Storm Forecast
Valid: Sun 01 May 2011 06:00 to Mon 02 May 2011 06:00 UTC
Issued: Sun 01 May 2011 05:27
Forecaster: SCHLENCZEK
A level 1 was issued for N Morocco / N Algeria mainly for excessive rainfall, large hail and severe wind gusts.
A level 1 was issued for parts of Greece, Crete, the Aegean Sea and SW Turkey mainly for large hail and severe wind gusts.
SYNOPSIS
Northeastern Europe and parts of eastern and central Europe are located at the western edge of a trough in a strong northeasterly flow. CAA will tend to stabilize the airmass in the northern parts of Europe while the unstable airmass resides near the Alpes and over western Europe. From Morocco towards the Middle East, a strong westerly upper flow has established with some embedded shortwave troughs that may lead to isolated severe weather over the Aegean and parts of Greece / Turkey.
DISCUSSION
...N Morocco / N Algeria...
In the vicinity of an approaching upper low, some instability will be created over N Morocco / N Algeria during the day. There is a small overlap of 15 - 20 m/s 0-3 km shear and CAPE where isolated severe events are most likely to occur. The primary threat should be large hail and severe wind gusts in the first half of the period. Later on, storms will tend to merge into one or two large clusters with torrential rainfall being the main threat.
...SW / W Europe...
Some hundred J/kg CAPE should be created mainly through diurnal heating, leading to scattered thunderstorms which should be only briefly organized. An isolated large hail / severe wind gust event cannot be excluded but a threat level is not warranted.
...Alpine region, Slovak Rep, Hungary, Ukraine...
Diurnally driven convection is also expected in the Alpine region and parts of eastern Europe with similar values of CAPE compared to France and Spain. Deep layer shear is in order of 10 - 15 m/s which may allow some briefly organized multicells. Isolated large hail / severe wind gusts may occur but the area density of reports will likely stay below the level 1 threshold.
...Greece, Ionian Sea, Aegean, Crete, SW Turkey...
Ahead of an approaching shortwave trough, unstable air is advected towards Greece and Turkey. High CIN should preclude widespread initiation but 20 - 25 m/s deep layer shear and around 300 mē/sē SRH3 are in place which should be sufficient for isolated supercells if storms manage to develop. Therefore, large hail and locally severe wind gusts will likely be the primary threat. As overall precip signals are quite weak, a marginal level 1 is issued.
