Tag Archives: East London

London winter forecast 2018-19

Long range modelled forecasts have been all over the place of late and, looking at the underlying signals, it is easy to see why.

When I’ve produced these forecast in the past, in terms of QBO and ENSO data, there’s usually a lot of analogues to compare with. This year, however, seems to be an exception.

Considering QBO first I looked back over data to 1950 and found nothing similar for October. However, looking over the whole series the cyclical nature of this circulation may give some clue.

bestfit

Some 20 months were revealed, ranging from June 1959 to June 2015.  Using NOAA’s  Niño 3.4 region I narrowed this list down to the few that had an ENSO value of around +1 with a rising trend. With NOAA’s forecast of a Modoki El Nino (one that occurs in the central Pacific) this narrowed the list to just 1 period: June 2015. Considering maxima anomalies this would give the following winter.

winter 2018-19 max anomaly.PNG

The above would suggest 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?

winter 2018-19 precip anomaly

The above precipitation anomaly chart would suggest a wetter than average December,  January and February, though February by much less so.

It’s been a very busy autumn so I’m keeping this short.

The below figures, particularly January and February, may be different in the event of an SSW occurring. In all then.

The mean:
December: +0.8C
January: -1.2C
February: -1.7C
Overall: -0.3C (broadly average)

Precipitation:
December: 158%
January: 155%
February: 120%
Overall: 134%

 

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How cold will November end?

Twitter and other forums have been at fever pitch with excitement for a ‘nailed-on’ cold spell. 

But with many getting carried away over tales of a repeat of March’s ‘Beast from the East’ it is important to remember that snow in November is extremely rare in the south-east; despite predictions of the incoming upper air being very cold the ground is still very warm and will take time to cool.

However, as seen in November 1993, a week of hard frosts were enough to chill the ground enough for a decent week-long cold spell. Similarly, although the snow didn’t arrive in London until December, November 2010 was also cold enough.

The weather of late has been in an ‘average mood’ with the mean temperature in September and October both finishing at 0.2C below. The mean for the this month is currently (on the 15th) running 1.8C above average, therefore for the mean to finish the same as September / October would require a big cool down, as hinted by the models.

Will we see another an average, 1993 or a 2010 end to the month. My hunch is it will be something between the three.

Below is a graph that shows this November so far with average, 1993 and 2010 ends.
2018: 0.4
1993: -0.8
2010: -1.4

East London’s highs and lows of the last 60 years

The chart below shows every maximum and minimum temperature recorded in this area since January 1st 1959, some 21,860 days!

The extremes range from -12.7C recorded on January 31st 1972 to 37.5C on August 10th 2003.

After peaking in 2003, summer maxima seems to be in decline. Winter minima, by comparison, has been increasing since 2012

maxmin

October 2018: average and rather sunny

October was most notable for the amount of sunshine. Some 136 hours were recorded, that’s 127 per cent of average, the sunniest October for six years.

The mean temperature finished 11.6C, 0.2C below average, the same anomaly as September. And 1.6C cooler than October last year.

Some 52.1mm of rainfall was recorded, 78 per cent of the 1981-2010 average, the wettest October for four years.

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

October 2018 max.JPG

Perfectly average months are extremely rare

Readers of this blog know that I often described a month as fairly average – a look at local statistics shows that many months come in very close to the monthly mean.

But when you combine mean temperature with rainfall that is 100 per cent average it becomes very rare and non-existent with 100 per cent sunshine hours considered.

Of the 2650 months since 1797 just one, February 1972, saw a mean temperature and rainfall precisely average. However, sunshine hours were just 40 per cent of the 1981-2010 average.

To extend the data I included monthly rainfall totals that were between 90 per cent and 110 per cent of average. Even then just five more months were revealed: September 1806, February 1876, January 1883, October 1886 and March 1972.

Although on paper February 1972 was perfectly average a look at the weather for the month reveals typically variable weather. The website London Weather explains:

The maximum temperature was only 3C on the 1st as mild Atlantic air slowly displaced the very cold continental air eastwards. There were outbreaks of rain, and during the remainder of the first week, although mild, it was often dull and wet. During the second week, active frontal systems crossed the country bringing strong winds but with sunshine between the rain bands. After mid month, east winds returned, and although not cold, it was frequently dull.

Considering the Met Office forecast the mean for this month, October 2018, is set to finish precisely average. However, rainfall looks set to finish well under the average for the time of year.

September 2018: average, dry and sunny

September was most notable for the amount of cold nights. The record minimum was matched together with three further new entries into the top ten list of extremes back to 1959 – a rare occurrence.

The mean temperature finished 15.2C, 0.2C below average, ending a run of 5 months where the mean has been, at times, well above average.

Some 32.6mm of rainfall was recorded, 63 per cent of the 1981-2010 average. Some 183 hours of sunshine were recorded, 132 per cent of average and more than August!

For the first time in years the autumnal equinox period was very stormy, as shown by this graph.

wind run

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

Summary for September 2018 to follow…

 

London’s October extremes since 1959

October is one of those months that can see both ends of the spectrum; from calm ‘mists and mellow fruitfulness’ and, rarely, frost, to wet and wild systems whistling in off the Atlantic, best known being the 1987 Great Storm and, more recently, the St Jude storm.

