Mesoscale Discussion
Valid: Fri 25 Aug 2023 09:00 to Fri 25 Aug 2023 12:00 UTC
Issued: Fri 25 Aug 2023 09:39
Forecaster: TUSCHY

A MESOSCALE DISCUSSION was issued for parts of CNTRL/W/NW Germany. This MD is valid for the afternoon into the evening hours.

In general the anticipated event is on track.

Latest synoptic-scale front analysis places a cold front from S-Netherlands to roughly 100km E of Paris. It turns into a leisurely Nward sliding warm front, which extend NE towards Hannover. A WAA driven elevated cluster evolved over W-CNTRL Germany into Belgium next to the wavy synoptic-scale frontal boundaries and this cluster continues to track NE into the open warm sector (which features surface Ts in the upper tens at 09Z).

A broad area with lower pressure extends from the North Sea into Belgium with no dominant center yet analyzable. NWP guidance still brings a dominant center into NW Germay until the evening hours. Fuzzy MSLP gradient due to only marginal deepening rate results in limited influence on low-tropospheric wind profile.

Only weak IPV impulses cross(ed) this area with strong synoptic-scale subsidence persisting until the afternoon hours. CI very uncertain given diffuse background dynamics but orography/heating/residual outflow boundaries should serve as foci for isolated to scattered CI during the afternoon.

Current idea is to place a conditional risk for a few supercells in the warm sector, S of the mentioned elevated activity and N of a decaying cluster over S Germany. This would be the S part of the MD area (e.g. CNTRL Germany). Any eastward moving discrete cell poses all kind of (significant) hazards. However we need a lot of diabatic heating for sfc based activity with many models having a bad handling on current BL temperature stratification in this region. Hence confidence in CI is low for now. Nowcast trend of temperature evolution will be monitored.

Further N into NW Germany, forecast becomes very messy with bad handling of ongoing elevated cluster in NWP guidance but anticipated weakening/break-up of precipitaion/cloudiness around noon onwards could support at least temporal insolation/diabatic heating. Either emerging out of this cluster or with new development along the warm front, (semi) discrete cells may evolve within a favorable CAPE/shear space for multicells/isolated supercells. Heavy rain, hail and strong wind gusts will be the main hazard. LL stratification along the warm front should be monitored for an isolated tornado risk of any cell which travels along that boundary.