Storm Forecast
Valid: Tue 24 Oct 2023 06:00 to Wed 25 Oct 2023 06:00 UTC
Issued: Mon 23 Oct 2023 22:16
Forecaster: PUCIK/KUZMENKO
A level 2 was issued across W and central Italy mainly for severe wind gusts, tornadoes, large hail and heavy rainfall.
A level 2 was issued across NE Italy, W Slovenia and Istria mainly for heavy rainfall.
A level 2 was issued across Croatia mainly for severe wind gusts, heavy rainfall and tornadoes.
A marginal level 1 was issued across NW Spain and N Portugal mainly for heavy rainfall.
A marginal level 1 was issued across SW France mainly for severe wind gusts and tornadoes.
A level 1 was issued across SE France mainly for heavy rainfall and to the lesser degree for tornadoes and large hail.
A level 1 was issued across N Italy mainly for heavy rainfall.
A level 1 was issued across W Georgia mainly for heavy rainfall.
A level 1 was issued for Turkey mainly for heavy rainfall, large hail and severe wind gusts.
DISCUSSION
... NW Spain, N Portugal ...
A mix of heavy stratiform and convective rainfall is forecast along a warm front with elevated CAPE already on the cool side of the boundary. As the low-level shear is forecast to decrease substantially behind the warm front once the SBCAPE is present, the threat of severe wind gusts and/or tornadoes seems very marginal at the moment.
... W France ...
A low-end threat of tornadoes and severe wind gusts is forecast to develop along the coastline as a low passes to the N of the area. Marginal CAPE will develop within the core of the short-wave trough. An overlap of strong low-level shear with non-zero SBCAPE is forecast along the coastlines and stronger storms may be capable of severe wind gusts and/or a tornado. The highest threat will exist between 21 and 03 UTC.
... SE France ...
A threat of heavy rainfall is forecast across the area at the nose of a 15 - 20 m/s low-level jet and at least 500 J/kg of MUCAPE combined with moist profiles. The storms are forecast to be present across the area already in the morning and the threat will quickly decrease throughout the day. As the storms become more isolated in the late morning hours, a more isolated supercell may form in still strongly sheared environment with a threat of marginally large hail.
... Sardegna and Corsica ...
The storms affecting the islands will be initiated by the cold front that will cross the area by 15 UTC. At the same time, a pronounced short-wave trough at the mid to upper troposphere will provide synoptic-scale lift ahead and along the front. Further initiation may occur across the orography of the island themselves. Long and linear hodographs are forecast with up to 25 m/s of 0-3 km shear over Sardegna. With the area of lift travelling quite fast E and strong mean flow in the lower troposphere, severe wind gusts will be the primary threat.
... Italy ...
Numerous storms are forecast to be present across NW Italy in the morning hours with the main threat of heavy rainfall. Storms are forecast to spread further S especially after 12 UTC, coincident with the approach of both the front and the short-wave trough. CAPE will remain rather skinny given the lack of steep-midtropospheric lapse rates. Very strong vertical shear is forecast across central Italy with 0-3 km shear up to 30 m/s and curved hodographs with abundant low-level SRH. Very fast moving storms are forecast in this area with a mix of supercells and bowing segments. Severe wind gusts will be the primary threat, followed by the tornadoes. Large hail may occur as well with supercells. Heavy rainfall will be more likely further N, where slower moving storms are forecast.
... NE Italy, W Slovenia, Croatia, Montenegro ...
A long period of heavy rainfall with numerous rounds of showers/thunderstorms will be possible across NE Italy and Slovenia, starting already in the morning hours. Forecast profiles reveal almost all CAPE confined in the warm part of the cloud, combined with saturated profiles and low-level flow from the gulf towards the mountains. Further S, the storms will become more active in the evening to night hours as the short-wave trough approaches. Similar environment to central Italy is forecast here with very strong shear both in the lower and middle troposphere. Expect fast moving storms posing a risk of severe wind gusts. Tornado and large hail risk will be present especially if more isolated supercells manage to develop. The threat will gradually decrease after 00 UTC as the short-wave passes and a synoptic-scale descent with dry air intrusion will reduce the chances for initiation.
... NE Turkey, Georgia ...
Across Georgia, continuous onshore flow may lead to numerous rounds of showers and thunderstorms with a threat of heavy rainfall. Further S and SW, fatter CAPE profiles are simulated along with deeper boundary layers and higher LCLs. This will result in an increased risk of large hail and severe wind gusts across Turkey compared to Georgia.
