PITSFORD HALL WEATHER STATION
NORTHAMPTON, UNITED KINGDOM

MONTHLY WEATHER REPORT - MAY 2003

Headline: Changeable with low pressure influencing conditions 
throughout much of the month. High pressure brought a very 
warm spell in the final week.

As April came to a close on a very unsettled note so May began 
with low pressure close by bringing heavy rain on the 1st and 
2nd. The 1st caught the most rainfall of any day in May with 
9.1mm recorded over 7 hours. Although showers were accompanied 
by thunder in many parts, no such activity was recorded at 
Pitsford. Winds were also strong, mainly southerly, with gusts 
reaching 37mph on the 2nd. Drier and calmer conditions ensued 
on the 3rd and the 4th became noticeably warm with a daytime 
maximum of 22.1C. Some weak weather fronts crossed the county 
over the following week bringing a rather changeable theme of 
some warm sunny days broken up by rather cooler, cloudier days 
with spells of light rain or drizzle.

The weather from the 11th until the 21st was influenced by the 
passage of two low pressure systems to the north. As the first 
tracked across, it became noticeably cooler as winds veered 
round to a north-westerly direction. Overnight temperatures 
dropped especially, with a noticeable ground frost on the 15th. 
There were frequent showers and longer spells of rain often 
with thunder and/or hail mixed in. A transient ridge built in 
on the 14th giving a brief window before the second system edged 
in from the west. Again it remained cool, although the fairly 
brisk south-westerlies held up the overnight temperatures.

A third more discrete area of low pressure maintained the 
unsettled conditions from the 22nd to the 25th. Moving southwards 
across the North Sea the system brought with it some sharp 
showers to the county on the 24th.

The month came to a close as the Azores high expanded towards 
Scandinavia. This brought with it dry conditions and a consistent 
increase in daytime temperatures culminating in the highest 
maximum of the month on the 31st of 27.5C. Cloud was remained 
fairly extensive and persistent on the 27th and 28th, but 
generally sunshine totals were very respectible with 12.5 and 
12.4 hours being recorded on the 30th and 31st respectively.


Statistics - May 2003


Air Temperatures				
The Highest Maximum:			27.5C	on	31st
The Lowest Maximum:			13.1C	on	16th
The Highest Minimum:			13.6C	on	28th
The Lowest Minimum:			1.1C	on	15th
The Mean Maximum:			17.3C		
The Mean Minimum:			7.7C		
The Overall Mean:			12.5C		
Difference from the Monthly Mean:	0.1C		
				
Relative Humidity:				
Highest Relative Humidity (at 0900):	95.6%	on	17th
Lowest Relative Humidity (at 0900):	43.6%	on	15th
Mean Relative Humidity (at 0900):	72.3%		
				
Dew Point:				
The Highest Dew Point (at 0900):	15.0C	on	31st
The Lowest Dew Point (at 0900):		0.6C	on	15th
The Mean Dew Point (at 0900):		8.8C		
				
Rainfall:				
Total:					41.2mm		
Difference from the Monthly Mean:	82.7%		
Duration:				32.7hrs		
Highest 24 hour fall (from 0900):	9.1mm	on	1st
Rain Days (>/=0.2mm):			14			
Wet Days (>/=1.0mm):			11			
				
Sunshine:				
Total Duration of Bright Sunshine:	192.6hrs		
Sunniest day:				12.5hrs	on	30th
Days without sunshine:			2
Cloud cover (mean at 0900):		5.5oktas (68.8%)	
				
Pressure (reduced to sea level):				
The Highest Pressure:			1024.4mb	on	7th
The Lowest Pressure:			1000.7mb	on	2nd
Mean Pressure (recorded at 0900):	1013.8mb		
				
Winds				
Run of wind (mean over 24 hrs):		124.5miles		
Mean daily wind speed:			6.7mph	
Highest daily wind speed:		13.1mph	on	4th	
Run of wind (to date):			3859.9miles		
Highest Maximum Gust:			37mph	on	2nd
Highest wind strength (at 0900):	17.3mph	on	14th
Mean wind strength (at 0900):		7.3mph		
				
Winds from the Following Directions:				

N 0 NE 2 E 0 SE 3 S 13 SW 4 W 1 NW 6 Calm 2		
				
Ground Temperatures:			 	
Lowest Grass Minimum:			-1.2C	on	15th
Mean Grass Minimum:			5.4C		
Lowest Concrete Minimum:		1.2C	on	15th
Mean Concrete Minimum:			7.2C		
Lowest Bare Earth Minimum:		-2.0C	on	15th
Mean Bare Earth Minimum:		7.1C		
				
Soil/Earth Temperatures:		 		
Surface mean:				15.6C		
5cm mean:				12.5C		
10cm mean:				12.5C		
20cm mean:				12.4C		
30cm mean:				12.6C		
40cm mean:				12.5C		
50cm mean:				12.7C		
100cm mean:				11.2C		
				
				
Days with:				
Thunder:				2			
Hail less than 0.5mm:			2			
Hail greater than/equal to 0.5mm:	0			
Snow or snow & rain:			0			
Fog:					0	
Air Frost:				0
Ground Frost:				2					
						
Total Evaporation (tank)		63.16mm