Storm Forecast
Valid: Fri 22 Sep 2006 06:00 to Sat 23 Sep 2006 06:00 UTC
Issued: Thu 21 Sep 2006 19:35
Forecaster: TUSCHY

SYNOPSIS

A classical omega-pattern will be present during the forecast period with an intense upper-level trough over the eastern Atlantic Ocean and a closed upper-level low over SE Europe. In-between, WAA continues to support ridging over parts of central Europe.


DISCUSSION

...Extreme S-France...

An eastward moving cold front, crossing France from the west during the forecast period, will be the focus for TSTM development.... Main area of interest will be the level-1 region , where an intense LLJ ( weakening during the latter forecast period ) should help to advect a moist airmass well inland.
Combined with moderately steepened mid-level lapse rates, at least low-end instability release can be expected.
Enhanced LL shear and intensifying DLS would be favorable for storms to become severe with an isolated tornado / severe wind gust threat.
A possible southward extension of the level-1 area may become necessary later-on if the 12Z GFS trend will be right ( in developing a cluster of storms over the Balearic Islands during the night hours.)

Cold front should pass NW France during the morning hours and GFS indicates a broad area of instability release under a 30m/s DLS belt... No forcing ( respectively strong NVA on the backside of the departing frontal boundary ) should help to suppress any significant TSTM development.... However...won't exclude a few showers / isolated TSTMs which would pose a severe wind gust threat.

The approaching upper-level trough axis will reach the coastal areas of W-Portugal during the night hours.... A cool-down of the mid-levels should be conducive for at least low-moderate instability release ( mainly offshore, but also well inland over Portugal and extreme NW Spain ).... Strong DLS and enhanced LL shear, combined with low LCLs will be fine for storm organisation and an isolated tornado / severe wind gust report.