Storm Forecast
Valid: Sat 01 Jun 2019 06:00 to Sun 02 Jun 2019 06:00 UTC
Issued: Fri 31 May 2019 14:28
Forecaster: TUSCHY

A level 1 was issued across S-Bulgaria mainly for large hail.

A level 1 was issued across parts of Moldova and S-Ukraine mainly for large hail and a low-end tornado threat.

SYNOPSIS

On the synoptic-scale not much change to talk about. Progressive flow regime continues over N-Europe with wave-train of small-amplitude troughs racing east. Those waves miss connection to the quasi-stationary upper trough over S-Italy. This trough remains concreted in-between two broad ridges over SW/SE Europe.

Yesterday's wavy front over Moldova/Ukraine into Russia seems to shift a bit to the SE (partially outflow driven by yesterday's activity), but overall not much regional change is forecast.


DISCUSSION

... E/SE-Europe ...

We desist from discussing certain areas due to the diffuse nature of synoptic-scale forcing. Departing mid-level short-wave trough over Romania drifts W and deamplifies, leaving a rather smooth SW-erly flow regime behind, which affects most of Bulgaria, Romania into Moldova.
Similar ingredients to yesterday are forecast with moderate to rich low-tropospheric moisture beneath meager mid-level lapse rates causing MLCAPE to reside in the 500-1000 J/kg range. DLS increases from N to S with peak values around 15 m/s along the border of Bulgaria/Greece.

Romania and Moldova are probably influenced by the overnight convection with residual showers/thunderstorms and lots of cloudiness. Despite a gradual weakening/advection to the N, diabatic heating remains questionable for CI during the afternoon. Latest idea is to see some re-development along outflow boundaries and along the orography until the evening with locally heavy rain the main risk. Can't exlude isolated hail in strongest cells over S/far E Romania, but weak shear precludes a severe risk.

Bulgaria will see better diabatic input and we added a level 1 for S-Bulgaria. A few multicells with large hail are possible.

Another level 1 area was added for the S-Ukraine, where MLCAPE in excess of 1000-1500 J/kg overlaps with marginal DLS values (at or below 10 m/s). However, amount of CAPE in the hail growth zone indicates a risk of large hail with initiating storms. In addition better directional LL shear next to the front may yield a non-zero tornado risk. Overall this is enough for a level 1.
Further east, bad timing of early CI (limited diabatic heating until the early afternoon) and placement beneath the ridge preclude a level 1 for now.

Elsewehere, gusty winds and graupel/isolated hail accompany strongest activity.