Storm Forecast Valid: Mon 04 May 2015 06:00 to Tue 05 May 2015 06:00 UTC Issued: Mon 04 May 2015 00:03 Forecaster: VAN DER VELDE
A level 2 was issued for N Portugal and NW Spain mainly for tornadoes and severe convective wind gusts. A level 2 was issued for SW to N France mainly for severe convective wind gusts, large hail and tornadoes. A level 1 was issued for parts of Portugal, northern Spain, central and western France and the Benelux countries mainly for severe gust, large hail and tornado chances.
An active depression near Portugal is advecting significantly warmer, unstable air with a SSW-ly flow into southwestern Europe. It follows in the wake of an old low with its core west of Ireland which briefly brought a surge of warm air into western and central Europe. A remnant occlusion is decaying between Czech Republic and Ukraine. The Portuguese low is a highly baroclinic system with a marked warm front about 100 km north of the line Galicia - Switzerland during the afternoon. Strong flow veering with height is present across the warm sector and a Spanish Plume situation develops, this time separately from the Saharan Air Layer which runs over the western Mediterranean basin. Around 12Z the cold front enters the Iberian Peninsula and reaches SW France around 21Z along with the center of the low passing west of Brittany. By Tuesday 06Z the warm front is predicted to have reached northern Netherlands and central UK.