Has this winter been exceptionally windy?



Has this winter (so far) been exceptionally windy? That's been one particularly popular question over recent weeks. Data from NCEP suggests that for the months of November-December-January combined, mean surface winds have been much stronger than normal, especially across southern Britain and the Southwest Approaches - this is, of course, relative to average and does not necessarily suggest that southern Britain has been any windier than elsewhere in the country - Scotland, for example, is more accustomed to stronger winds than areas farther south, so even if it had been equally windy in Scotland and southern England this winter, there would still be a larger anomaly showing farther south where it is often not as windy.

The graphic below compares the same period with the previous 2 years, and while not strictly speaking 'winter' (which meteorologically is defined as December-January-February) it does indicate that so far this winter it has been much windier in parts of the country compared to the past 2 winters.

Another interesting aspect is that the mean wind direction (the arrows on the maps) highlight that the source of air so far this season has often been from the SW or SSW, i.e. a long fetch of warm, moist air from the Azores or the Canary Islands, and hence why it's often been so exceptionally mild (and damp, or even very wet in some areas). Last winter the mean direction was more of a W or WNW, still relatively mild just not as exceptionally so. The same also applies to 2013-2014 with a mean W or WSW flow from the Atlantic.

Dan Holley  9th February 2016


December 2015: record-breaking warmth and distinct absence of frost

December 2015 will, for many, be remembered by just how exceptionally, and consistently, mild it was - in fact, as the graph below highlights, every single day throughout the month saw daytime maxima above average at least somewhere in East Anglia. The same is also true for November, with the exception of one weekend around 21st-23rd where a brief northerly plunge of cold air saw some sharp frost and few wintry showers in parts of the region.

The mean temperature for East Anglia was 10.0C for December, which is 5.5C above average, making it not only the warmest December on record and smashing the previous record of 7.8C set way back in 1934, but also warmer than any November since records began. A far cry then from just 5 years ago when December 2010 set records for the coldest ever, with a mean temperature of just 0.0C - 4.5C below the average.

The persistent, humid southwesterly flow in December 2015 meant that it was often cloudy, with 83% of the average amount of sunshine hours, but rainfall was close to normal at 98% of the average.

Data: Met Office

Given how exceptionally mild the month was, the distinct lack of air frosts (0.2 days, compared with the average of 10.1 days) meant that the month produced the lowest number of December air frosts on record. In fact, the only time when air temperatures fell below freezing across East Anglia was actually during the early hours of 1st January (but still technically considered 31st December as each day's extremes/totals are measured between 09:00 - 09:00 UTC).

Dan Holley  5th January 2016