Valid: Wed 10 Dec 2014 06:00 to Thu 11 Dec 2014 06:00 UTC
Issued: Tue 09 Dec 2014 21:11
A level 1 was issued for N Ireland and W Scotland mainly for severe wind gusts.
SYNOPSIS and DISCUSSION
Satellite loops reveal a deep cyclonic vortex centered just south of Iceland as of Tuesday 20 UTC. Center of the low will shift towards the Norwegian Sea with steep pressure gradient to the south inducing very strong low-level flow. 850 hPa winds will reach 25 - 40 m/s and the strongest windgusts will impact especially western Scotland, locally exceeding 33 m/s. Steep lapse rates of the polar airmass will likely contribute to the marginal destabilisation with CAPE values 100 - 200 J/kg possible. Lack of concentrated mid to upper tropospheric forcing now precludes a scenario with strongly forced QLCS. However convection and associated downdrafts may enhance the wind gusts during the passage of showers or weakly electrified thunderstorms. Thus, a Lvl 1 is introduced.
Another region with DMC will be the southern Mediterranean, especially just off the Tunisia coastline, towards southern Greece. Marginally unstable airmass will be located south of the warm front. Lack of steep lapse rates and strong vertical wind shear will preclude any significant severe weather risk.