February
February is probably the most difficult month to forecast. At this point there are indications that the Scandinavian block is likely to become re-established. If the stratospheric polar vortex is yet to reform in the lower part of the stratosphere, then the possibility remains that a further cold outbreak is possible as cold continental air will never be too far away. In fact, if it does then the possibility remains that any cold spell in this month could deliver the coldest conditions of the winter. This scenario can be highlighted by looking at the 500hPa anomaly chart below:
However, if the stratospheric vortex is gaining strength at this time, then initially settled conditions should prevail before the westerlies become re-established.
Overall the temperatures will be around average and the month is likely to start be drier than average as any early cold spells are likely to be countered with later milder weather and more rainfall expected towards the end of the month.
Winter Overall
Overall, we are likely to see a winter that starts off slowly, but gains momentum as the stratospheric vortex is destroyed by tropospheric wave activity. This will significantly increase the risk of a cold and snowy spell in the heart of winter, which will then slowly fade as the stratospheric vortex slowly recovers.
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