Tag Archives: wanstead

Halfway through winter: where’s the snow (again)

Five years ago I blogged about the lack of snow at the midway point through winter. This winter there has been a similar total lack of snowfall though this time it is benign anticyclonic conditions that have characterised the past 45 days rather than the raging zonality of the winter of 2013/14 which ended completely snowless in this area.

A look at the statistics reveals that the midway point of winter is the mildest for 3 years and the 6th mildest since 1960. There has also been around half the rainfall that we had to this point in 2018. Sunshine is similar and below average.

Since December 1st, Wanstead has recorded just 7 air frosts – 5 fewer than last year. The coldest night was just -2.5C. The current mean temperature this winter to January 14th is 6.9C with rainfall 60.6mm.

Further scrutiny of stats for the Wanstead area reveal few years were similar to this winter. Using my method for finding patterns stretching back over 50 years to forecast this winter I picked out years that were +/- 10% of the 2018/19 rainfall total. From these I then weeded out the seasons where the mean was within +/- 10% of the this year. This gave a list of three winters with similar temperature and rainfall.

50%

The other winters weren’t anything special with ‘snow lying’ days below the median for this area of six.

nevis
Snow go: just patches of snow were visible on the upper runs of Nevis Range at the weekend on Jan 12th

As I write there are signs that the weather is going to turn colder this week. Whether it will be cold enough for snow remains to be seen though the ECM model is hinting at a rise in pressure around Greenland. A situation that *could* be conducive for something colder long term.

In summary, the probability at this point of at least one fall of snow before the end of February could be put at 100 per cent. Whether it will be abundant or merely a dusting is impossible to tell.

Elsewhere in the UK it has been similarly lacking in snow. During a visit to Fort William at the weekend locals told me that there has been no significant snow since October / November and that even frosts were few and far between. The lifts around Nevis Range looked forlorn against a green backdrop. And it wasn’t until I got to the summit of Ben Nevis and Aonach Mor that I saw any of the white stuff.

 

 

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A winter drought

Rain today (January 16th) is the first meaningful fall since before Christmas, putting an end to the 23-day long dry spell.

This meteorological drought, rare given that it spanned Christmas and New Year Storm singularities, these having 84 and 86 per cent probabilities respectively, was the 3rd equal longest winter drought.

The only other similar droughts in a list that dates back to 1887 were 19/12/2008 – 03/01/2009 and 17/12/1972 – 02/01/1973.

winter droughts

The last precipitation I recorded was from a weak occlusion that followed a cold front on the evening of December 23rd.

This synoptic set-up was followed by a build in air pressure that peaked on the morning of January 3rd; 1043.8mb was the highest reading in this area for at least 10 years and is the highest pressure I have measured.

A fuller version of London droughts in all seasons can be found here.

Winter proper to arrive mid January

Weather models are continuing to struggle in the aftermath of the stratospheric sudden warming on January 1st. The GFS and ECMWF have flip-flopped: on one run decent northern blocking extends southward only for the dreaded European high to appear on the next.

Using a combination of QBO and ENSO data featured in my winter forecast and statistics from previous SSWs (including 2013 and 2018) achieved the following results shown in this graphic.

jan max

Although some days in the next week or so will be cold it is not until the 14th that conditions start to bite, the start of a week-long cold spell that will probably be more notable for cold than snowfall.

The rapid recovery in temperature would suggest that the Azores / European high making a return. With the MJO moving back and forth between phase 7 and 8, and looking at the behaviour of previous cold spells, this would make sense.

14th
The GFS has been churning out some very strange charts of late

As for February, unless there are further SSWs to disrupt the polar vortex, and depending on its recovery, it is unlikely we will see a repeat of the winter of 1984/85 that I hinted at last month. The graphic below, however, would suggest another cold spell in the third week of February.

feb m

 

 

Wanstead Weather: 2018 review

This year finished as the 7th warmest on record – some 0.8C warmer than the 1981-2010 average.

Only two months of 2018 were more than 1C below – the means of April, May, June and July were at least 2C above average.

Rainfall was less remarkable with the year finishing 97 per cent of average. The total of 584.4mm puts it as the 81st driest since 1797, just over 20mm wetter than 2017.

It was a sunny year with 1,641 hours of sunshine recorded. That’s 111 per cent of average, the 23rd sunniest since 1881.

weather stats 2018

 

mean 2018

rain 2018

sunshine 2018

For a review of each month, click JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember

You can read the national review of weather events at the Met Office blog here.

 

 

 

 

December 2018: average and benign

December was most notable for benign weather, totally in contrast to last December which saw snowfall.

