Tag Archives: East London

March 2019: mild and wet

March was mild, particularly compared with last year. And wet though, like February, the rain fell at the start of the month, leaving a dry end.

The mean temperature finished 9.4C that’s 1.7C above average and over 3C warmer than last March.

Some 54.5mm of precipitation was recorded,  134 per cent of the 1981-2010 average.

Some  109 hours of sunshine were recorded, that’s  precisely average.

Just one air frost was recorded.

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

march 2019
‘Feels like’ maxima.
march 2019 feels like
key
Advertisements

Is it warm, cold or just normal?

Saying how warm or cold a day feels is subjective; one person’s hot day in spring is another’s ‘on the warm side’. Similarly when someone says the temperature on any given day is ‘normal for the time of year’ others will be exclaiming how cold they’re feeling.

The ‘heatwave’ in February was a case in point. Though many places recorded their warmest February maxima on record many were saying it was just a nice, warmer than normal spell of weather.

Some years ago the Met Office issued guidance on how warm or cold a day was relative to the anomaly. Earlier this month the table was posted on Twitter and I have plotted a graph for the spring period.

Today’s (March 22nd) maximum of 11.1C is therefore described as ‘normal’.

temp feel

cold hot warm

 

Spring or still winter? Plants reveal all.

With the record warm spell last month and high sunshine totals you would think that the growing season is well under way. Spring bulbs have been out for weeks, trees are blossoming and many shrubs are on the verge of flushing.

But a look at the local temperature records over the last six years shows that things aren’t as advanced as previous seasons.

Considering the period from December 1st – in recent years a date when it is common to see bulb shoots beginning to emerge – to March 10th reveals the following table in terms of growing degree days.

growing degree days

The warm days of last month were cancelled out by cold, frosty nights, leading to little net warmth. And the last ‘growing degree-day’ was on March 2nd. Nevertheless growth is further on than last year that saw record cold in March. 

The season is a long way behind 2015-16, however, which saw a record-breaking mild December.

Looking at the list below, and the at best average outlook, we’ve still got a way to go before we’ll see most trees in full leaf…

plant development
This list courtesy of Wikipedia

 

 

Winter 2018/19: average with extremes

The winter of 2018/19 will probably be remembered most for the remarkable warmth in the last week of February. And for its lack of snowfall.

The mean temperature finished 6.1C, that’s 0.7C above average, the mildest for 3 years.

Rainfall was below average: 127mm fell, that’s 87 per cent of average and the driest for two years.

Sunshine was well above average: 211.6 hrs is 126 per cent over average, the sunniest for seven years.

The warmest day of the winter occurred on December 30th with 14.2C recorded. The warmest night was on January 28th when the temperature fell to just 10.8C.
The wettest day of the winter occurred on January 2nd when 15.3mm was recorded.

Snow first fell on 5 days between January 22 and February 1st: five days of snow falling and two days of snow lying over the three months is below average.

There were 29 air frosts during the three months, seven above the 1981-2010 average.

A full weather diary is available for the months of DecemberJanuary and February. To view full stats for each month follow this link:http://1drv.ms/1kiTuzv

TMax winter

Summary for period 01/12/2018 to 28/02/2019

Temperature (°C):
Mean (min+max)   6.1
Mean Minimum     2.6
Mean Maximum     9.7
Minimum          -6.5 on 30/01/2019
Maximum          18.7 on 26/02/2019
Highest Minimum  11.5 on 06/12/2018
Lowest Maximum   1.3 on 23/01/2019
Air frosts       29
Rainfall (mm):
Total for period 127.0
Wettest day      11.4 on 20/12/2018
High rain rate   28.1 day 26/01/2019
Rain days        31
Dry days         59
Wind (mph):
Highest Gust     31.1 on 09/02/2019
Average Speed    2.8
Wind Run         6152.3 miles
Gale days        0
Pressure (mb):
Maximum          1043.8 on 02/01/2019
Minimum          980.4 on 01/12/2018
Days with snow falling         5
Days with snow lying at 0900   2
Total hours of sunshine        0.0

February 2019: very mild and sunny

February was most notable for how mild daytime temperatures were in comparison with night-time.

The 27th and 26th saw diurnal ranges of 19.4C and 19.3C respectively, the highest range recorded in any February since 1959, helped by huge temperature anomalies brought by the synoptic conditions. Although the UK maximun temperature record for February was broken with Kew Gardens reaching 21.2C the February TMax record in Wanstead, 19.7C set in 1998 remained intact.

The mean temperature finished 7C, 1.7C above average, the mildest February for 5 years.

