Tag Archives: wanstead

November 2019: coldest for nine years

The November monthly mean finished 6.4C, that’s 1.6C below average, the coldest November since 2010. It was the third month of 2019 where the monthly mean temperature finished below average.

The wet theme of October carried on into November; the 68.5mm collected was 116 per cent of the 1981-2010 average, slightly drier than last years.

Some 59.7hrs of sunshine were recorded, 102 per cent of average, the dullest for four years.

There were six air frosts.

You can find my thoughts on how winter is going to pan out here.

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

nov t.PNG

Summary for November 2019 – to follow

London winter forecast 2019/20

For this year’s winter forecast, because of time constraints, I am sticking purely to what the local analogues reveal.

Meteorological autumn was the wettest for 18 years and the coolest for 6 years, revealing some interesting similarities with past climate. Considering data back to 1797 I was able to make the following suggestions on how the next 90 days may unfold.

December is most likely to be on the cold side with rainfall slightly below average.

January is most likely to finish average temperature-wise and wetter than December.

London’s February extremes temperature also look average overall and the precipitation signal also creeps up in comparison to the first two winter months.

Best chance for snow? Impossible to pin down but the coldest weather is likely to be at the beginning of February, the third week of January and just after Christmas.

The warmest period looks to be around January 10th while there’s also a signal for that often phenomena of milder temperatures just before Christmas day.

Most of the probabilities in the above statements are relatively low and are explained in the table below.

Mean temperature 2019/20

December January February
1981-2010 average 5.6 1981-2010 average 5.3 1981-2010 average 5.3
Forecast median 4.4 Forecast median 4.7 Forecast median 5
Rather cold 40% Normal 40% Normal 44%
Normal 28% Rather cold 32% Rather cold 32%
Mild 20% Very cold 12% Mild 16%
Cold 4% Mild 12% Cold 4%
Very cold 8% Cold 4% Very cold 4%

 

Rainfall 2019/20

December January February
1981-2010 average 53.2mm 1981-2010 average 55mm 1981-2010 average 40.1mm
Forecast median 48.3mm Forecast median 55mm Forecast median 40mm
Wet 32% Wet 32% Wet 36%
Normal 20% Normal 28% Normal 36%
Dry 48% Dry 36% Dry 28%

Months of perpetual cold

It’s been a while since this region has seen a sustained colder than average period. Though the past few weeks have seen colder than normal weather we have to go back to the beginning of 2015 where at least three consecutive months were colder than the 1981-2010 average.

The spell, which coincided with winter, was unremarkable with just one day of lying snow. The season finished 55th out of 73 of the most recent winters,  the anomaly for the 90-day period was -0.3C. For deep, lasting snowfall events a monthly mean temperature must be at least 2C colder than average.

For anything ‘snow-worthy’ you have to go back seven years to a 10-month long colder than average spell that began in September 2012 and coincided with probably the last winter I can remember that had more than one cold spell with snow that lasted longer than a few days. The average mean for this spell was -1.3C.

The most potent cold period occurred during the winter of 1984/85, a winter where snow lay nearly a foot deep by the end of January and where seven ice days were recorded – these days we’re lucky to record just one ice day per winter! Only just behind was the 3-month period January to March 1987.

As with previous blogs I have devised a way of ranking these cold periods, by dividing the mean with the length in months. The first nine months of 1986 achieved the highest ranking, a period that included the 5th coldest February in this area since 1797.

rank

And in chronological order…

chron

cold month index

It is looking like the mean this November will finish below average, making it the second month in a row, something that hasn’t happened since March last year. Will December make it three in a row and a new addition to the list?

 

October 2019: wettest since 2004

The wet theme of the final week of September carried on into October; the 100.3mm collected was 150 per cent of the 1981-2010 average, the wettest 10th month for 15 years.

The monthly mean finished 11C, that’s 0.8C below average, the coldest October since 2012. It is only the second month of 2019 where the monthly mean temperature finishes below average.

Only 72hrs of sunshine were recorded, 68 per cent of average, the dullest October since 2002.

