Storm Forecast
Valid: Fri 03 Jun 2016 06:00 to Sat 04 Jun 2016 06:00 UTC
Issued: Thu 02 Jun 2016 20:17
Forecaster: TUSCHY
A level 2 was issued for parts of Bulgaria/NE Greece/NW-Turkey mainly for large hail, isolated severe wind gusts and excessive rain.
A level 1 was issued for N-Spain mainly for large hail.
A level 1 was issued from Romania to Benelux mainly for isolated large hail, excessive rain and a severe wind gust or two.
SYNOPSIS
Weak geopotential height gradients prevail over Europe. Longbreathed cyclonic circulation over CNTRL Europe weakens and moves towards Benelux. A stronger mid-level wave exits the Ionian Sea to the east and is accompanied by rather strong mid-level flow of up to 30 m/s at 500 hPa. An intense trough over N-Norway/Sweden rotates east/southeast while weakening a bit.
Regarding surface fronts, the main feature is an occlusion over N-Norway/Sweden which is pegged to the aforementioned trough and moves to the SE. Else no fronts - important for DMC initiation - are predicted.
DISCUSSION
... SE Finland ...
Prefrontal air mass features moderate BL moisture beneath weak mid-level lapse rates. Still enough for 400-800 J/kg MLCAPE. Forcing will be induced by the front and the approaching upper trough. Although the strongest wind field is confined to the post frontal air mass, 15-20 m/s DLS affects the front. However current idea is that a prefrontal convergence zone will serve as focus for CI. This would lessen the overall severe risk and hence no level 1 was issued. In general, strong wind gusts and isolated large hail can be expected with strongest storms. In addition, clustering storms will add an heavy rainfall risk. The activity weakens beyond sunset.
... Bulgaria/NE Greece/NW Turkey ...
Approaching mid-level wave from the west combined with plenty of diabatic heating will induce scattered to widespread thunderstorms. Modest mid-level lapse rates atop adequate BL moisture results in 500-1000 J/kg MLCAPE. DLS of 10-20 m/s (increasing from N to S) points to a risk for organized multicells with a large hail and strong wind gust risk. Given amount of forecast CAPE, a very large hail is possible in the level 2 area. Betimes, thunderstorms grow upscale into numerous clusters with an heavy rainfall risk.
... CNTRL - / E- Europe ...
Another day with widespread CI until sunset and a gradual downswing thereafter. DLS of less than 10 m/s and BL mixing ratios of 9-10 g/kg indicate an enhanced risk for slow moving effective rain producing showers/thunderstorms with a gradual upscale growth into numerous clusters. During initiation, isolated large hail (but mainly large amounts of small hail) and gusty winds are forecast. Betimes the risk transforms into an heavy rainfall risk with numerous flash flood events expected. The highest risk for excessive rain arises from S-Poland to Moldova with peak PPWs and backbuilding tendencies of storms. W-Germany experiences similar PPWs, but slow forward propagating storm vectors should keep probabilities for training storm activity on the lower end side.
Right now, no region with high confidence for extreme rainfall amounts can be detected and hence no level 2 was issued. Mesoscale boundaries and orography probably dictate that risk.
... N-Spain ..
Steep mid-level lapse rates atop rich BL moisture from the Bay of Biscay assist in a narrow tongue of more than 1 kJ/kg MLCAPE. Despite weak shear, strong updrafts may produce a few large hail events. Storms move to the SE with a weakening trend during the night. Locally heavy rain may occur with clustering storms.
