Warm, humid Miterranean air and instability
Extreme rainfall In the run-up to a low pressure system over Spain, moist, unstable and warm Miterranean air was brought from the south towards southern France on October 15, 2024, which subsequently l to widespread heavy rainfall with embd thunderstorms in the Cévennes. The low pressure system then slowly shift northeastwards, so that the rainfall was somewhat less widespread, but still remain convective. On October 17, another low pressure system approach from Spain and, due to large-scale uplift, again l to widespread, more intense showers with thunderstorms.
Geopotential at 500 hPa and temperature field at 850 hPa of the IFS on 15.10.2024, 15 UTC (left) and on 17.10.2024, 12 UTC (right), the Cévennes area is approximately mark as a black ellipse.
Geopotential at 500 hPa and temperature field at 850 hPa of the IFS on October 15, 2024, 15 UTC (left) and on October 17, 2024, 12 UTC (right), the Cévennes area is roughly mark as a black ellipse. (Source: ECMWF/MeteoSwiss)
Animation of the radar and satellite image
(IR) from October 15, 2024, 15 UTC to October 18, 2024, 0 UTC. The Cévennes area is mark in r.
Animation of the radar and satellite image (IR) from October 15, 2024, 15 UTC to October 18, 2024, 0 UTC. The Cévennes area is mark in r. (Source: MeteoSwiss)
Locally more than 800 mm in 48 hours
MétéoFrance measur the following rainfall amounts in the argentina mobile database Cévennes of the Ardèche within 48 hours up to 8 p.m. on October 17th (source: www.infoclimat.fr):
840mm in Borne – Croix-de-Bauzon
684mm in Vialas
664mm in Loubaresse
663mm in Mayres
617mm in Usclades-et-Rieutord
547mm in Villefort
546mm in Saint-Maurice-de-Ventalon
539mm in Mazan-l’Abbaye
538mm in Sainte-Eulalie
Further information on the current event can be found
here
.
A complex dynamic is also responsible
It was not only the warm, humid and unstable Miterranean focus on our wordpress vps offer air that contribut to this heavy rainfall event in the Cévennes. Dynamic processes at altitude also play an important role, which are describ below:
Large-scale lifting: As mention above, the two low pressure agb directory systems coming from Spain in particular caus large-scale lifting of the air mass, which intensifi the precipitation process over a large area.
Convective and topographical uplift: supply of a moist and unstable air mass, which favors thunderstorms (convective drive), from a still warm Miterranean region (moisture input through evaporation). This air mass hit the elevations of the Cévennes in the lower layers with south to southeast winds and was dynamically lift.
Combination of these factors: The intrusion of dry air from the stratosphere (also call dynamic tropopause), combin with the upper low,