Monthly Weather Review - Pitsford Hall

Headline: Coldest December since records began in 1931. Frequent snowfall, but no significant accumulations until the 22nd.

December began with a north-south split across the British Isles: the northern half of the country being influenced by high pressure centres over southern Scandinavia and the North Atlantic, whereas the south came more under the influence of low pressure over much of mainland Europe. Weak frontal systems introduced snow showers across Northamptonshire on the 2nd. The month also started cold with snow lying on the ground from the snow event at the end of November and temperatures during the daytime only rose a degree or two above freezing. The high over the northern half of Britain retreated on the 3rd allowing a succession of frontal systems in from the north-west. Some significant snowfall was experienced across the county overnight into the 4th as significantly colder air was introduced. Daytime temperatures fell and by the 6th failed to get above freezing. With very light winds, fog was experienced on several mornings, depositing rime on the 6th.

High pressure over the North Atlantic drove eastwards into the British Isles on the 8th. As this high drew closer it set up a dominant Arctic airflow across the UK. Weak frontal systems worked southwards along the east coast bringing snow showers, which included a few light flurries across the county. With clearer skies, temperatures overnight fell sharply. -9.4C was recorded on the morning of the 8th at Pitsford. However, over the next few days the high would lose its Arctic influence and start to draw in air from a milder source south-west of Iceland and begin to retreat slightly. Consequently, although daytime temperatures rose climbing to 8.0C at Pitsford on the 11th, it remained rather cloudy. In fact, although this high remained in place until at least the 15th, it frequently changed position and would re-introduce a colder northerly wind.

A dramatic change took place in the weather on the 16th. A deep low developed over Scandinavia and as Britain lost control of its high pressure centre, a strong Arctic blast was unleashed across the country. The transformation from mild conditions with rain in the morning to freezing temperatures and snow in the evening were a notable feature of the day’s weather at Pitsford. Over the next few days the cold low over Scandinavia would sink south-eastwards and remain fairly stationary across the south-west of Britain introducing further snow showers. Some parts of the county saw significant falls, notably around Daventry and Towcester, although Northampton escaped with a relatively light dusting. The last weak frontal system associated with this low lay across the county on the 22nd giving the first major snowfall event in Northampton during the early morning. 7.0cm of lying snow was recorded at Pitsford at 0900 GMT and transport was disrupted across the county. Over the next few days, with low pressure now over central Europe maintaining a cold northerly airflow across the UK, snow would remain lying on the ground right up until Christmas. Whereas, no new snowfall was reported on Christmas Day, there was still 4.0cm of lying snow and with high pressure in charge the day began with a hard frost (-7.4C) and remained below freezing all day.

As December drew to a close, the high which was dominant during the Christmas period moved south-eastwards allowing milder air in from the south-west. Low pressure centred over Iceland and the North Atlantic would drive a series of frontal systems in from the south-west which introduced some significant rain across the county overnight on the 27th into the 28th. However, the situation did not remain cyclonic for long as high pressure became established on the 30th settling the weather down some rather grey days with persistent fog and very little breeze.

Overall this was the coldest December since local records began in Northampton in 1931.

Air Temperatures    
The Highest Maximum: 8.0 C on 11th
The Lowest Maximum: -2.2 C on 20th & 25th
The Highest Minimum: 4.0 C on 30th
The Lowest Minimum: -9.4 C on 7th
The Mean Maximum: 2.5 C  
The Mean Minimum: -2.9 C  
The Overall Mean: -0.2 C  
Difference from the Monthly Mean: -5.3 C  
    
Solar Radiation    
Maximum (at 0900): 127.0 W/m^2 on 10th
Mean (at 0900): 29.7 W/m^2  
    
Relative Humidity:    
Highest Relative Humidity (at 0900): 100.0 % on 4th, 5th, 8th, 28th, 29th, 30th & 31st.
Lowest Relative Humidity (at 0900): 55.6 % on 17th
Mean Relative Humidity (at 0900): 91.8 %  
    
Dew Point:    
The Highest Dew Point (0900): 4.8 C on 29th
The Lowest Dew Point (at 0900): -10.2 C on 17th
The Mean Dew Point (at 0900): -1.6 C  
    

Rainfall:    
Total: 18.4 mm  
Percentage of the Monthly Mean: 34.3 %  
Duration: 22.5 hrs  
Highest 24 hour fall (0900 to 0900): 6.0 mm on 27th
Rain Days (>/=0.2mm): 11   
Wet Days (>/=1.0mm): 6   
    
Sunshine:    
Total Duration of Bright Sunshine: 27.0 hrs  
Sunniest day: 6.4 hrs on 7th
No. of days without sunshine: 17   
Percentage of the Monthly Mean: 42.4 %  
Cloud cover (mean at 0900): 6.1 oktas 76.3 %
    
Pressure (reduced to sea level):    
The Highest Pressure (at 0900): 1037.8 mb on 15th
The Lowest Pressure (at 0900): 992.8 mb on 18th
Mean Pressure (at 0900): 1015.7 mb  
    
Winds    
Run of wind (mean over 24 hrs): 96.7 miles  
Mean daily wind speed: 5.2 mph  
Run of wind (cumulative): 2996.4 miles  
Highest Maximum Gust: 37 mph on 1st
No. of gusts of 50mph or more: 0   
Highest wind strength (at 0900): 19.6 mph on 23rd
Mean wind strength (at 0900): 7.1 mph  
    
Winds from the Following Directions:    

N 8 NE 3 E 2 SE 1 S 3 SW 2 W 4 NW 7 Calm 1
    
Concrete     
Lowest Concrete Minimum: -9.6 C on 7th
Mean Concrete Minimum: -3.6 C  
    
Evaporation    
Piche 12.5 ml  
Pan – not available (frozen throughout the month)
    
Days with:    
Thunder: 0   
Hail <5mm: 0   
Hail >/=5mm: 0   
Snow or snow & rain: 8   
Snow lying: 16   
Fog: 6   
Air Frost: 21   
Duration of Air Frost: 398 hrs
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.