Storm Forecast
Valid: Sun 26 Jul 2015 06:00 to Mon 27 Jul 2015 06:00 UTC
Issued: Sun 26 Jul 2015 01:04
Forecaster: TASZAREK

A level 2 was issued for parts of W Russia mainly for the severe wind gusts, large hail, tornadoes and excessive precipitation.

A level 1 was issued for parts of W Russia, E Estonia, E Lithuania, E Latvia, Belarus, Ukraine, N Romania and N Moldavia mainly for the severe wind gusts, large hail and excessive precipitation.

A level 1 was issued for N Italy mainly for severe wind gusts, large hail and excessive precipitation.


SYNOPSIS

Polar air mass is placed in NW, W and central Europe with two troughs located over Ireland and S Scandinavia. Tropical and unstable air mass will be pushed during the forecast period towards NE and E Europe. Jet streaks are located over S British Isles, N France, Switzerland, Benelux and W Russia. A long-wave with axis placed over Baltic countries will create favorable conditions for the severe weather occurrence in W Russia.

DISCUSSION

...parts of W Russia, E Estonia, E Lithuania, E Latvia, Belarus, Ukraine, N Romania and N Moldavia...

NWP models predict that a thunderstorms will form along a low-level convergence zone (with mixing ratio up to 13-14 g/kg) that during the forecast period will be stretching from Estonia up to N Romania. Line of the storms will move eastwardly except N part of the line where the training storms are expected. In a narrow zone along W Russian border, a 15 m/s DLS overlapping with CAPE up to 3500 J/kg will create good conditions for storm clustering into multicells and mesocyclones. Within these storms large hail and severe wind gusts are expected. Increased LLS up to 10 m/s and 0-1 SRH ~ 100 m2/s2 will also provide conditions for tornadoes if isolated supercells will occur. It is not ruled out that the N part of the convergence line may evolve into squall line capable of producing severe wind gusts. The line will initiate in the morning hours but the highest threat for the severe weather occurrence will fall on the late afternoon hours. Very high values of PW along the convergence zone (40 mm) and relatively slow motion of the thunderstorms in the S part of the line create threat for excessive precipitation and local flash flooding. Thunderstorm should be active until the forecast period.

...N Italy...

This region lies in the exit of the jet streak located over France. DLS exceeding 20 m/s overlaps with weak CAPE up to 500-600 J/kg and 0-3km SRH ~ 100-200 m2/s2. Although there is uncertainty related to CI in this area, thunderstorms may evolve into supercells capable of producing large hail and severe wind gusts if DMC will occur.