By Eric Leister, AccuWeather meteorologist
July 18,2017, 10:25:26PM,EDT
A surge of warm, humid air into the United Kingdom will set the stage for dangerous thunderstorms lasting into Wednesday.
Very moist air from the Mediterranean will build across the U.K., making it feel muggy and creating ideal conditions for heavy rain and thunderstorms.
The storms will move into southern England by late in the day and continue to spread northward into Wednesday.
Rainfall will continue to advance northward on Wednesday, bringing downpours throughout northern England and reaching Edinburgh and Glasgow by late morning.
The heaviest downpours are expected from Northern Ireland into Scotland Wednesday afternoon and evening, while showers and thunderstorms become more isolated throughout Wales and England.
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Ample moisture will result in torrential rainfall at times, with rainfall rates in excess of 25 mm (1.00 inch) per hour and some locations seeing up to 75 mm (3 inches) of rain within a few hours.
Rainfall of this magnitude can result in dangerous flash flooding and significant travel delays.
While flash flooding and frequent lightning will be the most widespread threats, damaging winds will also be possible.
Wind gusts over 80 km/h (50 mph) can result in downed trees and power cuts.
The strongest storms will bring the threat for damaging hail, though this is expected to be isolated.
Improved weather is expected across much of the U.K. on Thursday, with a mixture of cloud and sunshine though there will be the threat for a few showers.