Storm Forecast
Valid: Thu 13 Feb 2014 06:00 to Fri 14 Feb 2014 06:00 UTC
Issued: Wed 12 Feb 2014 22:18
Forecaster: GATZEN

A level 1 was issued for central and eastern France, Switzerland, northern Italy, and the northern Adriatic mainly for severe wind gusts and tornadoes.

SYNOPSIS

The large-scale flow across Europe is dominated by an amplified trough over the central parts. It will slowly move eastward over the central and east Mediterranean. Further north, a south-westerly flow has evolved ahead of an intense Atlantic trough that will extend into central Europe at the end of the period. A strong mid-level jet streak will affect an area from France to the Balkan States. At low levels, rather high moisture is expected ahead of the European trough across south-eastern Europe. Rather good low-level moisture present over south-western Europe will spread into central Europe on Thursday ahead of the approaching jet streak.

DISCUSSION

France to Balkans

A strong north-westerly mid-level jet streak will spread across southern France and into Italy during the period. It will provide strong DCVA at its cyclonically sheared flank. At lower levels, warm air advection is expected in the range of the nose of the jet streak. Additionally, a plume of moist maritime air masses will spread from the Bay of Biscay into France. Latest soundings indicate that CAPE is well possible in this air mass (Camborne!).

Storms may form in the morning and noon hours across western or central France and spread east and south-eastward during the day. Given the strong background flow and rapid storm motion, intense convection can produce severe wind gusts. Limiting factor will be dominating low-level cold air advection and weak low-level convergence along the cold front. Therefore, only a level 1 is issued.

Despite the wind threat, tornadoes are not ruled out especially with isolated storms in the warm air mass with favorably veering profiles ahead of the cold front. Storms are forecast to spread into Switzerland and northern Italy in the afternoon and evening hours. Severe threat is not expected to weaken due to the strong dynamic weather pattern, and severe wind gusts and tornadoes are still not ruled out.

Late in the period, convective activity will spread into the Adriatic Sea and Balkan region, where low-level convergence and moisture will increase during the night hours. New cell development is expected to pose a threat of severe wind gusts, tornadoes, and marginally severe hail. Limiting factor is the weak low-level convergence. A level 1 seems to be warranted, though.