A White Christmas?

Possibly! That is the answer! As we move closer to the festive season, it's looking more likely that we will see a return to the bitter cold patterns we have seen over the past few weeks, with the possibility of Atlantic blocking through January which will mean sustained and bitter cold, for many weeks to come. From today, we start to see a very slight warm up until around Saturday. Temperatures will still only be around 6c by day, and followed by Frosts overnight. From Saturday, that is when the fun and games start as temperatures begin to fall away again. As we enter the new week, we will see firming up of the weather patterns, but for now take a look at this;

The Arctic oscillation chart, to put it simply, when the lines go above the centre line, it is positive and below the line, negative. I have highlighted the charts position during the current/last cold spell, and as you can see, it was negative. Strong negative indicates cold Arctic conditions from a High pressure, Northern blocking, that prevents the usual Atlantic patterns of weather in the UK. The steeper the negative, the stronger the block, the colder it is for us. As you can see from the forecast line, it is possible the negative will be even more intense than recently, indicating a strong pattern of sustained cold that will take some shifting! If this was to happen, be prepared for more record breaking low temperatures, and more Snow.

The chart you see above is the AO archive. The red indicates a positive AO year, the blue a negative one. The past two Winters, and now this one, have provided us with very cold weather and Snow. As you can see, the AO has been negative. Looking at previous years, you can identify the level of Atlantic driven years we have had. As you can see, as we enter 2011, the AO is forecast negative again, but how low will we go? Exciting times ahead :)