Storm Forecast Valid: Sat 20 Jul 2013 06:00 to Sun 21 Jul 2013 06:00 UTC Issued: Fri 19 Jul 2013 20:57 Forecaster: TUSCHY
A level 2 was issued for NE Spain mainly for large to very large hail, severe downbursts, heavy rainfall amounts and an isolated tornado event.
A level 1 surrounds the level 2 mainly for the similar risks but with no extreme events expected.
A level 1 was issued for N-Morocco, N-Algeria and N-Tunisia mainly for an isolated but very large hail and severe downburst event.
A level 1 was issued for parts of France, Switzerland, parts of Austria and Italy mainly for large hail, strong to severe downbursts and heavy rainfall amounts. An isolated excessive rainfall event is possible. An isolated tornado event is possible, too.
A level 1 was issued for parts of Moldova, parts of the Ukraine into extreme W-Russia mainly for a few large hail and strong to severe wind gust reports.
Another day is in store where a pronounced blocking takes place in the steering flow regime over Europe. A strong deep and warm high pressure area over the North Sea remains essentially unchanged regarding strength and placement compared to yesterday. The only sign of movement/expansion is seen along its southern fringe, where rising heights are forecast over Benelux and Germany. Along its southern fringe, the leftovers of the previous blocking event still meander to the ESE over S/C France and Italy. In fact, the strongest vortex will be the one over N-Italy with a closed circulation and a cold thermal print at 500 hPa, whereas the rest over S-France resembles more an elongated channel with cooler mid-levels (east-est aligned).
The strong upper trough over E/NE Europe continues to amplify and it approaches the northwestern part of the Black Sea during the overnight hours. This feature tries to constrict into a cut-off low, but another impulse approaches Norway/Sweden from the NW and probably delays any cut-off process at least beyond our forecast period.
An upper level ridge over far N-Africa expands a bit to the north and covers parts of the W-Mediterranean. A very hot and well mixed continental/desert air mass remains in place with convection once again being confined to the mountain areas along the coast.
At the surface, the southward blasting cold front gradually approaches Romania/Bulgaria with significantly drier postfrontal air affecting most parts of E-Europe. More synoptic fronts enter the scene from Norway/Sweden like a warm front, which will cross the Baltic Sea around midnight. Ongoing prefrontal low/mid tropospheric CAA and approaching WAA from the west result in more stable conditions spreading E/SE-wards (convective-wise).