The GFS countdown to Christmas Day

xmas2412
The op chart for Christmas Day on 24/12 shows the UK split between influence from a low to the north of Scotland and a European high giving a balmy SW’ly . Rain moves up from the SW during the day. Temps in London rising to 13C after a low of 4C. Best chance of anything wintry northern Scotland

The odds for snow on Christmas Day have been shortened for those that live in northern Scotland, reflecting the latest operational model runs that suggest the current mild regime will continue in the south.

 

The operational runs of the weather model GFS began to include Christmas Day in its forecast on December 9. Admittedly T+384 is la-la land in terms of trying to accurately predict what the weather will be like on the day but I thought it would be fun to see how the outcome changes over the next two weeks or so.

William Hill odds for snow on Christmas Day:
9th: London 5/1; Aberdeen 5/2; Edinburgh 3/1; Glasgow 3/1; Newcastle 4/1; Belfast 5/1;  Birmingham 6/1; Norwich Airport 7/1; Penzance 10/1
10th: unchanged. 11th: unchanged. 12th: unchanged. 13th: unchanged. 14th: unchanged. 15th: unchanged. 16th: London 8/1; Aberdeen 7/2; Edinburgh 4/1; Glasgow 4/1; Newcastle 5/1; Belfast 5/1;  Birmingham 7/1; Norwich Airport 10/1; Penzance 16/1.

22nd: London 12/1; Aberdeen 5/2; Edinburgh 7/2; Glasgow 7/4; Newcastle 5/1; Belfast 10/3;  Birmingham 10/1; Norwich Airport 10/1; Penzance 12/1.

23rd: London 18/1; Aberdeen 5/2; Edinburgh 7/2; Glasgow 7/4; Newcastle 5/1; Belfast 10/3;  Birmingham 10/1; Norwich Airport 10/1; Penzance 16/1.

My predicted outcome for London made at the beginning of December:  TMax: 7C  TMin: 1C Moderate westerly 60% chance of rain shower 1hr of sunshine

