09-08-2018 00:33 | Estofex | m.b.t. 09-08-2018 t/m 10-08-2018
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Storm Forecast
Valid: Thu 09 Aug 2018 06:00 to Fri 10 Aug 2018 06:00 UTC
Issued: Thu 09 Aug 2018 00:33
Forecaster: GATZEN
A level 2 was issued across eastern France, Benelux, and north-west Germany mainly for severe wind gusts, excessive rain, and to a lesser extent tornadoes and large hail.
A level 2 was issued across Finland mainly for severe wind gusts and tornadoes.
A level 1 was issued across north-eastern Spain, southern France, northern Italy, eastern Germany and north-western Poland mainly for large hail, severe wind gusts, and excessive precipiation.
A level 1 was issued across northern Algeria mainly for large hail and severe wind gusts.
DISCUSSION
SYNOPSIS
Between a west-European trough and the amplified east-European ridge, a strong south-westerly flow extends from the Iberian Peninsula to the North Sea and Scandinavia. An intense vort-maximum rotates around the base of this trough and crosses northern France, the Benelux countries, and southern Scandinavia as a negatively tilted short-wave trough. At lower levels, relatively strong cyclogenesis is expected by latest models, with a cold front moving eastwards across France and a warm-sector with backing low-level winds farther east. A broad area with CAPE develops from the west Mediterranean to northern Finland and will be the focus of severe weather on Thursday.
DISCUSSION
North-eastern France, Benelux, north-western and northern Germany
Ahead of the approaching negatively tilted trough, a deepening surface low is expected to move from northern France to Denmark during the period. Backing surface winds to the north of this low cause moisture return into western Germany during the morning and noon. Additionally, strengthening southerly winds in the warm sector east of the low will cause steep lapse rates to spread northward from the Alpine region into Germany. With some diurnal heating, 1000 J/kg MLCAPE may be possible over western and central Germany. Farther west, both moisture return and lapse rate increase are a bit questionable. Latest models suggest that convective storms and stratiform rain will spread northward across the Benelux countries in the morning hours, limiting the chance of SBCAPE. Nonetheless, severe thunderstorms are not ruled out capable of producing severe wind gusts, excessive precipitation, and maybe a tornado. If backed surface winds can form in the afternoon hours and SBCAPE evolves far to the west across western Germany into the Benelux countries and north-eastern France, long and favourably curved hodographs will be supportive for well-organized storms including supercells. Severe wind gusts and tornadoes will be possible if this scenario comes true.
Strong or severe winds in the wake of the developing cyclone may occur but are not included in the threat levels since convective storms will be absent.
Farther east, partly linear organized clusters of storms are forecast that quickly spread north and north-east. Although deep layer vertical wind shear is below 20 m/s, supercells are not excluded that pose a threat of severe wind gusts, large hail, and tornadoes. Over northern Germany, clusters of storms may produce excessive precipitation. With strong low-level vertical wind shear, tornadoes are also possible with embedded supercells.
(alleen de voor NL relevante tekstdelen zijn overgenomen, klik hier voor de volledige forecasts, red.)
Verwachtingen/waarschuwingen
