Storm Forecast
Valid: Wed 10 Jan 2018 06:00 to Thu 11 Jan 2018 06:00 UTC
Issued: Tue 09 Jan 2018 21:19
Forecaster: PUCIK

A level 1 was issued across Portugal and NW Spain mainly for tornadoes and to the lesser degree for marginally severe wind gusts.


SYNOPSIS and DISCUSSION

A blocking situation is continuing over Europe with a large ridge stretching from the Eastern Mediterranean into Sweden in the beggining of the forecast period. A short-wave trough will progress from the Central Mediterranean towards Turkey during the day, eroding the ridge at its base. In the core of the trough, steep lapse rates under the cold mid-tropospheric temperatures will result in scattered thunderstorms. However, overlap with strong vertical wind shear will be rather poor, precluding more organized convection and enhanced severe weather threat.

Towards west, a fast moving short-wave, associated with a frontal system will progress from the Atlantic eastwards, subsequently stalling over the Bay of Biscay. As a cold front crosses Portugal, embedded thunderstorms may form in marginal CAPE environment. Strong vertical wind shear suggests that few of the cells could acquire rotation. Forecast soundings reveal strong lower tropospheric shear and low LCLs around 12 UTC, pointing at a tornado threat. Marginally severe wind gusts may occur as well in stronger downdrafts.