  • Please note that the outcome will change markedly from run to run, day to day. The best hint of what the weather will be like will be from T=240z (10 days) and, reliably, T+120z. If the pattern is zonal then detail can only start being pinned down at T+72z.|
xmas091206z
5C, variable winds with threat of rain approaching from south-west. Chance of wintry showers Liverpool northwards. Snow On Christmas Day 5/2 Aberdeen Airport 3/1 Edinburgh Airport 3/1 Glasgow Airport 4/1 Newcastle Airport 5/1 Belfast Int. Airport 5/1 Leeds Bradford Airport 5/1 Liverpool Airport 5/1 London Heathrow 6/1 Birmingham Airport 6/1 Dublin Airport 6/1 Manchester Airport 7/1 Bristol Airport 7/1 Cardiff Airport 7/1 Norwich Airport 10/1 Penzance RNAS Culdrose
xmas1012
The operational chart for Christmas Day on 10/12 shows ridging from the south allowing a brief spell of quiet weather. Temps in London a couple of degrees above freezing with frost at night. A flurry possible almost anywhere though east coast most likely.
xmas1112500mb
The op chart for Christmas Day on 11/12 shows a ridge bringing a brief spell of cold, quiet weather. Temps in London about 6C after a cold, possibly frosty start. Dry to start though increased risk of rain from the west later. Best chance for anything sleety probably Glasgow…
xmas1212
The op chart for Christmas Day on 12/12 shows the UK in a col. Rain a possibility almost anywhere but chiefly in the SW and south. Temps in London about 6C and a low of 3C. Best chance for anything wintry probably Aberdeen toward midnight…
xmas1312
The op chart for Christmas Day on 13/12 shows the UK in a returning N’ly regime. Heavy rain spreading in to SW and S. Temps in London about 12C and a low of 6C. Best chance for anything wintry in the far north
xmas1412
The op chart for Christmas Day on 14/12 shows the UK in a returning N’ly regime. Starting dry in the SE but rain spreading in later. Temps in London peaking at 13C after a low of 10C. Best chance for anything wintry in the far north
xmas1512
The op chart for Christmas Day on 15/12 shows the UK split between a returning N’ly regime and a large area of high pressure centred over Switzerland, advecting warm air from North Africa. Mostly dry across the UK with best chance of precipitation NW Scotland. Temps in London peaking at 10C after a low of 7C. No chance of anything wintry, anywhere
xmas1612
The op chart for Christmas Day on 16/12 shows the UK split between a returning N’ly regime and a large area of high pressure over central Europe, advecting warm air from North Africa. A band of rain lies across the UK though dry in the SE. Temps in London peaking at 13C after a low of 11C. No chance of anything wintry, anywhere
xmas1712
The op chart for Christmas Day on 17/12 shows most of the UK in a balmy SW’ly regime, controlled by a strong high pressure over central Europe. Air over the SE is all the way from the Sahara. Any precipitation confined to Scotland. Temps in London peaking at 11C after a low of 8C. No chance of anything wintry, anywhere
xmas1812
The op chart for Christmas Day on 18/12 shows the UK split between influence from a low centred over Iceland and a European high giving a balmy SW’ly . Air over the SE is from northern Spain. A band of rain heralds cooler air from the NW. Temps in London peaking at 11C and falling away during the day. Best chance of anything wintry Western Isles of Scotland
xmas1912
The op chart for Christmas Day on 19/12 shows the UK split between low centred off north of Scotland introducing a cooler NW’ly airstream while south just about hangs on to the European high. A band of rain clears SE early on 25th from the NW. Temps in London peaking at 10C and falling away during the day. Best chance of anything wintry high ground in N England and northern Scotland
xmas2012
The op chart for Christmas Day on 20/12 shows the UK split between influence from a low to the north of Scotland and and a European high giving a balmy SW’ly . Rain moves in from the west during the day. Temps in London rising to 12 after a low of 4C. Best chance of anything wintry northern Scotland
xmas2112
The op chart for Christmas Day on 21/12 shows the UK split between influence from a low to the north of Scotland and and a European high giving a balmy SW’ly . Rain moves in from the west during the day. Temps in London rising to 12 after a low of 4C. Best chance of anything wintry northern Scotland
xmas2212
The op chart for Christmas Day on 22/12 shows the UK split between influence from a low to the north of Scotland and a European high giving a balmy SW’ly . Rain moves up from the SW during the day. Temps in London rising to 13C after a low of 4C. Best chance of anything wintry northern Scotland
xmas2212
The op chart for Christmas Day on 22/12 shows the UK split between influence from a low to the north of Scotland and a European high giving a balmy SW’ly . Rain moves up from the SW during the day. Temps in London rising to 13C after a low of 4C. Best chance of anything wintry northern Scotland
xmas2312
The op chart for Christmas Day on 23/12 shows the UK split between influence from a low to the north of Scotland and a European high giving a balmy SW’ly . Rain moves up from the SW during the day. Temps in London rising to 13C after a low of 4C. Best chance of anything wintry northern Scotland

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Blitz bombs bring more terror to Woodford

The run up to Christmas 75 years ago saw yet more terror in the form of Luftwaffe bombs falling on an already shellshocked population in east London.

The final raid of the year, on the evening of December 8th, saw yet more tragedy befall the borough of Woodford.

wordsworthJust after 7pm a high explosive bomb fell in St Albans Road, killing three people. And at 10.25pm a paramine was dropped on Wordsworth Avenue, South Woodford, killing 14 people and injuring 41.

It was the second deadliest day of the Blitz for the two boroughs which had already endured three months of bombing raids that had left 27 dead and over 100 injured.

The weather was fairly typical for early December, some winter sunshine with a high of 6C followed by a minimum of 2C. Really cold weather didn’t arrive until much later in the month.

Over a period of eight months around 450 bombs were dropped on the two boroughs, killing 129 people and injuring 194.

From autumn to spring in December 1806

When I was writing up my winter forecast I came across an analogue that was very similar to what happened during the period November 10th to December 31st.

mean 1806 v 2015
The period November 10th – December 31st in 1806 and 2015 show some striking similarities. It is also notable that mean during 2015 was 3C higher than 1806. Is this a question of synoptics or a warming world?

 

The results showed a close similarity between the two periods, November 10th – December 31st, though the mean in 2015 was some 3C warmer than 1806. Is this a question of synoptics or is this area now 3C warmer than it was just over 200 years ago?

