War ja Zeit für's Update...
Ich habe gestern Abend wirklich überlegt loszufahren, weil ich vorallem diese Karte sah:
Aber auch um 18z bzw. 21z wird es an der slowenischen und kroatischen Küste in Sachen Wasserhosen / Tornados interessant.
Auf einer anderen Webseite sah ich einen relativen schwachen 300er, der zudem weiter westlich zu erkennen ist. Ein Argument zu zögern. So wunderte ich mich sehr, als Estofex schrieb:
"... North Italy towards Adriatic sea ...
Significant heights falls and quite impressive jet streak will be spreading into Alpine region, while a Lee surface low forms beneath the rather strong upper-level divergence in the left-exit jet region over NW-ern Italy during the early afternoon hours. Ahead of the system, rapid warm air advection will be spreading northwards from Adriatic sea, recovering the BL moisture with mixing ratios up to near 7-8 g/kg. Height falls and cooling mid-levels aloft will result in marginal instability release. With a developing secondary surface low, curving wind profiles from southerly to more easterly directions should be sufficient enough for formation of several low-level convergences zones across the Po valley. There, storm initiation is likely which is simulated by several models as well.
Models are predicting surface dewpoints near 10-12°C which is actually not too far away from the reality as observed values on Monday were not much different. Depends on cloud cover, instability build-up will be on going during the daytime hours. Between 500 and 800 J/kg of MLCAPE seem reasonable given the current observations. Within the jet axis, relatively strong wind shear at all levels will be present which will be supportive for organized convection once storms manage to initiate. Multicells and a few supercells will form, posing a threat for large hail and damaging winds. Despite the favorable veering winds profiles with height and quite impressive LL shear/SREH, some uncertainities are present for a tornado threat, as rather limited BL moisture limits the higher chances for tornadogenesis. Although, better LL moisture seem located toward the Po valley delta where tornadic supercells cannot be completely ruled out.
Later in the night, convection will be spreading towards the central Adriatic and western Balkans along the moving front, but instability slowly diminishes while moving more inland. With an exception of costal areas of eastern Adriatic sea, where overlaping instability and moderate shear seem maximized, no organized storms are expected."
Das norditalienische Lee-Boden-Tief ist mir schon klar und das ist eine gute Bedingung. Das sich bildende Sekundärtief und die erhebliche Warmluftadvektion aus Süden habe ich hingegen nicht gesehen. Zudem erstaunt mich diese Aussage ("the left-exit jet region over NW-ern Italy .."), weil ich den Jet woanders lokalisierte (vielleicht im falschen Lauf).
Tornadische Superzellen über der Po-Ebene werden nicht ausgeschlossen ("...located toward the Po valley delta where tornadic supercells cannot be completely ruled out."). Das Level-1-Gebiet ist schon ziemlich gross gefasst. Im Bereich Venedig gab's immer wieder Wasserhosen / Tornados. Der letzte war in Pio-X, nordöstlich von Venedig.
Gruss Cyrill
