This weekend marks the halfway point through winter. Though December brought some snow January has been broadly average – really cold air has been absent with only one air frost recorded this month.
The cloudy, anticyclonic type weather is about to be replaced, however, with cold, polar maritime air this week set to flood down from the north-west.
Since December 1st, Wanstead has recorded 12 air frosts – about average. The coldest night was just -3.7C. The current mean temperature this winter to January 14th is 5.7C with rainfall 111mm – statistics that are remarkably similar to the winters of 2012/13 and 1990/91. Both those seasons were followed by cold late winters, February 1991 saw some of the deepest snow that I’ve ever seen in the south-east; the mean temp for that February finished 1.6C, the 14th coldest in the local series going back to 1797.
Using my method for finding patterns stretching back over 50 years to forecast this winter I picked out years that were +/- 10% of the 2017/18 total rainfall. From these I then weeded out the seasons where the average temperature was +/- 10% of the 2017/18 mean.
This gave a list of just two other winters with similar temperature and rainfall. Both winters had above average ‘snow lying’ days, the long terms average for this area being six.
Before any readers accuse me of going all Daily Express with the title of this blog I would emphasise that this piece doesn’t echo the latest long-term output from the models, which are in a state of flux, caused mostly by the evolution of the explosive cyclogenesis expected midweek. It is simply a reflection of what the local data is telling me.
A 100% guarantee of snow isn’t such a fantastical claim as, during the past 10 years, there is only one winter when no snow fell or was lying at 9am!
In terms of the rest of the winter, outside of the models, I would expect a couple more snowfall episodes, similar to the ones we had in January and February 2013. A repeat of February 1991, while not impossible, looks unlikely – there seems to be far too much energy coming from the Atlantic to allow the all important Scandinavian / Russian high to form and exert its influence far enough west for long-lasting cold and snow.