29-05-2017 | Estofex | m.b.t. 29-05-2017 t/m 30-05-2017
A level 1 and level 2 were issued for parts of England, BeNeLux, parts of France and N Spain mainly for large hail, severe wind gusts and to a lesser extent for excessive precipitation.
Storm Forecast
Valid: Mon 29 May 2017 07:00 to Tue 30 May 2017 06:00 UTC
Issued: Mon 29 May 2017 07:00
Forecaster: PISTOTNIK
A level 1 and level 2 were issued for parts of England, BeNeLux, parts of France and N Spain mainly for large hail, severe wind gusts and to a lesse extent for excessive precipitation.
SYNOPSIS
A subtropical ridge stretches from Algeria towards central Europe. It is flanked by two weak long-wave troughs over eastern Europe (with a cut-off low over Greece and Turkey) and from Ireland to Spain, yielding an ill-defined, stationary omega pattern. To its north, a strong zonal flow is in place from N Scandinavia into NW Russia, where a surface cyclone intensifies at the southern rim of a body of arctic air.
A long, wavy frontal boundary from NW Russia across Belarus, Poland, Germany and France into Spain is the main focus for possible thunderstorm development. Further south, warm to hot and mostly dry conditions prevail.
DISCUSSION
... England across BeNeLux and France into N Spain ...
The tail of the frontal boundary fans out over western Europe. Vertical wind shear increases again ahead of the next long-wave trough (rising from 10 to 20 m/s across the lowest 3 km from S to N). The plume of the richest low-level moisture is advected into N France and Belgium, where 2m dewpoints slightly above 20°C may even support CAPE up to 3000 J/kg. Otherwise, CAPE is expected mostly on the order of 500 to 1000 J/kg and its overlap with the increasing shear regime appears quite solid.
Scattered storms will initiate when diurnal heating manages to erode and break the cap, or aided by sea breeze fronts or outflow boundaries. They will organize into multi- and supercells with a primary risk of large hail, severe downbursts and excessive precipitation. Low-level shear is not particularly enhanced, but a tornado is not ruled out in case of favorable interaction of outflow boundaries with the sea breeze front or with each other.
Upscale growth into an MCS may occur and excessive precipitation may become another hazard at this later stage in the evening. The timing and placement of such a cluster are still uncertain, but the level 2 area with the most plentiful low-level moisture appears to be at the highest risk. It could continue into the night and may travel into the Netherlands and westernmost Germany with an ongoing, slowly decreasing severe weather threat.
(alleen de voor NL en direct aangrenzende gebieden relevante tekstdelen overgenomen, klik hier voor de volledige forecast, red.)
Hagel(-schade) | Onweer/blikseminslag | Verwachtingen/waarschuwingen | Wateroverlast/(zware) neerslag | Wind/storm (-schade)