Storm Forecast
Valid: Tue 20 Apr 2010 06:00 to Wed 21 Apr 2010 06:00 UTC
Issued: Mon 19 Apr 2010 22:37
Forecaster: KOROSEC

A level 1 was issued for western Turkey mainly for large hail, strong winds and lesser extent for excessive rainfall.

SYNOPSIS

A large trough over eastern half of Europe shifts eastwards while deepening towards the SE Europe on Tuesday. At surface, an attendant surface depression moves ahead of it towards the Black sea. Embedded in this large main European trough, another trough/upper low moves from North Sea into southern Scandinavia.

A new trough/upper low approaches Iberia towards the Wednesday morning hours. The rest of Europe, except the Alpine region and most of Italy which again becomes unstable during the day, will remain stable.

DISCUSSION

... Western Turkey ...

The deepening trough will affects Aegean Sea and western Turkey during the first half of the period before shifting further east and outside our forecast area. A strong WAA spreads NE-wards ahead of this trough where destabilization continues across the warm sector ahead of the surface front. Several hundreds J/kg of MLCAPE seem reasonable to result in environment with steep lapse rates, while well overlaping with moderate shear. Therefore, an organized convection seem likely to occur, posing a threat for large hail and strong winds. Especially over the western Turkish complex terrain, longer lasting convection may enhance excessive convective rainfall/flash flood threat as well. It seems that surface based convection may occur as well, then a 10-15m/s of 0-3km layer shear seem favorable also for a few LL mesocyclones and enhanced threat for tornadogenesis. But with only marginal SREH, this threat seem quite limited attm.

... central Italy and Alpine region ...

Diurnal driven showers and thundertorms are again forecasted as warm/moist airmass becomes weakly unstable with daytime heating. The higher probabilites seem confined mostly to the complex topography of central Italy and across the Alps. Given the only weak shear in place, no severe weather is expected.

... North sea towards Denmark ...

With an approaching upper low/trough and surface front across the North sea, a forced line of convection is possible. GFS model agrees in minor instability and some electrified convection could occur. A strong wind gusts seem to be the main threat, but staying below the severe criteria.