PITSFORD HALL WEATHER STATION
NORTHAMPTON, UNITED KINGDOM

MONTHLY WEATHER REPORT - JULY 2001

Monthly Assessment

Headline: A warm first week gave way to a protracted period 
of cool unsettled weather with substantial rainfall. A return 
to very warm weather in the latter half as a ridge of high 
pressure held sway. 

The first week of July had a generally warm theme. Daytime maxima 
topped 24C on consecutive days with the highest maximum of July 
(29.3C) recorded on the 3rd. Although thunderstorms broke out 
over a large part of England and Wales on the 3rd, the county 
escaped largely dry.

The following two weeks saw a generally unsettled spell of weather. 
A succession of lows brought cool conditions to the county and 
there were frequent showers and longer spells of rain. Many of 
the passing fronts brought thundery conditions to many areas, 
although the county again escaped with fairly modest falls. The 
17th and 18th were particularly wet owing to the passage of an 
active low and slow moving fronts from the south-west towards 
the North Sea. 30.4mm fell at Pitsford Hall on 17th over 11.5 hours, 
with a further 14.4mm falling on the 18th. Some very localised 
flooding was reported.


The fourth week began a gradual warming trend as a ridge of high 
pressure set in. Winds became very light and calm at times with 
some good spells of sunshine. By the final week of July daytime 
maximum temperatures had recovered to the high twenties, 29.1C 
being recorded on the 29th at Pitsford Hall and temperatures as 
high as 32C being reported from the south-east.

A weak cold front edging southwards as the month came to a close 
saw a return to cooler and fresher conditions, although remaining 
fairly warm in the sunshine.



Climatological & Agromet Statistics - July 2001

Climatological Statistics - Pitsford Hall

Air Temperatures				
The Highest Maximum: 29.3C on 4th
The Lowest Maximum: 16.4C on 18th, 19th
The Highest Minimum: 18.8C on 29th
The Lowest Minimum: 6.7C on 15th

The Mean Maximum: 22.4C
The Mean Minimum: 12.8C
The Overall Mean: 17.6C
Difference from the Monthly Mean: +0.7C
				
Relative Humidity:				
Highest Relative Humidity (at 0900): 95.9% on 8th
Lowest Relative Humidity (at 0900): 55.4% on 2nd
Mean Relative Humidity (at 0900): 78.5%
    
Dew Point:				
The Highest Dew Point (at 0900): 17.5C on 29th
The Lowest Dew Point (at 0900): 8.4C on 12th
The Mean Dew Point (at 0900): 13.8C
				
Rainfall:				
Total: 77.8mm
Difference from the Monthly Mean: 162.4%
Duration: 38.7hrs
Highest 24-hour fall (from 0900): 30.4mm on 17th
Rain Days (>/=0.2mm): 12
Wet Days (>/=1.0mm): 9
Lowest pH: 5.5 on 10th
			
Sunshine:				
Total Duration of Bright Sunshine: 179.4hrs
Sunniest day: 11.5hrs on 4th
Sunless days: 2
Cloud cover (mean at 0900): 5.2 oktas (65.0%)
				
Pressure (reduced to sea level):				
The Highest Pressure: 1026.7mb on 2nd
The Lowest Pressure: 994.4mb on 18th
Mean Pressure (recorded at 0900): 1013.1mb
		
Winds:				
Run of wind (mean over 24 hrs): 77.2 miles 
Mean daily wind speed: 4.2mph
Highest 24-hour Wind Speed: 9.5mph on 5th
Run of wind (to date): 2392.6 miles
Highest Maximum Gust: 33mph on 18th
Highest wind strength (at 0900): 19.6mph on 19th
Mean wind strength (at 0900): 5.6mph
		
Winds from the Following Directions:				
N 5, NE 1, E 2, SE 0, S 3, SW 7, W 2, NW 6, Calm 5
	
Days with:				
Thunder: 0
Hail less than 0.5mm: 0
Hail greater than/equal to 0.5mm: 0   
Snow or snow & rain: 0
Snow lying: 0
Fog: 0
Air Frost: 0
Duration of Air Frost: 0 hrs
Ground Frost: 0

Evaporation: 

The recording of evaporation using the Hook-gauge evaporimeter 
has been discontinued. Year-round recordings of evaporation 
will commence in the autumn using a Piche evaporimeter.	

	
Agro-Meteorological Statistics - Pitsford Hall Agromet Site (Brixworth)
				
Ground Temperatures:			 	
Lowest Grass Minimum: 4.3C on 15th
Mean Grass Minimum: 11.2C
Lowest Concrete Minimum: 8.0C on 15th
Mean Concrete Minimum: 13.6C
Lowest Bare Earth Minimum: 7.7C on 15th
Mean Bare Earth Minimum: 13.3C
				
Soil/Earth Temperatures (under grass):		 		
Surface mean: 15.5C
5cm mean: 16.0C
10cm mean: 16.3C  
20cm mean: 17.7C  
30cm mean: 18.1C
40cm mean: 18.2C
50cm mean: 18.4C
100cm mean:  17.2C
	

				
Climatological observations made at 0900 UTC. 
Agro-meteorological observations made at 0700 UTC. 
Averages refer to the period 1971-2000.