On 15 May, with a low-level depression over the Austrian Alps, westerly winds were blowing over northern Italy and the Alps at levels above 2–3 km.
05 July 2022
15 May 2012
By HansPeter Roesli (EUMETSAT)
At lower levels weaker southerly winds predominated (see cross section, source: ECMWF).
Typical for this situation Mediterranean air was advected through the gap between the Apennines and the western Alps into the western part of the Po Valley (see 10 meter winds , sorce: ECMWF). Thanks to diurnal heating the front of the airmass was marked by an arc of small cumulus clouds (initially partly hidden by some cirrus). Approaching the alpine foothills, the convection slightly intensified and gave rise to light showers in the evening (see animation). Later on the arc of cloud merged with the convective cloud cover that had developed over the southern Alps in the same time period.