Monthly Weather Review - Pitsford Hall

Headline: The wettest May since local records began in Northampton which also included one of the wettest Bank Holiday weekends.

The month began with an area of high pressure across the British Isles with a centre north of Shetland. Consequently, the beginning of May was dry with some good sunshine particularly on the 1st and 2nd. However, with winds coming in from the north or north-east daytime temperatures generally fell from highs of around 20C on the 1st to just 12C on the 4th.

A sudden change in the weather was introduced on the 6th as an active low tracked past the north of Scotland driving a frontal system eastwards across the UK. The front introduced some rain across the county and brought about a sudden change in wind direction to a significantly milder southerly allowing daytime temperatures to recover, all be they temporarily. Over the next few days a frontal wave would come to dog the southern half of the UK being driven further south over the near continent by the 8th. Occasional light showers were recorded during this period across the county spaced between spells of sunshine. Winds remained fairly brisk.

Low pressure developing west of Ireland pushed eastwards towards the UK during the 9th and 10th and then remained fairly stationary over the British Isles allowing bands of rain to circulate round. Some significant rain fell across the county on the 10th with nearly 19mm recorded in just over 12 hours at Pitsford. This low had started to fill by the 12th which, despite the odd shower, was a largely dry day across the county with some good sunshine ahead of another deluge on the 13th. The latter was ushered in on a developing low to the south-west. 15.3mm of rain was recorded in about 8 hours at Pitsford.

A very transient ridge was introduced across the southern half of the UK from the Azores overnight on the 15th but by 0900GMT cloud and outbreaks of rain were working into the county linked to yet another active low. A further 13.8mm of rain would fall at Pitsford before 0900GMT the following morning. Shortly after this low had cleared the east coast a succession of fronts introduced further spells of rain. However, these fronts did make for a milder day on the 15th. Unfortunately, this frontal system was linked into a particularly deep low which was to work slowly past the north of Scotland over the next few days. This low had a significant influence across a large part of the UK and the trailing cold fronts on the 16th introduced yet more rain.

A more settled spell of weather then followed as the UK came under the influence of high pressure which was to extend from southern Scandinavia to the Azores by the 21st. Initially this high dominated the whole of the British Isles, but in its latter stages by the 24th had shrunk to the southern half of England and Wales. The county enjoyed some fine sunny days with light winds and temperatures rose to a high of 23C by the 23rd.

By the 25th the high pressure had lost control across the south as an active cold front introduced outbreaks of rain from the north-west. 9.4mm of rain fell in nearly 12 hours by 0900GMT on the 26th, yet this unsettled spell was to be but an overture to the 30.8mm of rain which was to fall by 0900GMT on the 27th unfortunately coinciding with the Whit Bank Holiday weekend. Much of the rain was attributed to an active low which tracked across southern Britain. The low fuelled some strong winds, up to 47mph at Pitsford which led to loss of power to 100 homes in neighbouring Brixworth. Outbreaks of rain and strong winds continued into the 28th but eventually cleared eastwards later in the day.

Low pressure was still influencing the weather as the month came to a close. Apart from an unexpected late ground frost on the 30th, temperatures generally rose as the wind swung round from north to south. To make sure that this May would become the wettest on record in Northampton, a further 8.1mm of rain would fall before 0900GMT on 1st June.

Air Temperatures    
The Highest Maximum:   23.0C on 23rd
The Lowest Maximum:   9.4C on 28th
The Highest Minimum:   14.8C on 24th
The Lowest Minimum:   2.5C on 30th
The Mean Maximum:   16.2C  
The Mean Minimum:   8.0C  
The Overall Mean:   12.1C  
Difference from the Monthly Mean: -0.4C  
    
Relative Humidity:    
Highest Relative Humidity (at 0900): 95.3% on 7th & 15th
Lowest Relative Humidity (at 0900): 58.4% on 1st
Mean Relative Humidity (at 0900): 80.0%  
    
Dew Point:    
The Highest Dew Point (0900):  14.0C on 24th
The Lowest Dew Point (at 0900): 5.0C on 28th
The Mean Dew Point (at 0900):  9.1C  
    
Rainfall:    
Total:     130.3mm  
Difference from the Monthly Mean: 261.6%  
Duration:    94.0hrs  
Highest 24 hour fall (0900 to 0900): 30.8mm on 27th
Rain Days (>/=0.2mm):   20   
Wet Days (>/=1.0mm):   15   
    
Sunshine:    
Total Duration of Bright Sunshine: 142.4hrs  
Sunniest day:    11.3hrs on 1st
No. of days without sunshine:  4   
Difference from the Monthly Mean: 83.8%  
Cloud cover (mean at 0900):  6.3oktas  (78.8 %)
    
Pressure (reduced to sea level):    
The Highest Pressure:   1023.5mb on 23rd
The Lowest Pressure:   998.9mb on 27th
Mean Pressure (recorded at 0900): 1011.5mb  
    
Winds    
Run of wind (mean over 24 hrs): 101.9miles  
Mean daily wind speed:   5.5mph  
Run of wind (cumulative):  3159.7miles  
Highest Maximum Gust:   47mph  on 27th
No. of gusts of 50mph or more:  0   
Highest wind strength (at 0900): 26.5mph on 28th
Mean wind strength (at 0900):  7.3mph  
    
Winds from the Following Directions:    

N 3 NE 4 E 0 SE 2 S 5 SW 2 W 3 NW 5 Calm 7   
   
    
Ground Temperatures:     
Lowest Grass Minimum:   -1.8C on 30th
Mean Grass Minimum:   5.0C  
Lowest Concrete Minimum:  2.0C on 30th
Mean Concrete Minimum:  7.1C  
Lowest Bare Earth Minimum:  2.6C on 30th
Mean Bare Earth Minimum:  7.6C  
    
Soil/Earth Temperatures:     
Surface mean:    13.5C  
5cm mean:    12.5C  
10cm mean:    12.7C  
20cm mean:    13.1C  
30cm mean:    13.4C  
40cm mean:    13.3C  
50cm mean:    13.6C  
100cm mean:    12.3C  
    
Days with:    
Thunder:    1   
Hail <5mm:    0   
Hail >/=5mm:    0   
Snow or snow & rain:   0   
Fog:     0   
Air Frost:    0   
Ground Frost:    1   
Gales:     0   
    
Total (Pan) Evaporation:  70.98mm

All data © Pitsford Hall weather station.

The weather station publishes a full Monthly Weather Report (ISSN 1741-4733) which is distributed to libraries across Northamptonshire. This report comprises a full UK weather diary, reports of extreme weather events across the county, statistics from Pitsford Hall's affiliated stations across the county as well as news from the weather station itself. Individuals may download this report for £2 or take out an annual subscription for the paper-based report for £25. Click here for further details.