Storm Forecast
Valid: Sun 29 May 2011 06:00 to Mon 30 May 2011 06:00 UTC
Issued: Sun 29 May 2011 05:49
Forecaster: SCHLENCZEK
A level one threat was issued for W / NW Iberia mainly for isolated excessive rainfall.
A level one threat was issued for S / SE Iberia and the N Maghreb States mainly for large hail and severe wind gusts and to a lesser extent for excessive rainfall and tornadoes.
A level one threat was issued for W Ukraine, Belarus and W Russia mainly for large hail and severe wind gusts and to a lesser extent for tornadoes.
SYNOPSIS
As the upper cut-off low west of Portugal moves slowly eastwards, WAA over Spain and Portugal will continue. Towards the east, recent soundings show an EML. Near the southern tip of this low, a 30 m/s upper jet streak leads to enhanced shear in the 0-6 km layer.
The cold front over the eastern parts of Europe is still present and some hundred J/kg CAPE are likely to be created by diurnal heating. Remnants of an upper cut-off low over the E Mediterranean will lead to some instability but rather weak shear over the Balkan Peninsula and W Turkey, including the S Adriatic and the Ionian / Aegean Sea. The recent conditions with a relatively cold mid troposphere and rich BL moisture may allow one or two waterspouts but a threat level is not introduced.
Isolated showers and thunderstorms are also expected over parts of Norway and Sweden in the vicinity of an upper shortwave trough. Severe weather is not expected as shear and instability are quite marginal.
DISCUSSION
...S Iberia, N Morocco towards N Tunisia...
A good overlap of 20 - 25 m/s deep layer shear and some 500 - 1000 J/kg MLCAPE is expected over the N Maghreb States and S / SE Spain. Storms will tend to become well-organised multicells or supercells which may pose a risk of large hail and severe wind gusts. High effective PWAT is forecast for the western parts of Iberia. Continuous development of thunderstorms may lead to heavy rainfall and local flooding. Further east, PWAT is much lower and the likelihood of flash floods is significantly lower.
...Ukraine, Belarus, W Russia...
Ahead of an upper shortwave trough over the Baltic States, some 500 - 1000 J/kg MLCAPE overlap with 15 - 20 m/s of 0-6 km shear and 150 - 200 mē/sē SRH3. Some linear multicell segments and supercells may develop and will pose a threat of large hail and severe wind gusts. A few tornadoes are not ruled out either as LCL / LFC heights are much lower than over Iberia, and some 10 - 15 m/s LLS are locally present. If storms tend to stay discrete, the potential of severe weather should be at the upper edge of a level 1 threat. Storms will likely continue through the evening / night hours.
