Outlook DAY 1 (valid: 12/08/2019)
A large long-wave trough from the W Europe and N Atlantic drifts east while strong upper ridge over the central Europe and N Mediterranean moves further onto the Balkans. Very strong jet develops in between these two large scale features, providing good support for storm initiation. A weak short wave move across the Baltic region.
MDT / ENH risks have been issued for NW Italy into Switzerland and W Austria with threat for severe storms, capable of producing large to very large hail, severe winds and torrential / excessive rainfall with flash floods. Very strong 50-70 kt shear overlapped with moderately strong MLCAPE near 2500-3000 J/kg will again support isolated to discrete supercells with very large hail and damaging winds. Persisting training cells could locally lead into flash floods across the complex terrain.
MDT / ENH risks have been issued for NE Austria, Czechia and Slovakia into S Poland with threat for severe storms, capable of producing severe winds, large hail, torrential rainfall and tornadoes. Discrete organized storms are expected to develop along the diffuse front by mid afternoon within moderately unstable and strongly sheared airmass. Long-lived and fast-moving supercells with bowing segments are likely. Good LL winds with enhanced SR helicity will also support tornadic storms. Storms will merge into clusters in the evening hours.
SLGT risk has been issued for areas surrounding the MDT risks from SE France, N Italy across the Alps towards Poland, Belarus and N Ukraine with more isolated threat for severe storms, capable of producing severe winds, large hail and torrential rainfall. SLGT risk has been expanded into Belarus / Ukraine due to potential for late evening damaging MCS.
SLGT risk has been issued for the Baltic countries into NW Russia with threat for isolated severe storms, capable of producing severe winds, marginal hail and tornadoes. A few organized storms / supercells are possible within strong 50 kt shear and around 1000 J/kg of MLCAPE with good helicity, supporting damaging winds and tornado or two.
MRGL risk have been issued for N Morrocco, N Algeria and SE Spain with threat for isolated severe storms, capable of producing severe winds, large hail and torrential rainfall.
TSTM risk areas have been placed where convective storms are likely to occur but should remain sub-severe.