week or so will begin to settle down, we’ve also seen some Starosphere warming over the Arctic which would tend to tie in with a weakening of the Polar Vortex.

Next, we’ll take a look at the 500MB anomaly charts

The chart above shows that the ECM (on the left) and the GFS (on the right) are in conflict with each other at the moment, the GFS is keen to continue with Low Pressure in charge whilst the GFS brings in more settled conditions under High Pressure between days 8-10. The conflict between these two models brings the confidence in the forecast down. Lets take a look at the operational models for the 17th January and compare them, please be aware that the charts below have a tendency to change very quickly.

ECM Model

The above two images show both models for the 17th January, whilst they’re similar in building High Pressure across Scandinavia, the ECM is far more bullish about bringing cold across the UK, whilst the GFS holds back, keeping the cold locked away to our North East. Below is the GFS Ensemble members, and whilst some are trending for cooler weather, there’s not a huge amount of agreement.

So I think, as we go through into the second half of January temperatures will become more average and High Pressure does look increasingly likely to build to our North-East, but whether we can tap into this cold is still questionable, there’s definitely nothing within the models or the teleconnections posted in this article to suggest we’re about to be plunged into a severe, sustained cold spell, if anything, temperatures will return to average with snowfall being limited to higher ground in the North and with a slight weakening of the Polar Vortex thanks to an increasingly negative AO, we’re likely to see less deep areas of low pressure through the second half of the month, too.

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