Storm Forecast
Valid: Thu 02 Nov 2017 06:00 to Fri 03 Nov 2017 06:00 UTC
Issued: Wed 01 Nov 2017 22:35
Forecaster: GATZEN

A level 1 was issued for Portugal and NW Spain mainly for tornadoes.

SYNOPSIS / DISCUSSION

A short-wave trough travels from south Scandinavia to the Ukraine within a north-westerly flow at the flank of low geopotential across north-eastern Europe. Along the region with strong PV advection, steep lapse rates are expected. These can partly overlap with rich low-level moisture, in particular along the shores of the Baltic Sea. However, there are only weak indications that a convective line can form, likely due to stable low levels. However, some isolated storms may be possible. Given strong low-level shear exceeding 10 m/s, a tornado and severe wind gusts are not ruled out.

Over south-western Europe, a southerly flow has evolved ahead of the cut-off low. Rich maritime moisture is advected onshore across Portugal and northern Spain. Lapse rates are steep due to continuous warming of a cold air mass across the warm sea waters. A frontal boundary slowly moving inland will be the focus of thunderstorm development. Strong low-level vertical wind shear across western Iberia will allow for some tornadoes especially near the coasts.