Storm Forecast
Valid: Wed 10 Jun 2026 06:00 to Thu 11 Jun 2026 06:00 UTC
Issued: Tue 09 Jun 2026 16:19
Forecaster: TUSCHY

A level 2 was issued for parts of N Italy into far S Austria and W/CNTRL Slovenia mainly for an augmented tornado threat (a strong event is possible). A very large hail risk exists for the Italian/Slovenian level 2 with otherwise large hail forecast. Severe gusts are expected and confined swaths of damaging gusts not ruled out.

A level 1 surrounds the level 2 with similar hazards but lowered probabilities.

A level 1 was issued for parts of Slovakia east into the far W Ukraine/S Poland mainly for an isolated tornado risk and otherwise for hail, gusts and heavy rain.

A level 1 was issued for NE Algeria into Tunisia mainly for large to very large hail and severe gusts.

A level 1 was issued for S Turkey mainly for large hail and strong to severe gusts.

A level 1 was issued for parts of NW Russia for hail and gusts.


SYNOPSIS

The general pattern features a progressive eastbound moving upper trough over CNTRL Europe with a building ridge upstream into W/NW Europe. Elsewhere, rather broad/diffuse and weak height gradients prevail with scattered to widespread CI probabilities within an extensive plume of 25-35 mm PWAT, which extends from the W/CNTRL Mediterranean NE into Belarus before turning NW towards Scandinavia.
A belt of strong mid/upper level winds accompanies the progressive trough, but the best kinematic environment remains detached from the mentioned unstable airmass for most parts. Hence only a rather confined corridor of organized DMC probabilities exists over parts of S-CNTRL into E-CNTRL Europe.

A progressive and partially occluded cold front shifts NE towards Russia and bends back SW towards N Italy, where it turns quasi-stationary/wavy. IFS-ENS features numerous weak LL vortices along that boundary, but a zonally elongated cloud of individual IFS-ENS members indicates lingering issues in where exactly any vortex could develop. This uncertainty persists for this forecast period.

DISCUSSION

... N Italy to S-Austria ...

A S/SE ward shifting cold front gets (partially) blocked by the Alps, which assists in a plume of moist air over N Italy. This airmass turns unstable during the day, as mid/upper levels cool. This cooling trend is accompanied by a passing upper trough, which affects N Itlay from the late afternoon into the overnight hours as it passes E towards Czechia.

Similar to yesterday, we expect LL mixed mixing ratios in the 10-12 g/kg range with surface dewpoints in the mid to upper tens and up to 20C next to the Adriatic Sea (with SST anomalies up to +2K). Also, yesterday's soundings like Udine and Cameri showed weak capping, a rather moist profile and MUCAPE up to 2500 J/kg around peak heating. Despite some weakening of the mid-level lapse rates, that kind of background should easily support MUCAPE in the 1500-2500 J/kg range for today's setup.

Kinematics are impressive as DLS exceeds 25 m/s, whereas 3km bulk shear intensifies into the 20 m/s range. The main issue with this setup will be a rather parallel alignement of the background shear vector to the SE-ward sagging front. Also, shear vector points into the orography (although with a smaller angle), so clustering will be an issue mainly next to the frontal zone. At the same time however, rather late arrival of the main synoptic forcing could improve the setup for more discrete convection S of the frontal boundary.

Early CI is forecast from N/CNTRL Lombardy into Trention-Alto Adige (TAA) towards S-CNTRL Austria, where repeated and temporarily training convection clusters betimes with heavy rain (40-80 l/qm/12h) and isolated gusts the main risk. An isolated tornado event is certainly possible, especially when some temporal diabatic heating materializes. We expanded lighting and level 1 areas deep into Austria to account for a broad MUCAPE plume expanding N.

From the early afternoon onwards, the main interest for organized DMC activity develops over S Lombardy into S-TAA, Veneto towards Friuli Venezia Giulia. Some lingering issues exist, e.g. if a weak cap at 850 hPa remains present and how BL mass response occurs with any evolving depression.
Despite those issues, NWP guidance like ID2/ICON paints a rather impressive setup for long-tracked supercells with large to very large hail (hail diameter in excess of 5 cm possible), severe gusts (up to 40 kt flow at H7 with mixed subcloud layers) and locally heavy rain.
Another hazard will be an augmented tornado threat. Although initial LCLs start rather high, a decreasing LCL trend is expected towards the evening and in areas, where showers passed by. There is a chance for a strong tornado event and in case the mesoscale setup turns more favorable, even an intense event cannot be ruled out with the main risk area from CNTRL/E Veneto into Friuli Venezia Giulia. It is worth noting, that EPS has its strongest UH tracks more W into the Lombardy, which probably reflects the uncertainty on where any LL vortex evolves with maximized backed BL winds ahead. Nowcast is needed if any mature supercells moves f.ex. along a W-E aligned moisture boundary with rich moisture to the S and more rain-cooled air to the N. This could steer any discrete storm E with an hightened tornado threat.

