Outlook day 1 (valid: 30/03/2018)

VALID FOR 30-03-2018






SYNOPSIS

Europe is dominated by a large upper trough spreading into central Europe with a surface frontal zone moving east through Friday. Very cold mid levels spread across the Bay of Biscay.

DISCUSSION

A SLGT risk has been issued for parts of N Italy, N Adriatic sea, W Slovenia and NW Croatia with threat for excessive rainfall due to continuous orographic precipitation combined with some convection. Locally more than 100 mm is expected in 24 hours. Additionally, strong warm advection should result in weakly unstable airmass (MLCAPE of near 400-800 J/kg) within strong (25+ m/s) deep layer shear and good helicity across the N Italian plains. Some severe storms could be possible in the afternoon hours, mainly with severe winds and marginally large hail threat.

A SLGT risk has been issued for ESE France into N Switzerland with threat for isolated severe storms along the surface cold front pushed from the west. Models are in good agreement: some marginal instability (400-700 J/kg of MLCAPE) will yield in the afternoon hours, supportive for organized storms capable of producing heavy rainfall and strong to severe winds.

A MRGL risk has been placed around the SLGT risk areas where isolated threat for organized storms exists, some storms could enhance severe winds and heavy rainfall threat.

A MRGL risk has been issued for S Bay of Biscay, N Spain into SW France where some isolated threat for severe storms with severe winds and marginal hail exists.

A WNTR risk has been issued for west-central Alps with threat for excessive snowfall above 2000m ASL where locally 50-75cm if fresh snow seems likely.