Storm Forecast
Valid: Tue 25 Dec 2007 06:00 to Wed 26 Dec 2007 06:00 UTC
Issued: Mon 24 Dec 2007 13:11
Forecaster: DAHL

SYNOPSIS

Large-scale upper trough is present over the E Atlantic and NW Europe ... making slow eastward progress while closing off into an upper cut-off low over W Iberia late in the period. Another cut-off cyclone is present over central Europe and will slowly move into the N Balkans until early Wednesday morning. Weak southern branch of the upper frontal zone, featuring a stationary trough over the NE Maghreb States, is covering the southern and eastern Mediterranean. At low levels, large Atlantic SFC low pressure complex will affect northern and central Europe while high pressure persists over E Europe. A weak SFC low is expected to develop over the south-central Mediterranean Sea late in the period ... otherwise, quiescent conditions prevail over the Mediterranean regions.

DISCUSSION

... central Mediterranean ... Ionian Sea ...

It seems that main focus for convective activity will be tied to the southern-stream upper trough over the NW Maghreb States. Persistent DCVA-forced ascent should promote at least scattered thunderstorm in weakly unstable thermodynamic environment over the Ionian-Sea region. Deep shear should exceed 20 m/s suggesting some threat for well-organized multicellular storms and mesocyclones. However, it does not seem that thunderstorm coverage will be very large, and any severe event will likely be quite isolated. Still, a level-one threat seems to be marginally warranted. Main threat should be marginally severe hail/wind, though weak capping and nearly saturated boundary layer suggest that brief tornado could occur as well.


... Otherwise ...

Sporadic lightning may accompany convection in the polar air over the North Sea, but remain too isolated to warrant a thunderstorm area.

Southern Iberia may also experience marginally deep convection, maybe resulting in a few lightning strikes, but it also appears that a thunderstorm area is not necessary with this activity.