Storm Forecast
Valid: Wed 09 Aug 2023 06:00 to Thu 10 Aug 2023 06:00 UTC
Issued: Tue 08 Aug 2023 17:38
Forecaster: GROENEMEIJER

A level 1 was issued across the Caucasus region, adjacent southwest Russia, and northeast Türkiye, mostly for large hail and isolated heavy rainfall.

A level 1 was issued across North and Northwest Anatolia primarily for large hail.

SYNOPSIS

An intense northwesterly jet stream initially located from NW of Scotland to central Germany translates southeastward. To its north, a complex low moves slowly northward across Scandinavia. Further downstream, a ridge across eastern Türkiye and the Caucasus region is filled with hot low-level air and steep mid-level lapse rates. Isolated to scattered storms in this region will have strong updrafts capable of producing large or even very large hail. Elsewhere, any convective storms will mostly be sub-severe.

DISCUSSION

Caucasus, adjacent southwest Russia, and Northeast Türkiye...

Steep mid-level lapse rates are forecast in this region, which should promote updraft steeps in the hail growth zone with any storms that form. Given adequate deep-layer shear (0-6 km bulk shear of 15-20 m/s) a few supercells with large hail may develop. However, the initiation of storms will be quite isolated across large parts of the level 1 since the level of free convection is relatively high and some convective inhibition will likely remain present in many places. The most likely locations of convective initiation are the slopes of the Caucasus range and the Black Sea coast.

Northern Anatolia...

As further east, isolated to scattered storms are expected to form across the western level 1 as well. Rather steep mid-level lapse rates and adequate 15-20 m/s of 0-6 km bulk shear will allow for a few supercells here as well. The main risk of these storms should be large hail here as well.

SE Germany, Czechia, Austria, W Slovakia, Hungary, Slovenia, Croatia, and NE Italy...

This area will be affected by the left exit region of the mid/upper-level jet, and some instability will develop in response to the storm lifting. The depth of convection appears to be limited to around 5 km and the amount of CAPE on the order of 500 J/kg. This limits the severe threat to an extent that a level 1 does not seem warranted, also because only little storm-relative helicity is forecast.