05-07-2024 21:30 | Estofex | m.b.t. 06-07-2024 t/m 07-07-2024
Storm Forecast
Valid: Sat 06 Jul 2024 06:00 to Sun 07 Jul 2024 06:00 UTC
Issued: Fri 05 Jul 2024 21:30
Forecaster: ROSBERG/OBERHUBER
A level 2 was issued across Germany, Austria, Czech Republic and Poland mainly for severe wind gusts and large hail. A level 1 was issued surrounding the level 2 area for the same hazards but with lower probability.
A level 2 was issued across NW Italy and S Switzerland mainly for excessive convective precipitation and large hail. A level 1 was issued surrounding the level 2 area for the same hazards but with lower probability.
A level 2 was issued across Russia for large hail, severe wind gusts and excessive convective precipitation. A level 1 was surrounding the level 2 area but with lower probability.
A level 1 was issued across southern Scandinavia for tornadoes and severe wind gusts.
A level 1 was issued across Spain, Turkey, the Black Sea region, the Caucasus-region and southern Russia for large hail and severe wind gusts.
SYNOPSIS
A large upper-level longwave trough over northwestern and northern Europe is almost stationary. On the southern flank of this longwave trough, an intense fast-moving shortwave trough is expected to move from The British Isles to southern Scandinavia. An associated strong mid-level jet will pass over northwestern Europe and into central Europe and Scandinavia.
Another shortwave trough across Finland and western Russia is expected to move northeastward. The large longwave trough is flanked by an upper-level ridge that is located from the central part of the Mediterranean up across eastern Europe. East of the upper level high, an upper-level low over Turkey is moving slowly eastward.
At the surface a low pressure across the southwestern North Sea is moving towards central Scandinavia, while deepening. The associated cold front that is located from the North Sea down across Benelux, western France and northwestern Spain is expected to move eastward into central Europe, Scandinavia and the Baltic States during the forecast period. This cold front will be the main trigger of DMC across these areas.
The surface low might also generate severe non-convective wind gusts of 25 m/s, due to a strong pressure gradient, across coastal areas of The Netherlands, northwestern Germany and parts of southern Scandinavia.
Another cold front with widespread showers and storms over western Russia is moving eastward. A surface low across the eastern part of the Black Sea is nearly stationary and is also expected to trigger showers and storms across this region.
The central and eastern part of the Mediterranean and eastern Europe are expected to see stable conditions in connection with a surface high over these areas.
West and north of the surface low and the cold front across The British Isles, northern Scandinavia and Finland, showers and isolated storms are expected to occur in the cold and unstable airmass. No deep and vigorous convection is expected due to low EL-heights, lack of steep mid-level lapse rates and absence of strong deep layer shear. That being said, small hail, heavy rain and gusty winds might occur in stronger cells. In areas where low-level winds will be weak and where surface convergence will be present, a water- or landspout cannot be ruled out as some low-level CAPE will be present in the cold airmass.
DISCUSSION
... France, Germany, Austria, Czech Republic, Poland ...
In front of the incoming cold front widespread CI is expected over central Europe. Overnight convection over southern France is still ongoing in the morning hours. In an environment with low CAPE and moderate to high shear marginally large hail and isolated severe wind gusts are expected, if some storms manage to become surface based during the day over France and northern parts of Switzerland.
Over E Switzerland, S Germany and W Austria daytime heating leads to build-up of CAPE in the range of 1000 to 1500 J/kg. First storms are expected to initiate in the early afternoon hours along the northern edge of the alps. Within 15 to 20 m/s of DLS storms will quickly form to multicells and some supercells with risks of large hail and severe wind gusts. Right moving storms along the northern alpine rim could benefit from locally enhanced deep layer windshear due to incoming mountain valley winds. These storms would be able to produce very large hail.
Around the border from Germany to Czech Republic and NW Austria low level moisture tends to be lower. Boundary layer is well mixed, with spreads exceeding 15 K. Forecast soundings indicate some shape of inverted-V. Current thinking is that in such an environment incoming storms will create an increasingly strong cold pool. Thus, storm mode should mostly change to line segments and, while moving east, main risk is going to be severe wind gusts.
Some high resolution models indicate swaths of severe wind gusts in the range of 25 to 35 m/s from SE and E Germany all the way to northwestern Austria, western Czech Republic and western Poland. Taking into account the fact that high resolution models at times overestimate cold pool strength and severity of severe wind gusts.
However, confidence is high enough to issue a broad level 2.
While the wind gusts in the southern part of the level 2 are mostly thermodynamically driven, kinematics are slighly more favorable over eastern Germany and western Poland. 0-3 km bulk shear up to 15 m/s should compensate the lack of CAPE in this regions.
(alleen de voor NL en aangrenzende gebieden relevante tekstdelen overgenomen, klik hier voor de volledige forecast, red.)
Hagel(-schade) | Onweer/blikseminslag | Verwachtingen/waarschuwingen | Wind/storm (-schade)
