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Mesoscale Discussion 99
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MD 99 graphic

   Mesoscale Discussion 0099
   NWS Storm Prediction Center Norman OK
   0640 AM CST Tue Feb 12 2019

   Areas affected...Portions of far southeastern LA...eastern/southern
   MS...and western/central AL

   Concerning...Severe potential...Watch unlikely 

   Valid 121240Z - 121515Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Isolated strong to damaging winds and perhaps a brief
   tornado may occur this morning with a line of thunderstorms moving
   eastward. Watch issuance remains unlikely in the short term.

   DISCUSSION...A line of low-topped convection has recently
   consolidated across parts of eastern MS and far southeastern LA
   ahead of a surface cold front. Strong low-level shear is present
   over this region, as a 40-50 kt southwesterly low-level jet noted on
   the 12Z sounding from LIX is forecast to move slowly eastward this
   morning. 0-1 km shear around 30 kt has been noted on recent VWPs
   from the KLIX radar, and effective SRH around 250-335 m2/s2 should
   support some low-level rotation with the strongest updrafts embedded
   within the line. The main limiting factors which will probably
   preclude a greater severe risk are weak instability and generally
   modest low-level moisture ahead of the line of storms. Surface
   dewpoints remain in the low to mid 60s across this region as of 12Z,
   with upper 60s dewpoints confined to the southern LA Coast and
   vicinity. Widespread cloudiness will tend to limit diurnal heating,
   and low-level lapse rates will likewise struggle to steepen this
   morning across western/central AL. Accordingly, MLCAPE is expected
   to remain at or below 500 J/kg with poor mid-level lapse rates
   present across this region. Still, an isolated strong to damaging
   wind gust could occur with any downdraft along/ahead of the line. A
   brief tornado also cannot be ruled out given the strong low-level
   shear. Regardless, weak instability should keep the overall severe
   threat marginal, and watch issuance remains unlikely at this time.

   ..Gleason/Edwards.. 02/12/2019

   ...Please see for graphic product...


   LAT...LON   30868828 30418884 30188952 30408994 30968975 31198952
               31448936 32018928 32658905 33248849 33618762 33548727
               33178707 31188793 30868828 

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