Longest winter ‘heatwave’ since 1959

With the return of more seasonal temperatures February 2019’s heatwave already seems like a distant memory.

Looking back at the stats for this area the past eight days have seen an average anomaly of 7.7C, beating the previous eight-day long warm spell of December 2015, which returned a mean anomaly of 7C. That spell was quickly followed six-day long warm spell that had a mean anomaly of 6.6C. There appears no chance of the heat returning any time soon.top 5 winter heatwaves

Wanstead missed out on breaking the February high temperature record. While Kew Gardens recorded a high of 21.2C, the local area reached just 18.7C, falling short of the record of 19.7C set in 1998.

St James’s Park, our closest official climate station, set a new top 3 of TMax values. , as did Heathrow.

 

Diurnal temps present a clothing challenge

The erratic onset of spring in some years often presents that problem of what to wear every morning. During the current warm spell I’ve seen all manner of attire on the school run; everything from T-shirt and shorts to full winter regalia topped off with hat and gloves.

The position of the sun is now bringing in to range the season when the gap in temperature between day and night can be at its greatest.

On Saturday (23/2), virtually unbroken sunshine and ‘thick’ air saw the temperature in Wanstead peak at 16.1C before clear conditions overnight saw the minimum plunge to just 0.2C. The gap of 15.9C represents the fourth highest diurnal temperature range for February in this area back to 1959.

feb diurnal
Top 10 February diurnal temp ranges

 

Looking at the year as a whole the greatest range is 20.8C with the months of May and June the most likely to see the condition.

top 10 diunrals
Top 10 diurnal temperature ranges since 1959

 

Gertrude, Fionn and Erik were all bluster

Since the Met Office introduced its system of naming storms at the beginning of the autumn season in 2015 the effects felt in the capital have been fairly limited.

Introduced partly in response to the devastation caused by the St Jude Storm in October 2013 every wind storm since has failed to live up to the hype, at least at a local scale.

Woodford Green tree
This tree at the side of the road in Woodford Green was a victim of the St Jude Storm in 2013

Of course many storms have caused major disruption elsewhere, not least Storm Desmond, floods from which devastated Glenridding in the Lake District.

But closer to home many of these storms have been marked simply by a higher than average ‘wind run’, the number of revolutions of this weather station’s anemometer.

The windiest days in this locality coincided with Storms Gertrude, Fionn and Erik but these were minnows compared with St Jude and the most recent devastating storm in living memory, the Great Storm of 1987.

The graphs below also highlight the ongoing problem of naming storms in that some of the windiest days in this area occurred when there was no named storm.

The windiest day in the dataset was June 6th 2017 when a low pressure system saw Force 9 winds recorded in the Channel. Locally the day was very blustery and trees that were in full leaf were blown down.

met office storms

storm season 2015-16

storm season 2016-17

storm season 2017-18

storm season 2018-19

 

An erratic season for snow in the Alps

Earlier this winter there were many reports on how good snowfall had been in Austria. But on closer inspection it was clear that the weather pattern at that time only favoured certain resorts.

In contrast with last year the totals I’ve used in my cross section of the range don’t look that exciting; Bourg-St-Maurice, the jumping off point for Savoie resorts including Les Arcs and Val d’Isere, has recorded 96mm of precipitation this season, in stark contrast to the 433mm it recorded last season between Christmas Day and February 5th.

In Switzerland Arosa, a resort well placed to pick up snow from any direction, has recorded the same this season as last. Totals in Davos are well down on last season. Similarly San Bernardino has recorded about half the amount of precipitation than it did last season. Its location toward the southern side of the range has been sheltered from the prevailing winds this year. That said it did enjoy a big dump last week.

Going further south and east St Vallentin in Italy has recorded about a third what it did at this stage last season.

Mean temperatures overall are about 2C to 3C lower than they were last season.

snowmap update
30-day precipitation totals reveal that Bourg St Maurice recorded just 96mm, compared with last year’s 433mm while Obertauern in the east recorded 77mm, compared with 106mm the same period last year

 

A winter heatwave

It is 21 years ago this month that London and most of the southern half of the UK experienced a remarkably warm spell of weather during what had been a mild winter.

The spell, which saw the record warmest February day on the 13th (19.7C), satisfies the Met Office’s old criteria of a heatwave whereby the maximum temperature is 5C or more above average for five consecutive days.

While these spells are fairly common in summer they are very rare during a meteorological winter. During the last 60 years the only other periods to have experienced a heatwave in winter are December 1966 and 2015.

Weather charts for this week look remarkably similar though, according to the latest forecasts, values will be nothing like they were in 1998.

Since this was published this 2019 spell has satisfied the Met Office criteria. But the anomalies are not yet as impressive as 1998.

1998 2019

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feb 1998 maxes

 

 

Days in Wanstead Park, 200 years apart

During a miserably cold and wet stroll around the golf course in Wanstead Park I happened upon the remains of Wanstead House – basically a deep excavation where the basement and kitchens once were.

As a freezing cold mixture of rain, sleet and snow fell, gradually thawing the remnants of last night’s snow, I wondered what the weather was like when this magnificent building last stood. Luke Howard’s entry in The Climate of London revealed that the weather on this day 200 years ago was remarkably similar.

WP weather

As I stood and tried to imagine what the house must have looked like it occurred to me that 200 years is a mere blip in time in the history of the Earth. People come and go, buildings rise and fall but the weather goes on and on.

* There’s a fascinating extract on Wanstead from James Dugdale’s The New
British Traveller (1819) that you can find here.

** This video clip shows the site where Wanstead House once stood.

 

January 2019: rather cold, dry

January was most notable for being on the cold side, in contrast to December.

The mean temperature finished 4.1C, 1.1C below average, over 2C colder than last January.

Some 32.9mm of precipitation was recorded, 62 per cent of the 1981-2010 average, about half what fell last year, the driest January since 2006

Some 55 hours of sunshine were recorded, that’s 109 per cent of average, sunnier than last year.

Fourteen air frosts were recorded.

There were four days where snow fell but only one day of snow lying, 1cm on 23rd.

To view full stats follow this link:http://1drv.ms/1kiTuzv

My winter forecast went a bit awry in December – I predicted a mean of +0.8C, the outcome was +1.7C. January has been much better, I predicted -1.2C, the outcome is -1.1C! Also… “And another cold spell end of January into the first week of February?”
For February I predicted a mean of -1.7C. The current pattern to continue and signs on the EC of a more robust cold spell with air supplied by a Scandinavian high?