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Lynxus

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    Convective/Storm Discussion Thread - 19th May 2018 onwards

    in Storms & Severe Weather

    Posted

    image.thumb.png.35c208b5a7aafb3d96bc2d5d92661160.png

    2 minutes ago, Ben Sainsbury said:

    If we take a look at the cloud height on the Sat24: https://en.sat24.com/en/nl/km

    It is clear for the most part that the storms in the far SW are decaying. 

    And if anything the very large active storm possible MCS over France is maintaining, if not growing in size. We should expect further activity by 7/8pm.

    Isnt for the most part unstable air in the shaded area?

    I suspect things to kick off properly down south/SW in about an hour.

    Convective/Storm Discussion Thread - 19th May 2018 onwards

    in Storms & Severe Weather

    Posted · Edited by Lynxus

    1 hour ago, Lauren said:

    Thanks Harry. I've got that but what exactly is it I'm looking for that says storms?

    I personally look at a few things.

    Storms are generally caused by converging different masses of air. (Ie, hot air hitting cold air) , This difference creates the condensation, convection etc needed for larger clouds, storms and in extreme cases tornadoes etc.

    There is a good guide here about UK storms: 

     

     

    That said, Here is what I look for.

    Sea level pressure, Gives a good indicator of air masses, Their direction and where you sit between them.

    airpressure.png

    This shows the UK being suck between pressure systems.. So we have movement.. Air is moving about.. Its not like we are stuck dead under a high pressure system.

    I also look at wind directions.

    ukwind.png

    These can show where air is "converging" and likely a good place where storms may be.

    ukprec.png

    Precip charts are obviously a good chart to show where rain and intensity may be... Its  a bit of a cheat, but shows it none the less.

    ukcapeli.png

    Cape and Lifted index is also a good one to look at.

    These show how much potential energy is about for a storm to use and the lifting values along with it.

    Strong cape values and low lifted values are good indicators. Lack of these doesnt mean no storms but with it can mean bigger and more likely storms.

     

    The above 3 charts all show the convergence line, the PPN and cape values in the same place roughly. This is a good sign for say 09:00 tomorrow morning that the south of the UK have some big storms.

     

    There are other charts can help bolster out the detail but this is a good indication.

    There is also a storm risk chart that is useful for confirming your thoughts.

    ukstormrisk.png

     

    -----------

     

    This afternoon does indeed look good for the south.

    ukcapeli.png

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