Forecast Update
Valid: Thu 22 Jul 2010 11:00 to Fri 23 Jul 2010 06:00 UTC
Issued: Thu 22 Jul 2010 11:08
Forecaster: GATZEN

A level 2 was issued for northern Sweden and Finland mainly for tornadoes and severe wind gusts.

A level 2 was issued for Eastern Spain mainly for large hail.

A level 1 was issued for south-eastern France to south-western Germany mainly for tornadoes and large hail.

A level 1 was issued for southern and eastern Germany mainly for large hail, severe wind gusts and excessive rain.

A level 1 was issued for the southern British Isles mainly for tornadoes.

SYNOPSIS

Please refer to the main outlook, issued at Wed 21 Jul 2010 21:03 Z.

DISCUSSION

Eastern Spain

Ahead of the southern tip of the trough, a strong south-westerly mid-level jet will affect Spain. Strong diurnal heating is expected, resulting in steep lapse rates spreading northward, and a low will likely develop over central Iberia along the cold front entering the northern portions. The associated low-level easterly winds will advect rich low-level moisture from the west Mediterranean into eastern Spain, where instability up to 1500 J/kg 30 hPa MLCAPE is expected. Widespread storms are likely that will have a great potential to become supercells as 25-30 m/s deep layer vertical wind shear and about 100 m²/s² 0-3km helicity will be present. Main severe threat will be large hail and locally severe wind gusts until the night hours. Given the widespread nature of expected large hail, a level 2 was issued in this update.

England

Underneath the through centre, weak tornadoes are not ruled out given weak vertical wind shear and quite good low-level buoyancy and convergence. As models do agree well on this situation, a level 1 was issued for the noon and afternoon hours.