The area’s first frost arrived 10 days before the median date back to 1959. And 3 days earlier than last year. A shower with >5mm hail was observed on the 9th.

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

oct max

Summary for October 2019

Temperature (°C):
Mean (1 minute)  11.5
Mean (min+max)   11.3
Mean Minimum     7.6
Mean Maximum     15.0
Minimum          -0.8 day 27
Maximum          20.4 day 14
Highest Minimum  11.9 day 05
Lowest Maximum   10.3 day 28
Air frosts       1
Rainfall (mm):
Total for month  100.3
Wettest day      16.6 day 05
High rain rate   20.1 day 01
Rain days        20
Dry days         11
Wind (mph):
Highest Gust     21.3 day 25
Average Speed    2.0
Wind Run         1492.7 miles
Gale days        0
Pressure (mb):
Maximum          1026.6 day 29
Minimum          996.6 day 01
Days with snow falling         0
Days with snow lying at 0900   0
Total hours of sunshine        72

September 2019: wettest since 2006

Most of the rain of September 2019 fell in the last week making what was a fairly unremarkable month weatherwise the wettest September for 13 years.

Some 63.9mm of rain fell which is 123 per cent of average.

The monthly mean finished 15.8C, that’s 0.4C above average, the warmest September for 3 years, 0.6C warmer than last year.

Sunshine, at 150.5hrs, 107 per cent of average but over 30 hours fewer than last year.

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

sept

Summary for September 2019

Temperature (°C):
Mean (1 minute)  15.5
Mean (min+max)   15.8
Mean Minimum     11.1
Mean Maximum     20.5
Minimum          5.2 day 17
Maximum          26.0 day 15
Highest Minimum  15.7 day 23
Lowest Maximum   16.1 day 09
Air frosts       0
Rainfall (mm):
Total for month  63.9
Wettest day      14.9 day 24
High rain rate   28.2 day 27
Rain days        14
Dry days         16
Wind (mph):
Highest Gust     23.5 day 27
Average Speed    2.5
Wind Run         1809.2 miles
Gale days        0
Pressure (mb):
Maximum          1036.8 day 13
Minimum          992.3 day 29
Days with snow falling         0
Days with snow lying at 0900   0
Total hours of sunshine        0.0

August 2019: warmest for 4 years

Apart from the hot four days in the last week August 2019 was fairly unremarkable.

Overall the monthly mean finished 19.9C, that’s 1.4C above average.

Rainfall at 37.7mm, was 75 per cent of average,  the driest for 3 years. Sunshine, at 180hrs, the sunniest for 3 years.

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

august max

Summary for August 2019:

Temperature (°C):

Mean (1 minute)  18.9
Mean (min+max)   19.3
Mean Minimum     13.9
Mean Maximum     24.7
Minimum          8.8 day 20
Maximum          32.6 day 27
Highest Minimum  19.5 day 07
Lowest Maximum   17.9 day 14
Air frosts       0
Rainfall (mm):
Total for month  37.7
Wettest day      12.6 day 14
High rain rate   65.8 day 09
Rain days        11
Dry days         20
Wind (mph):
Highest Gust     22.1 day 10
Average Speed    2.6
Wind Run         1941.4 miles
Gale days        0
Pressure (mb):
Maximum
Minimum
Days with snow falling         0
Days with snow lying at 0900   0

July 2019: a new Tmax record

July 2019 saw the month’s daily maximum record broken on the 25th with a high of 36.8C, The reading beat the previous record set on July 1st 2015 by 0.8C and was the second highest reading recorded in this area. Cloud that drifted in mid afternoon put paid to any chance of all-time record though Cambridge, further north, managed to break the UK record with a reading of 38.7C. This temperature set in the Botanic Gardens beat the previous record of 38.5C set in Brogdale, Kent, in 2003.

 

north
The weather enclosure in the Cambridge Botanic Gardens meets WMO guidelines

Although it has been mentioned that the Cambridge site appears to be overdeveloped it meets the WMO standard and the Met Office are happy with the record.

