Storm Forecast
Valid: Thu 01 Feb 2018 06:00 to Fri 02 Feb 2018 06:00 UTC
Issued: Wed 31 Jan 2018 23:44
Forecaster: GATZEN

A level 1 was issued across western Croatia, Montenegro, and Albania for extreme rainfall and to a lesser extent tornadoes.

A level 1 was issued across western central Italy and central Tyrrhenian Sea for extreme rainfall and to a lesser extent tornadoes and large hail.

SYNOPSIS / DISCUSSION

A west-European trough starts to amplify on Thursday, is will extend southward into the Iberian Peninsula late in the period. A broad south-westerly flow evolves ahead of the trough axis, affecting the western and central Mediterranean. A moist air mass will spread north-eastwards east of a quasi-stationary frontal boundary. This air mass is expected to be slightly unstable, partly originating from steep lapse rates of the Atlas mountains especially located over the Tyrrhenian Sea. Farther north-east, moist profiles are forecast across the Adriatic. Here, weak CIN and relatively high precipitable water indicate a flash flood risk. As the frontal boundary will move only slowly, areas with additional upslope flow are highlighted by a level 1 threat in the from the evening hours towards the end of the forecast period. Over the Tyrrhenian Sea, an additional risk of large hail and severe wind gusts is issued, given larger CAPE, strong vertical wind shear and therefore better storm organization. Tornadoes are not ruled out in the environment with long low-level hodographs, favourably veering profiles, and some low-level buoyancy.

Western Europe is affected by an intense PV intrusion. Steep lapse rates spread southward quickly. However, low-level moisture is limited in a northerly surface flow, and low-level cold air advection results in weak low-level convergence. Convective cells forming linear elements may be the dominant storm mode. Severe wind gusts are not ruled out.