PITSFORD HALL WEATHER STATION
NORTHAMPTON, UNITED KINGDOM

MONTHLY WEATHER REPORT - SEPTEMBER 2002


Headline: With the exception of significant rainfall on the 9th, 
mainly anticyclonic and warmer than average. 

The first few days of September were dry with good spells of
sunshine. In fact the sunniest day of September was the 1st 
with 11.0 hrs recorded. High pressure moved steadily eastwards 
and, by the 4th, the situation became inflenced by low pressure 
developing over the North Sea. It was also reasonably warm with 
daytime maxima in the low 20s. Mornings were affected by mist 
and fog, especially on the 4th which left recordable moisture.

An unsettled spell characterised the second week. Low pressure 
moved southwards from Iceland and this brought with it spells 
of rain. A second more active low moved across the county from 
the south-west during the 9th depositing copious amounts of 
rain. In fact, rainfall on the 9th amounting to 25.9mm at 
Pitsford Hall was to account for a little over 75% of the 
total rainfall for September.  This rainfall was torrential 
in places resulting in significant flooding elsewhere in the 
country, notably Swanage where 121mm fell in 24 hours. 
Fortunately, the county escaped relatively unscathed.

Anticyclonic conditions developed over Scandinavia from 
the 10th onwards extending a ridge across the region. A 
settled spell of weather resulted. Temperatures were initially 
fairly respectable with maxima in the low 20s until the 14th, 
but thereafter they began to cool down significantly with winds 
taking a more northerly direction. Despite some showery rain 
on the 22nd and 25th, high pressure continued to dominate the 
scene right through until the end of the month. In the final 
week, night-time temperatures had started to fall quite 
significantly. On the 24th the grass minimum at Pitsford 
Hall registered 2.8C.  

The northerly flow of air was finally swung round from the 
south as high pressure retreated eastwards in the last few days. 
Although it remained chilly by night with early morning mists 
fairly prevalent, daytime maxima had risen a good few degrees 
above average for the time of year.


Climatological and Agromet Statistics - September 2002


Air Temperatures				
The Highest Maximum:			23.1C	on	5th
The Lowest Maximum:			15.5C	on	15th
The Highest Minimum:			15.6C	on	12th
The Lowest Minimum:			6.2C	on	1st
The Mean Maximum:			19.1C		
The Mean Minimum:			10.3C		
The Overall Mean:			14.7C		
Difference from the Monthly Mean:	1.0C		
				
Relative Humidity:				
Highest Relative Humidity (at 0900):	98.8%	on	28th
Lowest Relative Humidity (at 0900):	69.9%	on	7th
Mean Relative Humidity (at 0900):	81.2%		
				
Dew Point:				
The Highest Dew Point (at 0900):	15.8C	on	12th
The Lowest Dew Point (at 0900):		8.2C	on	1st
The Mean Dew Point (at 0900):		11.7C		
				
Rainfall:				
Total:					34.1mm		
Difference from the Monthly Mean:	60.1%		
Duration:				10.6hrs		
Highest 24 hour fall (from 0900):	25.9mm	on	9th
Rain Days (>/=0.2mm):			4			
Wet Days (>/=1.0mm):			2	
Lowest pH:				6.31 	on 	6th		
				
Sunshine:				
Total Duration of Bright Sunshine:	142.0hrs		
Sunniest day:				11.0hrs	on	1st
Sunless days:				5
Cloud cover (mean at 0900):		5.1 oktas (63.8%)	
				
Pressure (reduced to sea level):				
The Highest Pressure:			1031.8mb on	1st
The Lowest Pressure:			1005.7mb on	8th
Mean Pressure (recorded at 0900):	1021.0	mb		
				
Winds				
Run of wind (mean over 24 hrs):		82.4	miles		
Mean daily wind speed:			4.5	mph	
Highest 24-hour wind speed:		7.8	mph	on	5th	
Run of wind (to date):			2390.5	miles		
Highest Maximum Gust:			28	mph	on	22nd
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 7 E 3 SE 2 S 2 SW 1 W 1 NW 5 Calm 1
	
				
Ground Temperatures:			 	
Lowest Grass Minimum:			2.8C	on	24th
Mean Grass Minimum:			7.5C		
Lowest Concrete Minimum:		4.7C	on	24th
Mean Concrete Minimum:			9.1C		
Lowest Bare Earth Minimum:		1.2C	on	24th
Mean Bare Earth Minimum:		9.6C		
				
Soil/Earth Temperatures:		 		
Surface mean:				15.2C		
5cm mean:				14.2C		
10cm mean:				14.6C		
20cm mean:				15.0C		
30cm mean:				15.4C		
40cm mean:				15.5C		
50cm mean:				15.9C		
100cm mean:				15.9C		
				
				
Days with:				
Thunder:				0			
Hail less than 0.5mm:			0			
Hail greater than/equal to 0.5mm:	0			
Snow lying:				0
Fog:					1
Air Frost:				0
Duration of Air Frost:			0 hrs
Ground Frost:				0

Total Evaporation (tank)		58.00 mm