Storm Forecast
Valid: Wed 10 Aug 2016 06:00 to Thu 11 Aug 2016 06:00 UTC
Issued: Wed 10 Aug 2016 07:06
Forecaster: PUCIK
A level 1 was issued for SE Spain mainly for large hail and severe wind gusts.
A level 1 was issued for parts of Algeria and Tunisia mainly for large hail and severe wind gusts.
A level 1 was issued for N Italy, parts of Croatia, Bosnia, Serbia, E Hungary and E Slovakia mainly for large hail, severe wind gusts and excessive precipitation.
A level 1 was issued for Turkey mainly for large hail and severe wind gusts.
SYNOPSIS
Synoptic-scale situation over Europe is dominated by a highly amplified trough stretching from Scandinavia through central Europe, N Italy towards E Spain. Similarly extensive cold front flanks the trough, covering W Russia, extreme E Poland, E Slovakia, Hungary towards Croatia. Front itself is much less pronounced (being affected severely by the Alpine range and Pyrennees) over Italy and parts of Spain. This front and a moist airmass ahead of it will become the foci for tstm development during the day over multiple regions.
DISCUSSION
... SE Spain ...
A surface high pressure just offshore results in a moist onshore flow with dewpoints along the coastline up to 20 deg C. A large cloud shield is visible on the satellite with embedded tstms, probably associated with translating trough. Further development is forecast ahead of it, in the environment of moderate vertical wind shear (DLS values around 15 m/s). Some well organised tstms, including supercells are possible and would pose primarily threats of large hail and severe wind gusts. Lacking overlap of very steep lapse rates with low-level moisture (lapse rates are displaced to the west) precludes higher MLCAPE values, which should stay around or below 1000 J/kg.
... Algeria, Tunisia ...
A similar situation to Spain will exist over the region with moist onshore flow pushing more abundant low-level moisture towards the region with steeper lapse rates, resulting in the development of latent instability. Overlaped by 20 m/s W-ly 500 hPa flow, well organised tstms, once they initiate, are quite possible, and may be capable of large hail and severe wind gusts.
... N Italy towards Serbia, E Hungary and E Slovakia ...
Along the aforementioned cold front, tstms have already developed in the discussed region. More specifically, a backbuilding complex near the Gulf of Genoa slowly propagates S-ward and an disorganized cluster of elevated cells over Slovenia quickly moves NE-ward. 00 UTC soundings confirm strengthening of mid to upper tropospheric flow associated with the trough, which should promote better storm organisation, including long-lived multicells and some supercells as DLS reaches 15 - 25 m/s. Degree of instability will be limited by the lack of steep mid-tropospheric lapse rates, but several hundreds to around 1000 J/kg of MLCAPE are expected. Overall, a combination of threats, including large hail, severe wind gusts and excessive rainfall warrants a Lvl 1 for this area. The highest threat will exist over N Italy and parts of Bosnia / Serbia, where the most abundant low-level moisture is observed.
... Turkey ...
High-based tstms, organised into multicell clusters with DLS values around 10 m/s will form as daytime heating destabilises the boundary layer over the region. Isolated large hail and downburst events are quite possible given the environment of high LCLs and very steep lapse rates.
