Storm Forecast
Valid: Sat 25 May 2024 06:00 to Sun 26 May 2024 06:00 UTC
Issued: Fri 24 May 2024 18:54
Forecaster: PISTOTNIK

A level 1 is issued for wide areas between Italy, S Finland and Romania, and a level 2 for parts of Austria, the Czech Republic, Germany and Poland mainly for excessive convective precipitation and large hail, and to a lesser degree for severe convective wind gusts.

A level 1 is issued for parts of Turkey and Iran for excessive convective precipitation, large hail and severe convective wind gusts.

SYNOPSIS

Under weak pressure gradients, several mid-level and surface lows affect most parts of Europe from the British Isles to central and E Europe, the Balkans, Turkey, and increasingly even into Italy and Greece, bringing seasonably tempered and quite unsettled weather. A blocking anticyclone remains placed over Scandinavia and W Russia, and a brief outbreak of polar air floods N Scandinavia at its forward flank. A weak subtropic ridge extends into the Iberian Peninsula, but does not amplify any further.

DISCUSSION

... European level 1 and level 2 areas ...

The warm and moist airmass under rather cyclonic influence and weak dynamics allows the buildup of mostly moderate CAPE after some hours of diurnal heating (mostly in the 500 to 1000 J/kg range, regionally less or somewhat more). Scattered to widespread, disorganized, daytime-driven thunderstorms will again form over orographic features, along outflow boundaries, insolation gradients, other (diffuse) convergence zones, and ahead of travelling upper-level vorticity maxima. Single cells, some multicells and larger clusters are the expected convective modes. The primary hazard is excessive rain, while the strongest pulse storms can also bring marginally large hail, plentiful small hail and/or isolated severe downbursts. Parts of Austria, the Czech Republic, SE Germany and W Poland are upgraded to a level 2, since convergent near-surface winds and weak synoptic lift (both from warm air advection positive vorticity advection) under fairly robust CAPE hint at a particularly high storm coverage.

... E Turkey and Iran ...

At the forward flank of the easternmost cut-off low, low to moderate CAPE and some synoptic lift allow scattered daytime-driven storms as well, mostly over orographic features. Deep-layer shear around 15 m/s favors multicells and perhaps a few transient supercells. Isolated to scattered large hail, severe wind and excessive rain events may occur.