Severe storms to be expected across Greece, Turkey, Albania and North Macedonia



  • Valid: Tue 24 Sep 2019 06:00 to Wed 25 Sep 2019 06:00 UTC
    Issued: Mon 23 Sep 2019 21:28
    Forecaster: DAFIS

    • A level 2 was issued for W Greece for excessive precipitation, large hail, severe wind gusts, and tornadoes.
    • A level 2 was issued for SE Greece and W Turkey for excessive precipitation, large hail, severe wind gusts, and tornadoes.
    • A level 1 was issued for Albania, North Macedonia, Greece, and Turkey for excessive precipitation and tornadoes.

    photo:Estofex;desc:Storm Forecast valid Tue 24 Sep 2019 06:00 - Wed 25 Sep 2019 06:00 UTC;

    Synopsis

    As the jet stream enters the Mediterranean, a strong westerly flow has been established in the largest part of South Europe. Abundant low-level moisture and strong synoptic lift due to a short-wave trough which crosses the Balkans will feed numerous storms, potentially severe. In NW Europe a deep cyclone is approaching, bringing moist air masses from the Atlantic. Weak instability is forecast for this part of the continent but a few storms may form.

    Disscusion

    Greece, Turkey, Albania, and North Macedonia

    The approaching trough from NW will provide strong lift to unstable air masses that lie over the Adriatic and the Ionian Seas and later those over the Aegean Sea. High-moisture content near the coasts of W Greece and Albania can potentially lead to high-precipitating storms. NWP models predict MLCAPE values that exceed 2000 - 2500 J/kg, overlapping with 20-25 m/s DLS and 15 m/s 0-3km bulk shear.
    Moreover, low-level veering winds create a few hundreds of low/mid-level helicity, increasing the probability for supercells able to produce all kinds of severe weather. For the west coasts of Greece the main threats until 12z on Tuesday 24/09 will be large hail, severe convective wind gusts, and tornadoes. Curved low-level hodographs, more than 1000 J/g MLCAPE, strong helicity and low cloud bases are indicators for potential tornadogenesis. For the rest parts of W Greece, Albania and North Macedonia, the main threat will be excessive precipitation from training convection.

    Later in the afternoon and night of Tuesday, the severe weather threat will be high in the Aegean Sea. High CIN values over Cyclades will most probably inhibit CI where CAPE is calculated to exceed 2000 J/kg. An unobstructed westerly flow will bring very moist air masses on the shores of SW Turkey as the jet stream is wrapped over Greece. Orographic features will provide strong lift to air masses characterized by more the 15 g/kg mixing ratios and PWAT is calculated to exceed locally 40 mm. Flash floods are expected in the islands of the Aegean Sea and parts of SW Turkey. A few supercells may form, able to produce tornadoes and large hail.
    Finally, a convergence zone in eastern continental Greece during the night of Tuesday and early morning of Wednesday 25/09 will be also hot-spot for excessive convective precipitation.

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