Rainfall was also remarkably similar: 87.7mm fell from 10/10 – 31/12, just over 5mm more than 1806.

rain 1806 v 2015
The period November 10th – December 31st in 1806 and 2015 show some striking similarities. It is also notable that mean during 2015 was 3C higher than 1806. Is this a question of synoptics or a warming world?

Luke Howard, in his first volume of The Climate of London, describes a very warm December that followed on from a warm November that fooled flora and fauna into thinking spring had begun early.

Howard’s statistics are very high: a November mean of 9.5C while December was 7.2C. CET that November was 2.3C above average while December was 3.3C above average. Considering the England Wales Precipitation series a slightly wetter than average November was followed by a very wet December – over 250% the monthly average.

“The catkins of the filberts expanded prematurely. On December 25th a hedge sparrow’s nest was taken at Doveridge, Derbyshire, with four eggs and near Warwick a green linnet’s with two eggs. It is worthy of remark that the heat was the same on December 24th as on June 24th last – on both those days the thermometer being nearly 60F.”

Howard goes on to describe how the south-west wind had “reigned for weeks” – for most of November and December before finally giving way at the turn of the year.

“The south west wind which had so long reigned yielded just at the close of the year to the north and west . Some frost ensued which, however, had not the characters of permanence being neither ushered in by driven snows nor accompanied with a dry and serene atmosphere.”

The River Lea close to where Luke Howard's laboratory stood by wanstead_meteo
The period November 10th – December 31st in 1806 and 2015 show some striking similarities. It is also notable that mean during 2015 was 3C higher than 1806. Is this a question of synoptics or a warming world?

His description is not dissimilar from what is known as a “three-day toppler” cold spell where a dominant European high briefly gives way to cold air from the north-west or north, bringing often heavy snow to Scotland and the north but just a few cooler days in the south, before the cold feed is cut off as the high re-establishes itself.

Howard also describes how the warmth affected plants.

“The effects of the late high winter temperature on vegetation must have been obvious to everyone who has seen the country. To the very close of the year the grass continued to grow, the daisies to enamel the turf and many of the inmates of our gardens native and exotic to thrive and blossom. Even hyacinth bulbs left in the open beds shot up and flowered. Ten years ago winter came on six weeks earlier and with considerable severity.”

Words that echo what’s going on this month, particularly in the south-west where I’ve heard reports of roses still in bloom and affected by greenfly whiles daffodils look like they will be out in a couple of days.

January and February 1807 were, by the standards of that time, roughly average.

Will Christmas Day 2015 be white in London?

Over the next two weeks speculation on Christmas Day weather will inevitably build. Will Christmas be white or green?

Shoulder of Mutton lake, Wanstead PArk

At this range it is impossible to tell from standard meteorological models though from the 15th, 10 days before the big day and when models can start to be relied upon for at least a general trend, the pieces of the weather jigsaw will start to fall into place.

Latest odds offered by bookies William Hill for a single snowflake at London Heathrow are currently 5-1, slightly shorter than I’d expect at this time of year. With the predominance of the European high I’d expect those odds to start to lengthen.

In terms of proper snow falling and settling, there has not been a white Christmas in Wanstead for over 30 years. In 2010, we could still see the Christmas card Victorian snow scene in small patches if our gardens, but these were leftovers of a previous dump, so it doesn’t count. There has been snow on several Boxing Days in Wanstead (1995 and 1996) and in the weeks running up to Christmas, but not on Christmas day itself. The most typical Wanstead Christmas day weather is mild and dry, although it has rained on 13 of the last 34 Christmas days.

Tree damage by the war memorial in Wanstead High Street by Scott Whitehead

In an earlier blog I had a look at what the last 170 or so Christmas Days in London were like weatherwise and found that snow actually falling on the day is extremely rare. Since 1840 there have been just 19 occasions of snow or sleet falling on the capital on Christmas Day which equates to a probability of just under 11%. If you consider that the last ‘white Christmas’ (see note) was in 1996,  then we are well overdue one.

