Storm Forecast
Valid: Tue 02 Feb 2021 06:00 to Wed 03 Feb 2021 06:00 UTC
Issued: Mon 01 Feb 2021 21:27
Forecaster: DAFIS

A level 2 was issued for E Greece and W Turkey mainly for excessive convective precipitation, large accumulations of small hail and tornadoes.

A level 1 was issued for W France mainly for severe convective wind gusts.

SYNOPSIS

A long-wave trough with a neutral tilt and an axis extending from Scandinavia towards Libya has established a strong south-westerly flow in Eastern Mediterranean. More specifically, NE Greece and Turkey experience strong thunderstorms with devastating floods, which will continue to affect the area on Tue 2 Feb 2021.
More to the west, an intensifying ridge will result in an anticyclonic wave breaking over the Central-Eastern Mediterranean, but the main interest is focused on a couple of short-wave troughs crossing fast the northern parts of France. The advection of warm and moist air masses from the Atlantic and a maritime polar air mass to the north, result in a very strong jet stream over France.

DISCUSSION

.... Greece and Turkey ....

A level-2 area threat has been issued for the eastern parts of the Aegean Sea where a strong a persistent low-level convergence line is forecast on Tue 2 Feb. The available NPW models show unstable air masses converging over this area for more than 24 hours until the early morning on Wed 3 Feb. The low values of CAPE and shear suggest that large hail or exceptionally strong wind gusts are not probable, but small hail and in large quantities cannot be ruled out. In addition, several waterspouts are expected during training convection and can pose a threat to the coasts.

.... France ....

Two short-wave troughs will cross the NW parts of France on Tue 2 Feb. The first may result in scattered thunderstorms and strong convective wind gusts but the second trough during the night and early morning on Wednesday may pose a serious threat. At the surface, a low-pressure system with a minimum SLP lower than 992 hPa is expected to pass over Brittany and at the warm sector, CAPE is forecast to reach values up to 400 J/kg, overlapping with more than 20 m/s DLS. Any storm that will form close to the coasts of Britanny will be able to produce extreme wind gusts of up to 30 m/s.