Storm Forecast
Valid: Tue 19 May 2026 06:00 to Wed 20 May 2026 06:00 UTC
Issued: Mon 18 May 2026 14:37
Forecaster: TUSCHY
A level 2 was issued for parts of the Ukraine mainly for large to very large hail and severe to damaging gusts.
A level 1 surrounds the level 2 with similar hazards but lowered probabilities.
A level 1 was issued for SE Finland mainly for large to isolated very large hail and strong to severe gusts.
A level 1 was issued for parts of SW Russia mainly for large hail and gusts.
SYNOPSIS
A filling trough over CNTRL into SE Europe breaks up into a progressive wave, which crosses the Aegean Sea E and numerous lifting waves over NW Europe. A new digging trough over the NE Atlantic and attendant WAA increase thickness over SW Europe with a building ridge, which amplifies into a new blocking feature for the following days. Blocking persists over NW Russia.
The main synoptic-scale boundary of interest is the one, which affects far NW Russia and bends S/SE towards Belarus/Ukraine, spearating an hot and well mixed airmass to the S/E from a more humid and cooler one to the N/W.
DISCUSSION
...Far E Europe and adjacent areas ...
Rising heights/MSLP over W Russia pushes the boundary deeper into the Ukraine whereas a lifting depression over NE Europe causes some eastbound motion over/E of the Baltic States. The inflection point evolves over E-CNTRL Belarus and lifts also N.
Constantly improving mass flux convergence over the CNTRL Ukraine and adjacent areas pushes mixed BL moisture in excess of 10-12 g/kg beneath mid-level lapse rates approaching 8K/km. Resulting MUCAPE resides in the 1000-2000 J/kg range with a confined belt of robust CAPE in the 2000-3000 J/kg range next to the boundary itself.
Shear improves from E to W and initiating cells pose a large to very large hail risk with 5 cm hail reports (and more) anticipated. DCAPE in excess of 1 kJ/kg also indicates a severe downburst threat with mature convection. Betimes, clustering lowers the hightened hail threat a bit but increases swaths of severe gust and heavy rain at the same time. A confined level 2 was added and broadened zonally to reflect some frontal placement issues in model data.
Further N into Belarus, anticyclonic mid/upper flow regime is forecast with only subtle waves passing N. Some models stay very reluctant with CI, whereas others indicating at least some CI. We follow the idea that at least isolated storms evolve in the vicinity of the front itself, where near uncapped conditions exist. 800-1500 J/kg MUCAPE and DLS locally up to 15 m/s are enough for any robust updraft to become organized for a bit with large hail and strong to severe gusts the main hazard. Dry mid-levels and entrainment could lower final updraft strength a bit (lowered ECAPE) but a broad level 1 was still added (once again adjusted E/W to account for NWP uncertainties regarding frontal placement and therefore probably too broad in the end. Nowcast refinement of the frontal placement is needed).
... SW Russia (SW of Volgograd) ...
The mentioned frontal boundary bends E and aligns more zonally with augmented CAPE and shear (1000-1500 J/kg MUCAPE and up to 15 m/s 3/6 km shear). Organized convection with large to isolated very large hail and severe gusts is forecast due to cyclonic flow aloft with passing low-amplitude waves also anticipated.
... S Finland ...
A warm front lifts N during the day, which results in a broadening warm sector beyond noon. Forecast soundings and hodographs of ICON are impressive for this area with 1500 J/kg MUCAPE, 20 m/s DLS, 14 m/s 3 km shear and elongated/curved hodographs. The main caveat will be capping issues, although some areas could see near uncapped conditions around peak heating. Despite anticyclonic flow aloft, a passing/lifting wave over SW Finland could add enough background support for numerous thunderstorms along the zone with maximized mesoscale convergence next to the front itself. Large hail is forecast and even an isolated 5 cm hail event cannot be ruled out if a discrete storm crosses the warm sector. Strong to severe gusts are also forecast. This activity weakens around sunset onwards.
... Lightning areas ...
Elsewhere, shear/CAPE remains too marginal for a severe risk. However, spotty events are still possible like a coastal tornado event along the coasts of Greece/atop the Aegean Sea and SW Turkey but also isolated hail and gusts. NE Germany to far W Poland could see a few small hail/gust events with EL heights up to 6 km and mixed BL conditions but this is also not enough for upgrading right now.
