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Mesoscale Discussion 182
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   Mesoscale Discussion 0182
   NWS Storm Prediction Center Norman OK
   0202 PM CST Tue Feb 14 2017

   Areas affected...Portions of southern/eastern
   LA...western/central/southern MS

   Concerning...Severe potential...Watch unlikely 

   Valid 142002Z - 142230Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Areas east of Tornado Watch 33 are being monitored for
   isolated severe potential this afternoon. Present indications are
   that additional/downstream Watch issuance is unlikely.

   DISCUSSION...Substantial weakening has been noted with a convective
   line crossing parts of western LA. As the broader precipitation
   pattern associated with this MCS has transitioned from
   trailing-stratiform to leading-stratiform, warm-sector
   destabilization attendant to 1007-mb surface low analyzed in
   northwest LA has been restricted. Furthermore, the 18Z Slidell LA
   sounding indicates that the low levels north of the immediate Gulf
   Coast are only modestly moist, with a lowest-100-mb mean mixing
   ratio of 10.8 g/kg. Surface dewpoints have mixed out into the upper
   50s to around 60F across many parts of central/southern MS and
   southern LA where insolation has occurred peripheral to denser
   MCS-related cloud canopies. As such, observational trends suggest
   that inland destabilization remains quite muted ahead of any remnant
   convection accompanying the MCS, and this activity may pose only
   marginal/isolated severe potential through late afternoon as it
   spreads across parts of the Lower MS Valley region.

   Regardless, a well-defined surge of drying is evident on the upshear
   side of the MCS -- based on the larger-scale bowed precipitation
   pattern accompanying the aforementioned activity. The related
   augmentation of a midlevel speed maximum by the remnant mesoscale
   circulation may provide sufficient wind fields for conditional and
   isolated damaging-wind potential if any more robust convective cores
   were to evolve in the strongly sheared environment. Areas of partial
   insolation -- especially from central MS to southeast LA -- may have
   boosted low-level lapse rates sufficiently to support such
   potential. Somewhat richer Gulf moisture just offshore may be
   advected inland with time, and this could eventually translate to a
   modest increase in severe potential near the coast. However,
   substantial uncertainty in these scenarios remains.

   ..Cohen/Hart.. 02/14/2017


   ATTN...WFO...JAN...LIX...LCH...SHV...

   LAT...LON   29659196 30739218 31959224 32829129 33089055 32878994
               30799014 29659028 29349097 29659196 

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Page last modified: February 14, 2017
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