Valid: Fri 30 Nov 2018 06:00 to Sat 01 Dec 2018 06:00 UTC
Issued: Thu 29 Nov 2018 17:52
A level 1 is issued for Syria, Iraq and SE Turkey for large hail, severe convective wind gusts and flash floods.
A level 1 is issued for Cyprus and around for flash floods, large hail and (non-supercellular) tornadoes.
Cyclonic activity has strongly increased in the North Atlantic sector and has produced a series of storm cyclones that mature and decay between Iceland, Scotland and Norway. An increasing zonal mid-level flow at their southern flank starts extending onto the continent. An embedded mid-level trough and an occluded frontal system stretch from Scotland to Spain at Fri 06 UTC and proceed into central Europe and the central Mediterranean region. Late in the forecast period, the warm sector of a new frontal wave approaches Ireland and England.
The streamline and temperature pattern further east still features remnants of the latest blocking episode. A cut-off low stretches from the Ukraine to the eastern Mediterranean Sea. Its northern part gradually integrates into the advancing Atlantic jet stream, whereas its southern part moves eastward. A strong surface high retreats from eastern Europe into Russia. A body of extremely cold air over Romania gradually disperses and weakens.
... east Mediterranean, Near East ...
CAPE on the order of 500 J/kg is present in the range of a weak surface cyclone over the east Mediterranean Sea, and will also develop in respose to daytime heating over land. Synoptic lift and a lack of capping will produce scattered to widespread thunderstorms.
Storms in Syria, Iraq and SE Turkey can organize well under 0-3 km shear around 20 m/s ahead of the mid-level trough. Large hail and severe wind gusts are possible, as well as flash floods, the latter especially in later stages when upscale growth is an option. A high-end level 1 is issued to cover those threats. Limiting factor is the rather modest CAPE magnitude and the risk that too much low-level moisture is mixed out.
Vertical wind shear decreases and retreats to higher levels over the east Mediterranean Sea. Cyprus might still experience some slow-moving multicells with a risk of heavy rain, moderately large hail and one or two (probably non-mesocyclonic) waterspouts. Further west, vertical wind shear will decrease to almost zero values, and storms will only affect offshore areas.
Storm activity will gradually decay overnight as the mid-level trough departs to the Near East and surface-based instability over land vanishes.
... west Mediterranean ...
A few hundred J/kg of CAPE will develop under the new mid-level trough. Scattered, low-topped thunderstorms will form and extend east- to southeastward. Isolated heavy rain and waterspouts are not ruled out along the Cote d'Azur, which experiences some hours of convergent and upslope flow. Otherwise, limited CAPE and weak vertical wind shear should preclude severe weather.
... The Channel, Bay of Biscay, coasts of W France ...
In the range of the mid-level trough, widespread showers with gusty winds are expected from the morning to the afternoon, before the trough moves onto the continent. However, neither wind maxima above 25 m/s nor lightning appear likely enough to issue a level 1.