Monthly Weather Review - Pitsford Hall

Headline: High pressure dominated the weather for much of the month giving a protracted dry spell for the first fortnight. Most of the month’s rain fell in a few days towards the end of the month linked to a slow moving depression to the south-west.

The end of April saw the UK coming under the influence of a deep area of low pressure. This feature was still around on the 1st giving rise to some showers. Over the next couple of days high pressure centred over the near continent extended to cover the eastern half of the UK. This high fed in a southerly airflow from France encouraging temperatures to rise. The position of this high gradually moved northwards to the North Sea blocking the passage of frontal systems which began to pile in off the Atlantic from the 4th. There was a small amount of rain on the 4th, but otherwise it would remain dry for a good fortnight with temperatures continuing to climb well above the average for early May reaching 26.2C at Pitsford on the 11th. Most days recorded some good spells of sunshine, in excess of 12 hours on the 7th. The high over the North Sea joined up with a ridge from the Azores high on the 10th then moving its position to the north of the British Isles encouraging cooler air from the north-east. Consequently, daytime temperatures dropped markedly.

By the 15th the high was beginning to lose control, particularly across the south as low pressure over Biscay was beginning to drive frontal systems northwards. The front made an impact on Northamptonshire with some 8.5mm of rain recorded at Pitsford over the space of 14.7hrs. Further spells of rain followed on the 16th and 17th before a ridge of high pressure extended southwards from Iceland on the 18th. With the north-easterly airstream maintained temperatures remained depressed, in fact the overnight low on the 19th moving into the 20th fell to just 3.0C at Pitsford. This high stayed fairly stationary until the 23rd when it gave way to an occluded front working in off the Atlantic. This brought a small amount of rain to the county, sufficient just to dampen surfaces. However, over the next few days the associated low moved to the south-west and deepened introducing some strong easterly winds and spells of heavy rain from the 25th through to the 27th. In fact, over this three day period raintall totals reached 44.2mm at Pitsford, getting on for a whole month’s rainfall, and winds on the 25th and 26th exceeded 40mph. Throughout this period, high pressure had maintained a position to the north of Scotland maintaining fine and settled weather in the north of the UK. However, as this retreated on the 28th it only encouraged further spells of rain across the county. The strongest winds though were transferred northwards and conditions become much calmer here.

As the month came to a close, barometric pressure was fairly slack across Northamptonshire. The county enjoyed dry days on the 30th and 31st, although it remained rather overcast with morning mist tending to linger with negligible wind. With temperatures exceeding 20C on the 31st the high humidity threatened thunderstorms during the afternoon, but these did not materialize.

Air Temperatures    
The Highest Maximum:   26.2C on 11th
The Lowest Maximum:   11.7C on 16th
The Highest Minimum:   13.1C on 11th
The Lowest Minimum:   3.0C on 20th
The Mean Maximum:   18.5C  
The Mean Minimum:   8.8C  
The Overall Mean:   13.7C  
Difference from the Monthly Mean: +2.4C  
    
Black Bulb    
Maximum (at 0900):   34.0C on 6th
Mean (at 0900):    21.8C


Relative Humidity:    
Highest Relative Humidity (at 0900): 98.8% on 27th
Lowest Relative Humidity (at 0900): 55.3% on 20th
Mean Relative Humidity (at 0900): 76.4%  
    
Dew Point:    
The Highest Dew Point (0900):  13.6C on 5th
The Lowest Dew Point (at 0900): 3.4C on 20th
The Mean Dew Point (at 0900):  9.5C  
    
Rainfall:    
Total:     72.3mm  
Difference from the Monthly Mean: 145.2%  
Duration:    67.2hrs  
Highest 24 hour fall (0900 to 0900): 17.7mm on 26th
Rain Days (>/=0.2mm):   12   
Wet Days (>/=1.0mm):   10   
    
Sunshine:    
Total Duration of Bright Sunshine: 162.2hrs  
Sunniest day:    12.5hrs on 7th
No. of days without sunshine:  4   
Difference from the Monthly Mean: 95.4%  
Cloud cover (mean at 0900):  5.5oktas (68.8%)
    
Pressure (reduced to sea level):    
The Highest Pressure:   1026.3mb on 5th
The Lowest Pressure:   1002.4mb on 28th
Mean Pressure (recorded at 0900): 1016.2mb  
    
Winds    
Run of wind (mean over 24 hrs): 105.1miles  
Mean daily wind speed:   5.7mph  
Run of wind (cumulative):  3257.0miles  
Highest Maximum Gust:   48mph on 26th
No. of gusts of 50mph or more:  0   
Highest wind strength (at 0900): 19.6mph on 24th
Mean wind strength (at 0900):  8.3mph  
    
Winds from the Following Directions:    

N 3 NE 15 E 6 SE 3 S 2 SW 0 W 0 NW 0 Calm 2   
    
Concrete     
Lowest Concrete Minimum:  1.0C on 20th
Mean Concrete Minimum:  7.8C  
    
Evaporation    
Piche     80.4 ml  
Pan     69.04 mm
    
Days with:    
Thunder:    1   
Hail <5mm:    1   
Hail >/=5mm:    0   
Snow or snow & rain:   0   
Snow lying:    0   
Fog:     0   
Air Frost:    0   
Gales:     0 


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.