Storm Forecast
Valid: Mon 07 Jul 2025 06:00 to Tue 08 Jul 2025 06:00 UTC
Issued: Sun 06 Jul 2025 21:49
Forecaster: PUCIK
A level 2 was issued across N Italy, S Slovenia and W Croatia mainly for severe wind gusts, large hail and heavy rainfall.
A level 2 was issued from NE Hungary through E Slovakia into W Ukraine and E Poland mainly for severe wind gusts and to the lesser degree for large hail and heavy rainfall.
A level 1 was issued across central Italy mainly for heavy rainfall, large hail and severe wind gusts.
A level 1 was issued E Slovenia and SE Austria mainly for heavy rainfall.
A level 1 was issued from E Croatia through S Hungary into Romania and W Ukraine mainly for severe wind gusts and large hail.
A level 1 was issued from Belarus into E Lithuania and Latvia and NW Russia mainly for severe wind gusts.
A level 1 was issued across central-north Russia mainly for severe wind gusts and large hail.
DISCUSSION
... N Italy ...
Two rounds of storms are anticipated over the area. The first round is forecast in the morning hours in the eastern half of the highlighted area with elevated storms capable of heavy rainfall and isolated instances of large hail. Weakening trend in the storms is forecast towards the noon with some clearing as dry air in the mid-troposphere arrives after the first short-wave trough. Compared to Sunday, modest mid-tropospheric lapse rates are forecast and also less low-level moisture with MLCAPE values rising to mostly 1000 to 1500 J/kg.
A quite complicated scenario unfolds further. Pressure is forecast to fall ahead of rapidly approaching short-wave trough. Some models depict drying with downslope winds behind the Apennines reaching almost the whole NW Italy, while in others the dryline stays close to the mountains. Moisture advection from the Adriatic Sea thanks to the easterly flow may raise the CAPE values to around 2000 J/kg, overlapping with 20 - 30 m/s of 0-6 km bulk shear. Majority of the shear will be confined to the layer of 3-6 km or even higher up and will be unidirectional. Coverage of storms will rapidly increase after 18 UTC as storms spread E and SE wards. Mix of linear segments and supercells is likely with threats of severe wind gusts and large hail. Very large hail will be possible with the more intense supercells near the Adriatic Sea. Storms will continue into the night as the short-wave passes the region.
... Central Italy ...
Models suggest a continuation of overnight thunderstorm activity into the morning hours with forecast profiles supportive of isolated severe weather given decent CAPE and vertical wind shear conducive to supercells. Another round of storms is possible in the second half of the night towards Tuesday morning, but is more questionable than the storms of the previous night, especially given the dry layer present in the mid-troposphere.
... S Slovenia to W Croatia ...
Same as over Italy, two rounds of storms are expected. The morning storms will be capable of heavy rainfall with hail and wind/tornado risk increasing south towards Croatia, where stronger vertical wind shear and higher CAPE is forecast. Storm activity will clear from west in the late morning hours with a pause in the activity in the afternoon hours. As the short-wave trough approaches from Italy, supercells and linear segments will progress across the Adriatic Sea towards the region supported by substantial CAPE over the sea and shear conducive to well-organised storms as 0-3 km bulk shear reaches around 20 m/s. Coverage of storms will begin to increase after 18 UTC in Slovenia and after 21 UTC in Croatia. Heavy rainfall, large hail and severe wind gusts are all possible with wind gust and hail risk increasing further south with increasing CAPE and low-level shear. Tornadoes are not completely ruled out, but rather stable low-levels are simulated in all models in the night hours when low-level shear reaches higher values. Expect the storms to continue into Tuesday morning hours.
... Hungary through Slovakia into Poland, Ukraine and Romania ...
Along and ahead of a cold front, modest mid-tropospheric lapse rates will combine with the near-surface humidity of around 12 g/kg, yielding MLCAPE values of 1000 to 2000 J/kg. The highest CAPE is forecast right along the boundary with CAPE decreasing both towards the colder air to the west, but also to the east towards the drier airmass, characterised by deep boundary layer. Storms will enter the area from Croatia and Slovenia in the morning hours, first crossing Hungary and then ejecting towards Slovakia and Poland with additional storms forming along the front. 0-3 km shear values of 15 to 20 m/s parallel to the front suggest rapid upscale growth with one or two bow echoes likely within the Lvl 2. Severe wind gusts will be the dominant threat, followed by heavy rainfall in the western flank of the area. Large hail will be possible earlier on before the storms grow upscale and in case some storms maintain supercell mode for some time before being overrun by the boundary surging east.
More isolated storm development is forecast within the warm sector over Ukraine and Romania, especially near the Carpathians. Forecast profiles suggest deep boundary layer combined with 0-3 km bulk shear of around 15 m/s. Expect primarily severe wind gusts and some isolated instances of large hail with stronger updrafts.
... Eastern Baltics, Western Russia, Northern Belarus ...
A highly questionable forecast across the area, where deepening low-pressure system passes from Poland to Estonia. Strengthening low-level flow is forecast within the warm sector, yielding strongly curved hodographs with substantial low and deep layer shear. While wind profile would favour intense, well-organised storms, both degree of CAPE and initiation is questionable. Current thinking is that at least isolated high based storms will form within the warm sector and will be capable of severe wind gusts. While not very likely, a scenario ending with a tornadic supercells may ensue if a decent CAPE profile forms. This should be put into consideration when forecasters track the evolution of the low-level moisture.
... central - North Russia ...
Scattered to widespread storms are forecast in an environment of MLCAPE of around 1000 J/kg and 0-6 km bulk shear between 15 and 20 m/s. A mix of linear segments and supercells is forecast with both severe wind gusts and large hail possible.
