Storm Forecast
Valid: Tue 17 May 2011 06:00 to Wed 18 May 2011 06:00 UTC
Issued: Mon 16 May 2011 20:46
Forecaster: SCHLENCZEK

A level one threat was issued for the Balkan Mountains and the W Black Sea region mainly for large hail and severe wind gusts.

A level one threat was issued for N Morocco mainly for large hail and severe wind gusts.

SYNOPSIS

A weakening upper cut-off low over the S Adriatic moves slowly to the SSE. East of this low, some warm and unstable air is advected towards Bulgaria and Romania which leads to some hundred J/kg CAPE.

Another upper low west of Iberia will reach the coastal regions of Portugal on early Wednesday morning.

Cold air convection is expected in parts of Scandinavia in the vicinity of an upper shortwave trough which moves eastwards across S Norway and Sweden.

DISCUSSION

...Iberia and N Maghreb States...

Some low-end instability is expected over the Iberian Peninsula and the N Maghreb States. Over Iberia, deep layer shear is quite marginal but CIN is low and storm coverage should be much higher than over Morocco and NW Algeria where both CIN and shear are significantly higher. The latter region could get one or two isolated organized multicells / supercells with large hail and severe wind gusts which requires a marginal level 1.

...Western Black Sea region, Balkan Mountains...

Ahead of the approaching cut-off low, some instability overlaps with 10 - 15 m/s of 0-3 km shear. Shear and instability should be supportive for some organized multicells with marginally severe hail / wind gusts but forcing should be much weaker than on Monday which limits storm coverage and severity. Nevertheless, a marginal level 1 was issued for this region.

...S Scandinavia...

Low-end instability should be expected in the vicinity of the upper cold core of the trough centered over S Scandinavia. Deep layer shear and instability tend to avoid each other in this region and overall threat for severe weather should be marginal.