Outlook day 1 (valid: 21/04/2018)
VALID FOR 21-04-2018
A ridge / high pressure system dominates most of south-central Europe. A weak upper low rotates SW of Iberian peninsula while a large trough/cyclone remains over E Atlantic. Another short wave / upper low maintains over N Middle East. A deep cyclone over NW Russia pushes a cold front across E Europe with a diffuse frontal SFC boundary extended towards W Europe.
An ENH risk has been issued for S Portugal and S Spain with threat for severe storms, capable of producing severe winds, torrential rainfall and large hail. Moderate instability within moderately strong shear and good helicity will support organized storms along the cold front. Training cells could result in excessive rainfall threat locally. A good LL helicity will enhance tornadic threat as well.
SLGT/MRGL risks have been placed surrounding the ENH risk where severe but more isolated storms are possible.
SLGT/MRGL risks have been issued for the Middle East with threat for severe storms, capable of producing torrential and excessive rainfall, large hail and severe winds.
A MRGL risk has been issued for N France into S England with threat for isolated strong to severe storms. A good instability overlaps with low shear but slow moving storms could bring some hail accumulation (locally some large hail is possible) and torrential rainfall.
A MRGL risk has been issued for W Russia into NE Ukraine with threat for isolated strong to severe storms, capable of producing some marginal hail and strong to severe winds.