Yuletide and winter

Christmas was green this year. I watched the GFS weather model ebb and flow toward a correct forecast at a few days out. The conclusion of settled and cool weather was not a million miles different from what the model suggested conditions would be like at 15 days out.

Yuletide weather since the 1840s Christmas in Victorian London is often portrayed as very cold and snowy – picture perfect images of Yuletides past always scream out at us every year we open a box of Christmas cards. But a look back through the meteorological records of the Royal Observatory at Greenwich reveals a very different reality.

Winter Index Snow is a very rare commodity in lowland Great Britain – even rarer in the Home Counties, and in our part of east London.  This regional study of snowfall uses data from the Met Office’s now defunct Snow Survey of Great Britain. and using a winter index attempts to rank every winter since the record-breaking snowy one of 1946/47.

Winter forecast 2018-19 My annual winter forecast, made on December 1st, suggests there being a general cool down through December with a cold spell starting just before Christmas into the new year? And another cold spell end of January into the first week of February? Though it is impossible to gauge weather on any particular day the trend so far is promising.

The most potent cold spells since 1960 Cold weather can be very variable. In this blog I’ve considered spells where the maximum didn’t exceed 2.8C. The results spanned from the cold spell of March 2013 to the mammoth 31-day Siberian blast that began on Boxing Day 1962.

Heading for a 1984/85 style winter? With talk of an imminent SSW I thought it would be interesting to have a look back at previous SSWs and see what precedents could be found. December so far is showing similarities with 1984. During the winter of 1984-85 the polar vortex split on January 2nd, setting up that month to be among the coldest of the 20th century.

Centuries of London fogs: while the pea soupers of the past no longer plague the capital the conditions that allowed them to form still occasionally materialise, vastly impacting the air quality.

The last Thames Frost Fair: In 1814 the Thames froze over to a depth that was thick enough to allow the population to hold festivities on the ice. Meteorological readings from the season compare well with the winter of 1962/63.

When the River Lea was a mile wide: mention winter and most people will think of snow and ice. However, the season can also bring days of heavy rain. And when a period of heavy rain struck immediately after a cold spell in January 1809 disaster struck.

Colin Finch’s 38F rule: if the maximum temperature is 38F (3.3C) or less for four consecutive days before Christmas Day there is a very good chance that the following winter will be very cold.

-20C in east London: in February 1816 perfect radiation conditions over thick snow enabled Luke Howard to record -5F

The January 1987 cold spell The mercury plunged during this Siberian blast with central London recording a maximum on the 12th of only -5.5C.

The February 1991 cold spell Unusually deep snowfall in central London. The 20cm recorded at St James’s Park on the 8th was the greatest cover recorded at the site since the severe winter of 1962/63.

Record cold pools and snowfalls 1987 and 1991 saw very cold air flood in from the continent but there’s been far more incidents over the years.

Beast from the East, part 2: this spell followed on the heels of the original severe spell that began at the end of February 2018. There’s also a history of March cold in this blog.

London’s monthly winter extremes since 1959: December, January, February

Alpine snowfall variability: Snowfall in the Alps has been poor in recent seasons. Though the range has definitely warmed the variability and ebb and flow of the climate means it is impossible to say with confidence that by the end of this century the slopes won’t be covered in the white stuff.

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Meteorology-based musings about east London and beyond

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