Storm Forecast
Valid: Mon 06 Jul 2015 06:00 to Tue 07 Jul 2015 06:00 UTC
Issued: Mon 06 Jul 2015 05:51
Forecaster: VAN DER VELDE
A level 2 was issued for NE Poland, Lithuania, W Belarus, S Latvia mainly for severe convective wind gusts, large hail and tornadoes.
A level 1 was issued for parts of C France, N Italy, Austria Czech Republic, Slovakia and Poland mainly for large hail.
SYNOPSIS
A cold front belonging to a low over southern Scandinavia traverses central Europe and the Baltic States today. The front remains stationary along the Alps and France, where a ridge is building up ahead of a new low affecting Ireland and UK.
Along the warm side of the front over 1000 J/kg MLCAPE is generally present. with 2500 J/kg or more over NW Italy, as well as 10-15 m/s deep layer shear sufficient for strong multicell and isolated supercell storms. Most dynamic lifting will pass over northern Poland and the Baltic area.
DISCUSSION
...Poland to Latvia...
Nocturnal convection stopped in the western half of Poland. GFS model suggests weakly capped CAPE with early renewed development, preventing buildup of energy compared to the previous day. The mixing ratios at the surface over Poland are generally 11 g/kg with maxima of 13-14 g/kg in the north. DLS over 15 m/s stimulates supercell mode while linear forcing tends to group storms into linear clusters. Corfidi vectors support forward-building MCS and delta-theta-e locally over 20K supports intense downdrafts with severe wind gusts. Large to very large hail is possible in some storms and aided by high cloud bases with steep lapse rates above. This extends approximately up to Latvia, where lapse rates decrease, cloud bases are low and low-level shear (0-3 km >15 m/s, 0-1 km >10 m/s) supportive of tornadoes and bow echoes.
...France, Italy, Austria...
High MLCAPE over NW Italy, LCL around 2000m and reasonable shear supports very large hail and local severe wind gusts. Lift is not strong and a cap needs to be overcome. Weaker cap and a bit lower CAPE should be present in Austria. Over France, limited initiation is expected but over Massif Central SREH over 200 mē/sē is supportive of supercells if initiation occurs. Modest chances of this also occur along the north side of the Pyrenees. Elevated parcel convection can develop at night over SW France.
...Ireland and UK...
A warm sector develops slight CAPE, most of it elevated and over Ireland during the afternoon. There is enhanced SREH in GFS which may overlap with CAPE, as well as over 10 m/s 0-1 km shear and low LCLs. An isolated tornado may not be ruled out if a storm manages to form and organize.
