08-07-2023 22:45 | Estofex | m.b.t. 09-07-2023 t/m 10-07-2023
Storm Forecast
Valid: Sun 09 Jul 2023 06:00 to Mon 10 Jul 2023 06:00 UTC
Issued: Sat 08 Jul 2023 22:45
Forecaster: GROENEMEIJER
A level 2 was issued across the eastern Benelux and Northwest Germany for severe wind gusts, large hail, and excessive rainfall.
A level 1 was issued across an area surrounding the level 2 including a large portion of France, Germany, and northern Switzerland for severe wind gusts, large hail, and excessive rainfall.
SYNOPSIS
A cyclonically curved jet is gradually approaching western Europe from the west. Forcing for upward motion is expected to trigger storms in a moderately sheared environment in which substantial surface-based instability should build during the day setting the stage for severe storms.
Near the top of a ridge in the flow around a Saharan elevated mixed layer, isolated hailstorms may form over the Alps.
A deep slow-moving mid-level trough is located over the Black Sea and is associated with plentiful precipitation and thunderstorms in the region, especially near the low-level low and where low-level flow is upslope.
Downstream of it, across parts of Russia, a stagnant warm front is associated with fairly strong low-level shear and slow-moving and training storms potentially leading to flash floods and possibly one or two tornadoes.
DISCUSSION
France, Benelux, Germany, Switzerland...
Model guidance suggests that an elongated zone of convergent winds, related to a cold front, will stretch from the northern Netherlands to southwestern France. Substantial MLCAPE on the order of 1500-2000 J/kg will build in response to the diurnal heating of the most low-level air mass near this boundary. There, approximately 20 m/s of deep-layer shear will be present, suggesting that storms will be well-organized.
In particular, across the level 2 area, quite high storm coverage is simulated. The severe risk will be large (2-5 cm) hail with any more isolated storms, but most convection-allowing models do simulate a quick transition into a linear mode, which would elevate the wind risk. These models suggest the highest risk of wind gusts will develop in case a bow echo propagating north-northeastward along the boundary materializes. However, this does not seem to be the most likely scenario. Regardless of the scenario, scattered severe wind reports are likely, but in case of such a bow echo wind speeds may become extreme and exceed 32 m/s.
Overnight the storms should gradually diminish in intensity and move eastward across Germany and the North Sea into Denmark.
(alleen de voor NL en direct aangrenzende gebieden relevante tekstdelen overgenomen, klik hier voor de volledige forecast, red.)
Hagel(-schade) | Onweer/blikseminslag | Tornado/hoosverschijnsel(en) | Verwachtingen/waarschuwingen | Wateroverlast/(zware) neerslag | Wind/storm (-schade)
