04-07-2023 22:55 | Estofex | m.b.t. 05-07-2023 t/m 06-07-2023
Storm Forecast
Valid: Wed 05 Jul 2023 06:00 to Thu 06 Jul 2023 06:00 UTC
Issued: Tue 04 Jul 2023 22:55
Forecaster: GROENEMEIJER
A level 3 was issued over the NW Netherlands mainly for severe wind gusts and to a lesser extent for tornadoes and heavy rainfall.
A level 2 was issued across the Netherlands and northwest Germany for severe wind gusts, heavy rainfall and to a lesser extent for tornadoes.
A level 2 was issued for parts of Northeast Spain mainly for large hail.
A level 2 was issued across Czechia, East Germany, and Southwest Poland for all hazards.
A level 1 was issued across extreme northern France, Belgium, a large part of North and Central Germany, Poland, Czechia, and Austria for severe wind gusts and across Czechia, eastern Germany and Poland to a lesser extent for tornadoes and large hail.
A level 1 was issued across the southern Alps and north Italy mainly fo large hail and local heavy rainfall.
A level 1 was issued over East Spain mainly for large hail.
A level 1 was issued across the central and eastern Balkan Peninsula mainly for heavy rainfall, and to a lesser extent for large hail.
SYNOPSIS
An intense mid-level vorticity maximum that has transitioned into a closed circulation across the southern North Sea moves to Southwest Sweden. It is associated with a surface low that rapidly develops in the 00 - 12 UTC timeframe producing widespread extreme wind gusts across the level 2 area. A cold front moves quickly eastward across Germany into Poland and southern Sweden. Further south, moderate westerly flow affects the Alpine region and the central Mediterranean, setting the stage for a few more severe hailstorms as CAPE builds diurnally. Across Spain, mid-level flow is markedly stronger, leading to stronger wind shear. Storm coverage is isolated, but may be scattered to widespread in vicinity of the Pyrenees, where a level 2 appears to be warranted. Across the Central and eastern Balkans, flow is much weaker. Abundant humidity and fairly steep lapse rates suggest a risk of local severe weather there.
DISCUSSION
Benelux, Germany, and surrounding regions...
At 22 UTC Wednesday IR/water vapour satellite imagery is consistent with the consensus of the numerical weather prediction models that calculate the rapid development of a small surface cyclone across the southern North Sea ahead of a strong mid/upper-level vorticity maximum. The models suggest that a line of thunderstorms will move north-eastward along a cold front across northern France into the Benelux and Germany prior to the forecast period. Along this front, the strong background wind field and strong low-level shear suggests that sever wind gusts may occur along with a risk of short-lived tornadoes along it. The front should be near a line from Bremen to Frankfurt am Main around 06 UTC.
Further west, across the southern North Sea and the Netherlands a back-bent/instant occlusion will form with associated sting-jet like wind maxima with local wind gust speeds on the order of 30 - 35 m/s, and locally higher. As the cyclone is filled with surface-based and elevated convective elements with isolated lightning, we will consider all wind gusts to be within scope of this ESTOFEX forecast. We estimate the risk of extreme gusts of more than 32 m/s large enough to warrant a level 3 for the region most at risk.
Within subsequent ICON-D2 model runs some members show intense, rotating, convective cells embedded within the developing back-bent occlusion over the Netherlands during the 4 UTC - 10 UTC time frame, that could create localized very severe wind swaths with gusts over 40 m/s, this scenario not being supported by other convection-allowing models. A risk of such extreme gusts and tornadoes cannot be ruled out though. As the cyclone matures, the severe westerly winds on the southern flank will translate north-eastward across northwestern Germany.
(Alleen de voor NL en direct aangrenzende gebieden relevante tekstdelen zijn overgenomen, klik hier voor de volledige forecast, red.)
Tornado/hoosverschijnsel(en) | Verwachtingen/waarschuwingen | Wateroverlast/(zware) neerslag | Wind/storm (-schade)
