Storm Forecast
Valid: Tue 07 Oct 2025 06:00 to Wed 08 Oct 2025 06:00 UTC
Issued: Mon 06 Oct 2025 10:24
Forecaster: TUSCHY
Two level 2 areas were issued across parts of S Turkey mainly for excessive rain.
A level 2 was issued for NE Bulgaria and E Romania mainly for excessive rain.
Two level 1 surround both level 2 for a similar hazard with lowered probabilities. In addition we expect an isolated tornado risk along the coasts.
A level 1 was issued for the N Aegean Sea mainly for an heavy rain and isolated tornado risk.
SYNOPSIS
The deep and anomalous strong upper trough (about to transform into a cut-off) over SE Europe dictates the weather over SE Europe and brings lots of rain. This trough gets framed by ridging to its W and N. Hence the thunderstorm probabilities stay confined to SE Europe.
DISCUSSION
UPDATE from SWODY2 to SWODY1:
The level 2 over E Romania was expanded S to NE Bulgaria to account for lingering and back-building convection before noon. We also expanded the level 2 a bit more inland to highlight the convective-dominant rainfall threat. Confined swaths of 100-250 l/qm in less than 12h are possible and a few significant flash flood events are forecast. Please be aware of the more extensive rainfall risk, driven by persistent isentropic ascent. This risk drives the general flood risk (which extends more inland and into N Bulgaria) but won't be covered with ESTOFEX as we only cover the dominant convective component. The rain/flash flood risk continues beyond 06Z and could become focused next to Constanta.
No major changes for the rest of the outlook so please refer to the previous discussion, attached below.
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... SE Europe ...
Placed beneath the upper low, an active day with thunderstorms is forecast for a broad area.
First the eastbound moving cold front over SW to S Turkey sparks a progressive MCS event, which brings heavy rain, gusty winds, some (small) hail and an isolated tornado risk along the coastal areas. We added confined level 2 areas, where orography forces BL flow to converge for a longer period with EPS/ENS data highlighting these areas with 24h rainfall amounts in excess of 100 l/qm. Excessive rain is forecast along the orography/coasts and flash flooding is possible. The progressive nature of this event however should limit the peak amounts.
Further W, beneath the upper low, slow moving/quasi-stationary convection occurs f.ex. over the N Aegean Sea with heavy rain and a few waterspouts, which equals a level 1.
Atop the Ionain Sea into the Sea of Crete, bands of convection bring bursts of heavy rain and an isolated spout risk. We opted to keep this below a level 1 for now due to the progressive nature of convection.
Romania into far N Bulgaria may see an heavy rain event with 24h totals in the 50-100 l/qm scale over a broad area. This however is not driven by upright convection but more through persistent isentropic ascent with embedded convective elements.
A different story for E Romania, where a strong E-erly flow regime advects an unstable (roughly 500 J/kg MUCAPE) and moist airmass (atop 1-2 K positive SST anomaly) onshore. Coastal convection stays near surface based and we could see a few training/backbuilding clusters over E Romania. Dependant on where these clusters start backbulding, we could see excessive rainfall amounts on a regional scale along the coast with 100-250 l/qm in less than 12h. Right now the ensemble/deterministic forecast pool is rather consistent in showing high amounts with good run-to-run consistency so we already added a level 2 for excessive rain. Flash flooding is possible with one or two significant events not ruled out (with and augmented general flood risk further inland - please refer f.ex. to GLOFAS and your local NMS for that risk).
