Storm Forecast
Valid: Sat 07 Apr 2018 06:00 to Sun 08 Apr 2018 06:00 UTC
Issued: Fri 06 Apr 2018 20:58
Forecaster: GROENEMEIJER

A level 1 was issued across parts of Northwest Anatolia mainly for hail, and across the Eastern Aegean Sea region for hail and tornadoes or waterspouts.

SYNOPSIS

An elongated North-South oriented trough west of Ireland and Iberia moves very slowly eastward, while an mid/upper-level cut-off low develops across Central Iberia. A southerly flow over much of Western Europe advects warm air northward, the air-mass being not sufficiently unstable and moist for convective storms. Within a broad ridge over central Europe, a small cold-core low moves from Croatia to Czechia. Another cold-core low moves from the Southern Aegean Sea to Southwest Turkey.

DISCUSSION

West Anatolia and Aegean Sea...

In vicinity of the low across the Eastern Aegean Sea fairly steep low-level lapse rates are forecast. Combined with adequate moisture around 1000 J/kg of CAPE should be available, which will lead to widespread thunderstorms. Weak cyclonic low-level winds and low LCL heights suggest that waterspouts or an isolated weak tornado are possible in addition to hail with maximum diameters up to around 2-3 cm.

Northwest Anatolia...

A combination of relatively humid low-level air across the lower areas of Northwest Anatolia and steep mid-level lapse rates advected off the high terrain will lead to sufficient instability for scattered storms along the moutain slopes. Deep-layer shear is moderate to strong, which will help storms to become severe and produce isolated large hail. The storms will not survive long after moving into the lowland, because the air-mass will be capped there.

East Portugal and Southwest Spain...

NWP models predict steep low-level lapse rates to develop in the wake of the eastward moving frontal zone, which will lead to widespread storm initiation. These storms could bring hail with diameters around 2 cm. Even though an isolated weak tornado cannot be ruled out, the risk is deemed too low for level 1.