Storm Forecast
Valid: Sat 30 Jul 2011 06:00 to Sun 31 Jul 2011 06:00 UTC
Issued: Fri 29 Jul 2011 21:12
Forecaster: VAN DER VELDE
A level 1 and 2 were issued for central Ukraine and surroundings mainly for severe convective wind gusts and large hail.
A level 1 was issued for NE Spain mainly for large hail.
SYNOPSIS
A large upper trough covers Europe. The main SFC low pressure areas are over Poland and Belarus. Slight low pressure centers are also found over northern Italy, eastern Spain/Balearic Islands, and Romania/Ukraine. Strongest QG lifting takes place over the stationary occlusion over S Sweden/E Germany/W Poland/Czechia, which may feature also some embedded convection and produce copious rainfall. The other zone of strong lift migrates from Romania into Ukraine and is associated with a mid level PV maximum and cold front.
DISCUSSION
...Moldova, Ukraine...
Positive factors for severe convective storms are present in the form of strong ascent (as described before). The cold front will be moving into 1000-2000 J/kg MLCAPE. Bulk shear over 0-6 km layer will be 10-15 m/s (not too strong) and 1-8 km over 20 m/s. 0-3 km SREH increases to 250 mē/sē locally. Likely convective mode is clusters with chance of large hail (somewhat reduced by medium LCL heights (1000m)), transitioning into a squall line. While the parameters look overall most supportive of level 1, the vigor of the PV max / low dynamic tropopause pushing into the region has the potential of creating a more organized severe weather threat.
...eastern Spain...
Deep layer shear of 15-20 m/s over 0-6 km with around 200 mē/sē SREH, fair for large hail. However, a NNW-SSE band of subsidence entering the region around noon will possibly suppress convective initiation or upscale growth and a large warm cloud depth in the strongest CAPE region is also not too favorable. In NW Catalonia the factors seem best, and level 1 is warranted.
