Extended Forecast
Valid: Thu 13 Jun 2024 06:00 to Fri 14 Jun 2024 06:00 UTC
Issued: Tue 11 Jun 2024 21:59
Forecaster: TUSCHY
A level 2 was issued across parts of SE Europe mainly for large to very large hail and severe wind gusts (extreme events are possible for both hazards). A few tornado events are also forecast with a significant event not ruled out.
A level 1 surrounds the level 2 for similar hazards but lower probabilities.
A level 1 was issued for W/SW Russia mainly for heavy rain and large hail.
SYNOPSIS
The doiminant longwave trough over N-/W Europe breaks up into a progressive part, which lifts NE into the Baltic States while leaving a lower-amplitude trough behind to the S. This trough gradually moves E into the anomalous strong subtropical ridge, which brings hot conditions to SE Europe. This residual trough weakens while crossing Italy SE.
Another impulse enters the broad complex of low geopotential hights over NW Europe during the forecast. This new energy carves out a new dominant and anomalous intense trough over/S of Ireland.
Convective-wise the wavy frontal boundary over SE Europe and W Russia once again becomes the main focus for organized convection. Numerous smaller-scale depressions evolve along that boundary and serve as foci for enhanced DMC activity.
DISCUSSION
... SE Europe ...
As it is most often the case for a SWODY 2 (severe weather outlook day 2), the details regarding CI and coverage of DMC activity remain a bit diffuse for many areas. The EFI foci from yesterday's outlook remain present and cover most of SE Europe. Hence a broad overlap of strong to extreme DLS with CAPE in the 800-1500 J/kg range exists.
Despite the cyclonic flow aloft, background forcing for most areas begins on the weaker side but increases in general from the W during the forecast period as the low-amplitude trough approaches. Early CI occurs along the orography over Croatia/Bosnia and Herzegovina, Serbia into Romania and Bulgaria although CI becomes a bit more uncertain towards Bulgaria with enhanced capping issues.
Inititaing cells pose a large hail and severe wind gust threat but the risk for destructive hail and swaths of hurricance-forced wind gusts increases during the afternoon hours as storms mature.
Forecast hodographs within the level 2 area are long and rather straight with splitting supercells probable. Any deviating cell will ingest more streamwise inflow and could mature into long-tracked supercells with extreme events possible. Right now with still an active SWODY 1 ahead, it does not make any sense to highlight any corridors with maximized severe but Serbia into Romania and maybe S into N-Bulgaria seem to be the main risk area for mature supercell activity. Weak background forcing also increases chances for more discrete thunderstorm activity. Despite rather high LCLs, we do not want to rule out an isolated strong tornado event with intense/mature mesocyclones.
A risk of numerous tornadic supercells with intense tornadoes possible extends from E Bosnia and Herzegovina into Serbia, where LCLs remain lower and discrete/intense supercells move E (next to very large hail and severe wind gusts). An upgrade for parts of the level 2 is possible.
... Italy ...
Numerous multicells and a few supercells are possible next to the Adriatic Sea, where ICON f.ex. indicates an overlap of 2 kJ/kg MUCAPE and 30 m/s DLS with fat/tall CAPE profiles, whereas EZ remains more reluctant. Any deviating cell would take a path more parallel to the coast with large hail, severe gusts and a tornado risk forecast. Further N, DLS decreases with an increasing heavy rain threat.
... Russia ...
Ongoing heavy rain event with embedded convection sparked this broad level 1 area. In addition, more isolated CI further S will be also accompanied by large hail due to high CAPE values.
