SEVERE storm and hail warnings have been issued in Spain – as 100mm of rain fell in just one hour at a holiday hotspot leaving cars submerged under water. Locals and tourists are bracing for

Scholars and designers of early warning systems say that there are still huge gaps in our ability to predict flash floods and warn those at risk.

"We have lived here 21 years in Los Lunas, and I've never seen it out here like this," Kitty Adams told KOAT on Thursday after her yard was severely flooded.

Dr Neumann said it is difficult to give early warning in flash floods driven by rainfall, because they can ‘happen in a matter of minutes’, and even when forecasters can tell that a thunderstorm will bring heavy rain, it’s hard to predict exactly where that will be.

A flash flood warning was released by the National Weather Service on Monday at 7:06 p.m. in effect until 9 p.m. for Allegheny and Butler counties.