VALID FOR 05-12-2013

Between the large ridge over WSW Europe and deep trough over NNW Europe, an explosive cyclogenesis takes place within the exit region of the powerful mid level jet. It develops north of UK and rapidly translates across the North Sea and Denmark towards Baltics on Thursday.

*** A significant windstorm “Xaver” is forecasted to take place on Thursday, bringing extreme damaging winds across the North sea and surrounding coastal areas of UK, Denmark and NW Germany ***

A HIGH risk has been issued for N UK and Scotland across North Sea into extreme N Netherlands, NW Germany and Denmark with threat for extremely severe and damaging wind gusts. A broad area within the HIGH risk will be exposed to very dangerous weather situation with extreme wind gusts in excess of 130-150 km/h. A powerful sting jet could form within this cyclone, which could enhance the extreme damaging winds potential even more and wind gusts well in excess of 150 km/h could then become quite likely. However, some models are simulating some marginal instability, which mostly stays behind the main frontal boundary crossing the region. So extreme and damaging wind gusts are mostly expected as non-convective in nature. If convection could become deeper, some storms could enhance tornado threat given the very extreme low-level shear and helicity, but this threat seem quite conditional attm.

Surrounding the HIGH risk, a MDT/SLGT risks has been issued with threat for severe winds. A MDT risk has also been extended towards the Baltics and into Norwegian sea where another deep surface cyclone is expected with an intense low/mid level jet streak on its back side.