Mesoscale Discussion
Valid: Mon 01 Jul 2019 15:00 to Mon 01 Jul 2019 21:00 UTC
Issued: Mon 01 Jul 2019 15:11
Forecaster: PISTOTNIK

This Mesoscale Discussion (MD) is issued to highlight an ongoing risk of severe to extremely severe thunderstorms in S Germany and N Austria.

According to the 12z Munich and Vienna soundings, about 2000 to 2500 J/kg CAPE are present in the north Alpine forelands. Latest satellite, radar and station data indicate that numerous outflow boundaries are converging in this region, which have emerged from early orographic storms to the south (over the Alps) and two large storm clusters to the West (Bavaria) and north (Czech Republic). In addition, the wind shift line of the cold front is currently (15 UTC) located near a line from Prague to Lake Constance and triggers further storms in those regions that have yet been spared from previous activity. All in all, a very high storm coverage is expected in the next couple of hours across the highlighted area.

Vertical wind shear is lower than in the area further north (discussed in a separate MD) with 0-6 km bulk shear between 10 and 15 m/s. However, its overlap with extraordinary CAPE values is sufficient to support widespread severe and isolated extreme hail and wind events, confirmed by reports of up to 6 cm sized hail and wind gusts up to 100 km/h so far.

With maturing and growing storm clusters and deeper subcloud layers towards the east (as indicated by 2m temperatures up to 39C and 2m dewpoints around 18C in E Austria and W Slovakia), the risk of severe wind gusts should gradually become dominant. In addition, some flash floods are possible, as well as still large hail especially under discrete updrafts.