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Mesoscale Discussion 1717
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   MESOSCALE DISCUSSION 1717
   NWS STORM PREDICTION CENTER NORMAN OK
   1230 PM CDT WED AUG 19 2015

   AREAS AFFECTED...CNTRL/NRN/ERN MS...NRN/WRN AL...MIDDLE/WRN
   TN...SERN AR

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 191730Z - 192000Z

   PROBABILITY OF WATCH ISSUANCE...40 PERCENT

   SUMMARY...TSTMS AFFECTING THE REGION THIS AFTERNOON WILL HAVE THE
   POTENTIAL TO POSE A RISK FOR PRODUCING ISOLATED TO PERHAPS WIDELY
   SCATTERED DMGG WIND GUSTS. WHILE NOT IMMEDIATELY LIKELY...THE
   ISSUANCE OF A SEVERE THUNDERSTORM WATCH MAY BE NEEDED FOR PARTS OF
   THE AREA THIS AFTERNOON.

   DISCUSSION...WITHIN A NIL-CAPPING...RICH-TROPOSPHERIC-MOISTURE
   REGIME SAMPLED BY AREA 12Z RAOBS...CONVECTION WILL CONTINUE TO
   DEVELOP AND SPREAD NEWD ACROSS THE REGION THROUGH THE AFTERNOON. THE
   NRN EXTENT OF THE LEADING EDGE OF A LOOSELY ORGANIZED MCS OVER THE
   CNTRL GULF COAST IS SPREADING NEWD THROUGH THE VICKSBURG MS AND
   JACKSON MS AREAS TO THE PINE BELT...AND WILL CONTINUE DEVELOPING
   NEWD ACROSS PARTS OF THE ARKLAMISS REGION AND SURROUNDING AREAS.
   VISIBLE SATELLITE IMAGERY INDICATES CONVECTION DEEPENING IN ADVANCE
   OF THIS ACTIVITY IN TANDEM WITH DIURNALLY INVIGORATED PBL
   CIRCULATIONS INTO NRN MS. FRONTAL ASCENT OFFERED BY A BAROCLINIC
   ZONE PROGRESSING SEWD ACROSS THE MID-SOUTH MAY ALSO OFFER EVENTUAL
   DEVELOPMENT OF SFC-BASED CONVECTION FOLLOWING ONGOING ANA-FRONTAL
   ACTIVITY PROVIDED ADDITIONAL PRE-FRONTAL SFC DIABATIC HEATING.

   JACKSON MS...MEMPHIS TN...AND NASHVILLE TN VWPS ARE SAMPLING
   AROUND-30-KT MID-LEVEL SWLYS WITH MODERATE 1-2-KM-AGL FLOW /20-30
   KT/ THAT MAY SUPPORT NEWD-MOVING COLD POOLS OFFERING A RISK FOR
   STRONG TO PERHAPS DMGG WIND GUSTS -- ASSISTED BY VERTICAL TRANSPORT
   OF RELATED HORIZONTAL MOMENTUM IN CONVECTION. LOCAL MULTICELL
   CLUSTERS EMANATING FROM AMALGAMATING COLD POOLS WOULD LOCALLY
   ENHANCE SUCH POTENTIAL...AS MLCAPE AROUND 1000-2500 J/KG SUPPORTS
   SOME INTENSE UPDRAFTS. PW VALUES AROUND 2.0-2.3 INCHES PER GPS DATA
   IMPLY THAT WATER-LOADING WILL FURTHER AUGMENT WET-MICROBURST
   POTENTIAL.

   REGARDLESS...EARLIER RAOBS INDICATE POOR MID-LEVEL LAPSE
   RATES...WHICH MAY BE A SUBSTANTIAL DETERRENT TO THE OVERALL SVR-TSTM
   THREAT. FURTHERMORE...WATER-VAPOR LOOPS IMPLY A DEARTH OF UPWARD
   MOTION AT THE SYNOPTIC SCALE...REDUCING OVERALL CONFIDENCE IN A
   WW-WARRANTING SVR RISK. REGARDLESS...CONVECTIVE TRENDS WILL BE
   MONITORED THROUGHOUT THE DAY...AND A WW COULD BE NEEDED IF A MORE
   ORGANIZED SVR RISK WERE TO BECOME APPARENT.

   ..COHEN/CORFIDI.. 08/19/2015


   ATTN...WFO...MRX...OHX...BMX...HUN...MOB...MEG...JAN...LZK...

   LAT...LON   31918839 31438920 31788986 32489032 33519129 34059145
               34589099 35099017 36148844 36448728 36368603 35878563
               34878593 33498688 32458784 31918839 

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Page last modified: August 19, 2015
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