Hier eröffne ich mal den Gewitterthread für heute und für morgen (weis snicht, ob es heute genug Stoff gibt, um einen separaten Thread zu starten
).Bei Estofex befindet sich die Schweiz heute teilweise im Level-1-Gebiet mit folgender Beschreibung:
Für Freitag ist die ganze Schweiz Level 1:France, central and southwest Germany, Switzerland...
GFS and ECMWF both simulate some storms that develop further south along the frontal zone across France and central/southwestern Germany during the evening and overnight. However, both CAPE and shear should become smaller further to the southwest along the zone, so that the level 1 cover only SW Germany and NE France, where a few large hail events will be possible.
Wobei dies hier jedoch noch relativ unsicher tönt;)... South / east and northeast Germany, parts of the Czech Republic, Austria and Switzerland ...
Eastward trailing cold front sparks scattered to widespread thunderstorms during the forecast period. The cold front position is captured well by all models, which push the front out of Germany until 06Z with the fastest motion over north/central Germany and a trailing part over southern Germany. Numerous mid-level impulses, embedded in the cyclonic flow cross the area during the forecast from SW but the focus agian is the prefrontal convergence zone and the surface front.
The quality of the prefrontal boundary layer looks promising with dewpoints in the upper tens and even 20°C can't be ruled out. EML atop that airmass fans out but remains still steep enough for 500 - 1000 J/kg prefrontal MLCAPE release over NE/E-Germany and somewhat higher values over S/SE-Germany.
Shear in the lowest 3km but also 6km is moderate with 15m/s and 20m/s respectively, but that's more than adequate for organized thunderstorms along the cold front. Preceding convergence zone could outrun that favorable shear, especially over SE Germany, but better instability may compensate that to some degree.
Thunderstorm initiation again is a bit diffuse that far out with isolated to scattered thunderstorms ongoing at 06Z. Later the day, conditions improve rapidly especially over southwest / central / east and northeast Germany and a mixture of multicells and supercells is forecast with large hail and strong to severe wind gusts. Initiation over SE-Germany may be delayed a bit due to foehn conditions, but thunderstorms also develop during the late afternoon and evening hours with an hail/wind risk. Thunderstorms also affect the Czech Republic and western Poland during the evening and night hours with a gradually diminishing severe risk as instability weakens.
The level 1 also covers most parts of Switzerland and the Alps mainly due to excessive rain. However, large hail and strong wind gusts are forecast dependent on how far south and east the jet expands. Model discrepancies are still present.
Uncertainties remain:
* where is the cold front situated at the start of the forecast. GFS decelerated the progression of the front in the past few runs, but convection from the night before could push the surface front further east than expected.
** coverage of elevated thunderstorms over Sweden. The level 1 may be expanded well to the north due to MUCAPE/shear overlap with an hail risk
*** Parts of the level 1 may see an upgrade, most likely a swath from southwest/central/east and northeast Germany. Uncertaintiy of the final position of the front, degree of insolation and debris of mid-/high cloud layer of the storms the night before preclude that upgrade
Betreffend Regen wiedersprechend sich die Modelle (wie so oft
). GFS rechnet für heute keine Niederschläge, und erst für morgen ab Nachmittag geringe Mengen. JMA rechnet heute mir ein wenig Regen in der Westschweiz, morgen eher NW und übermorgen NE.Interessant ist jedoch: Auch wenn GFS eigentlich hier praktisch keinen Niederschlag berechnet, so sind sich doch die meisten GFS-Läufe (mehr als 90%), dass in der CH heute Niederschlag fallen wird (Ensembles bei Wetteronline)
Viele Grüsse
Lukas
, aber draussen auf der Wetterfront tut sich was: Die KF wellt ganz schön ordentlich, besonders schön grad auf Niederschlagsradarzu sehn über England und France. Zudem schon präfrontales Gewitter über Kölner Bucht (nein, Köln liegt nicht am Meer 
