Forecast Update
Valid: Wed 17 Feb 2010 09:00 to Thu 18 Feb 2010 06:00 UTC
Issued: Wed 17 Feb 2010 08:48
Forecaster: PUCIK

SYNOPSIS

The major feature on the satellite data seems to be a large cyclonic vortex centered over the British Isles, filled with cold airmass. Its trough is stretching to the Western Mediterranean. Over the Southern Mediterranean, an active frontal zone results in a strong jet-stream from mid to upper levels of troposphere. Several embedded short-waves to the north of the jet-stream will influence the weather over this region.

At the moment, it does not seem that there are favorable conditions for severe thunderstorms at any extent of the European continent, but there are several regions that might experience deep moist convection and thery are described in more detail below.

An interesting point is a rapidly developing low to the southwest of Iberia, which will probably significantly influence the weather in the following forecast period, but till Thursday 06 UTC it does not seem that it will reach SW Iberia and its surrounding coasts.


DISCUSSION

...Western/Central Mediterranean...

Advection of cool airmass over the warm sea surface along with upward motions stimulated by the PVA ahead of the approaching trough will result in a marginal destabilisation. MLCAPE values are predicted to stay around 500 J/kg. No concentrated mesoscale lift will result in only isolated to scattered storm coverage over the region, but more plentiful storm initiation is expected closer to the western coasts of Corsica/Sardegna islands or the western coast of Italy by Thursday morning. With quite small values of CAPE and weak wind shear, environment does not seem too conducive to the severe convection.

...Southern Ireland to Normandy...

On the forward flank of the trough, upward synoptic scale motion is forecast and scattered convection is already visible on the satellite images around Ireland. MLCAPE values might reach 500 J/kg per GFS , but ECMWF is less optimistic. Another detrimental factor might be weak moisture content, with mixing ratios between 4-5 g/kg. Very isolated lightning might occur, but its scarcity does not warrant a thunderstorm area.