Storm Forecast
Valid: Sun 30 Sep 2007 06:00 to Mon 01 Oct 2007 06:00 UTC
Issued: Sat 29 Sep 2007 19:42
Forecaster: DAHL
SYNOPSIS
Dominant features on the upper-air analyses remain the two large-scale upper troughs/lows over southern Scandinavia and off the SW European Atlantic coast, respectively. A large SFC pressure area is accompanying the Atlantic trough, resulting in southerly winds and warm advection at low levels over the southwestern parts Europe. Most of the rest of the European continent is dominated by cool polar air.
DISCUSSION
... western Mediterranean ...
It seems that the steepest mid-level lapse rates and accordingly the potential for large CAPEs will be present over the southern/southwesternmost parts of the Mediterranean Sea. Deep shear of 15-20 m/s is simulated to persist through the day. However, models are reluctant in producing convective precip over this region, and confidence in widespread convective development is quite limited. Best chance seems to exist over Sardinia and Sicily. Those cells that do form will have potential of becoming severe, mostly with large hail and severe wind gusts.
... western Iberian Peninsula ...
Along and ahead of the cold front trailing from the Atlantic low-pressure system, scattered thunderstorms will likely develop over western Iberia. Shear profiles will be quite strong with up to 25 m/s DLS and 10 m/s LLS. This implies that a few storms may become supercellular, with threats for large hail and isolated/brief tornadoes.
... southern Scandinavia ... Denmark ...
Scattered, relatively shallow thunderstorms should persist over southern Scandinavia, Denmark, and adjacent waters beneath the upper thermal low. At some places, low-level buoyancy may be sufficient for stretching pre-existing vertical vorticity along mesoscale boundaries, which will likely be present/evolve over the region ... resulting in some threat for waterspouts/non-supercellular tornadoes. GFS predicts that LL lapse rates will be rather weak (between 5 an 10 K/km), suggesting that the allover threat is somewhat limited. Will thus not issue a categorical rist at the moment.
