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Mesoscale Discussion 1637
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   MESOSCALE DISCUSSION 1637
   NWS STORM PREDICTION CENTER NORMAN OK
   1153 AM CDT SAT AUG 30 2014

   AREAS AFFECTED...PORTIONS OF MISSISSIPPI AND WESTERN ALABAMA

   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

   VALID 301653Z - 301930Z

   PROBABILITY OF WATCH ISSUANCE...20 PERCENT

   SUMMARY...THUNDERSTORMS WILL OVERSPREAD THE REGION DURING THE NEXT
   SEVERAL HOURS AND COULD PRODUCE ISOLATED DMGG WIND GUSTS.
   HOWEVER...WW ISSUANCE IS UNLIKELY.

   DISCUSSION...THUNDERSTORMS DEVELOPING NEWD/NWD FROM THE CNTRL GULF
   COAST HAVE CONGEALED INTO A LOOSELY ORGANIZED SQUALL LINE FROM NEAR
   NATCHEZ TO S OF MCCOMB. THIS ACTIVITY WILL CONTINUE TO SPREAD ACROSS
   THE REGION DURING THE AFTERNOON...AS LOW/MID-LEVEL SLYS STEER COLD
   POOLS NWD WHILE MAINTAINING A PLUME OF VERY MOIST AIR. VIS IMAGERY
   INDICATES ADEQUATE INSOLATION AMIDST TRANSLUCENT MID/HIGH CLOUDS TO
   SUPPORT NWD-STREAMING CLOUD STREETS FROM WHICH ADDITIONAL CONVECTION
   IS BLOSSOMING S OF INTERSTATE 20 IN MS AND AL -- HIGHLIGHTING THE
   LACK OF ANY APPRECIABLE CONVECTIVE INHIBITION. THUNDERSTORMS WILL
   CONTINUE TO BLOSSOM FROM THIS REGIME...AS WELL. AND...WITH THE
   DIURNAL HEATING OF THE MOIST BOUNDARY LAYER CHARACTERIZED BY
   LOWER/MIDDLE 70S DEWPOINTS...MODIFICATIONS TO THE 12Z JACKSON
   MISSISSIPPI RAOB INDICATE MLCAPE ON THE ORDER OF 1500-2500
   J/KG...WHICH SHOULD SUPPORT A FEW STRONG STORMS.

   GIVEN THE TROPICAL NATURE OF THE TROPOSPHERIC MOISTURE...WITH THE
   AFOREMENTIONED SOUNDING AND GPS DATA INDICATING 2.2-2.4-INCH PW
   VALUES...WATER LOADING WILL ENHANCE THE RISK FOR WET MICROBURSTS
   CAPABLE OF LOCALLY DAMAGING WIND GUSTS. FURTHERMORE...THE PRESENCE
   OF 20-30 KT OF 1-4-KM-AGL FLOW SAMPLED BY THE JACKSON VWP MAY BE
   SUFFICIENT TO ENHANCE THE DMGG-WIND RISK VIA CONVECTIVE MOMENTUM
   TRANSPORT...AND PERHAPS OFFER SUFFICIENT LOW-LEVEL SHEAR FOR A WEAK
   TORNADO. HOWEVER...POOR MID-LEVEL LAPSE RATES...COMBINED WITH WEAK
   DEEP-LAYER SHEAR...SHOULD REDUCE THE OVERALL SVR-TSTM POTENTIAL.

   ..COHEN/HART.. 08/30/2014


   ATTN...WFO...BMX...HUN...MOB...MEG...JAN...LIX...

   LAT...LON   31429066 32509069 34688974 34888778 34228742 31588777
               31068908 31429066 

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Page last modified: August 30, 2014
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