Storm Forecast
Valid: Sun 24 Sep 2023 06:00 to Mon 25 Sep 2023 06:00 UTC
Issued: Sun 24 Sep 2023 06:23
Forecaster: PUCIK
A level 1 was issued across Ireland and parts of England and Scotland for severe wind gusts and tornadoes.
A level 2 was issued across N Greece, Northern Macedonia, S Serbia, W Bulgaria and W Romania mainly for very large hail, damaging wind gusts, tornadoes and heavy rainfall.
A level 1 was issued across Belarus mainly for large hail and severe wind gusts.
DISCUSSION
... Ireland to N England and S Scotland ...
A sharp short-wave trough is forecast to cross the area in the evening to night hours. Strong synoptic-scale lift and drop in the 500 hPa temperature will result in a pocket of steeper mid-tropospheric lapse rates and marginal CAPE. At first, CAPE will be elevated with some embedded showers or weak thunderstorms embedded in the main stratiform rain shield. At and behind the cold front, strongly forced linear segments may form with surface-based CAPE. Strongly sheared environment with 0-1 km bulk shear reaching 15 m/s will yield isolated severe wind gust and tornado threat.
... Greece to Romania ...
As of 05 UTC, surface observations show a large area of dewpoints of 15 to 17 deg C ahead of the cold front. Very steep mid-tropospheric lapse rates, reaching up to 7.5 K/km in 850-500 hPa layer have been advected over Greece, Bulgaria and Romania. Ahead and along the front, high MLCAPE values are forecast, reaching 1500 to 2500 J/kg. At first, high CIN is forecast in the warm sector, but it will erode near the frontal zone towards the afternoon and evening hours. At first expect elevated storms on the cool side of the front with large hail and heavy rainfall threat in substantial MUCAPE values.
Surface-based storms will start form in the afternoon, with the highest coverage between 18 and 00 UTC. By 18 UTC, vertical wind shear will substantially increase over the area, yielding environment conducive for intense supercells and bow-echoes with 0-6/0-3 km bulk shear around 20 m/s. Very large hail and damaging wind gusts are expected with the more intense storms. Hodograph curvature will further increase towards the night over Bulgaria and Romania as the low-level flow increases over the stabilizing boundary layer. Very high SRH is forecast, especially in the 0-3 km layer, with values locally over 300 m2/s2. Before the storms become elevated this is expected to increase the low-level rotation in supercells and also the risk of tornadoes. Storms will continue to the late night hours and even in elevated form will still pose a risk of heavy rainfall and large hail.
... Belarus to W Russia ...
An elevated complex of storms is currently moving over Belarus with a risk of isolated large hail and heavy rainfall. Towards the afternoon, storms may become surface-based, increasing the risk of severe wind gusts as 0-3 km bulk shear reaches 15 m/s.
