Storm Forecast
Valid: Sun 24 Apr 2011 06:00 to Mon 25 Apr 2011 06:00 UTC
Issued: Sun 24 Apr 2011 03:32
Forecaster: DAHL

No threat levels issued.

... SYNOPSIS ...

A high-over-low block pattern will exist over Europe early in the period, with an upper ridge present over Scandinavia and an upper low over Iberia and the W Mediterranean. A compact upper low will drop south at the eastern periphery of the upper ridge, affecting mainly Poland, E Germany, and the Czech Republic. At the surface ... largely quiescent synoptic conditions will exist, which are characterized by weak high pressure over the northern portions of Europe and weak low over the Mediterranean.

... DISCUSSION ...

... central to SW Europe ...

It looks like scattered thunderstorms will form with diurnal heating in weakly capped and weakly unstable air across much of central into SW Europe. Rather deep boundary layers suggest that a few strong wind gusts could occur. If storms coagulate into clusters in the late afternoon/early evening hours, cold-pool forcing could briefly support line segments capable of wind/hail approaching severe levels. However, the majority of the storms should be weak and individually short-lived.

It seems that the storms developing over Poland will benefit from their proximity to the upper low. CAPE will be quite weak, but rather deeply mixed sub-cloud layers and some 15 - 20 m/s 0-6 km bulk shear suggest that an isolated marginally severe wind/hail event cannot be discounted. However, the best shear should exist rather early in the day, weakening and becoming offset from the unstable air as the day progresses. A LVL1 threat thus does not seem to be required.