Storm Forecast
Valid: Fri 31 May 2024 06:00 to Sat 01 Jun 2024 06:00 UTC
Issued: Thu 30 May 2024 22:26
Forecaster: PUCIK
A level 1 was issued across E Spain mainly for severe wind gusts and large hail.
A level 2 was issued across N Croatia mainly for heavy rainfall, large hail, severe wind gusts and tornadoes near the coastlines.
A level 1 was issued across N Italy mainly for heavy rainfall (especially the Alpine area), large hail and to the lesser degree for tornadoes near the coastlines.
A level 1 was issued across Hungary, Slovakia and E/Central Czechia mainly for heavy rainfall, marginally large hail and to the lesser degree for tornadoes.
A level 1 was issued across W Czechia, E Germany and W/N Poland mainly for heavy rainfall.
A level 1 was issued across S Sweden and Denmark mainly for heavy rainfall and to the lesser degree for large hail.
A level 1 was issued across Finland mainly for large hail, severe wind gusts and heavy rainfall.
A level 1 was issued from the Baltics towards Ukraine mainly for large hail, heavy rainfall and severe wind gusts.
A level 2 was issued across the Caucasus area mainly for large to very large hail, heavy rainfall and damaging wind gusts.
A level 1 was issued across Turkey mainly for heavy rainfall and large hail.
A level 1 was issued across S Russia mainly for large hail and heavy rainfall.
DISCUSSION
... SE Spain ...
Easterly upslope flow from the Mediterranean Sea towards the higher terrain initiated by the heat low over the interior Spain will increase both the CAPE and also the shear over the area. While the LFC will be quite high, convective precip signals in the models weak and there is some disagreement concerning CAPE, at least widely isolated storms are possible. Given the Inverted-V profiles, solid shear and majority of CAPE in the temperature zone below -10 deg C, storms will bear risks of severe wind gusts and large hail.
... Italy to Croatia and Slovenia ...
A deep trough will affect the weather over the area already in the early morning hours. It's expected that a number of storms will exist over N Italy and the N Adriatic coastline with the primary threat being heavy rainfall. Strong low-level shear along the coastline may support a tornado as well. More rounds of storms will follow with another wave expected in the noon to early afternoon hours, starting over the Apennines and spreading through the Adriatic Sea and Istria towards continental Croatia and SW Hungary. With 0-6 km shear around 20 m/s, well-organised storms, including supercells are likely. The second round of storms will bear risks of large hail, severe wind gusts and potentially a tornado. Tornado risk will be again the highest near the E Adriatic coastline. A lvl 2 is issued where the combined risk is the highest. As dry air in the mid-troposphere overspreads the area from the west, the storm activity will subside, starting from early afternoon hours in Italy.
... Hungary, Slovakia, Czechia, E Germany ...
Owing to the deep trough over the Alpine area, cyclogenesis is forecast across SE Germany with a belt of moist airmass wrapped around the low from Hungary, Slovakia through Czechia into Germany. Heavy rainfall event is forecast across E/SE Germany and extreme W Czechia. Forecast profiles reveal that in some areas (designated by Lvl 1), the primary stratiform rainfall can be enhanced by convection. Further east, rainfall will be primarily convective. Forecast profiles show low LCLs, high RH throughout the troposphere and substantial CAPE in the warm part of the cloud. Therefore, storms will be efficient heavy rain producers. Excessive rainfall will thus be the primary risk. Especially across Hungary, CAPE profiles suggest also risk of marginally large hail. Over all countries, some models show curved (albeit short) hodographs with 0-1 km shear around 7 m/s and 0-1 km SRH locally around 100 m2/s2. While the primary convective mode will not be supercells, it's possible that some storms will attain brief low-level rotation and a tornado is not ruled out.
... Denmark, S Sweden, Finland, N Poland through the Baltic countries into Ukraine and Russia...
Large area of N to NE Europe will be under weak synoptic-scale forcing with a weak frontal system between the Baltics and Belarus and over S Sweden. Basically the whole area will involve MLCAPE > 500 J/kg with expansive regions of possible thunderstorm occurrence. Regions with higher likelihood of severe weather are denoted by Lvl 1s. For N Poland, the main risk will be heavy rainfall. Across the Baltics, S Sweden and Poland, the risk of large hail will be present as well, given more substantial CAPE in the cold part of the cloud, plus shear allowing for at least multicellular organisation. The strongest shear is forecast across N Finland. From the Baltics further E or NE, forecast profiles also show Inverted-V shapes, suggestive of potential for isolated downbursts.
... Caucasus area ...
A severe weather outbreak is expected over the region. A short-wave trough is forecast to approach from SW with 15 - 20 m/s of 500 hPa flow on its forward flank. Significant WAA advection regime will yield widespread low-level forcing over the area, increasing towards the west and towards the evening hours. Scattered to widespread storms are forecast with primary initiaton mechanism being the orography, followed by the cold front. Steep lapse rates will be advected over the area, yielding MUCAPE values between 1k and 2.5k J/kg. With deep-layer shear between 15 and 25 m/s, expect well-organised storms, including long-lived supercells. Storms will transition into elevated mode as cooler air near the surface spreads from W behind the cold front.
Current thinking is that the primary threat will be large to very large hail from surface based or elevated supercells. The highest conditional threat of very large hail will be in the E/SE of the designated Lvl 2 area with the highest values of buoyancy in the temperature below -10 deg C. Damaging wind gusts may occur as well especially if storms cluster together, forming linear convective systems. The upscale growth will also eventually increase the chances of heavy rainfall, which will be the highest in the W part of the highlighted Lvl 2 area.
... Turkey ...
A gradient in the degree of vertical wind shear will exist across the designated Lvl 1 area, moving from the core of the trough with weak shear to its forward flank with stronger shear. Within the core, expect heavy rainfall as the primary threat, shifting to large or even isolated very large hail in NE part of Turkey, where the shear should allow for some supercells.
