Storm Forecast
Valid: Thu 27 Aug 2020 06:00 to Fri 28 Aug 2020 06:00 UTC
Issued: Wed 26 Aug 2020 22:41
Forecaster: GATZEN

A level 1 was issued across north-eastern Spain for large hail and severe wind gusts.

SYNOPSIS

A strong zonal mid-level flow has established across Central Europe in the wake of a rather weakly amplified trough over eastern Europe. Mid-level ridging affects southern Europe ahead of another Atlantic trough than enters the British Isles. At lower levels, a broad frontal zone is located across France, the Alps, and the northern Balkans. QG lift is weak over most places.

Some rich moisture is remaining across the Mediterranean, where mid-level subsidence limits the vertical extend of convection. An exception is the Iberian Peninsula with steep mid-level lapse rates as well as the eastern parts of Turkey into the Caucasus mountains. Initiation is uncertain in most areas given weak lift. Best potential is expected across the southern Alps althoug strong vertical wind shear limits the probability of convection initiation. Storms that manage to develop are forecast to organize and posing a threat of large hail and severe wind gusts.

Low-topped storms are forecast within the torugh's bases across Ireland and Poland into Belarus. Due to strong low-level shear, tornadoes are not ruled out, but overall threat is expected to be low.

DISCUSSION

North-eastern Spain

Some warm air advection is expected to increase the frontal boundary across northern France during the day. Due to some Mediterranean moisture advecting onshore and overlap woth steep mid-level lapse rates, MLCAPE of 1000 J/kg can develop. In the mountains, initiation is expected, and due to strong deep-layer shear, some supercells are not ruled out. Main threat will be large hail and severe wind gusts. Storms will decay soon after sunset.