Storm Forecast
Valid: Tue 09 Aug 2011 06:00 to Wed 10 Aug 2011 06:00 UTC
Issued: Mon 08 Aug 2011 18:32
Forecaster: KOROSEC
A level 1 was issued for parts of NW Russia and E Belarus mainly for strong/severe wind gusts and a couple of tornadoes.
A level 1 was issued for parts of Marocco and Algeria mainly for large to very large hail and severe wind gusts.
A level 1 was issued for parts of N Germany, Denmark and Baltic sea mainly for a few tornadoes/funnels or waterspouts.
A level 1 was issued for areas from E Adriatic sea across the central Balkans into NE Europe mainly for marginal hail, intense rainfalls and strong wind gusts.
A level 1 was issued for parts of N Italy mainly for large hail and strong wind gusts.
SYNOPSIS
A large-scale trough continues moving across NE Europe with several disturbances around its base. The most pronounced are the short-wave trough across the Alps/northern Balkans and another one in NW Russia. At surface, a cold front associated with a surface low centered over Scandinavia extends SW-wards from the NW Russia towards the western Balkans. An occluded front affects Denmark and surrounding areas. A ridge builds up into WSW Europe.
DISCUSSION
... NW Russia and E Belarus ...
A short-wave trough on the edge of the main long-wave trough exits NE Europe. There, quite some forcing will be available in the left-exit jet region. At surface, a well-defined frontal system moves into NW Russia. Despite only marginal instability available, very strong shear (25-30 m/s) and SR helicity (in excess of 300 m^2/s^2) favours severe storms to take place. Quite impressive LL shear/SREH enhances the threat for a couple of tornadoes. Additionally, intense rain and strong/severe wind gusts will be possible. A MCS could form in the afternoon from the clustering of earlier activity.
... parts of Marocco and Algeria ...
Another day with some isolated severe storms. NE flow from the SW Mediterranean will advect hot/moist airmass into the parts of Algeria and Marocco, providing ample instability with steep lapse rates aloft. With high LFC a large to very large hail will become likely with the strongest storms. Additionally, strong evaporative cooling should enhance the severe wind gusts threat.
... parts of N Germany, Denmark and Baltic sea ...
Placed beneath the quite cold mid-levels, daytime heating and steep lapse rates aloft will release moderate instability. With almost no CIN available, convection will be rather widespread. Deep layer shear remains very low, while moderate LL shear will remain in place. Expect some organized low topped storms, some of them might become supercellular and could produce funnel clouds or a few weak tornadoes. Closer to the core of the upper low to the east, very low shear at all levels and high LL instability/lapse rates suggest that a couple of water- or landspouts will be possible as well. Small hail showers may be accompanied by the intense cells.
... areas from E Adriatic sea across the central Balkans into NE Europe ...
A cold front will be weakening and slowing down while moving across the Balkans. Only some hundreds of CAPE seem to release ahead of it over the E-CNTRL Balkans and across the central Adriatic sea. As mid-level jet remain strong, around 25-30 m/s of deep layer shear will still be in place, providing environment for organized storms. Those could produce some strong winds and excessive rain locally.
... parts of N Italy ...
After the passage of the main trough towards the Balkans, another short-wave trough crosses the Alps in the peak daytime hours from the NW. Unseasonably cold mid-levels will provide ample instability under the PV maximum. Its likely that storms will initiate over the central Alps and move towards SE. Still moderate shear will be sufficent for organized convection and a few isolated high based supercells will be possible. High LFC and cold air aloft suggest that large hail and locally some strong winds could occur.
