Day 4-8 Convective Outlook Issued on Feb 20, 2011

ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 200947
   SPC AC 200947
  
   DAY 4-8 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   0347 AM CST SUN FEB 20 2011
  
   VALID 231200Z - 281200Z
  
   ...DISCUSSION...
   AN ACTIVE PATTERN WILL PERSIST THROUGH THE PERIOD WITH THE POTENTIAL
   FOR A SIGNIFICANT SEVERE WEATHER OUTBREAK ON THU/D5.
  
   ON WED/D4...MODEL CONSENSUS HAS A BROAD BELT OF SWLY FLOW ALOFT FROM
   NRN MEXICO ACROSS THE CNTRL AND ERN U.S...AHEAD OF AN UPPER TROUGH
   AXIS THAT IS FORECAST TO BE IN THE VICINITY OF THE BAJA CA/SRN CA
   COAST WED MORNING. WELL AHEAD OF THIS FEATURE...LOW LEVEL MOISTURE
   WILL BEGIN TO STREAM NWD OFF THE GULF OF MEXICO AS A LARGE SURFACE
   HIGH OVER THE ERN STATES GRADUALLY SHIFTS OFFSHORE.
  
   BY THU MORNING...A SURFACE LOW IS FORECAST TO BE SOMEWHERE ACROSS
   NWRN TX OR CNTRL OK WITH BOUNDARY LAYER DEWPOINTS AS HIGH AS 60F UP
   TO THE LOW CENTER....AND UP TO A WARM FRONT THAT WILL EXTEND EWD
   ACROSS NRN OK/AR OR PERHAPS SRN MO. A SURFACE LOW AND POTENT UPPER
   LEVEL JET STREAK WILL THEN CONTINUE EWD ACROSS THE LOWER MS AND INTO
   THE TN/OH VALLEYS BY 00Z.
  
   UPPER LEVEL COOLING AND A PLUME OF STEEP DEEP LAYER LAPSE RATES WILL
   OVERSPREAD THE WARM SECTOR...CREATING A VERY UNSTABLE SITUATION.
   ALTHOUGH THE EXACT GEOMETRY OF THE TROUGH MAY NOT BE WELL HANDLED
   THIS FAR IN ADVANCE...THE CURRENT MODEL DEPICTION WOULD INDICATE THE
   POTENTIAL FOR NUMEROUS SUPERCELLS ALONG THE DRYLINE/COLD
   FRONT...RATHER THAN A MORE LINEAR STORM MODE. IN THIS SCENARIO...A
   SUBSTANTIAL TORNADO THREAT COULD MATERIALIZE BY AFTERNOON AND
   EVENING.
  
   BY FRI/D6...A SEVERE THREAT OF SOME FORM MAY REMAIN ALONG THE COLD
   FRONT...AS IT APPROACHES THE ERN SEABOARD...BUT TIMING OF THE FRONT
   AND PREDICTABILITY BECOME TOO LOW FOR ANY ADDITIONAL SEVERE AREAS.
  
   ..JEWELL.. 02/20/2011