May Thunderstorms

12:19pm Tuesday 6th May 2008

In May a very warm or a hot spell usually occurs. Sometimes the Spanish Plume pumps northward on a southerly wind flow bringing temperatures in the range of 25-30c 77-86f. The mainland of the UK warms up quickly and growth of our plant life speeds up dramatically. Swifts and swallows make their way northward from Africa on these warm southerly winds.

As France hots up often the pressure falls, we call these thermal lows. On the weather chart it shows up as a slack area of low pressure with very few isobars around it. This thermal low containing plenty of heat and moisture moves northward often into England and Wales. An area of thundery activity develops over France and transfers northwards on several days in succession. The heat and moisture of the atmosphere fuels those developing storms, and they often develop into severe high level thunderstorms causing flash flooding. Strong winds at this time of year in the Sahara Desert whips up sand way up into the atmosphere, transports it to the UK on those southerlies, encounters the rain bearing clouds bringing red rain. After the moisture has evaporated away, the sand can be clearly seen on windows, car windscreens and other surfaces. If forest fires occurs abroad, sometimes ash is also transported to the UK. I feel that May 2008 will bring these conditions at some stage. Lets wait and see whether I'm right.

Next Week.....Interesting facts about Thunderstorms.The answer to last weeks question: The Gulf Stream.This weeks question:

Does a Thermal Low bring:

A/ Cold dry weather.

B/ Warm humid thundery weather.Good Luck.Glossary: Convection: The transfer of heat within a gas or liquid by the movement of the gas or liquid. The warm fluid expands becoming less dense, and rises with cooler, denser fluid sinking to replace it. The weather for the coming week Monday 5th May-Friday 9th MayHigh pressure from the near continent building in across the UK, fending off any real fowl weather.Much of this week into weekend fine warmer and placid with a light east/south-east airflow coming in around that high pressure. Mild nights with any storms later few.Maximum temperature 23-25c 73-77f.Minimum temperature 10-14c 50-57f.Last Weeks Observations (Monday-Sunday)Highest day temperature............20.0c 68f on Friday 2nd May.Lowest night temperature...........0.9c 34f on Monday 28th April.Wettest day..............................15.1 mm on Tuesday 29th April.

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