Mesoscale Discussion

Mesoscale Discussion
Valid: Mon 10 Jun 2019 16:00 to Mon 10 Jun 2019 18:00 UTC
Issued: Mon 10 Jun 2019 16:08
Forecaster: PISTOTNIK

This Mesoscale Discussion (MD) is issued to monitor a probably beginning severe weather outbreak in central Europe.

A convective line has formed at the leading edge of formerly elevated convection over Switzerland and Baden-Wuerttemberg and is tracking ENE-ward into Bavaria. In particular, a strong supercell at its southern end is crossing Munich in these minutes. Severe downbursts, 2 cm sized hail and very heavy precipitation have already been reported with this storm.
Convection is expected to further intensify as it encounters warmer and moister air along its track with rising CAPE values - per 12z soundings and latest surface observations probably on the order of 1000-2000 J/kg over the Czech Republic and 2000-4000 J/kg over northern Austria, where the potent air mass is, however, strongly capped and gradually shifted northward as South Foehn winds push a dryline into the forelands.
The Bavarian storms will probably continue to propagate towards the warmer air and head for Bohemia rather than Saxonia, i.e., the most likely track continues to shift further southeastward (albeit with still considerable uncertainties). Other convection is moving from northern Italy into Austria - in case it survives the belt with hot but dry South Foehn winds and can dock with the Bavarian storms, the resulting risk area would shift even further southeast.
Large to very large hail (in particular with supercells), severe wind gusts and heavy rain (in particular with the convective line) are likely.

A handful of supercells has also initiated over NW Poland near the nose of the warm air advection regime in an environment of 1000-2000 J/kg CAPE and 10-15 m/s 0-3 km shear per 12z Wroclaw and Lindenberg soundings. Current storms will gradually move over cold sea breezes from the Baltic Sea and become elevated, but outflow boundaries should be monitored for possible secondary storms with a continued hail risk.

In-between these two areas, elevated convection moving from central to E and NE Germany still shows no sign of becoming surface-based, but this is still likely in the next few hours. In that case the severe weather risk would increase as well.

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