Storm Forecast
Valid: Sat 01 Aug 2015 06:00 to Sun 02 Aug 2015 06:00 UTC
Issued: Fri 31 Jul 2015 21:09
Forecaster: DAFIS
A level 2 was issued for West Mediterranean mainly for large hail, excessive rainfall, severe wind gusts and an isolated tornado event.
A level 1 surrounds the level 2 area for the same threats but with less coverage.
SYNOPSIS
A trough east of the Iberian Peninsula, which shifts east and enters the West Mediterranean during the forecast, encounters a very humid and unstable, tropic environment around the Balearic Islands and Corsica, where DMC is expected.
Most of North Europe is under a pool of cold mid-levels and an amplifying low pressure system is located NW of the UK where heavy (most non-convective) rainfall is forecast.
Another LL vortex is located in NE Scandinavia, which shifts E during Saturday, over Kola Peninsula. Moreover, countries in South Balkans will experience some evening storms as some weak instability is forecast under non sheared environment.
DISCUSSION
.... West Mediterranean ....
As the upper-air trough enters the Gulf of Lion, overnight storms will continue to move east. The development of more than 2000 J/kg MLCAPE offshore, around the Balearides Islands which overlaps with 25-30 m/s DLS, 15-20 m/s 0-3 km shear and SREH 0-3 km of more than 300 mē/sē will assist any thunderstorm to acquire rotation in a short amount of time with very large hail possible. Onshore, in Spain, CAPE values are significantly lower but no cap is forecast and strongly sheared environment will enhance the formation of well organized cells with large hail and/or excessive rain. An isolated tornado / waterspout event in the Balearides Islands is not excluded due to strong LLS.
Later on, after 12:00 UTC, the threat is located in far SE France and NW Italy, where strong DLS is formed with moderate CAPE values. Most of CAPE will be capped during the day and only over Corsica and NW Italy will be effective, giving the chance for organized clusters of storms to result in flash floods. The large level 2 area is issued despite the isolated instability, because any storm that forms, will be able of large hail, severe wind gusts and excessive rain.
.... Rest of Italy and Balkans ....
Diurnal heating will result in SBCAPE of 800 - 1200 J/kg but weak DLS indicates weak and isolated storms, dissipating until the night hours. A few hail reports are possible, especially in southern parts of Italy, but the weak shear precludes a level 1.
