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Mesoscale Discussion 620
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   MESOSCALE DISCUSSION 0620
   NWS STORM PREDICTION CENTER NORMAN OK
   1045 AM CDT WED APR 27 2011
   
   AREAS AFFECTED...FAR EASTERN LA AND NORTHERN/CENTRAL PORTIONS OF MS
   INTO AL
   
   CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY 
   
   VALID 271545Z - 271715Z
   
   A LONG LEAD-TIME/LONG DURATION PARTICULARLY DANGEROUS /PDS/ TORNADO
   WATCH WILL LIKELY BE ISSUED SOON...MOST CERTAIN ACROSS
   NORTHERN/CENTRAL PORTIONS OF MS.
   
   VISIBLE SATELLITE/SURFACE OBSERVATIONAL TRENDS IMPLY RELATIVELY
   QUICK AIRMASS RECOVERY/DESTABILIZATION IS OCCURRING FROM LA INTO
   MS/AL THROUGH MID/LATE MORNING. THIS IS THE CASE NOT ONLY FOR IN THE
   VICINITY OF EARLY MORNING WEST-EAST OUTFLOW ACROSS MS/AL...WHERE
   SURFACE TEMPERATURES/DEWPOINTS HAVE EACH INCREASED 8-12F OVER THE
   PAST 2 HR...BUT ALSO IN THE WAKE OF AN APPARENT WAVE-LIKE FEATURE
   SPREADING EASTWARD CROSS CENTRAL PORTIONS OF MS/LA AS A CU FIELD
   OTHERWISE CONTINUES TO INCREASE/MATURE ACROSS NORTHEAST LA.
   
   AIDED BY STRONG AMPLIFICATION/INTENSIFICATION OF AN INCREASINGLY
   NEGATIVE TILT SHORTWAVE TROUGH/ASSOCIATED JET STREAK LATER TODAY...A
   VOLATILE SCENARIO IS EXPECTED TO UNFOLD THROUGH THE AFTERNOON.
   CONVECTIVE INITIATION OF VIGOROUS CONVECTION BY EARLY/MID AFTERNOON
   IS WELL SUPPORTED BY EXPERIMENTAL GUIDANCE SUCH AS SEVERAL RECENT
   HRRR RUNS AND THE 12Z WRF-NMM. SHORT TERM FORECAST SOUNDINGS FROM
   GUIDANCE SUCH AS THE RUC/12Z NAM...ACCENTUATED BY VERY LONG/STRONGLY
   CURVED LOW LEVEL HODOGRAPHS...SUPPORT THE NOTION OF SUPERCELLS
   CAPABLE OF STRONG/POTENTIALLY VIOLENT TORNADOES THIS AFTERNOON/EARLY
   EVENING ESPECIALLY ACROSS THE HIGH RISK AREA.
   
   ..GUYER.. 04/27/2011
   
   
   ATTN...WFO...BMX...HUN...MOB...MEG...JAN...LIX...
   
   LAT...LON   31159161 32529178 34858972 34838959 34778787 32968780
               31678864 31309016 31159161 
   
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Page last modified: April 27, 2011
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