Storm Forecast
Valid: Wed 17 Jun 2026 06:00 to Thu 18 Jun 2026 06:00 UTC
Issued: Tue 16 Jun 2026 12:36
Forecaster: TUSCHY
A level 2 was issued for parts of N-Algeria mainly for large to very large hail and severe gusts.
A level 1 surrounds the level 2 for similar hazards with lowered probabilities.
A level 1 was issued for N Portugal/NW Spain mainly for heavy to isolated excessive rain and isolated hail/gusts.
A level 1 was issued for parts of Greece into SW Bulgaria mainly for heavy rain and a few hail/gust reports.
A level 1 was issued for E Slovakia/Hungary into NW Romania and W Ukraine mainly for isolated hail and gusts. A low-end tornado risk exists.
A level 1 was issued for parts of Slovenia into far NE Italy mainly for some hail and gust reports.
SYNOPSIS
A blocking anticyclone builds over CNTRL Europe with the most robust part (also in PV field) centered over CNTRL Europe, where elongated integrated vapor transport (IVT) vectors point to effective moist static energy advection into the building anticyclone, also seen by TPW anomalies in excess of 200% to the backhground climatology spreading into NW Europe. In the meantime, the ridge further S is less stable with numerous IPV maxima seen in NWP data (one over Morocco lifting N towards the Iberian Peninsula with another trough moving from the Ionian into the Aegean Sea).
An active upper trough passage is forecast over E Europe with an elongated vorticity lobe breaking apart towards the Black Sea/E Ukraine during the end of the forecast (indicating splitting energy transfer into the wave over SE Europe and also E into the mentioned progressive trough, which moves further into Russia).
CNTRL/S Europe stays avoid of any synoptic-scale front, as the most active ones stay N of the unstable air. Hence not much influence into today's convective setup is forecast from that end. Only a weak cold front, attached to a wave, which crosses N Ukraine east, stalls over E-CNTRL Europe and could become a focus for at least isolated DMC activity.
DISCUSSION
... N-Algeria ...
Despite reluctant thunderstorm activity in most deterministic runs, EPS/ENS data indicate a rather active day along the periphery of the leisurely N-ward lifting wave, which is later analyzed in IPV data over SE Spain.
In addition to the synoptic-scale forcing, backed winds at low/mid-levels (near orthogonal to the Atlas Mountains) increase the general upslope flow component with additional lift.
Scattered CI is forecast with 1500-2000 J/kg MUCAPE S of the orography and even higher peaks along the mountains, as 2m dewpoints in excess of 20C are analyzed along the coasts.
DLS decreases from W to E (20 m/s to 10 m/s) but it remains questionable how effective this shear values will be, as NWP guidance points to capped conditions up to H7. However past events (with similar conditions) showed healthy satellite signatures of updrafts and offered decent report coverage, so not much trust in the vertical T/Td profile of NWP gudiance along the complex orography exists. Hence a level 2 upgrade was performed.
Numerous high-based thunderstorms could bring large to isolated very large hail and severe gusts next to heavy rain, in case they evolve along the coast (within the plume of moist marine air).
... NW Spain and N Portugal ...
Pushed by onshore flow from the 1.5-2K too warm ocean and placed in a weak upper divergent flow regime NW of the mentioned upper low, a diurnal driven CAPE build-up into the 1000-2000 J/kg range is forecast. Placed along the fringes of the NE ward advecting and highly anomalous TPW plume (offshore), deep moist profiles meet weak shear/slow storm motions, so expect strong pulsating updrafts with some hail and gusts but mainly heavy to locally excessive rain.
Numerous strong pulsating updrafts are also forecast along the Pyrenees, but less instability and better entrainment lowered confidence in severe activity below the level 1 threshold.
... Greece to SW Bulgaria ...
A similar setup to the one mentioned above evolves beneath the upper wave over SE Europe. 1-2 kJ/kg MUCAPE and very weak steering support scattered to widespread slow moving/clustering convection with heavy rain, some hail and gust issues. The activity weakens beyond sunset.
... E Hungary to E Slovakia into far W Ukraine and NW Romania ...
Beyond noon and during the passage of the upper trough, a confined corridor along the SW-ward sagging (and later stalling) cold front evolves, where CAPE/shear overlap is adequate for a few better organized thunderstorms. DLS of 15-20 m/s and 0-3 km shear up to 15 m/s with somewhat better LL hodograph curvature are forecast next to the front and a few multicells/isolated supercells could evolve.
The main focus will be initiating convection along the N Hungarian mountains, which shift SE into the E Great Plains of Hungary. Hail and strong gusts will be the main hazard although an isolated torndo event cannot be ruled out with regionally lowered LCLs.
...Far NE Italy into Slovenia ...
A passing wave could spark a few thunderstorms in a supportive CAPE/shear space with point-source forecast soundings over Slovenia highlighting spots with MUCAPE in excess of 1500 J/kg and DSL up to 15 m/s. Drier air at lower/mid-levels could be a reason for reluctant CI in model data but also the late wave's arrival with its timing already well into the afternoon hours including only modest lift (with the strongest energy shifting into Poland/Slovakia).
Nevertheless a few organized updrafts are forecast to move S with some hail and strong to isolated severe gusts.
... Lightning areas ...
Elsewhere, the stage is set for broad areas with thunderstorm activity, however no real focus was seen for more upgrades. Far S Germany could see a few temporal rotating cells admits regionally enhanced shear also by Alpine pumping (an isolated funnel/graupel event). Far NW Russia could see a spotty risk for small hail/heavy rain and gusts along the deformation band with an isolated hail/gust risk further S, but this, too, does not need an upgrade right now.
