Storm Forecast
Valid: Tue 05 Jul 2011 06:00 to Wed 06 Jul 2011 06:00 UTC
Issued: Mon 04 Jul 2011 22:28
Forecaster: SCHLENCZEK

A level 1 was issued for S Italy, Sicily and S Adriatic / Ionian Sea mainly for large hail and severe wind gusts.

A level 1 was issued for N Belarus, E Baltics and W Russia mainly for excessive precipitation and large hail.

SYNOPSIS

A large low pressure system over the East Atlantic moves across the British Isles on Tuesday. Some convection is expected near the upper cold core of this low where a few hundred J/kg CAPE should be available in a weakly sheared environment.

Another upper low is initially located over N Italy and moves eastwards towards the Dinaric Mountains. To the south of this low, moderate instability is in place with strong deep layer shear and QG forcing from the upper vort-max. This setup will likely lead to severe weather across S Italy and the Ionian Sea region, including Greece.

The third upper level vortex is centered over western Ukraine and provides strong WAA for western Russia. The most significant threat of severe weather is expected east of the Ural Mountains, though.

DISCUSSION

...S Italy, Sicily, Ionian Sea...

Some 15 - 20 m/s of deep layer shear are present at the southern tip of the upper low which moves across the Mediterranean area during the afternoon. Compared to Monday, instability is somewhat reduced and therefore convection should be less organised. Nevertheless, a few organised multicells and supercells may produce isolated large hail and isolated marginally severe wind gusts due to strong winds at 700 hPa. Overall convective activity is likely to weaken after sunset as instability decreases due to less strong low level WAA further downstream.

...W Russia, Belarus, Baltics...

Some 500 - 1000 J/kg MLCAPE near the center of the low pressure system combined with 10 - 15 m/s of 0-6 km deep layer shear may support some more organized multicells over W Russia and Belarus / N Baltics. The main threat should be marginally severe hail and local excessive precipitation as continuous moisture advection at lower levels should sustain the convection for a long period of time. A few places within the LVL1 area might get favourable LL directional shear and enhanced SRH1 for an isolated tornado event but the tornado threat is considerably low.

...Other regions...

Overall instability and shear is rather weak in the other parts of Europe. Nevertheless, a few storms might produce isolated marginally severe hail. Most of the convection is diurnally driven and will rapidly diminish after sunset.