Storm Forecast
Valid: Wed 26 Jun 2019 06:00 to Thu 27 Jun 2019 06:00 UTC
Issued: Tue 25 Jun 2019 23:14
Forecaster: PUCIK

A level 1 was issued over Lithuania and Belarus mainly for large hail, severe wind gusts and excessive rainfall.

A level 1 was issued over the Alpine range mainly for large hail, severe wind gusts and excessive rainfall.

A level 1 was issued over the Caucasus mainly for severe wind gusts and to the lesser degree for excessive rainfall.


SYNOPSIS

Main macrosynoptic features over Europe during the forecast period will be a large and persistent cyclonic vortex over the Atlantic and a ridge stretching from the West Mediterranean into the Alpine region. In between of these two features, a strong WAA regime will advect unseasonably hot airmass over France with 850 hPa temperature exceeding 28 deg C over southern part of the country by the evening. A large cluster of elevated DMC embedded in a stratiform rain shield is simulated by NWP, wrapped around the cyclonic vortex from the Bay of Biscay towards W and NW.


At the same time, in W to NW-ly flow over N part of Europe, a broad short-wave trough is forecast to cross Scandinavia towards the Baltic states. In conjunction with the trough, cyclogenesis is forecast over the Baltic States with a cold front extending from Central Germany through Poland towards Belarus by Thursday 06 UTC. Drier, polar airmass will advect behind the cold front, significantly reducing the dewpoints in its wake. As the front encounters moist airmass over parts of Central and E Europe, isolated to scattered DMC is forecast to form.


DISCUSSION

... Lithuania to Belarus ...

Convective coverage is forecast to increase during the overnight and early morning hours as the frontal system crosses the area. Forecast soundings suggest elevated convection along the advancing warm front and surface based storms in the warm sector despite the overnight hours. Lack of steep lapse rates will preclude high CAPE values, but 500 to 1000 J/kg of ML/MUCAPE will be widely available by 06 UTC. An elevated MCS may form over the warm front, posing threats of excessive rainfall and marginally large hail. Behind the warm front, long and linear hodographs suggest that isolated splitting supercells and linear segments may form, with threats of isolated large hail and severe wind gusts. Storms will spread towards E and SE during the night hours.

... Alpine range ...

While initiation is highly questionable over the area, given the presence of pronounced ridge and virtually no synoptic-scale support, CAPE values exceeding 3000 J/kg could easily support strong cells capable of large hail and/or severe wind gusts. Weak shear suggests disorganised and short-lived pulse storms. Even though storms will decay rather quickly, their slow moving nature may concentrate heavy rainfall over small area, exacerbating the flash flood threat.

... Caucasus ...

Isolated to scattered DMC is forecast, initiated by the mountains and thanks to the deep and dry boundary layer, may be capable of isolated severe wind gusts.