Some 33.7mm of precipitation was recorded, 86 per cent of the 1981-2010 average, about the same as last year.

Some 124.6 hours of sunshine were recorded, that’s 170 per cent of average, the sunniest February for 11 years.

Ten air frosts were recorded.

There was one day where snow fell and one day of snow lying, 1cm on 1st.

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

feb max 2019
Summary for February 2019

Temperature (°C):
Mean (1 minute)  7.0
Mean (min+max)   7.2
Mean Minimum     2.5
Mean Maximum     11.8
Minimum          -3.9 day 02
Maximum          18.7 day 26
Highest Minimum  7.6 day 28
Lowest Maximum   2.2 day 01
Air frosts       10
Rainfall (mm):
Total for month  33.7
Wettest day      6.7 day 03
High rain rate   8.1 day 03
Rain days        10
Dry days         18
Wind (mph):
Highest Gust     31.1 day 09
Average Speed    2.7
Wind Run         1793.2 miles
Gale days        0
Pressure (mb):
Maximum          1038.4 day 25
Minimum          986.4 day 01
Days with snow falling         1
Days with snow lying at 0900   1

Longest winter ‘heatwave’ since 1959

With the return of more seasonal temperatures February 2019’s heatwave already seems like a distant memory.

Looking back at the stats for this area the past eight days have seen an average anomaly of 7.7C, beating the previous eight-day long warm spell of December 2015, which returned a mean anomaly of 7C. That spell was quickly followed six-day long warm spell that had a mean anomaly of 6.6C. There appears no chance of the heat returning any time soon.top 5 winter heatwaves

Wanstead missed out on breaking the February high temperature record. While Kew Gardens recorded a high of 21.2C, the local area reached just 18.7C, falling short of the record of 19.7C set in 1998.

St James’s Park, our closest official climate station, set a new top 3 of TMax values. , as did Heathrow.

 

A winter heatwave

It is 21 years ago this month that London and most of the southern half of the UK experienced a remarkably warm spell of weather during what had been a mild winter.

The spell, which saw the record warmest February day on the 13th (19.7C), satisfies the Met Office’s old criteria of a heatwave whereby the maximum temperature is 5C or more above average for five consecutive days.

While these spells are fairly common in summer they are very rare during a meteorological winter. During the last 60 years the only other periods to have experienced a heatwave in winter are December 1966 and 2015.

Weather charts for this week look remarkably similar though, according to the latest forecasts, values will be nothing like they were in 1998.

Since this was published this 2019 spell has satisfied the Met Office criteria. But the anomalies are not yet as impressive as 1998.

1998 2019

This slideshow requires JavaScript.

 

feb 1998 maxes

 

 

January 2019: rather cold, dry

January was most notable for being on the cold side, in contrast to December.

The mean temperature finished 4.1C, 1.1C below average, over 2C colder than last January.

Some 32.9mm of precipitation was recorded, 62 per cent of the 1981-2010 average, about half what fell last year, the driest January since 2006

Some 55 hours of sunshine were recorded, that’s 109 per cent of average, sunnier than last year.

Fourteen air frosts were recorded.

There were four days where snow fell but only one day of snow lying, 1cm on 23rd.

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

My winter forecast went a bit awry in December – I predicted a mean of +0.8C, the outcome was +1.7C. January has been much better, I predicted -1.2C, the outcome is -1.1C! Also… “And another cold spell end of January into the first week of February?”
For February I predicted a mean of -1.7C. The current pattern to continue and signs on the EC of a more robust cold spell with air supplied by a Scandinavian high?

Update on effects of the polar vortex split

More than three weeks have now past since the polar vortex split on January 1st.

London’s weather has turned colder and there’s even been a (small) fall of snow but the negative anomalies recorded so far are less than those experienced during the ‘Beast from the Eastevents last March.

In the graph below I have plotted the mean anomalies since the day of the PV split against the mean anomalies recorded from the day of the PV split in February 2018.

The effect this year is much less pronouced so far: over the last 24 days the average mean anomaly has been -0.7C, compared with -2.1C last February/ March.

jan 2018 2019

The NOAA anomaly map for the week of January 13th-19th shows much of NW Europe has experienced a positive anomaly with any serious cold restricted to Norway and Sweden and Greece.anom jan 13th to 19th

It has been mentioned that the variables with this SSW are very similar to 2004. Using the anomalies generated after the 2004 event resulted in the graphic below.

3 years compared

Taking it at face value would suggest that two more snow events could be possible at the beginning and middle of February – a cold but not severe pattern currently reflected in the models – but forget any repeat of last year’s Beast from the East.

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.