But the weather doesn’t adhere to human created calendars and behave like it should on any given day. But patterns in any given year can sometimes repeat though correctly predicting they will happen is more down to luck. Nevertheless I’ve had another look at my calculations for this winter and see if there is any way I can make a prediction for Christmas Day.

I firstly had a look at Christmas Day stats overall since 1840. The most common group of maxima in the series is 8.1C and above. This occurred 70 times or 40%. I then had a look at the years that most closely follow this October and November. Ten years were on the list – two saw a white Christmas: 1938 and 1968. Snow often falls before and after Christmas.

xmas 2015So my guess for the weather on Christmas Day this year is for a maximum temperature of 7C after an overnight low of around 1C. With a 60% chance of rain in a stiff westerly wind there is a chance of something sleety falling.

But the fact that 20 per cent of the years in the above series saw a ‘white’ Christmas suggests that, unlike last year which I called right, there is at least *some* chance of snow falling. If you insist on having a flutter, however, Liverpool airport at 5-1 looks most generous.

Going on past form it is possible that Christmas Day will be the ‘changeover’ day for something a bit more wintry as we head into the new year – but it looks like the north Midlands northwards will be the main beneficiary of any of the white stuff

* The definition of a white Christmas used most widely – notably by the bookies – is for a single snowflake, even if it lands in the midst of heavy rain, to be observed falling in the 24 hours of 25 December at a specified location recognised by the Met Office.

** On average, snow or sleet falls in the UK 5 days in December, compared with 7.6 days in January, 6.8 days in February and 6 days in March. White Christmases were more frequent in the 18th and 19th centuries, even more so before the change of calendar in 1752, which effectively brought Christmas back by 12 days. Climate change has also brought higher average temperatures over land and sea and this generally reduces the chances of a white Christmas.

November 2015: Very mild and dull

The final month of autumn was most notable for its warmth and lack of sunshine.

14112015 rain
Rainy days were common through November. This system brought 5.6mm 

The November mean was 10.5C, the third warmest on record back to 1797. Only 2011 and 1994 were warmer.

Just 31.7 hours of sunshine were recorded in this area: 54% of average, the dullest November for 47 years, and 9th dullest in the series going back to 1881

Rainfall was more run-of-the-mill: 64.3mm fell during the month: that’s 109% of average.

The warmest day occurred on the 6th with 17.2C recorded. The first air frosts of autumn were recorded. The lowest temperature occurred on the 21st when the mercury fell to -4.1C.

The wettest day was on the 3rd when 7.5mm of rain fell. There were only three completely dry days during the month – a real problem for anyone who works outside.

photo (8)
The beginning of the month was foggy

The sunniest days were on 21st and 22nd when four hours of sunshine were recorded.

What has December got in store weatherwise? The models today (December 1st) suggest the beginning of winter will be held at bay with most model output keeping the Atlantic in control of the weather – persistent high pressure to the SW, south and SE and a strong jet stream funneled between this high pressure zone and low pressure to the north and NW.

Winds throughout the first 15 days will be blowing from between SW and NW.

Because of the exceptionally mild November I wonder how accurate my long range method will be in estimating December – but in the interests of consistency I’ll have a crack anyway.

A mean of about 5.1C with 70mm of rain, on the wetter side of average and with average to slightly below sunshine. The highest probability is for rather cold at 50% probability. Average 25% and rather mild, suggested in my winter forecast, comes in at 25% probability.

My November outlook for temperature was way off. I predicted a mean of about 9C, rather mild, but the result was 10.5C, very mild. This chance showed at just 6% probability.

Here follows the full weather diary for November. To view full stats follow this link:http://1drv.ms/1kiTuzv