Compared with 2003 the heat this time was far more widespread and further north, with many stations recording higher values than 2003, as shown by these 24 hours to 6pm readings below.

 

In 2003 some 44 stations recorded 30C or above whereas this year some 67 reached 30C or higher.

Though the heat was record breaking it was much shorter lived than 2003. Like last month and July 2015 the 9-day temperature trace is far more ‘pointed’ – perhaps a symptom of the changing behaviour of the jet stream.

Overall the monthly mean finished 19.9C, that’s 1.4C above average though 1.8C cooler than last July – the warmest month on record.

Rainfall at 61.5mm, was 141 per cent of average,  the wettest for 2 years. Sunshine, at 165hrs, is 85 per cent of average and well down on last July’s 273hrs.

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

2019july
‘Feels like’ maxima.
juky feels
June 1981-2019 maximum anomalies
july all.PNG

 

The 12 month rolling rainfall total is…

Summary for July 2019

Temperature (°C):
Mean (1 minute)  19.8
Mean (min+max)   19.9
Mean Minimum     14.7
Mean Maximum     25.1
Minimum          9.2 day 03
Maximum          36.8 day 25
Highest Minimum  19.6 day 23
Lowest Maximum   19.5 day 27
Air frosts       0
Rainfall (mm):
Total for month  61.5
Wettest day      20.6 day 19
High rain rate   16.1 day 18
Rain days        10
Dry days         21
Wind (mph):
Highest Gust     16.8 day 20
Average Speed    2.2
Wind Run         1664.1 miles
Gale days        0
Pressure (mb):
Maximum          1029.0 day 03
Minimum          1004.8 day 30
Days with snow falling         0
Days with snow lying at 0900   0
Total hours of sunshine        0.0

June 2019: record heat spike

June 2019 saw no high temperature records broken but a jump in anomaly, produced on the 29th by the 3rd hottest June day back to 1959, is higher than any I can find back to that year..

The only phenomena similar that I can find, albeit in the other direction, is the Beast from the East in March 2018 that sent temperatures plummeting.

The month finished a little above average though the final figure, like May and April, masked cool warm spells.

The mean temperature finished 16.9C that’s 0.8C above average, the coolest for 3 years.

Rainfall was 63mm, 123% of average, the wettest for 2 years. Sunshine was 158 hours, 88.7% of average, and dullest for 3 years.

A timelapse of the longest day can be found here.

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

june 2019
‘Feels like’ maxima.
12.1
June 1981-2019 maximum anomalies
june anoms

 

The 12 month rolling rainfall total, thanks to a wetter than average month, has moved above 500mm again.

Summary for June 2019

Temperature (°C):
Mean (1 minute)  16.8
Mean (min+max)   16.9
Mean Minimum     12.1
Mean Maximum     21.7
Minimum          7.1 day 08
Maximum          33.6 day 29
Highest Minimum  18.0 day 24
Lowest Maximum   14.4 day 10
Air frosts       0
Rainfall (mm):
Total for month  63.3
Wettest day      18.7 day 10
High rain rate   20.1 day 09
Rain days        13
Dry days         17
Wind (mph):
Highest Gust     24.4 day 08
Average Speed    2.7
Wind Run         1932.6 miles
Gale days        0
Pressure (mb):
Maximum          1031.5 day 27
Minimum          998.4 day 07
Days with snow falling         0
Days with snow lying at 0900   0
Total hours of sunshine        0.0

 

 

 

 

 

 

 

The coldest and wettest days of June

Looking out the window on a cold and miserable June afternoon yesterday reminded me of similar such days during the Seventies and Eighties.

But the mind plays tricks and I wondered if these kind of days were that common in the past.

To weed out the also-rans qualifying days had to be sunless with an anomaly that was at least 4C cooler than the daily average and rainfall of at least 12mm.

This gave the following list.

24hrd

So, in the last 60 years there have been only 12 days similar to June 10th 2019. That would give a probability of less than 1% (0.00743)

Looking elsewhere it would appear that there was much more rain to the north, south and west of Wanstead.

rain all