Storm Forecast
Valid: Thu 07 Jul 2016 06:00 to Fri 08 Jul 2016 06:00 UTC
Issued: Wed 06 Jul 2016 23:27
Forecaster: GATZEN

A level 1 was issued for the Iberian Peninsula mainly for large hail, excessive precipitation, and severe wind gusts.

A level 1 was issued for northern Morocco and Algeria mainly for large hail.

A level 1 was issued for the southern Alpine region mainly for large hail and excessive precipitation.

A level 1 was issued for parts of Turkey mainly for large hail.

SYNOPSIS

A short-wave trough progresses over eastern Europe. In its wake, ridging affects most of central, eastern, and southern Europe, but also France due to a cut-off process over the Iberian Peninsula. At low levels, a northerly to westerly low-level flow is expected across central, eastern, and much of southern Europe. This is associated with relatively dry air masses over many regions. Rich moisture can be found over the central and east Mediterranean as well as around the shores of the Iberian Peninsula. Lapse rates are quite poor except for the northern and central Iberian Peninsula with a pronounced elevated mixed layer.

DISCUSSION

Iberian Peninsula, northern Morocco and Algeria

A cut-off low will form from a trough currently placed west of the Iberian Peninsula and is expected to move slowly east. At lower levels, an elevated mixed layer is present atop of quite rich boundary layer moisture. Diurnal heating will again result in moderate CAPE of 1000 to more than 2000 J/kg.

Storms are expected to initiate in the noon and afternoon hours over the mountains and the high terrain of central Spain. Remaining outflow boundaries from overnights storms can also support initiation. Later on, clusters of storms are expected to develop. Less storms are forecast in the south-east where capping is expected to be strongest, but some isolated storms are not ruled out over the mountains as well.

Storm organization is limited with large-scale deep-layer vertical wind shear around 10 m/s expect for the eastern parts than are affected by a jet streak ejecting into the west Mediterranean. Multicells may be capable of producing large hail given strong buoyancy in the hail growth layer. Excessive rain is possible as storms are rather slow moving. Severe gusts are not ruled out of cold-pool driven clusters form. A higher potential for large or very large hail is forecast for any storm that evolves over south-eastern Spain and northern Algeria as strong deep layer vertical wind shear is expected and supercells can form.

Storms will go on until the night hours and are expected to decay overnight.

Southern Alps

Moist air masses are situated to the south of the Alps and can spread northward in response to diurnally driven upslope flow. Lapse rates are expected to improve during the day and will be advected east-south-eastward, where an overlap with the moist boundary-layer is possible. Storms are forecast to initiate over the southern Alps and can move eastward. Some large hail is forecast especially in the eastern parts where 0-3 km vertical wind shear is forecast to be around 10 m/s. Additionally, local excessive precipitation is possible.

Turkey

In a rather cool air mass, storms are expected especially in the southern portions in response to strong diurnal heating and an approaching mid-level trough. Vertical wind shear is about 10-15 m/s, so storm organization is limited. Main severe threat will be a few hail events.