Storm Forecast
Valid: Fri 29 Mar 2024 06:00 to Fri 29 Mar 2024 06:00 UTC
Issued: Thu 28 Mar 2024 23:50
Forecaster: PUCIK/KUZMENKO

A level 1 was issued across S Spain mainly for heavy rainfall and tornadoes.

A level 1 was issued across E and N/NE Spain mainly for severe wind gusts, large hail, tornadoes and heavy rainfall on S Pyrenees.

A level 1 was issued across S and SE France mainly for large hail and severe wind gusts.

A level 1 was issued across Ukraine mainly for severe wind gusts.

DISCUSSION

... S Spain to SE France ...

At the mid to upper troposphere, a sharp short-wave trough is forecast to eject from Spain towards France. In the wake of the trough, a 50+ m/s jet-streak is simulated at 300 hPa level. Close to the surface, a pronounced wavy frontal boundary will stretch across Spain and France, its warm sector spreading further NE towards central Europe. A cold front part of the wave is forecast to cross Spain during the day while remaining quasistationary over France. There, the frontal passage is forecast in the night hours.

Modest low-level moisture combined with around 7K/km mid-tropospheric lapse rates will yield at least several hundreds J/kg of ML- and MUCAPE around and behind the frontal zone. Strong vertical wind shear is forecast across the whole warm sector and frontal zone.

The situation will begin with early morning storms over S Spain. Here, numerous storms will be possible. Low LCLs and deep warm cloud layer may result in isolated heavy rainfall events. Tornadoes may occur as well, given strong low-level shear. The storms will spread further N during the day. The organization will be into supercells or linear segments given 0-6 and 0-3 km shear exceeding 20 and 15 m/s respectively. Linear segments may be more likely given strong linear forcing and mean flow paralleling the front. Large hail is forecast with stronger updrafts and severe wind gusts especially with the linear segments and storms developing further E/NE in the drier environment. Curved hodographs with 0-1 km bulk shear > 10 m/s also point to the tornado threat. This threat may depend on the convective mode (supercells) and the pockets of moister airmass with low LCLs. An isolated heavy rainfall event in the S Pyrenees is possible as well given strong frontal lift and upslope flow.

Across France, storms should stay elevated with no to very sparse initiation signals in the warm sector by the models. Also here, a very strongly sheared environment is forecast. Large hail is quite likely with stronger storms. Besides that, severe wind gusts can occur as well, even though the elevated nature of the storms will limit this threat. The severe weather risk will decrease further NE with decreasing CAPE.

... Ukraine ...

A strong synoptic-scale forcing is forecast in the exit region of a cyclonically curved jet streak wrapped around a fast-moving trough. Associated with it will be a rapidly moving frontal system. Ahead of the cold front, marginally unstable airmass is forecast with high LCLs. Inverted-V profiles, combined with 0-3 km bulk shear locally exceeding 15 m/s suggest a threat of severe wind gusts with linear segments that will form along the front.