Storm Forecast
Valid: Thu 07 May 2020 06:00 to Fri 08 May 2020 06:00 UTC
Issued: Wed 06 May 2020 23:47
Forecaster: KAHRAMAN

A level 1 was issued across NW Iberian Peninsula mainly for large hail.

A level 1 was issued across parts of S and Central Turkey mainly for large hail.

A level 1 was issued across parts of NW Russia mainly for tornadoes and excessive precipitation.

SYNOPSIS

A weak through and associated shallow low pressure is over the North Atlantic, while a more pronounced, fragmented one extends from northern Scandinavia towards Aegean Sea, having spots of lows in the PVA zone ahead. The Central Europe is under a ridge and high pressure influence.

DISCUSSION

... Northwest Iberian ...

Up to 10 g/kg low level specific humidity and advection of 7-7.5 K/km lower-troposphere lapse rates from NW Africa create favorable conditions for thunderstorms over broader NW Spain and N Portugal. Lift is not warranted during earlier hours, but the late afternoon and evening hours reveal much less CIN and boundary layer disturbances, during passage of a vorticity maxima. Any storms formed inlands would have higher cloud bases, and steeper lapse rates below. Up to 25 m/s deep layer shear and moderate latent instability combination promote well-organized storms with large hail potential.

... Turkey ...

As the through propagates from Balkans to central Turkey during the forecast period, a plume of moist air is advected ahead of the associated cold front from SW towards N Turkey. With diurnal heating, S of Aegean Region, Mediterranean hinterland and central Turkey experience modest CAPE amounts. The upper level jet passes just above the region, enhancing the vertical wind shear. The left-exit section of the jet has minimal divergence in the timing of the expected storms, strengthening further in the night. In the south, the strong shear may destroy any storm occurrence due to skinny CAPE patterns. However, once a storm succeeds forming, it might be severe. A few supercells are possible in inner parts of Anatolia, fastly moving east. These can produce large hail. The low level shear is marginal, and the tornado potential is low, although not impossible. The storms should merge by later hours, evolving into an MCS moving towards the Black Sea.

... Northwestern Russia ...

Another hotspot for severe convection is northwestern Russia. There is a moderate CAPE and very strong deep layer shear overlap around the simulated low. 0-1 km shear reaches 10-15 m/s, while the LCL is simulated to be below 800-1000 m in most parts, supporting tornado formation. Long and straight hodographs indicate splitting supercells around more western and northern parts of the level 1 area issued. Further southern parts of the Level 1 has potential for excessive precipitation, with higher humidity owing to strong advection from the Caspian Sea.