Mesoscale Discussion
Valid: Fri 11 Apr 2025 09:00 to Fri 11 Apr 2025 13:00 UTC
Issued: Fri 11 Apr 2025 08:57
Forecaster: TUSCHY

This Mesoscale Discussion (MD) was issued to highlight a more focused severe risk. Please keep in mind that the MD's validity does not match the time-frame for organized DMC activity.

Not much change in the overall setup and CAPE/shear space to what was described in the extended outlook. However, a confined corridor of enhanced severe is evident in latest data, prompting the issuance of this MD.

As BL flow veers to a more southerly direction in the following hours, a moist marine airmass spreads NE deep into Spain. Diabatic heating improves during the day as a mid/upper dry slot approaches from the SW. A regionally enhanced WV moisture gradient indicates the placement of a N-ward sliding low-amplitude wave, which affects SW Spain during the afternoon into the evening. This feature, embedded in a cyclonic SW flow/WAA regime offers enhanced synoptic scale background forcing for the MD area. This forcing turns to subsidence towards SE/E Spain, which slides beneath the anticyclonic part of the upper jet.

Diffuse forcing and a weak/meridionally aligned low-tropospheric confluent wind field increase confidence in isolated to scattered thunderstorms during the afternoon into the evening hours. MUCAPE resides in the 400-800 J/kg range and the MD area will see the best shear overlap. DLS in the 20-30 m/s range and 15-25 m/s 0-3 km shear are all supportive for organized DMC with isolated hail (despite intense LL shear and rather skinny CAPE profiles) and a few strong to severe gust events (despite rather meager LL lapse rates).

Once again, a tornado risk is present with favorable LL speed/directional shear, including strong helical inflow into deviating storms. LCLs are a bit high compared the last severe event a few days ago, which could keep this risk more isolated. Nevertheless, especially IFS and also ICON show confined swaths of LCLs around 500-600 m and impressive CAPE/shear, so we cannot rule out a strong tornado event. Nowcast becomes important, if/where any cell becomes (near) surface based for focused LL rotation.

Thunderstorms weaken beyond sunset. No level upgrade was performed with this MD with ongoing uncertainties and potential low coverage of storms.