20-06-2023 00:51 | Estofex | m.b.t. 20-06-2023 t/m 21-06-2023
Storm Forecast
Valid: Tue 20 Jun 2023 06:00 to Wed 21 Jun 2023 06:00 UTC
Issued: Mon 19 Jun 2023 22:51
Forecaster: BEYER
A level 2 was issued for NE France and parts of BeNeLux mainly for large hail, severe wind gusts, and heavy precipitation. A tornado cannot be excluded.
SYNOPSIS
A complex synoptic situation on the forward flank of an amplified long wave trough influences large parts of SW, W, and C Europe. Several short-wave features can be anticipated in the prevailing upper-level SW flow.
On significant short-wave trough was responsible for the convective activity over France on Monday. Its remnants are crossing Germany NEward in the morning hours. These remnants and the weakening short-wave trough may influence the development in NE/E Germany and Poland during the afternoon.
Another prominent short wave feature will influence N France, Great Britain, and BeNelux in the second half of the day and the night hours. It is accompanied by an UL wind maximum (UL jet). In lower levels, a cold front can be analyzed that is followed by CAA.
Finally, several short-wave features are forecasted to develop N of the Pyrenees, Massif Central, and Alps. These features are induced by the named mountains (given the SW flow) and previous convection. They are a bit difficult to find in the weather maps but can be anticipated by IPV maxima. However, models differ (not surprisingly) in their positioning and timing.
E and SE Europe are influenced by another long wave trough. On its S flank, two weak UL lows can be found. One is moving from Belarus to Ukraine and another one is active over Turkey, leading to unstable conditions.
DISCUSSION
... NE France and parts of BeNeLux ...
On the forward flank of the approaching shot wave trough CAPE values of 1000 to 1500 J/kg are forecasted to develop over E France and parts of BeNeLux. CAPE can overlap with DLS values of around 15 m/s. During the afternoon hours, storms are forecasted to develop. They may become supercells as supported by ID2 UH tracks and may bring large hail and severe wind gusts.
Later in the outlook period storms are forecasted to organize into a line given the linear forcing (LL convergence along the slowly E ward moving cold front). This reduces the chance for large hail but still, severe wind gusts may play a role when bowing segments will develop.
Another threat is excessive precipitation, especially over NE France where the movement of the storms is rather parallel to the boundary. This may lead to repeated and persistent convection.
Finally, tornados cannot be ruled out during the phase of discrete storms. LCLs are forecasted around 1000 m and LLS will have values around 10 m/s.
During the late evening storms will weaken when the short wave feature is moving off to the N and CAA is flooding the area.
(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
