OnlineWeather.org.uk - UK Weather For the Week Ahead\title

http://www.onlineweather.org.uk/Warnings/Warnings.htm \n \n --------------------------

21:20GMT, 24/08/2008
Valid Date: 24/08/2008 to 30/08/2008
Valid Time: 0000UTC to 23:59UTC
-------------------------- Type of Weather: Heavy polar maritime airstream rainfall -------------------------- /n /n The north-westerly jet is causing persistent issues with heavy rainfall for many parts of the north-west, Northern Ireland and Scotland.
This weather is due to ease mid-week, with rainfall and cloudiness in Scotland becoming less intense as the upper level trough (high PV anomaly at 800hPa) shifts Westward from Scotland into the Atlantic. This shifting upper level vortex is due to a developing tropical maritime jet, which introduces some sheering and upper level disruption to troublesome and semi-persistant upper level PV feature.
From Thursday onwards the onset of upper level tropical maritime advection will result in a moister upper troposphere and more "stable" conditions for south-western Scotland and Northern-Ireland [although the stability of the mid-upper tropospheric layer will tend to increase]. The latter will lead to humid and overcast conditions for much of the north from Wednesday into the weekend, and warm/hot sunny conditions for much of England and Wales. There is an outside chance of localized heavy thundery rain, as intense surface heating combined with the moist mid-upper level atmosphere provides ideal conditions for thundery outbreaks by the Weekend.

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The risk of heavy rainfall and flooding from Monday to Thursday morning is of high level confidence >85%, with the highest associated flooding risks in the NW highlands.
The risk of persistant and heavy rainfall from Thursday afternoon onwards remains low at <30%. Outside risk of isolated thundery rainfall moving up the backbone of the UK during Friday and Saturday.

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24/08/2008, 21:20GMT