UK THUNDERSTORM WARNING


After initially issuing a thunderstorm watch, this has been upgraded to a weather warning based on the latest model outputs. The main risk seems to be from the rain with thunder and lightning confined to certain areas.

Valid: Thursday 28th June 10:00 – 23:00

Highlights

  • Theta-EW Plume across the UK thanks to low pressure to the South-West
  • Advancing cold front coinciding with this plume will allow heavy rain to develop
  • Wales and the central bulk of the country to see heaviest rainfall
  • Lightning mostly confined to South-East England and East Midlands

Synopsis & Forecast Detail

Over the last couple of days Low Pressure to the South-West of England has been pulling up some warm air all the way from Africa, this has allowed temperatures to steadily climb over the last few days and allowed something we call a Theta-EW Plume or a Spanish Plume to develop across the country, as a cold front associated with the Low Pressure system pushes Eastwards across the country, the temperature difference ahead and behind the cold front will allow some heavy rain to develop.

The heaviest of the rainfall looks likely to develop across Eastern Wales up into the Midlands and later on Northern England, due to the amount of rain we’ve seen in the last couple of weeks there is a risk of flooding where the heaviest rain is likely to fall. We also have an area of CAPE in the region of 700-900 J/KG and a LIFT of -3/-4 present across the Midlands heading South-Eastwards, as this cold front advances it seems very likely that elevated lightning will develop, especially across South-East England where it’s expected to remain largely dry, the Midlands are likely to see thunder and lightning embedded within the rainfall with a risk of hail present.

Weather Charts

This MetOffice FAX chart shows the Cold Front as it pushes North-Eastwards into the United Kingdom

This is the GFS CAPE & LIFT chart showing CAPE in the region of 700-900 J/KG and a LIFT of -3/-4, this is sufficient for thunderstorms

This NAE chart shows the progression of the rainfall

This NAE chart shows the progression of the rainfall

This NMM model shows the rainfall as it pushes across the United Kingdom, it is in line with the NAE model posted above

This NMM model shows the rainfall as it pushes across the United Kingdom.

This chart shows the Theta-EW Plume evident across the country with a value of 60

 

WEATHER WARNING ISSUED

Warnings Map – Click to Enlarge

 

Due to the nature of this weather event and previous heavy rainfalls we’ve seen likely it is deemed necessary to issue a warning for areas expected to see the heaviest rainfall.

Orange Zone – A weather warning has been issued, heavy rain will push North-Eastwards through the course of Thursday giving rise to dangerous driving conditions and a possibility of localised flooding. Localised thunder and lightning with a chance of hail is also expected within this region.

Yellow Zones – A weather watch has been issued, heavy rain is expected in these areas but it will tend to be patchier and more localised, whilst flooding is a possibility the rainfall is not likely to be persistent and therefore does not warrent a weather warning.

Lightning Bolt Symbols – These show the areas most at risk from thunder and lightning, the further South-East you head the more elevated this is likely to be, this simply means that it’ll generally be dry with flashes of lightning in the sky, due to the elevation it’s unlikely that thunder will be heard.

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  1. July Outlook | UK Weather Forecasts - June 27, 2012

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