Forecaster: Johannes Kahr (jfk)Kräftige Gewitter mit Unwetterpotential in Tirol
Auch heute Freitag muss man wieder mit teils kräftigen Gewittern rechnen. Auch wenn es vorerst lange stabil bleibt, nimmt am späten Nachmittag die Schauer- und Gewitterneigung vor allem im Westen stark zu. Gute Feuchte- und Energiebedingungen lassen mächtige Quellwolken entstehen, die sich zu organisierten Gewittern weiterentwickeln. Starkregen mit lokalen Überflutungen, Sturm und größerer Hagel sind im roten Warngebiet (LVL 3/4) die Hauptgefahren. Auch in Vorarlberg und Salzburg bis OÖ können einzelne Zellen auftreten, deren Intensität sollte aber geringer ausfallen. Auch am späten Abend sind noch weitere Gewitter möglich, erst in der ersten Nachthälfte wird die Gewittertätigkeit abnehmen.
Gültig von: 22.07.2022 / 15:00 Uhr
bis: 23.07.2022 / 01:00 Uhr
Erstellt: 22.07.2022 / 08:05 Uhr
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A level 1 and level 2 are issued for parts of Austria and far-south Germany for large hail, excessive convective precipitation and to a lesser degree for severe convective wind gusts.
Quelle: ESTOFEX (https://www.estofex.org/)... S Poland, Slovakia, Austria, far-south Germany ...
The stationary, diffuse frontal zone and a return of warm air advection aloft create a prime environment for moisture accumulation at low levels, which will likely support 2m dewpoints in the upper tens and CAPE in the 500-1500 J/kg range in a rather narrow belt on the immediate warm side of the frontal zone. Along the north Alpine foothills in Austria and far-south Germany, where moist northeasterly upvalley circulations ideally undercut the steep lapse rates of the hot airmass, even 2m dewpoints around 20C and CAPE up to 3000 J/kg appear likely by late afternoon. This belt of moderately to strongly unstable air is overspread by deep-layer shear around 15 m/s beneath the fringes of the jet stream.
In the absence of synoptic lift, primary convective initiation is expected to happen rather late and isolated, and will strictly be tied to the mountains. Forecast models agree on two hot spots over the Tatra mountains along the Polish-Slovakian border and in W to central Austria, whereas the lowlands separating the Tatras and the Alps will likely stay devoid of convection. Storms can organize into strong multicells or temporary supercells and may propagate some tens of kilometers into adjacent forelands in the evening, reinforced by secondary initiation at outflow boundaries. Curved wind profiles in the warm air advection regime favor right-moving storms, but these will stick to the mountains and face increasing competition as the evening proceeds, whereas the odd left-movers have better chances of feeding on the rich moisture reservoir and attaining supercell structures. The main hazards are excessive rain and large hail, plus perhaps isolated severe downbursts. A brief window for a few possible very large hail events opens up when left-moving storms detach from the Austrian Alps and enter the forelands. It is worth mentioning that - contrary to climatology - also the high elevations of the main Alpine crest face an unusually high hazard of severe, well-organized storms in such a hot airmass, which can import enough moisture also into the otherwise dry intra-Alpine valleys.