1st Foggy start, lifted to brief sunny spells early afternoon before mist thickened up again and saw Wanstead Flats’ fireworks cancelled
2nd Foggy start. This cleared earlier than yesterday but sunshine was weak
3rd Cloudy start though turned brighter at 10.30am. Spots of rain at 5.30pm then cloud and mild. Rain at first light
4th Rain to start then briefly brighter
5th Cloudy then rain from 2.30pm to 5.30pm. Mild and damp overnight
6th Short burst of rain at 9am then more at 9.45am. Further short bursts of rain but then mostly cloudy
7th Light rain to start, this grew heavier through the morning with quite gusty winds – the first of the autumn. Heavier showers earlier afternoon before the rain cleared at dusk
8th Cloudy with only brief brightness. A light shower in the evening
9th Cloudy through most of the day and very breezy. F6 at Walkie Talkie
10th Cloudy to start and very breezy. Spots of rain at 2pm
11th Cloudy through the day and breezy
12th Sunny start though cloud tended to fill in as breeze picked up from ‘Abigail’
13th Sunny start , gradually clouding over with some sharp gusty showers and a heavy one at 2pm
14th Light rain, becoming heavier though turning patchy around noon. Heavier again at 2pm. Petering out in the evening
15th Bright blustery start, the wind continuing through the day
16th Cloudy start with some initial brightness, then cloudy. Rain when we turned up at 8.45, heaviest at 10.45pm
17th Cloudy up until 1pm when it started to rain. Breeze began to pick up with gusty evening – 33.6mph was strongest gust since St Jude storm – wind moderated after 10pm but remained breezy
18th Sunny, bright start though gradually clouded over as breeze picked up. Some squally showers around, mostly south of the river with rain lashing off side of buildings
19th Cloudy start with light rain spreading in at 10am. Outbreaks of light rain until lunchtime then a heavier shower at 3pm. Then overcast and cooler
20th Cloudy start – this cleared just before 1pm to give sunny spells. NW’ly set in through the day with ever cooling air. Sleet falling at 7am
21st Cloudy with heavy burst of sleety rain at obs time. Sky quickly broke to sunny spells but a very cold wind. A cold night
22nd Sunny and sub zero to start after heavy overnight frost. Sunny spells through the day, the frost returning at 2.50am
23rd Sunny, frosty start with some alto cumulus. Cloud grew thicker with rain before midnight that was light through the early hours
24th Cloudy start but with light rain spreading in from 11.30am then stopping and staying cloudy.  More rain overnight
25th Light rain to start, stopping at 9.40am then cloudy. Temp dropped through the day with sunny spells
26th Sunny start then turned more cloudy at 11am
27th Cloudy start. Some warm sunshine late morning then turned cloudier with strong gusty squall at 7.30pm. Clear spells overnight that led to ground frost
28th Sunny start, clouding over at 10.30am before light rain spread at 2pm and then gusty winds after dark
29th Cloudy and breezy most of the day thanks to Clodagh
30th Cloudy and breezy with occassonal drizzle

London winter forecast 2015/16

Winter in the London area this year is likely to be average overall, following the pattern of the past two winters that saw little snow.

winter 2015-16A rather mild December, dominated by a SW’ly flow with only brief, cooler, NW’ly incursions, will be followed by a rather cold January and average February. Rainfall throughout is likely to be average or slightly above. Probabilities of this scenario are listed in the tables.

The best chance of any snow is most likely to be at the end of January, though given the generally mild pattern it is not likely to last longer than two or three days.

Much has been said about how El Niño will affect this winter. The more hysterical parts of the media tell us we will see a repeat of 2009-10, a cold winter that saw frequent snowfall. But their assertion ignores the fact that other winters following a strong El Niño have been exceptionally mild.

decThis autumn has shown some striking similarities with 1997, a record El Niño year, that was followed by a very mild winter in this area, the third warmest since 1797. This autumn was also similar to 1994 – another El Niño year – followed by the fourth warmest winter on record.

But just as you think the pattern is the same the El Niño this year is different in that it is an El Niño Modoki – a full-Pacific basin El Niño that differs from the one in 1997. In other words we really are in unfamiliar territory.

janSo before I get too bogged down in finding teleconnections with El Niño, perhaps it is wiser to go back to more traditional ways of trying to predict the coming season.

Before I trawled through the figures my initial gut reaction to this winter was that it would be mild – because of some blocking in September/October.

febAs well as my method of using rainfall and temperature I also considered other methods. One, of which I see mentioned very little these days, was Russian research that states that the weather pattern in the winter will be the opposite to the weather on September 17th and November 7th. This autumn September 17th was NE’ly and November 7th was SW’ly. So, of little use this year.

You can read the method 0f how I reached my conclusion here.

DJF max
This chart shows that the coolest spell is likely to be around January 27th