Netweather forecaster 'Brickfielder' - views 26th October 2007
My initial ruminations on the winter weather outlook are that there are a number of competing weather patterns each becoming dominant at different points as we go through the winter.

In other outlooks very little has been made of the record arctic ice melt during this summer and I think this has a part to play in our early winter weather. Ice will be slow to build in the Bering Sea and towards north Alaska which in turn will slow down any cold build up in those regions. This I think will reduce the temperature gradient across the north Pacific for the early part of winter although we should take into account the anomalously warm waters in the region. This will give a weaker jet and possibly less stratospheric wave driving. This is likely to push any cold arctic high more towards Greenland with its associated circling lows more likely to cross the UK once cold begins to build across Greenland.

Every model and every forecast I have seen for this winter has made a big deal out of the la Nina pattern. This will be a big influence not least because the GWO (global wind oscillation) will be in stage 1 with significantly reduced relative atmospheric angular momentum. This means as a whole signals for change may be weak due to la Nina. The type of weather we should expect is a trough over central or Western US with an Azores high generally pushed just to the east or over the UK. Dry grey mild comes to mind much like our current weather which I think will come and go as a background pattern as we go through the winter.

A different pattern relates to the interaction of the Asian summer wet monsoon and the East Asian winter monsoon. It is recognised that slightly wetter summer monsoons like this year tend to produce weaker and drier winter monsoons by nature of soil moisture affecting the build up of the Siberian high. This means that for the early part of the winter the Siberian high pressure is likely to be weak or displaced. This could bode quite well for an easterly across Europe during December bringing cold across North Africa, Italy and Spain. This pattern will also tend to weaken somewhat the la Nina pattern. Once cold really begins to build across Siberia the effects will diminish.

SST's (Sea Surface Temperatures) across the west Pacific and Indian Ocean are quite warm and we should expect some convectional activity as a result. Warmth building in the northern Atlantic and Pacific will need an outlet in terms of cyclogenesis and we should expect a period of storminess as the arctic finally starts to build cold and starts to meet these warm seas. My guess would be January into February for storminess although this will still be with the background la Nina grey and dry pattern.

The Easterly QBO this year is favourable for breaking rossby waves to drive stratospheric waves causing warmings. My feeling is that some potent storms during winter will trigger an early end to the polar vortex this year with a marked period where we have a fairly blocked pattern during late February into March.