Storm Forecast
Valid: Sat 26 Apr 2008 06:00 to Sun 27 Apr 2008 06:00 UTC
Issued: Fri 25 Apr 2008 16:43
Forecaster: TUSCHY
SYNOPSIS
Lingering WAA continues to support a strong ridge from Spain to Denmark. This ridge gets framed by two upper-level troughs, one over E - CNTRL Europe and the other on over the N - Atlantic. CAA continues over N - Sweden / Norway and NW Russia.
This constellation results in scattered thunderstorm development from SE Sweden to Greece. Best shear and instability stay separated during the period so no severe thunderstorms are forecast. The main risk will be strong wind gusts and sub - severe hail from pulsating thunderstorms.
DISCUSSION
... Sicily ...
Between 9Z and 15Z there is a time - frame where modest instability release and 15 - 30 m/s DLS overlap. This could result in an isolated large hail threat.
... W - Turkey ...
Between 12Z and 18Z, a strong shear gradient approaches from the east with DLS values between 10 and 30 m/s over the whole area of interest ( increasing from west to east ). SRH values are somewhat enhanced but best instability looks to develop too far to the west . Despite that we can't exclude that thunderstorms could benefit from stronger shear further towards the east with an enhanced large hail / severe wind gust risk.
Thunderstorms will expand rapidly northward over the western Black Sea area.
... NW Spain ...
A strong PVA maximum enters the area from the west during the late afternoon and evening hours. A combination of up to 1000 J/kg SBCAPE, increasing DLS and locally enhanced SRH values are all supportive for a few more organized thunderstorms with a large hail threat. Mid-level lapse rates, quite marginal during the daytime, increase constantly during the evening hours, which could offset slowly decreasing instability values. This favors a continued hail risk during the night hours over the level - 1 area.
Thunderstorms tend to develop over the Bay of Biscay during the morning hours, but instability will be too marginal to support long lived updrafts.
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