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Webinar: Heavy and Persistent Precipitation in a Quasistationary Convective System in SW England

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Thursday, 29 September 2016, 5:30

Thursday, September 29, 2016. 5:30 PM. Eastern Time. Webinar: Heavy and Persistent Precipitation in a Quasistationary Convective System in SW England. Alan Blyth, National Centre for Atmospheric Science, University of Leeds. Sponsored by National Center for Atmospheric Research. More information here.

 

Observations were made with three aircraft, a ground­based X­band radar and several other ground­based instruments during the COnvective Precipitation Experiment (COPE) in the southwest peninsula of England during the summer of 2013.  Convergence lines form in the region as a result of colliding sea­breeze fronts.  Convective clouds often develop along the lines that occasionally results in flash flooding. The most infamous recent example occurred in Boscastle in August 2004. The flash floods and convergence lines have been studied using models and the UK Met Office (MO) network radars and rain gauges, but observations of the microphysics and dynamics of the systems were never made until COPE.

Modelling results and observations will be presented in this talk of a quasi­stationary convective system on 3 August 2013 that had some similarities to the Boscastle case. Heavy precipitation persisted for several hours in localised regions, although a flash flood did not occur. The measurements on this day were made with two aircraft (University of Wyoming King Air and UK BAe 146), a mobile radar, the MO network of radars and ground­based aerosol instruments.  The mobile radar is a dual­polarisation Doppler X­band radar. It made PPIs with a volume return time of about 5 minutes.  The WRF model run at 400­m resolution and a detailed microphysics model were used to help interpret the observations. The warm rain process, supercooled raindrops, graupel and multiple thermals appear to be key to the intensity and persistence of the precipitation.

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