Storm Forecast
Valid: Fri 15 Jul 2016 06:00 to Sat 16 Jul 2016 06:00 UTC
Issued: Thu 14 Jul 2016 19:39
Forecaster: TUSCHY
A level 2 was issued for N-CNTRL Italy mainly for excessive rain.
A level 1 surrounds that level 2 mainly for heavy rain and a few waterspouts.
A level 2 was issued for an area from S-Croatia to Serbia to Romania mainly for excessive rain and very large hail.
A level 1 surrounds that level 2 mainly for large hail, excessive rain, isolated tornadoes and waterspouts along the Adriatic coast.
A level 2 was issued for parts of extreme W-Russia mainly for severe/damaging wind gusts.
A level 1 surrounds that level 2 mainly for large hail, severe wind gusts and a few tornadoes.
... SYNOPSIS ...
A pronounced upper trough remains anchored over the CNTRL Mediterranean. During the forecast, a marginal eastbound motion is forecast and the center will cross the S-Adriatic Sea during the overnight hours. Another trough with less amplitude lifts to the northeast from the Baltic States to Finland. Else, weak height gradients prevail.
An extensive front runs from Italy to Romania to the Baltic States before curving east towards Russia. Two low-tropospheric vorticity maxima - one over Italy and another one over the Baltic States - cause strong deformations of that boundary with cold fronts over the Ionian Sea / SW-Belarus/W-Ukraine and warm fronts over Serbia / Romania / N-Belarus. Another warm front approaches NW-Europe from the west, but the air mass at mid-levels remains too warm for deep moist convection.
... Italy ...
Widespread CI is expected all day long, both onshore and offshore as the upper low drifts to the SE. In general, weak background flow keeps DLS on the very weak side with less than 10 m/s. Disorganized multicells are forecast with slow storm motions, so heavy rain and numerous waterspouts (augmented LLCAPE) will be the main hazard.
The main severe risk however evolves along the backside of the SE-ward departing low. This deep vortex causes a long period with nearly orthogonal 20-25 m/s LL flow towards the mountainous/hilly part of N-/CNTRL-Italy. The air mass moistens over the Adriatic Sea and moderate CAPE build-up is forecast (400-800 J/kg MLCAPE). A quasi-stationary east-west aligned MCS will probably point towards N-CNTRL Italy and global models show QPF amounts of 100-250 l/qm/24h. Severe flash flooding is a distinct possibility!
... Parts of Croatia, Montenegro, Albania, Serbia, Macedonia, Bulgaria, Romania and Hungary ...
As the upper low approaches from the west, the left exit region of an intense mid/upper jet overspreads the area of interest and results in substantial upper-level divergence. Widespread thunderstorm development is anticipated all day long. The best overlap of 20-30 m/s DLS, modest BL moisture and somewhat steeper mid-level lapse rates (offering up to 1000 J/kg MLCAPE) exists along the Adriatic Sea, S-Serbia to W-Romania. Multicells/isolated supercells with all kind of hazards are forecast including large to very large hail, severe wind gusts and excessive rain. The large hail risk is also enhanced due to very high 0-3 km helicity values, which increases confidence in rotating updrafts, next to impressive DLS values. The tornado risk may be lowered due to an enhanced low-tropospheric T-Td spread. Betimes, storms grow upscale into a large slow-moving MCS over S-Serbia, W-Bulgaria and W-Romania with a motion to the NW. Global models indicate QPF amounts in excess of 100 l/qm/24h and severe flash flooding is possible. The level 1/2 were enlarged to the NW due to excessive rain. Further west towards S-Croatia, relaxing DLS causes slow moving thundertorms with excessive rain and a few waterspout reports along the coast.
...Far W-Russia and SE-Finland ...
Sharpening warm sector features moderately to weakly capped 500-1000 J/kg MLCAPE. Forecast soundings in this region indicate strong veering with 20 m/s 0-6 and 0-3 km shear, including SRH-1 in excess of 150 m^2/s^2. Well organized multicells and a few supercells are forecast with large hail,
severe wind gusts and a few tornadoes. A level 2 was added, where 0-3 km shear is maximized and swaths of severe / damaging wind gusts will be possible. Further to the NW - over SE-Finland - the closed warm sector / the occlusion feature favorable profiles for elevated convection with an heavy rainfall risk. Hence the level-1 was expanded to that region (inlcuding Estonia).
