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Dry Tongues


dave48

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Posted
  • Location: Godalming, Surrey
  • Location: Godalming, Surrey

    I have been looking in to dry tongues lately but there isn't a lot of information on them on the internet. Does anyone know much about them and also their relevance to thunderstorms and thunderstorm forecasting.

    Also, are they in any way related to troughs, there is a trough today marked on an slp map that fits exactly in to an area of dry air as seen on the humidity charts. Thanks.

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    Posted
  • Location: Jersey
  • Location: Jersey

    This might help. The second link (Power point presentation) is rather technical but you should be able to get something from it. Usually referred to as dry intrusions or dry slots.

    http://adsabs.harvard.edu/abs/1997MeApp...4..317B

    http://oiswww.eumetsat.org/WEBOPS/msg_inte...ppt#519,1,Slide 1

    Lots of good stuff here if you have the time:

    http://oiswww.eumetsat.org/WEBOPS/msg_inte...tion/index.html

    Gibli

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    Posted
  • Location: Cheddar Valley, 20mtrs asl
  • Weather Preferences: Snow and lots of it or warm and sunny, no mediocre dross
  • Location: Cheddar Valley, 20mtrs asl
    I have been looking in to dry tongues lately but there isn't a lot of information on them on the internet. Thanks.

    Nice cup tea perhaps?

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    Posted
  • Location: Ash, Surrey/Hampshire Border Farnborough 4 miles
  • Weather Preferences: All
  • Location: Ash, Surrey/Hampshire Border Farnborough 4 miles
    I have been looking in to dry tongues lately but there isn't a lot of information on them on the internet. Does anyone know much about them and also their relevance to thunderstorms and thunderstorm forecasting.

    Also, are they in any way related to troughs, there is a trough today marked on an slp map that fits exactly in to an area of dry air as seen on the humidity charts. Thanks.

    Hey Dave,

    I find I suffer from the very same problem. My situation occurs the day after a bottle of 'heavy' South African red

    with too many Sulphites in - especially one over 13.5% - say 14%+ ish. I suffer a terrible thunderstorm the next day.

    As for thunderstorm forecasting, I go to the wine store and look at the Sulphite content and % and deduce from that what the forecast for the next day will be.

    Depending on my choice, which is usually bad I hasten to add, I find that it is definitely related to a trough the next day. This is usually the onset of very dry air producing an extremely dry tongue.

    As for humidity - sheesh!

    Andy

    PS Don't try this at home...!

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    Posted
  • Location: City of Gales, New Zealand, 150m ASL
  • Location: City of Gales, New Zealand, 150m ASL

    They often slip in behind a cold front. They actually are part of the theory of mid latitudes along with warm conveyors and cold conveyors. A dry intrusion can trigger convection if it overruns aloft, meaning that the theta w will decrease with height and hence there is potential instability. This will need to be triggered by some lifting mechanism though, and surface convergence can do that.

    Best place to see them is on water vapour satellite imagery. They are very, very obvious on it.

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    Posted
  • Location: Coventry,Warwickshire
  • Location: Coventry,Warwickshire

    There are two main sources of dry air. The first is dry stratospheric air which is pulled down behind a cold front as it moves through. This is the mechanism which I think some have described here as a dry intrusion. The second source of dry air can be somwhere like the sahara and this can be advected north across spain by an approaching trough from the atlantic. This dry boundary layer air is synoptically lifted or lifted by orographic ascent over mountains from the surface (the point where it is lifted from the surface is the "dryline" ). Once lifted this dry boundary layer air becomes an elevated mixed layer. Below this layer the air becomes increasingly moist and trapped untill eventually it can break through the cap. A Spanish plume type event occurs. There are a number of scenarios that occur, but as far as the Uk is concerned most scenarios are missing wind shear as an ingredient. Typically the elevated mixed layer has lifted a good way by the time it reaches the UK and has had time to cool making the air pretty unstable. An interesting scenarios might include an small upper short wave crossing the region dragging down some colder dry air increasing instability

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