Mesoscale Discussion
Valid: Mon 01 Jul 2019 14:00 to Mon 01 Jul 2019 21:00 UTC
Issued: Mon 01 Jul 2019 14:02
Forecaster: TASZAREK

This Mesoscale Discussion is issued to highlight a risk for extremely severe thunderstorms capable of producing very large hail, damaging wind gusts and excessive precipitation in Czech Republic and S Poland.

DISCUSSION

Current teledetection observations indicate severe thunderstorms developing in CNTRL Czech Republic. According to sounding observations from Praga, Prostejov and Wrocław these are ongoing in the environment of around 20 m/s deep layer shear and 1000-2000 J/kg ML CAPE (although some NWP models indicate even 2500-3500 J/kg). Although hodographs are rather straight, updrafts are benefiting from strong shear and evolve into mesocyclones with a potential for producing very large hail (5cm+). Some of the storms in E Czech Republic have reflectivity up to 65-70 dBZ which may suggest very large hail already occurring in this area. Very steep lapse rates in 0-3km layer favor also severe and damaging winds within strong downdrafts. Due to complex orography, a local flash flooding events are also not ruled out given intensity of precipitation.

Although a broad anvil is currently developing thanks to these storms, a new convective initiation is expected in the next 1-2 hours over S Poland and parts of Czech Republic (SYNOP data indicate a temperature of 35C and dew points of 16C in both areas). Due to supportive strong-shear conditions and moderate instability, these storms may be also capable of producing extremely severe weather with very large hail, damaging wind gusts and excessive precipitation. Later in the evening, a large MCS should move into SE Poland and towards Ukraine and Belarus. Thanks to strong 0-3km shear (> 20 m/s) bowing segments within convective lines are not ruled out. These can lead to severe and damaging winds.