MeteoGroup – Winter 2016-17 Outlook (December – February)

On average through the next 3 months, low pressure and westerly wind flows are forecast to bring relatively mild and wet conditions to western half of Europe, including UK, France and Germany. Above‐normal temperatures and precipitation from northern Iberia, across France, to the British Isles and western half of mainland Europe.  Mild conditions will also extend northward across Norway and Sweden at times January and February, with Scandinavia more likely to see below normal temperature during December. Colder than normal conditions, on average through the three months, are anticipated for south-eastern Europe, the Adriatic region and southern Italy. Wet weather will tend to prevail over the Aegean Sea and Black Sea areas.

However, confidence in the forecast for winter 2016-17 has reduced over the last month, following the inclusion of the latest round of computer model forecast data also consideration of some conflicting statistical guidance, based on previous years that were most analogous to global weather and sea temperature anomalies observed in October 2016. For example, October 2016 saw strong and persistent high pressure over northern Eurasia and widespread anomalous cold and extensive snow cover over central Eurasia. A signal based only on past years with similar conditions in October suggest that much of central and northern Europe is likely to experience a cold winter. While this signal cannot be dismissed, a consensus of the remaining statistical guidance suggests it is unlikely that any episodes of cold weather over western Europe this winter will be severe or prolonged enough to prevent a seasonal net warm anomaly over western Europe.

Winter 2015-16 was dominated by a strongly positive phase of the North Atlantic Oscillation index (NAO), with above normal intensity and frequency of westerly winds over northern Europe and widespread anomalous warmth for long periods. The only major interruption to this pattern was a 2-3 week period of cold weather over Scandinavia and north-east Europe in January 2016. This coming winter, there is evidence to suggest a higher degree of sub-seasonal change and volatility in weather patterns over Europe, with the NAO index displaying more variability than last winter. This would feature several swings in weather type, from blocking high pressure regions and cold air outbreaks, with reduced wind and precipitation in the north (more likely during early winter) to more progressive westerly patterns with an active storm track from north-western Europe to southern Scandinavia (more likely mid-late winter). The Alps should experience several episodes of above normal precipitation, more likely during the first half of the winter. A few strong wind events over N Italy this winter too.