Storm Forecast
Valid: Sat 17 Feb 2007 06:00 to Sun 18 Feb 2007 06:00 UTC
Issued: Fri 16 Feb 2007 18:49
Forecaster: DAHL

SYNOPSIS

W European upper longwave trough is progged to evolve into a cut-off low early in the period ... leaving intense, meandering zonal upper flow over the northern portions of Europe. Low geopotential is present also over SE Europe, resulting in an omega-type upper pattern on Saturday. Low levels feature quite large and cold high pressure system over eastern parts of Europe and two low-pressure systems over the Biscay region and the S-central/SE Mediterranean Sea, respectively.

DISCUSSION

... SW Europe and SW Mediterranean Sea ...

GFS does not leave appreciable CAPE in the warm-sector air mass of the intense SFC low moving into the Gulf of Biscay, though shear profiles over France would be quite conductive to a persistent severe threat over the W Mediterranean and France. Since not even shallow CAPE is simulated ... will no longer maintain a categorical risk, though the cold front should be monitored for potentially severe convective development, which might require an upgrade on Saturday.

In the polar/Atlantic air in the wake of the front ... cellular convection should exist beneath the upper thermal low. 20 m/s deep shear will be present at the periphery of the upper low, and storms developing in this region may have some severe potential, mainly marginally severe hail and strong wind gusts. Low LCLs and weak LLS could be supportive of a few waterspouts. However, severe events should be too isolated to warrant a categorical risk.

Otherwise ... severe threat should be rather low.