Storm Forecast
Valid: Mon 02 Sep 2024 06:00 to Tue 03 Sep 2024 06:00 UTC
Issued: Mon 02 Sep 2024 00:11
Forecaster: PUCIK/ADAMOVSKY/BAART DE LA FAILLE
A level 1 was issued across Spain mainly for excessive rainfall and (very) large hail.
A level 1 was issued across Algeria and Tunisia mainly for large hail, severe wind gusts and excessive rainfall.
A level 2 was issued across the Tyrrhenian Sea mainly for (very) large hail and severe wind gusts.
A level 1 was issued across Corsica, Sardegna, Italy, the Alps, W Germany and BENELUX mainly for excessive rainfall and to the lesser extent for large hail.
A (marginal) level 1 was issued across N Estonia and S Finland mainly for severe wind gusts and tornadoes.
A level 1 was issued across Turkey mainly for excessive rainfall and large hail.
A level 1 was issued across S Russia mainly for (very) large hail and excessive rainfall.
DISCUSSION
...Spain...
A thermal low will develop over the central highlands, driving moisture advection from the east, setting up a dryline. At the same time, a frontal boundary will intensify across N and NW of Spain during the day, in conjunction with the heating of the terrain and the approach of a mid-tropospheric trough. Scattered to widespread storms are forecast across much of the area. Multicells will be the dominant convective type with with 0-6 km bulk shear around 15 m/s. Shear will increase towards S along the dryline and towards the evening, increasing the chances for supercell development. Forecast profiles suggest large hail and excessive rainfall as the primary threats. Very large hail is not ruled out with supercells. Coverage of storms will be lesser (isolated) towards the S of the dryline with some CIN present. With increasing strength of WAA along the frontal boundary, storms will persist overnight over N Spain in the elevated form, resulting in several heavy rainfall events.
... N Africa...
Isolated to scattered storms are forecast, initiated by the local orography. High moisture content with MLCAPE values > 1500 J/kg is simulated especially along the coastline with 0-6 km bulk shear between 10 and 15 m/s. A mix of multicells and supercells is forecast with with (very) large hail and excessive precipitation. Highest likelihood of these hazards is forecast across Tunisia. Further west into Algeria, boundary layer is drier, with main threat shifting more toward severe wind gusts.
... Sardegna through Tyrrhenian Sea towards Sicily ...
High CAPE is forecast to overlap with 0-6 km bulk shear between 15 and 20 m/s in the area. CIN and dry mid troposphere will likely prevent the CI before the trough approaches. Most storms are expected overnight with a combination of multicells and supercells and some potential for an upscale growth into an MCS. Main threats will be (very) large hail and severe wind gusts.
... Italy through the Alps into BENELUX ...
Scaterred to widespread storms are forecast to form along the local orography and on a diffuse frontal boundary over the NW part of the area. Given weak shear, disorganised storms are forecast. Main risk will be excessive rainfall and flash flooding from slow moving storms. Stronger cells may be capable of marginally large hail, especially over central Italy and NW Germany, where models show the highest CAPE. Over the Appenine mountains also some severe wind gusts will be possible due to the dryer lower levels.
... Bavaria and SW Czechia ...
These regions were excluded from the LVL 1 due to the limited storm coverage in the model simulations. One reason for this may be the effectof overnight and early morning convection is suggested. Mainly over the Sumava mountains, a few isolated excessive precipitation events are to be expected.
... Turkey, far SE Bulgaria...
A trough is forecast to lift from Turkey towards the Black Sea. Storms are forecas to be ongoing across the area already in the in morning hours on Monday. Further initiation is forecast in the during the day with some pulse storms over the mountains and the coastline. Marginal instability but a very moist profile and almost no storm movement will result in some flash flood events over the area. Towards the most eastern parts of LVL 1 the 0-6 km bulk shear will increase to above 15 m/s so a few supercells are not ruled out with a risk of large hail.
...Russia...
A few storms will initiate over the Caucasus mountains in the afternoon an environment of MLCAPE up to 2000 J/kg and 0-6 km bulk shear around 15 m/s. Main threat will be large hail. Storms will move over lowland. Further initiation is forecast in the late evening to night with elevated storms developing in the WAA regime. These storms will mainly pose heavy rainfall risk.
...Baltics to Finland ...
A tricky forecast to make. Models are in disagreement concerning the degree of CAPE and the coverage of storms along the front retreating towards the W. ICON-EU shows locally a pronounced overlap of CAPE and strong low-level shear/storm-relative helicity, while GFS shows almost no CAPE whatsoever. ECMWF suggests some storms mostly in the elevated form. Decided for a marginal Lvl 1 in the area, where there is the highest potential for storms to utilise strong low-level shear with marginal risks of severe wind gusts, tornadoes and excessive rainfall.
