Storm Forecast
Valid: Sat 28 Jul 2018 06:00 to Sun 29 Jul 2018 06:00 UTC
Issued: Sat 28 Jul 2018 01:23
Forecaster: TASZAREK

A level 2 was issued for S Scandinavia mainly for large hail, severe wind gusts, excessive precipitation and tornadoes.

A level 2 was issued for a corridor extending from SE France to SW Germany mainly for large hail, severe wind gusts and excessive precipitation.

A level 1 was issued for parts of W, CNTRL, SE and E Europe mainly for large hail, severe wind gusts and heavy precipitation.


SYNOPSIS & DISCUSSION

A long-wave trough travles through British Isles and affects part of W Europe and S Scandinavia. Broad high covers NE Europe while a weak horizontal pressure gradient dominates over most of CNTRL and SE Europe. Ridge covers Iberian Peninsula and W Medditeraenan. Strong diurnal heating inducing steep low-level lapse rates and high boundary layer's moisture (due to an increase in evapotranspiration) provides a good conditions for the development of DMC over majority of Europe. Except Iberian Peninsula, British Isles and norther periferies of NE Europe, ML MIXR exceeding 10-12 g/kg ensures healthy ML CAPE of 800-1500 J/kg. Values exceeding 2000 J/kg are available over Baltic Countries, Belarus and parts of W Russia, and are due to a combination of 12-14 g/kg and advection of steep lapse rates from the east. Due to lack of sufficient vertical wind sheear, majority of storms developing in CNTRL, E and SE Europe will be associated with pulse/single and multicell storm mode. These may be capable of producing local downburst type severe wind gusts, large hail and heavy precipitation leading to local flash flooding events. This threat will be especially evident in the eastern Europe where storms will be moving slowly and PW will exceed 40mm. Storms developing in Baltic countries and Belarus may evolve into supercells as SRH and LLS will be enhanced. These storms may be capable of producing large hail and even tornadoes, however the overall threat is limited due to undertain CI in this area among different NWP models. The highest threat for severe weather phenomena on Saturday is in western parts of Europe and S Scandinavia where an overlap of weak to moderate thermodynamic instability and enhanced vertical wind shear takes place. Under the support of 15-20 m/s DLS storms developing over SE France parts of Switzerland and SW Germany are expected to evolve into supercells and be capable of producing large hail and severe wind gusts. Within the passage of the shortwave trough and frontal boundary, another portion of severe thunderstorms will form in Benelux and N Germany and in the form of a convective line move eastward for the late evening and nighgtime hours. MCS within this system is likely. The main threat with these storms will be associated with severe wind gusts and large hail. The potential for multicell and supercell thunderstorms capable of producing large hail and tornadoes will be in southern portions of Norway and Sweden where ahead of the approaching trough, favourable vertical wind profiles (SRH > 150 m2/s2), enhanced LLS and low to moderate thernodynamic instability will overlap. Most of the thunderstorm activity should fade in the nighttime hours, except MCS over NE Germany, s storms over Baltic countries and S Norway.