Further W into the Piedmont area, a similar thermodynamic/kinematic background is present, although 3km shear relaxes somewhat. The deterministic runs are rather reluctant with CI, but EPS data reveals enough members, which support initiation. This is more realistic with the arriving upper trough from the W. All kind of severe is forecast, including large to very large hail, severe gusts and locally heavy rain. A few tornadoes are also possible, but again, LCLs start rather high next to lowered CAPE3 values. Any tornado risk gets dictated on the mesoscale.

Finally, towards Emilia Romagna into far S Veneto, the environment is prime for a few damaging hail/severe wind gust events, but CI could become an issue as main synoptic-scale lift arrives late and during the time-frame, as CIN increases. However some models show a weak passing wave around peak heating, so at least isolated supercells are possible.

A small level 3 upgrade was considered for SE Lombardy into Friuli Venezia Giulia but confidence in any exact hot spot for maximized severe remains too unclear that far out (also in deterministic and EPS fields).

... Slovenia into far S Austria and W Hungary...

The Italian level 2 was expanded into W/CNTRL Slovenia and far S Austria to account for a rather favorable afternoon/evening setup for severe thunderstorms.
First round could be isolated CI along the orogaphy during the afternoon hours in a favorable CAPE/shear environment with augmented STP/SCP. Forecast hodographs show impressive curviness in the lowest 3km with lots of streamwiseness and attendant vorticity. The main issue in NWP guidance is how moist the BL will be (e.g. how strong diurnal mixing lowers that moisture content and if we get some dried downslope winds from the Inner Carniola area, which could cause some capping issues). Overall the guidance and yesterday's synop reports support enough moisture and therefore a lingering risk for a few supercells with all hazards, including a tornado threat and large hail. This was covered with a level 1, which runs into NE Slovenia.

Confidence then inceases for mature and organized thunderstorms, including supercells, to approach W Slovenia in the evening hours from NE-Italy. All hazards are possible including swaths of damaging gusts, large hail and an augmented tornado threat. A strong event is not ruled out.

That late afternoon/evening tornado risk is also valid for Carinthia (S-Austria), where less CAPE meets very low LCLs (possible some prefrontal showers) and very strong shear, including impressive LL hodograph signatures. Hence the level 2 was nudged N into this area despite lingering uncertainties, how discrete convection will be as it arrives. In fact, any more robust cluster passing just S of Austria could keep the overall severe risk on the low-end side: a possibility, which has not much support in EPS data yet and hence was excluded for now.

The Austrian/Slovenian convection probably grows upscale into a progressive cluster during the evening into the overnight hours. Decreasing CAPE towards Hungary raises the question on how severe/organized this activity will be, especially if we get the cooling N-erly surface winds of the frontal passage way ahead of the cluster. However, nowcasting is needed as less capping could increase the severe gust risk with a mature MCS event (e.g. with a more elevated RIJ event). A level 1 was issued for this risk with all the uncertainties.

... Dinaric Alps ...

Beneath weak mid-level height gradients, a broad swath with MUCAPE in the 1000-2000 J/kg range overlaps with weak shear. Strong to isolated severe pulsating thunderstorms are forecast with some hail, heavy rain and gust issues. Automatic guidance placed rather aggressive probabilities for large hail over E Croatia, but CI remains questionable. Any thunderstorm there would take profit of strengthening shear and MUCAPE up to 2000 J/kg. With a clear minimum in EPS data (even in maximum fields), we kept this area free of a level 1 for now. Same for the pulsating convection elsewhere with isolated severe not ruled out.

... CNTRL/E-Slovakia into far S Poland and far W Ukraine ...

A cyclonic and diffluent upper flow regime affects the area, although not much synoptic-scale forcing is forecast to affect the area of interest. The main concern for CI will be a diffuse vortex spin-up along the wavy boundary with a confined area offering a favorable CAPE/shear space for organized multicells/isolated supercells. Shear is more borderline, but any near surface based cell could acquire some organization with large hail and strong gusts the main issue. An isolated tornado event is not ruled out in case a cell rides the near uncapped boundary along the warm side.

During the night, this convection grows upscale, as the structuring depression lifts NE. This is more a rain/spotty gust risk as CAPE turns elevated during the night.

... Atlas Mountains ...

A belt of brisk westerlies affects the area, so modest DLS up to 15 m/s meets 1500-3000 J/kg MUCAPE along the orography. Despite anticyclonic flow aloft, weak passing waves pose a temporal risk for CI with large to very large hail and damaging downbursts possible. A high-end level 1 was added to cover that threat.

... S Turkey ...

Numerous high-based thunderstorms occur along the coastal orography with hail and strong gusts the main hazard. Isolated severe is possible and a small level area was added.

... NW Russia ...

A confined level 1 was added for a few hail/gust producing multicells.