Storm Forecast
Valid: Mon 19 Aug 2019 06:00 to Tue 20 Aug 2019 06:00 UTC
Issued: Mon 19 Aug 2019 00:57
Forecaster: VAN DER VELDE

A level 2 was issued across N Spain mainly for large hail.

A level 2 was issued for Poland and N Belarus area mainly for large hail and severe wind gusts.

A level 1 was issued across the Alps mainly for excessive rainfall and large hail.

A level 1 was issued for central Turkey mainly for large hail.

A level 1 was issued for S Russia mainly for large hail.

SYNOPSIS

A large-scale upper trough extends across the NW half of Europe with its cold front from Finland, Baltic States, Poland, Alpine region, to N Spain. Cold airmass convection is mostly found over S and W Scandinavia. An upper cold pool is over Turkey. Warm moist surface air converging along the east side of the front and moderate lapse rates set up 500-1000 J/kg MLCAPE, the maximum over E Poland. A minimum in lapse rates is predicted over the central and eastern Alps to Czech Republic. An Atlantic shortwave trough comes to N Spain by the end of the period. In all level 1 and 2 areas deep layer shear is 15-20 m/s, sufficient for some supercells producing large hail.

DISCUSSION

...Poland, S Baltic states, Belarus...

The direction of shear and storm motion is mostly along the cold front, promoting linear convective systems with storm-relative inflow vectors from the warm side. With moderate shear the large hail threat is significant and convective development is forecast to be widespread. Severe wind gusts may occur but CAPE and delta theta-e appear a bit limited.

...Alps...

Slower storm motion and weaker lapse rates can cause excessive local rainfall, while in the France/Italy border region large hail is more likely.

...N Spain...

Capped during most of the day, energy can build up over the Ebro Valley to be released at night. Strong 25 m/s 0-6 km shear suggests supercells are quite likely with large hail and possibly severe wind gusts or excessive rainfall.