Mediterrâneo-2012

Tópico em 'Tempo Tropical' iniciado por stormy 2 Set 2012 às 23:08.

  1. stormy

    stormy
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    Super Célula

    Registo:
    7 Ago 2008
    Mensagens:
    5,100
    Local:
    Lisboa-Encarnação // Lagoa de sto André
    Pelos foruns Espanhóis e Franceses tem havido um enorme interesse em seguir a evolução de uma cut-off actualmente situada no Mediterraneo Oriental, pois alguns modelos mesoescalares teem andado a modelar nas ultimas runs um sistema subtropical ou tropical que deverá iniciar a sua genese já nas proximas horas.

    A nivel sinóptico teremos uma linha de convergencia, antiga frente fria, situada agora sobre a Argélia e a Tunisia, que nas proximas horas deverá ser reactivada por um impulso do jet, e assim que houver forçamento sinóptico verticalmente alinhado com os ventos convergentes á superficie, deverá ocorrer uma ciclogenese fraca.

    Durante o dia de amanhã essa baixa pressão deverá mover-se para NE colocando-se sobre as aguas quentes do Mediterraneo ( 26-28ºC), e começará a ganhar organização, sendo que neste trajecto para NE tambem se deverá afastar dos ventos intensos em altura ( shear) que ocorrem no bordo sul da cut-off, associados ao jet subtropical.

    Á medida que a depressão se aproxima do centro da cut-off, nos proximos 2 a 3 dias, deverá crescer a instabilidade termodinamica devido á presença de ar frio nos niveis altos, e assim fortes movimentos convectivos deverão tornar-se pressistentes o suficiente para que a depressão vá adquirindo cada vez mais caracteristicas tropicais e tambem intensidade.

    http://www.cazatormentas.net/foro/s...e-medicane-en-proximas-horas-septiembre-2012/
     
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  2. irpsit

    irpsit
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    Cumulonimbus

    Registo:
    9 Jan 2009
    Mensagens:
    2,057
    Local:
    Entre Mortágua e Tondela
    Muito interessante, e se bem que raro, estas tempestades tropical formam-se de vez em quando no Mediterrâneo.

    È pena é não haver qualquer seguimento oficial da bacia do Mediterrâneo.

    Vamos a ver o que causa, provavelmente ventos e chuva mais intensos na costa sul da França, Itália e Áustria.
     
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  3. ]ToRnAdO[

    ]ToRnAdO[
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    Cumulonimbus

    Registo:
    29 Ago 2006
    Mensagens:
    2,554
    Local:
    Vila Real de Sto António
    A depressões que tenham essas caracteristicas, chamam-se Medicanes, e não são tão raros como se julga.

    Há muito historial sobre este tipo de Tempestades no Mediterraneo que são em tudo semelhantes a um furacão só que em dimensões mais pequenas.
     
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  4. ]ToRnAdO[

    ]ToRnAdO[
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    Cumulonimbus

    Registo:
    29 Ago 2006
    Mensagens:
    2,554
    Local:
    Vila Real de Sto António
    Estofex:

    [​IMG]


    SYNOPSIS

    Isolated from the active westerlies over N-Europe, a cut-off low affects most parts of the W/C Mediterranean with no real net motion to the east. With the progressively more zonal mid/upper level flow over N-Europe, geopotential heights over C-Europe increase and support stable conditions. The same for SE Europe, where hot and dry weather continues.

    Side-note:

    At 19Z (2nd Sept.), a 568 gpdam upper low was situated just to the west of Sardinia, featuring an healthy mid/upper vortex in model data. However, buoy and surface observations show a broad and ill defined surface circulation atop the W/C-Mediterranean, with near surface streamline analysis indicating two well structured convergence zones (one west of Sardinia and the other atop the Tyrrhenian Sea). However, coastal synop data locally and temporarily support the evolution of small scale vortices, which envolve within the broad cyclonic circulation, probably spawned by local orography or regionally enhanced baroclinity (e.g. Tyrrhenian Sea). One of those vortices should evolve east of Corsica during the night hours (until my forecast starts), which however is not easy to verify due to a thick cirrus shield of an active warm conveyor belt (WCB) and missing offshore data. Forecast development however seems plausible due to a favorable placement beneath the left exit of a 50 m/s 300 hpa jet and the deep baroclinic zone nearby.

    During the forecast, the main scenario of interest will be the aforementioned small-scale vortex, which is forecast to loop cyclonically over Corsica and then towards Sardinia until the evening hours along the still existing N-S aligned convergence zone. Again, some models indicate rapid organization /a profound deepening rate of the depression's central pressure, which however will be challenged for the following reasons:

    I) Forward calculated near surface trajectories still indicate ongoing offshore flow from S-France, where BL moisture remains meager (dewpoints in the lower tens). Also, I do not yet trust forecast rich BL moisture from parcels, emerging out of the Adriatic Sea towards the west, as this air has to cross the rough terrain of N-C Italy. In addition, active storm clusters in the inflow fetch may prohibit the advection of the highest moisture content to the west.

    II) Any surface circulation evolves/moves atop the islands, which may inhibit or delay ongoing organization of the surface vortex.

    III) Despite a gradual breakup of the dry mid/high level inflow from the NW and south, it takes some time for the mid-level moisture to wrap around the main vortex. However with the approach of a decaying front from the NW (from France), better moisture may infiltrate into the circulation. Of main concern will be any influx of an EML from the south.

    IV) SSTs remain the coolest for the W-Mediterranean basin with readings in the lower twenties and a pretty shallow depth of the warm (near) surface layer.

    Nevertheless, the convergence zone and the movment into a weakly sheared environment (with DLS decreasing to less than 10 m/s) next to the available enhanced background vorticity may assist in the spin-up and strengthening of such a vortex. In case of a gradually organizing convective structure (banding)/increasing longevity of DMC, we do not want to rule out the necessity of the use of the Herbert-Poteat technique and subsequently the classification of a subtropical cyclone.

    During the night, this vortex continues to move eastwards atop the Tyrrhenian Sea, where conditions for further strengthening/organization seem more supportive (with higher SSTs and an ill defined warm eddy east of Sardinia). The evolving low will be monitored during the forecast and subsequent updates may be issued in case of organization. It has to be noted however, that none of the global/coarse models indicate any organized warm core development at this time.

    Fonte: www.estofex.org
     
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  5. irpsit

    irpsit
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    Cumulonimbus

    Registo:
    9 Jan 2009
    Mensagens:
    2,057
    Local:
    Entre Mortágua e Tondela
    Interessante ver as duas "tempestades tropicais" no satélite.

    Os restos do Kirk (agora nao-tropical) centrados na Islândia.
    E a formação de algo sem nome, centrado no Mediterrâneo.

    É bastante raro ver-se algo assim....

    htto://www.sat24.com (ver infrared)

    Da Islândia reporto apenas um dia muito chuvoso, algum vento e pressão baixa. Seria interessante saber o que se passa no Mediterrâneo.
     
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  6. FRibeiro

    FRibeiro
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    Cirrus

    Registo:
    26 Nov 2009
    Mensagens:
    96
    Local:
    Paris/Romainville
    Fica aqui uma imagem (de fraca qualidade) de "Medicanes" que existiram. Não sei se se formaram mais.
    Foto retirada do facebook.

    [​IMG]
     

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