The mean temperature finished 7.3C, 1.7C above average, the mildest December for three years though still over 3C cooler than that record breaking December

Some 60.4mm of rainfall was recorded, 114 per cent of the 1981-2010 average, over 20mm less than last year.

Some 39 hours of sunshine were recorded, that’s 97 per cent of average, duller than last year.

Five air frosts were recorded though only one was colder than -1C.

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

Summary for December 2018

Temperature (°C):
Mean (min+max)   7.3
Mean Minimum     4.4
Mean Maximum     10.1
Minimum          -2.5 day 24
Maximum          15.5 day 2
Highest Minimum  11.5 day 06
Lowest Maximum   4.1 day 14
Air frosts       5
Rainfall (mm):
Total for month  60.4
Wettest day      11.4 day 20
High rain rate   20.1 day 20
Rain days        14
Dry days         17
Wind (mph):
Highest Gust     26.6 day 21
Average Speed    3.0
Wind Run         2223.4 miles
Gale days        0
Pressure (mb):
Maximum          1036.8 day 31
Minimum          980.4 day 01
Days with snow falling         0
Days with snow lying at 0900   0
Total hours of sunshine        39.0
december 2018

A third of winter gone…

…And not a flake of snow. There’s been lots of talk about how an SSW will eventually usher in a cold January and February but it is by no means guaranteed.

The average maxima for this December will finish 10.2C, precisely the same as December 1985. Other Decembers that finished close to this average maximum are shown below.
As you can see apart from the middle of the month the temperatures are all over the place. And so are the conditions that followed in January and February.

december all.PNG

A closer inspection of every year reveals that just three were very similar to 2018: 1974, 1986 and 1988.

748688.PNG

Again, there’s plenty of spread. The 500mb reanalysis charts below show the situation of the northern hemisphere on December 31st of each year, including this year.

What followed in January 1975, 1987 and 1989?
January 1975 in this area was the warmest on record, back to 1797, while January 1989 was the 12th warmest. Conversely, January 1987 saw one of the coldest spells on record.

Perhaps it is fair to say that there is a 66 per cent chance of a very mild January, though you cannot discount the 34 per chance of another January 1987…

 

Heading for a 1984/85 style winter?

With talk of an imminent statospheric sudden warming (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: mean maxima is within 0.3C of 1984 while rainfall is virtually the same at around 30mm!

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, on a par with 1979 and 1987. A more recent January that was just as cold was 2010.

Indeed, the winter of 1984-85 was among the snowiest of the past 70 years, ranking at number 5 in my survey of winters.

1984-2018.PNG

een

A white or green Christmas 2018?

The GFS model is now within range of the big day on the 25th. From now until Christmas Eve I will be having a look to see what is on offer.

The first operational run suggests something of interest but please bear in mind there is a long way to go yet. While operational runs are often exciting, the below suggests a potent northerly with snow for many, the right hand average is much more realistic though admittedly boring.

My own guess at this stage is for something benign, a high of 6C with a low of 2C, perhaps some frost early or late on?

10th: Op run this morning is showing quiet weather. A high of 4C after overnight frost.

11th: Op run now shows a slack north-easterly and possible snow.

13th: An anticyclone to the north of Scotland continues to keep things seasonal on the op run this morning. The average again benign.

14th: More interest on today’s midnight run. The op shows a cold pattern. Frost early and late and a high of 2 or 3C. A chance of flurries. Even the average looks less mild!

15th: The interest of yesterday has faded. Not terribly mild but not cold either. Xmas morning starting chilly, 6C with rain in the evening, a warm sector bring the temp up to 10C in the evening. The average suggests something similar.

17th: All change again on the op run today with an Atlantic ridge with plenty of cloud. High 7C Low 4C. Gloomy. The Average less settled…

18th: The op this morning suggests the 25th will be something of a changover from the present regime to something more settled. The op chart suggests a temperature of 9C day and night though perhaps the reality may see some frost late on in the day.

20th: It’s looking quiet and calm.

21st: quiet and calm.

 

You can find out what every Christmas Day in London was like weatherwise here.

 

 

The green lung of Wanstead

The tree canopy cover map on the Mayor of London’s website reveals just how blessed Wanstead’s inhabitants are in terms of clean air relative to the proximity of the City.

Those living closest to the junction of Wanstead Park Avenue and Northumberland Avenue benefit most from Wanstead Park, Wanstead Flats and Bushwood.

green lung

city green lung

November 2018: average and rather sunny

November was most notable for the amount of sunshine. Some 79 hours were recorded, that’s 135 per cent of average, the sunniest November for two years.

The mean temperature finished 8.4C, 0.4C above average, the mildest November for three years.

Some 72.5mm of rainfall was recorded, 122 per cent of the 1981-2010 average, the wettest November for two years.

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

november 2018