Storm Forecast
Valid: Thu 20 May 2021 06:00 to Fri 21 May 2021 06:00 UTC
Issued: Wed 19 May 2021 22:12
Forecaster: GATZEN

A level 1 was issued across western Russia mainly for large hail, severe wind gusts and extreme rainfall.

SYNOPSIS

Low geopotential expands from the north-eastern Atlantic towards central Europe, with a trough center over the British Isles and another across much of eastern central Europe. The former is associated with a storm system and will amplify during the period, while the eastern trough will lift into Russia. At lower levels, cool and dry air masses prevail across Europe. A moist and warm air mass is located over Russia east of a cold front that further progresses today.

DISCUSSION

Western Russia

Latest model data indicate an unstable air mass east of the cold front. Deep inverted-v-profiles are expected within the warm air mass that is pushed east by a shallow cold front. Convection initiation is not too likely along this first cold front as lift will be shallow and LFCs rather high.

In the wake of the low-level cold front, a moist air mass spreads east that partly overlaps with steep lapse rates ahead of a second cold front that enters the level 1 area in the morning. Here, convection initiation is expected. In the morning, storms can be elevated, but surface heating is forecast to result in surface-based storms later. These will move towards the north almost parallel to the cold front that will gradually overtake these storms.

Initially, isolated storms are forecast that will organize into multicells and splitting storms given rather long, straight hodographs. Deep layer shear will be around 15-20 m/s. Large hail is forecast with these storms.

Later, clusters of storms are expected along the cold front with a lower hail, but increasing wind and rain threat. Main limiting factor is rather weak low-level moisture. Best moisture can be found in the northern part of the cold front. Here, storms may last through-out the night and move into Finland, where elevated storms are forecast during the night.