Category Archives: London weather

February 2017: mild, dry and dull

A cold spell that saw a thin temporary covering of snow wasn’t enough to stop February 2017 from finishing mild. The mean temperature of 6.9C was 1.6C above the 1981-2010 average, the mildest February for three years. feb

The 20th saw the warmest February day in 13 years recorded, the 17.5C reached was marginally cooler than the 17.9C recorded on February 4th 2004.

Rainfall of 31.5mm was 80% of average – the driest February for 4 years. It was a dull month, some 44.6 hours of sunshine were recorded, just 61% of average, the dullest for 5 years.

The wettest day occurred on the 26th with 9.2mm.

Air frosts: 2

Ground frosts: 8

Snow falling: 4

So what has March got in store weatherwise? My long range forecasting method suggests the most likely scenario to be something rather cold waverage to slightly below rainfall

My February outlook for temperature, rainfall and sunshine was poor again.

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

1st: Cloudy with light rain late morning. Remaining cloudy into the afternoon and overnight with further light shower before obs time.

2nd: Cloudy and becoming breezy. Some intermittently light rain then cloudy. Broken cloud overnight.
3rd: Bright start with sunny spells developing – feeling warm in the sun. Cloud built up afternoon with rain at 4pm and 6pm. Rain at 8am.
4th: Light rain to start then bright spells late morning. Feeling chilly.
5th: Misty start and foggy out toward Epping. Some bright spells though mostly cold and cloudy. Broken cloud overnight with frozen dew at dawn.
6th: Sunny start with just a few wispy cirrus around. Clouding over after noon with rain in evening, heaviest at 8.45pm with bursts through the night. Min temp was at 9am yesterday.
7th: Cloudy, calm and damp start. Then clearing in afternoon for some mild sunny spells.
8th: Cloudy start and feeling really cold. Thick stratus cloud remained overnight – snow grains seen just before obs time.
9th: Cloudy and dull, snow grains seen. Mostly drizzle through the day.
10th: Dull and raw with occasional drizzle, sleet and snow grains falling all day and through the night – temporary dustings.
11th: Very light snow falling at 9am.
12th: Light snow at 9am with 1cm settling at Stanstead. Then cloudy and cold all day.
13th: Sunny start with sunny spells, clearance at noon.
14th: Cloudy start with complete clearance at noon.  Then variable cirro cumulus.
15th: Cloudy start and cloudy all day with some rain.
16th: Cloudy start breaking to sunny intervals afternoon.
17th: Cloudy start breaking to sunny spells at 10.30am, long sunny spells and mostly clear overnight.
18th: Cloudy start  with complete clearance after noon – cloudier spells overnight.
19th: Bright start but clouded over. Some drizzle at dusk.
20th: Cloudy start but sunny spells developing mid morning. Date record broken and warmest February day for 13 years.
21st: Cloudy and mild all day. Breeze picking up in the evening and into the night.
22nd: Cloudy and breezy start, the wind increasing through the day with occasional light drizzle. Some squally winds overnight.
23rd: Cloudy but with cold front clearance coming through at obs time – sunny spells thereafter but with squally winds – these increasing through the day with damage reported and trees down – a woman killed in Wolverhampton from flying debris.
24th: Sunny periods and feeling warm though shade felt cold. Early ground frost before cloud moved in – burst of rain in early hours.
25th: Cloudy and miserable with some rain in the late afternoon.
26th: Cloudy and miserable all day.
27th: Cloudy start but moderate to heavy prolonged showers moving in from 11pm. A miserable day with limited brightness.
28th: Sunny, gin clear start but with cirrus building frost west. Rain at 2.45pm, sporadic through the rest of the afternoon / evening.

No ice day for London

There was much talk yesterday about a lot of the south of the England recording an ‘ice day’. screen-shot-2017-01-27-at-12-31-17

In the London area most places missed out because the temperature rose briefly above freezing around dusk and also just before the 0900 observation today.

So although it felt brass monkeys out there it doesn’t count.

Ice days are when the temperature fails to rise above -0.1C over a 24 hour period, usually from 0900 to 0900. The confusion over yesterday’s ice day was caused by the fact that some stations release a 06-18 maximum reading – both Kenley and Shoebury stayed below zero in this time period.

Ice days in the Wanstead area are probably even rarer than decent snowfalls. Since 1959 there have been 81 ice days.
The last time the temperature failed to rise above 0.0C was January 20th 2013. The last time the temperature failed to rise above -0.1C (a true ice day) was January 6th 2010.

screen-shot-2017-01-27-at-12-01-35

screen-shot-2017-01-27-at-11-51-46
Over a dozen stations stayed below freezing for 24hrs to 09z on January 27th

Stephen Davenport’s synoptic analysis of the event is included below:

“[The cold conditions were] all thanks to this nicely (or not nicely, depending on your view) blocked situation. On Tuesday 24th a 500 hPa ridge started build northeastwards to the north of  a small upper low situated over France. By 12z on Wednesday 25th it had cut off to leave a classic-looking Rex block over western Europe:

Surface winds from the Continent started to bring colder air across as the temperature anomaly analysis for 12z Wed 25th shows, while milder southerlies continued across Ireland and Scotland, and brushed western Wales and SW England:

By 12z Thursday 26th the block was becoming more omega-like…

… and cold air continued to percolate north-westwards from the Continent farther across the British Isles:

There’s a certain beauty in the sinusoidal flow around a Rex block, I always think.”