July has gained a reputation recently, especially with all the discussion about global warming, of being a very warm settled month but it is interesting how our memories can deceive us. Even in relatively warm summers there can be some very unsettled periods and as recently as July 2004 this proved to be the case.

The latter part of June 2004 had been unsettled and the month of July also began in the same vein but by the 6th as pressure built to the south west it seemed that perhaps some fine dry weather was at last on the way. However, it was not to be. Although winds swung to the south by the end of the first week a deepening Depression moving up across Biscay intensified quite rapidly and brought a spell of unseasonably strong winds and wet weather to the southern parts of the UK.

 

An area of heavy rain developed to the south across Northern France early on the 7th and tracked slowly north across England and Wales during the day. It was accompanied by strong winds from the north-east as the deep depression tracked up into the SW Channel approaches and continued to deepen further. This chart shows the depression as it stood at 00Z on the 8th; as deep as 991mb, just north of Brest (NW France); notice the very strong winds wrapped around it, shown by the tightly packed isobars:  

http://www.wetterzentrale.de/archive/2004/brack/bracka20040708.gif

 

Homes in East Anglia were left without power for many hours as gusts of Wind reached as high as 68mph at Culdrose (S Cornwall). There was widespread heavy rain; throughout East Anglia many places reported over an inch (25mm) during the afternoon and evening.

 

By the 8th with the low pressure now out into the North Sea a cold north-north east flow covered the country. Sennybridge (Powys) was cold with a maximum of just 9.6C, which is one of lowest ever maximum temperatures recorded in July as a low level station. Other places in the north of England and the West Midlands also had their coldest July day on record with most areas reporting maxes of just 12–13C.

 

Elsewhere in England, the weather improved for a time and the sun shone for a time. However this simply served to trigger some heavy Thunderstorms in the still unstable flow, and brought some further very heavy rain to many parts once again. Some of the storms became very slow moving especially over parts of the east of England. A storm that developed over RAF Wittering (Lincs) managed to give over 2 inches of rain (50mm) in just 2 hours, a huge amount, giving local flooding and bringing their rainfall total (to 18Z on the 7th), to over 4 inches (108mm to be precise) for the day.

 

July 2004 continued quite unsettled. On the 17th for example, an area of heavy thunderstorms moved across the south east of England, London and East Anglia. Some parts of East London reported up to 3-4cm hail causing local damage to foliage and property.

 

A few days later on the 22nd July an area of severe storms moved across the Midlands with reports of ball Lightning, tornadic vortices and wind gusts, which on investigation may have been as high as 115mph (100kt).

 

It should be a lesson to us to remember, that not all summer months live up to our expectations. The UK in summer is always liable to be at risk of some potentially very unsettled periods of weather, it is still the long periods of dry, hot weather that remain the rather more unusual event.