I’ve put together a few top 10s of stats for Wanstead, St James’s Park and Heathrow for the month of October.

october extremes

October SJP

Heathrow oct

Some national UK October values according to TORRO

Hottest: 29.4C March, Cambs – 1st 1985
Coldest: -11C Dalwhinnie 28th 1948
Wettest: 208.3mm Loch Avoich 11th 1916

In terms of climatology October maxima, considering the 1981-2010 average, shows a decline through the month, though around the 8th and 20th there is often a spike. This would reflect the October singularities; early October storms, between 5th and 12th, peaking on the 9th, occur in 67 per cent of years. St Luke’s summer, between 16th and 20th, peaking on 19th, also has a 67 per cent probability.
Mid-autumn storms occur between 24th and 29th October, with a 100% probability.

october average graph

The average rainfall graphic shows that downpour amounts are variable through the month. A tendency for dry weather around the 17th and 18th before the wettest days on the 20th and 21st.

October rainfall

 

 

 

London’s September extremes since 1959

September in recent years has often been a more summery month than August. But this month in some years can see a rapid onset of autumn.

I’ve put together a few top 10s of stats for Wanstead, St James’s Park and Heathrow for the month of September.

september extremes

SJP september

heathrow sept

Some national UK September values according to TORRO

Hottest: 35.6C Bawtry, South Yorkshire – 2nd 1906
Coldest: -4.5C Dalwhinnie, Highland, – 26th 1942
Wettest: 190.7mm West Stourmouth, Kent – 20th 1973

In terms of climatology September maxima, considering the 1981-2010 average, shows a slight decrease through the month, though around the 1st and the 22nd there is often a spike. This would reflect the September singularities; early September warmth occurs in 82 per cent of years while the ‘Old Wives Summer’ has a 64 per cent probability.

september mean

 

The average rainfall graphic shows that downpour amounts are variable through the month. A tendency for dry weather to the 8th prevails before the trend increases, the wettest days usually 13th and 19th.

sept rain

 

 

August 2018: average temps, rain, sun

August was a big let down in a summer that saw the mean temperature nationally match the UK’s best-ever summers.

summer max 2018
Summer maxima took a real dip during the first week of August

The mean temperature finished 18.9C, 0.7C above average.

Some 69.5mm of rainfall was recorded, 139 per cent of the 1981-2010 average. Some 169 hours of sunshine were recorded, 87 per cent of average. Apart from being 1.5C warmer than average it was a carbon copy of last August.

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

Summary for August 2018

Temperature (°C):
Mean (1 minute)  18.8
Mean (min+max)   18.9
Mean Minimum     13.8
Mean Maximum     24.3
Minimum          6.9 day 10
Maximum          33.1 day 03
Highest Minimum  19.1 day 03
Lowest Maximum   17.0 day 09
Air frosts       0
Rainfall (mm):
Total for month  69.5
Wettest day      13.6 day 16
High rain rate   48.3 day 10
Rain days        14
Dry days         17
Wind (mph):
Highest Gust     22.8 day 24
Average Speed    2.5
Wind Run         1841.7 miles
Gale days        0
Pressure (mb):
Maximum          1025.1 day 31
Minimum          1001.3 day 26
Total hours of sunshine        169

 

 

Summer 2018: second hottest since 1797

The results are in and statistics show that this summer was the second hottest in a local record going back to 1797. The mean temperature of 19.57C was 2.4C warmer than average, just six hundredths of a degree cooler than the summer of 2003.

A sustained period of heat that continued the theme of the hot late spring was enough to see a new entry into the hottest-ever list of heatwaves.  But the hottest weather was over by the end of July, August being very disappointing compared with the first two months of summer.

It was also the driest summer for 15 years. Just 87mm were recorded, that’s 60 per cent of average and just 7mm wetter than the historic summer of 2003, the year the UK’s highest temperature record was set.

It was the sunniest summer for 5 years: 663 hours of sunshine were recorded, over 100 hours less than 1976, the 24th sunniest summer since 1881.

Hottest day: 34.7C (26/7)
Coolest day: 17C (9/8)
Warmest night: 19.7C (26/7)
Coolest night: 6.4C (12/6)
Wettest day: 13.9mm (16/8)

summer max 2018

summer 2018 rain

Summary for period 01/06/2018 to 31/08/2018

Temperature (°C):
Mean (1 minute)  19.4
Mean (min+max)   19.6
Mean Minimum     13.7
Mean Maximum     25.5
Minimum          6.4 on 12/06/2018
Maximum          34.7 on 26/07/2018
Highest Minimum  19.7 on 26/07/2018
Lowest Maximum   17.0 on 09/08/2018
Air frosts       0
Rainfall (mm):
Total for period 86.9
Wettest day      13.9 on 16/08/2018
High rain rate   48.3 day 10/08/2018
Rain days        19
Dry days         73
Wind (mph):
Highest Gust     22.8 on 24/08/2018
Average Speed    2.6
Wind Run         5714.2 miles
Gale days        0
Pressure (mb):
Maximum          1029.9 on 21/06/2018
Minimum          1001.3 on 26/08/2018