Severe storms expected across Spain, the Alps, Czech, Poland, Belarus and Russia



  • photo:ESTOFEX;desc: Storm Forecast valid Tue 20 Aug 2019 06:00 - Wed 21 Aug 2019 06:00 UTC.;

    Valid: Tue 20 Aug 2019 06:00 to Wed 21 Aug 2019 06:00 UTC
    Issued: Mon 19 Aug 2019 21:25
    Forecaster: DAFIS

    • A level 2 was issued for N Italy, Austria, Slovenia, Czech Republic and Poland for severe convective wind gusts, large hail, and excessive precipitation.
    • A level 2 was issued for parts of Belarus, and W Russia mainly for large hail, severe wind gusts, and tornadoes.
    • A level 2 was issued for Turkey for large hail, severe wind gusts, excessive rainfall, and tornadoes.
    • A level 2 was issued for E Spain mainly for severe wind gusts and large hail.
    • A level 1 was issued for N Italy, SE Switzerland, Austria, Slovenia, Czech Republic, Slovakia, Poland, NW Ukraine Belarus, and W Russiaf or severe convective wind gusts, large hail, and excessive precipitation.
    • A level 1 was issued for Turkey, SE Ukraine, and Georgia mainly for excessive rainfall, large hail, and tornadoes.
    • A level 1 was issued for Spain mainly for severe convective wind gusts.

    Synopsis

    A broad trough with several embedded short-wave troughs covers a large part of the continent. A major impulse with an axis currently extending from the UK towards Spain is moving fast east and is about to result in the development of a strong jet-streak over Central Europe. Steep lapse-rates and rich low-level moisture will feed some strong thunderstorms, not only in Central Europe but also in the eastern parts of Europe.

    A cut-off low over Turkey will also result in widespread storm activity and locally enhanced thermodynamic parameters will lead to severe weather events on Tue 20/08. Another hot-spot for DMC will be E Spain where abundant moisture from the warm Mediterranean will feed the inland storms.

    Discussion

    Italy, Austria, Slovenia, Czech Republic, and Poland

    As the approaching trough results in widespread synoptic lift over C Europe, the underlying warm and moist, thus unstable, air masses will build several thunderstorms even before the maximum diurnal heat on Tue 20/08. Storms will develop in an environment characterized by 20-30 m/s DLS and 10-15 m/s 0-3km bulk shear, 1000-1500 J/kg MLCAPE with moderate NCAPE values but still, steep low/mid-level lapse rates and supercells are well possible.

    The storms will be able to travel long distances producing severe wind gusts and large hail. During the late afternoon and night some storms are expected in SE Czech Republic under a strongly sheared environment, propagating towards Poland. These storms may produce severe wind gusts and/or excessive precipitation.

    Belarus, and W Russia

    An almost stationary boundary exists over this area under steep lapse-rates that will build 1000-2000 J/kg MLCAPE. Moderate to strong DLS 10-15 m/s (locally more) increase the probability for large hail and severe wind gusts.

    Curved low-level hodographs also show a threat for tornadoes especially in the afternoon when 0-1 km shear is enhanced and shreh0-1km is maximized.

    Turkey, SE Ukraine, and Georgia

    A broad cut-off low over Turkey will create a favorable environment for DMC on Tue 20/08 and Wed 21/08. The low-level moisture advection from the Black Sea and E Mediterranean will provide the necessary fuel for diurnally driven storms. These storms will produce excessive precipitation near the core of the low-pressure system and locally there is an increased threat for large amounts of small hail accumulations.

    On the periphery of the cut-off low, DLS will reach values between 15-20 m/s and storms will be able to produce large hail and severe wind gusts. Near the coasts, tornadoes are well possible given the strong low-level wind shear overlapping with 1000-2000 J/kg MLCAPE.

    Spain

    A secondary short-wave trough will provide synoptic lift to unstable air masses near the coasts of E Spain. Orographic lifting will help to overcome the low-level convective inhibition and storms are expected around noon. Near the coasts PWAT is rather high and thermodynamic parameters such as MLCAPE and DLS suggest that storms will be able to produce large hail and severe wind gusts.

    More to the west of the level-2 area, the entrainment of mid-level dry air may inhibit convection, but if storms form, there is a high threat for severe wind gusts/microbursts.

    The ESTOFEX forecasts are published under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 license



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