Severe weather in North Italy and the Balkans



  • Valid: Tue 09 Jul 2019 06:00 to Wed 10 Jul 2019 06:00 UTC
    Issued: Mon 08 Jul 2019 22:45
    Forecaster: DAFIS

    A level 2 was issued for N Italy, France (Corsica), Slovenia, Croatia, Bosnia and Herzegovina, Montenegro, Serbia and Bulgaria mainly for large or very large hail, severe convective wind gusts and tornadoes.

    A level 1 was issued for NE Spain, S France, Italy, S Switzerland, S Austria, Croatia, Bosnia and Herzegovina, Montenegro, Serbia, North Macedonia, Bulgaria, N Albania and N Greece mainly for large hail, severe wind gusts and tornadoes.

    A level 1 was issued for NE Turkey and Georgia mainly for large hail and severe wind gusts.

    A level 1 was issued for parts of Russia for excessive precipitation and severe wind gusts.

    photo:ESTOFEX;desc: Storm Forecast valid Tue 09 2019 06:00 - Wed 10 Jul 2019 06:00 UTC.;

    SYNOPSIS

    A large synoptic vortex is found over the Baltic States and W Russia, and the jet stream in its southern flank over Central Europe is intensifying. The cut-off low over Spain is slowly moving east-northeast and it is weakening fast, but it has created a jet streak which will reach Italy on Tuesday 9 July 2019. Very moist air masses with steep mid-level lapse rates aloft are found in West and Central Mediterranean, as well as in the Balkans, where we expect numerous thunderstorms. Also, far Eastern Europe will experience some thunderstorms, locally producing severe weather.

    DISCUSSION

    N Italy, France(Corsica), Slovenia, Croatia, Bosnia and Herzegovina, Montenegro, Serbia and Bulgaria

    Air masses with very high theta-e values can be found over and around Italy, and West Balkans. Several shortwave troughs will cross North Italy and Central Europe traveling east to the Balkans, providing lift to these unstable air masses. Low-level convergence zones in the Po Valley will trigger convection even before 12z and storms will quickly be able to become supercells. NWP models forecast a highly volatile environment with more than 2000 J/kg MLCAPE and 20-30 m/s DLS. High values of SREH0-3km (150-300 m2/s2) also support the development of supercells able to create very large hailstones and severe wind gusts. The storms should move over the Adriatic Sea during the night of Tuesday and early morning of Wednesday, but they will still pose a threat to the east coast of Italy.

    Over the Balkans, the ongoing DMC in the North Adriatic Sea may produce locally severe weather especially in Croatia and Bosnia and Herzegovina by the morning hours of Tuesday. In the afternoon of Tuesday CAPE is forecast to range between 1000 - 1500 J/kg by both IFS and GFS, and DLS will locally reach 30 m/s. Strong 0-3km bulk shear and curved hodographs also suggest a high potential for supercells in the afternoon with an elevated threat for tornadoes. Storms will be able to travel long distances producing severe weather. During the night of Tuesday, the convection will be elevated but still large hail and severe wind gusts will be possible.

    NE Spain, S France, Italy, S Switzerland, S Austria, Croatia, Bosnia and Herzegovina, Montenegro, Serbia, North Macedonia, Bulgaria, N Albania and N Greece

    In NE Spain and South France, the remnants of the cut-off low will be still able to lift unstable air masses and even though the lapse rates are decreasing, large hail will be still possible given more than 1000 J/kg MLCAPE and 15-25 m/s DLS.

    In Corsica a level 2 area was issued as storms will get the benefit of strong DLS and to organize in big clusters, with some of the storms becoming supercells creating large hail or very large hail and severe wind gusts.

    For S Switzerland, S Austria, Central Italy and E Bulgaria, only a few storms will be able to produce severe weather and the main threat will be severe wind gusts given the high delta-theta-e values in NWP outputs.

    Turkey, Georgia and Russia

    An elongated cold front of the large vortex in Russia is extending from Russia towards N Turkey. On this boundary, plenty of moisture will feed storms that could get the benefit of locally enhanced DLS. Slow-moving storms, especially in Russia, will be able to produce excessive precipitation, while in Turkey and Georgia the main threat will be the severe wind gusts. Convection should be very limited during the night.



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