Storm Forecast
Valid: Fri 23 Dec 2016 06:00 to Sat 24 Dec 2016 06:00 UTC
Issued: Thu 22 Dec 2016 14:54
Forecaster: TUSCHY

A level 1 was issued for parts of Ireland and UK for severe wind gusts.

A level 1 was issued for parts of NW Scotland for severe wind gusts.

SYNOPSIS and DISCUSSION

Progressive wave train affects N-Europe, as numerous strong troughs move east. Ridging to the south builds into SW and CNTRL Europe and keeps the weather rather calm convective-wise. A quasi-stationary cut-off over SE-Europe brings unsettled conditions to the Aegean Sea and Turkey.

This pattern results in scattered showers with a few thunderstorms over the SW and S Mediterranean. Thunderstorm probabilities increase towards the east (Aegean Sea and E-Mediterranean) with MLCAPE rising to 500 J/kg . Weak shear precludes organized convection and nothing severe is forecast - excluding a marginal waterspout risk beneath stronger convection W/S of Turkey.

An intense extratopical cyclone between Iceland and Scotland features a pronounced warm seclusion with intense LL winds along a back-bent occlusion grazing far NW Scotland during the forecast. Negative LIs in 700 hPa to the south of the occlusion with 30-35 m/s LL winds point to an enhanced severe wind gust potential with maritime convection and a level 1 was issued.

This depression pushes a cold front over Ireland before noon and over UK until 18 UTC. A narrow cold-frontal rainband (NCFR) may evolve with swaths of enhanced wind gusts (850 hPa flow in excess of 25 m/s). This activity remains too shallow and probably non-electrified. Hence no lightning area was issued. However, some higher resolved models indicate a time-frame, where NCFR-structure could be organized enough for a more organized severe wind gust threat. For this area, a level 1 was issued.

Thunderstorm probabilities increase west of CNTRL Norway beyond 00 UTC. 25 m/s near boundary layer flow points to strong/ isolated severe wind gusts with stronger convection.