Storm Forecast

Storm Forecast
Valid: Wed 22 Sep 2021 06:00 to Thu 23 Sep 2021 06:00 UTC
Issued: Tue 21 Sep 2021 19:22
Forecaster: PUCIK

A level 2 was issued across E Spain and the Balearic Sea mainly for excessive rainfall, large hail and severe wind gusts.

A level 2 was issued across Morocco mainly for large hail and severe wind gusts.

A level 1 was issued across Spain mainly for excessive rainfall and large hail.

A level 1 was issued across the south - central Mediterranean, Sardegna and Sicily mainly for large hail and excessive rainfall.

A level 1 was issued across southern Turkey mainly for excessive rainfall and large hail.

A level 1 was issued across central Turkey and southern Caucasus mainly for severe wind gusts.


The synoptic-scale situation across Europe will be dominated by a deep cyclonic vortex centered over western Russia and its trough crossing the Balkans towards Turkey and the Black Sea. To the west, a ridge will stretch across central Europe and a deep cut-off low will linger over Spain, moving southwest during the forecast period. Numerous storms are forecast to form on the forward flank of the low across Spain with main threats of excessive rainfall and also large hail with well-organized storms forming in 0-6 km bulk shear values of around 15 m/.

A higher severe weather threat will develop along the E Spain coastline and over the Balearic Sea, on the edge of the EML overlapping with a very moist airmass.  As a surface low develops to the north of Africa, easterly to northeasterly surface flow will develop across the sea, changing to southwesterly aloft. A significant overlap of CAPE and deep-layer shear is simulated here, promoting well-organized and severe storms. The exact evolution of the storms is currently questionable with large model-to-model differences. ECMWF trends towards extremely heavy precipitation event across the E Spain coastline, while GFS and ICON keep the strongest storm confined to the sea, where high CAPE and very strong 0-3 km shear would enhance large hail and severe wind gust risk.  

Isolated severe weather risk is forecast across a large area from the Balearic Sea towards Sardegna and Sicily, denoting the EML and its edge. The organization of storms developing across the area will benefit from 15 to 20 m/s of 0-6 km bulk shear, which combined with high CAPE yields a high likelihood of severe storms given the successful initiation.

Another area of high CAPE is forecast across S Turkey, where scattered storms may be capable of large hail, excessive rainfall and severe wind gusts. Shear will get stronger and CAPE will decrease towards the continental Turkey and Caucasus, resulting in an isolated threat of severe wind gusts given long hodographs with 0-3 km bulk shear exceeding 15 m/s.

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