Forecast Update
Valid: Tue 19 Aug 2008 15:00 to Wed 20 Aug 2008 06:00 UTC
Issued: Tue 19 Aug 2008 15:23
Forecaster: VAN DER VELDE

Please refer to the current Forecast for details.

An update has been issued for parts of the Netherlands, northern Germany and southern Scandinavia.

12Z soundings of in particular Schleswig, De Bilt, Greifswald show considerable CAPE through the lowest 3 kilometers, values around 150-250 J/kg, allowing for rapid accelerations of parcels from the boundary layer. This supports the development of spouts (stretching of vertical vorticity). Greifswald has weak BL winds, while especially Scheswig which is also unstable over a deep layer has reasonable low level shear (7 m/s 0-1 km) that could become critical also for vortex-tilting, i.e. regular tornadoes. Farther south, subsidence inversion limits deep enough convection.

With current METARs showing mostly 15 kts low level winds (reducing vertical shear, and causing more mechanical BL mixing), and not much convergence seems present, conditions appear at most conducive to an isolated event or two, unless convection organizes better.