Storm Forecast
Valid: Tue 05 May 2026 06:00 to Wed 06 May 2026 06:00 UTC
Issued: Mon 04 May 2026 16:48
Forecaster: TUSCHY
A level 1 was issued for CNTRL/E-Germany mainly for heavy rain. Isolated hail/gusts are possible over E-CNTRL Germany.
A level 1 was issued for SE France into the NW Mediterranean and far NW Italy mainly for some hail, gusts and heavy rain.
A level 1 was issued for NE Poland into NW Belarus for some hail and a strong to severe gust threat.
SYNOPSIS
While strong westerly wave flux persists over Scandinavia, a more blocked and NAO- alike pattern further S offers a quasi-stationary/sheared trough over the Bay of Biscay with another/filling one over far SE Europe. In addition, the trough over SW Europe transitions into another positive tilted trough W of Morocco, with both features creating a broad belt with enhanced W/SW-erlies over parts of SW-into CNTRL Europe.
At the surface, an extensive wavy front extends from NW Russia SW towards N-CNTRL Germany, which is embedded within a structuring low pressure channel at the surface. Passing short-waves atop that boundary induce temporal BL responses with weak/transient MSLP minima. IFS-ENS has such a vortex over E-CNTRL Germany, which then shifts NE betimes.
DISCUSSION
... Germany ...
The airmass S of the mentioned boundary offers meager mid-level lapse rates atop a moist airmass, which offers TPWs a bit above the background climatology. This is also seen in a low-end signal within EFI CAPE for E-CNTRL Germany, where mid-level lapse rates steepen somewhat. So we expect MUCAPE maxima over E-CNTRL Germany into NW Czechia with values in the 500 to locally 900 J/kg range.
Final shear magnitude resides in the 10-15 m/s range, which is borderline strength for anything organized. However, dependant on the final MSLP geometry, we could see a rather helical SR-inflow with enhanced streamwiseness as BL wind field reacts to the potential/weak LL vortex (see IFS-ENS and some deterministic solutions). Main caveat will be slow storm motion but any more deviating cell over E-CNTRL Germany could be prone for some temporal rotation with a low-end tornado risk. Otherwise initiating cells take profit of enhanced MUCAPE with some hail and gust potential. Heavy rain on an isolated scale is also forecast with slow forward speed of convection.
At the same time, widespread CI occurs over SW Germany in response to an arriving short wave from the SW. This mostly sub-severe convection tends to cluster betimes as it shifts into CNTRL Germany with heavy rain the main hazard. This risk expands NE into NE Germany before weakening betimes. The final magnitude of the rainfall amounts depends on the final track/strength of the LL depression, so confined swaths with excessive rain are not ruled out.
Isolated/high-based convection over SE Germany poses some gust and small hail potential.
... SE-France ...
Ahead of the eastbound moving cold front, moisture return is underway with 500-900 J/kg MUCAPE forecast in a 15 m/s DLS environment. Strong to isolated severe thunderstorms are forecast with some hail, gust and heavy rain probabilities.
... NW Mediterranean ...
With the approach of the main lobe of energy from the W, mid-level winds increase to 50 kt or more which boosts DLS into the 20 m/s range. The main limiting factor for widespread organized DMC is a missing EML plume, so MUCAPE around 500 J/kg should assist in organized multicell activity. An isolated supercell however is certainly possible with a gust, hail and heavy rain potential.
We expanded the level 1 towards NW Italy for a localized nocturnal heavy rain risk with back-building convection.
... NE Poland into NW Belarus ...
An E-ward passing short wave intersects the boundary, where enhanced moisture results in MUCAPE up to 600 J/kg. The airmass S of the boundary is well mixed (partially up to 750 hPa), so high-based convection is possible. A confined swath of near effective/uncapped inflow exists, which could support a few multicells/isolated supercells with hail and strong to severe gusts. This activity weakens over NW Belarus until midnight. We opted to expand the level 1 further E, but displaced synoptic-scale forcing from the boundary lowers confidence in adequate thunderstorm coverage. Any cell, which evolves could produce similar hazards (on a local scale) into N-CNTRL Belarus.
... S Romania ...
Placed beneath a weak ridge, CI should stay isolated along the Transylvanian Alps and decays after moving off the orography. Weakly capped 500-1000 J/kg MUCAPE exist and any storm could produce temporal hail/gusts but this risk remains too marginal for any upgrade.
