Forecast Update
Valid: Fri 10 Jul 2009 12:00 to Sat 11 Jul 2009 06:00 UTC
Issued: Fri 10 Jul 2009 11:53
Forecaster: TUSCHY
A level 2 was issued for N-Italy mainly for large hail.
A level 2 was issued for parts of Bulgaria and extreme W-Turkey mainly for large hail.
A level 1 was issued for the N-Balkans mainly for large hail and severe wind gusts.
A level 1 was issued for parts of Romania, N-Greece and Macedonia mainly for large hail and severe wind gusts.
A level 1 was issued for parts of W-Russia mainly for large hail and severe wind gusts.
A level 1 was issued for parts of Finland mainly for large hail.
A level 1 was issued for N-Tunisia mainly for large hail.
A level 1 was issued for parts of Poland mainly for large hail.
SYNOPSIS
Please refer to the main outlook.
DISCUSSION
... N-Italy ...
Despite still existing concerns about the coverage of thunderstorms we went ahead and upgraded parts of N-Italy to a level-2. GFS is way too bullish with BL moisture recovery as current surface data reveal dewpoints in the mid tens with higher values along the coast. Lapse rates are forecast to steepen during the upcoming hours, so this could still boost CAPE release to 1000-1500 J/kg MLCAPE. Strong NW-erly flow above mountain range niveau is already present with 0-6km bulk shear of 15-20m/s and even higher values further west. A weak vorticity lobe ought to cross N-Italy from west to east from the afternoon hours onwards, so at least isolated initiation is expected, increasing in coverage and intensity in the level-2 area. The main reason for upgrading is the large to very large hail risk, given steepening mid-lelve lapse rates, strengthening shear and more discrete mode of thunderstorms.
Latest high resolution VIS images already show a few stronger Cu fields along the southern fringes of the Alps and we think that thunderstorms evolve during the next few hours, moving rapidly towards the S/SE in an increasingly favorable environment for supercells.
... SE-Bulgaria and extreme W-Turkey ...
Another upgrade was performed due to a large to very large hail risk. The boundary layer is warm and moist with dewpoints around 20°C in the level-2 area. 00Z Istanbul has a well capped profile but the level-2 ought to see weaker CIN build-up with steep mid-level lapse rates present. 15m/s DLS and some directional shear cause an augmented hail threat next to strong to severe wind gusts.
... Poland ...
A marginal level-1 was included due to the risk of isolated large hail reports, given cold profiles of the lower/mid atmosphere.
... E-Spain ...
A persistent convergence zone is seen half-way between the Balearic Islands and the E-coast of Spain. Initiation continues along its eastern tip and it can't be ruled out that more thunderstorms evolve along this zone. VIS images also show first initiation along the E-coast, so thunderstorm probabilities were increased. Despite favorable instability and modest shear overlap, very isolated nature of storms preclude the issuance of a level-1.
... NW-Germany and the Netherlands ...
The level-1 was downgraded as conditions now become more hostile for thunderstorms (slim instability). In addition, no enhanced spout risk is expected due to the gradual warming trend at all levels. The risk increases over E-Denmark and northeastwards but is too slim for a broad level-1 area.
No major changes for the rest of the outlook.
