Follow-up to yesterday’s NSSL WRF post

It looks like the NSSL WRF handled yesterday’s event pretty well.  It represented the heavy rainfall in northern FL quite well, and the multiple “waves” of relatively disorganized-looking convection over northern AL.  It was perhaps 1 squall line short of reality, and  it also overdid the supercell potential in southern MS and AL, as this scenario did not materialize.

Some comparisons are shown below:

  • The WRF reflectivity valid at 02z shows only 1 distinct squall line (1st image below) while the verifying radar shows 2 separate squall lines at 01z (2nd image).  The 01z OBS is shown since the western squall line dissipated after 01z.
  • The long-track supercell over southern MS and AL never materialized, as can be seen by the storm reports (3rd image).
  • An experimental “Surrogate Severe” product is being worked on at NSSL (4th image).  It combines severe values of many of the unique post-processed fields that Scott Dembek of SPoRT helped implement into the NSSL WRF (max hourly updraft helicity, 10-m wind speed, updraft/downdraft strength, and graupel density).  The smoothed product correlates fairly well with the severe reports yesterday.  These plots are available daily for the full-domain view of the NSSL WRF output by scrolling all the way down on the left-hand side.

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