Storm Forecast
Valid: Mon 24 Mar 2008 06:00 to Tue 25 Mar 2008 06:00 UTC
Issued: Mon 24 Mar 2008 00:43
Forecaster: GROENEMEIJER

SYNOPSIS

Within this forecast period, the developments near the base of the deep, intense longwave trough that dominates the flow pattern over Europe derserve most attention. At the trough's base over the Mediterranean Sea, a triplet of shortwave troughs (initially over the S Tyrrhenean Sea, N Algeria and SE France respectively) are projected to move east-northeastward during the forecast period. Simultaneously a surface low is projected to move from Slovakia to northern Belarus. Ahead of the trough pair, an intense cold front stretching from near the low's centre to north-central Lybia will move eastward to reach a line from the Russian/Belorussian border to the Sea of Asov to central Turkey and north-central Egypt on Tuesday morning.

W Greece, Albania on Monday morning...

It appears that little CAPE will be available in the cyclone's warm sector, except just ahead of the cold front. There, a strong 25 m/s low level jet advects moisture northward and DCVA-related upward motion ahead of the (second) Algerian trough will have a destabilizing effect. During the morning hours, linearly-organized convection is expected to ensue along the front as it approaches the Greek and Albanian west coast. Given that very strong shear is expected, with 0-6 km bulk shear values up to 40 m/s (!), and ample low-level helicity is forecast, these may well contain rotating updrafts / supercells. As a result, we expect strong and locally damaging winds to occur with these storms. Additionally, large hail (i.e. greater than 2 cm in diameter) is possible and perhaps a tornado or two. The activity will likely diminish as the storms move inland, where less moisture will be available.

N-central and NE Greece, Aegean Sea, NW and W Turkey...

Reintensification of the convective storms is expected over northern Greece and possibly over the northern Aegean Sea during the later afternoon or early evening. The storms will likely be quite similar to those earlier in the day over western Greece and Albania, and will likely be organized linearly and possibly include supercells with a large hail wind and tornado threat. After midnight, the storms will likely weaken as they move onto the Black Sea and into the Turkish highlands.

S Italy, W Greece, Albania from Monday afternoon into Tuesday...

Current model guidance suggests that a surface trough or cyclone will develop ahead of the third, trough originating from France, well within the postfrontal polar air, over the Tyrrhenean Sea, during Monday afternoon. Enhanced convective activity will probably be associated with that system as it moves eastward. Given the strong shear, these will likely again become well-organized into linear elements. The storms may well be capable of producing severe wind gusts and some small or even marginally severe hail.

Ukraine, Belarus...

As mentioned above, the air-mass is now believed to remain almost void of CAPE across northern parts of the warm sector, in contrast to the extended forecast issued earlier. As a result a thunderstorm area nor a threat level has been issued for these regions.