Storm Forecast
Valid: Sun 12 Jun 2011 06:00 to Mon 13 Jun 2011 06:00 UTC
Issued: Sun 12 Jun 2011 04:45
Forecaster: SCHLENCZEK

A level one threat was issued for N Iberia mainly for isolated large hail / severe wind gusts.

A level one threat was issued for S Finland and C Sweden / Norway mainly for large hail and excessive rainfall.

A level one threat was issued for W Turkey mainly for large hail and isolated severe wind gusts.

SYNOPSIS

A weak upper level disturbance is present over the Black Sea region. In its vicinity, low to moderate instability overspreads most parts of eastern and southern Europe.

Relatively warm air is found over the central parts of Scandinavia and the Baltic States where GFS expects some hundred J/kg CAPE. Vertical shear is quite weak but high PWAT and a slow storm motion may lead to excessive rainfall and flooding.

In an active westerly upper level flow, numerous shortwave troughs move across western and central Europe. One of those disturbances is located SW of Ireland on Sunday morning and will translate to the northeast while strengthening. A nearly total absence of instability in the region with the strongest shear and forcing indicates that severe weather will be unlikely. Some isolated severe convection may develop over the northern parts of Iberia in a low CAPE / high shear environment.

DISCUSSION

...N Iberia...

A tongue of warm and moist air (around 50 to 60°C Theta-E) resides over northern Spain and an approaching shortwave trough may lead to sufficient forcing for convective initiation. 0-6 km deep layer shear in excess of 20 m/s should support well-organised storms with possible marginally severe hail and isolated severe wind gusts. This risk is covered with a marginal level 1.

...C Norway / Sweden and S Finland...

Low to moderate instability is found in a region from the N Baltics and S Finland towards central Sweden and Norway. Although shear is quite weak (less than 10 m/s), steep lapse rates due to an EML and rich BL moisture (mixing ratio around 10 g/kg) may support some briefly organised multicells and pulsating storms which should be capable of producing isolated large hail. As storm motion is very slow, some regions within this level one area may get intense convective rainfall.

...W Turkey...

Some hundred J/kg MLCAPE are present over W Turkey in an environment with less than 15 m/s of 0-6 km shear. Recent soundings show that a dry layer in the mid troposphere is present which is likely to support isolated severe wind gusts and isolated large hail.