Severe storms expected across NW Mediterranean, Tunisia and S Italy



  • Valid: Tue 10 Sep 2019 06:00 to Wed 11 Sep 2019 06:00 UTC
    Issued: Tue 10 Sep 2019 00:28
    Forecaster: VAN DER VELDE

    • A level 2 was issued across Balearic Islands, Cataonia and SE France coast mainly for excessive convecctive precipitation, tornadoes, large hail.
    • A level 2 was issued across Sicily, Malta mainly for excessive convective precipitation and large hail.

    photo:Estofex;desc:Storm Forecast valid Tue 10 Sep 2019 06:00 - Wed Sep 2019 06:00 UTC;

    Synopsis

    A vigorous mid level low moves from Bay of Biscay via NE Spain and W Mediterranean Sea, with cold air and vorticity advection aloft meets warm humid low level air with over 1000 J/kg MLCAPE available across the Mediterranean. A shortwave ttrough passes over N Africa and S Italy. Another upper low moves northward over the Baltic Sea and Sweden with slightly unstable air.

    Discussion

    NW Mediterranean

    In the early morning, rhe cold front of the low wraps around the Pyrenees creating a strong convergence zone with trapped warm surface air over central Catalonia and the coast, where storms easily develop. The cold air will push this zone offshore during the afternoon, shifting focus to Mallorca and Menorca. SREH is soaring esoecially in GFS to 400 n2/s2, promoting development of supercells which can cause large hail, tornadoes, high winds and flash floods. A second wave comes to the E Catalonia coast at night when the flow turns easterly, as the low passes to the south. A convergence zone will impinge on the coast with slow storm motion or training storms, creating high precipitation amounts. High low level vorticity can spawn watersputs.

    Tunisia or S Italy

    GFS shows good uncapped parcel availability. CAPE around 2000 J/kg south of Sicily and significant SREH predicted by GFS could support supercells producing large hail and severe wind gustsm perhaps also a tornado. In addition storms may stick to the S coast of Sicily producing large rain amounts and flash floods.

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