mardi 25 février 2014

European Storm Forecast Experiment

Storm Forecast
Storm Forecast
Valid: Wed 26 Feb 2014 06:00 to Thu 27 Feb 2014 06:00 UTC
Issued: Tue 25 Feb 2014 17:28
Forecaster: PUCIK
No threat levels have been issued


A deep trough, filled with seasonably cold airmass at mid-levels will progress from the Atlantic towards Western Europe and the Western Mediterranean, amplifying to the Northern Africa. Trough is expected to "narrow" down and start to fill in during the forecast period. Just to the west, a pronounced short-wave will rapidly translate eastwards in the exit region of cyclonically curved delta of the 70 m/s jet-stream at 300 hPa. A deep low pressure system will be associated with this short-wave, exhibiting potent LLJ ahead of the progressing frontal boundary. Towards the eastern Europe, rather insiginificant weather pattern precludes any DMC with dry low-level airmass and weak lapse rates.

There will generally be 3 regions that may experience DMC during the forecast period:

1/ Coastal areas of the British Isles, associated with the post-frontal airmass with the steep lapse rates. Embedded convection along the front itself is not ruled out. Higher values of CAPE will be precluded by insignificant overlap of favourable lapse rates with more abundant moisture. This should limit the severe weather threat.

2/ In the post-frontal airmass especially over Southern / Mid France, under cold mid-level temperatures, with mixing ratios of just around 5 g/kg . Weak shear and low CAPE values (on the order of few hundreds J/kg) should preclude threat of severe weather.

3/ Ahead of the weak frontal boundary over the Western Mediterranean - from Algeria towards NW Italy. Here, better low level moisture might yield slightly higher CAPE values than in the remaining areas, but weak vertical wind shear should not allow for any well organised storms capable of severe weather. 

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