DAY 4-8 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0345 AM CDT TUE APR 22 2014

   VALID 251200Z - 301200Z

   ...DISCUSSION...
   ...SIGNIFICANT MULTI-DAY SEVERE EVENT EXPECTED ACROSS THE SOUTH
   CENTRAL U.S. SATURDAY AND SUNDAY...STRONG TORNADOES ARE POSSIBLE...

   22/00Z ECMWF IS EXHIBITING REASONABLE RUN-TO-RUN CONSISTENCY OVER
   THE LAST FEW DAYS WITH THE GFS NOW TRENDING TOWARD ECMWF SOLUTIONS. 
   THIS FORECAST IS HEAVILY WEIGHTED TOWARD THE ECMWF.

   EARLIER CONCERNS REGARDING A POLAR FRONT UNDERCUTTING STRONG SWLY
   FLOW ALOFT OVER THE SRN PLAINS ARE LESSENING.  WHILE UPPER BLOCK
   OVER CNTRL CANADA WILL ULTIMATELY FORCE A DOMINANT SFC ANTICYCLONE
   INTO THE MIDDLE OF THE CONUS...IT APPEARS THE LEADING EDGE OF THIS
   AIR MASS SHOULD STRUGGLE TO ADVANCE MUCH SOUTH OF I-70 OVER KS/MO
   THIS WEEKEND.

   STRONG MID-LEVEL SPEED MAX IS FORECAST TO DIG SEWD INTO THE LOWER CO
   RIVER VALLEY SATURDAY WITH UPPER DIFLUENCE EXPECTED ACROSS THE
   PLAINS AS FAR SOUTH AS WEST TX AT 27/00Z.  THIS EVOLUTION WILL ALLOW
   SUBSTANTIAL MOISTURE TO ADVANCE POLEWARD ACROSS THE SRN PLAINS WHERE
   PW VALUES SHOULD EASILY APPROACH 1.25 INCHES AS SFC DEW POINTS CLIMB
   THROUGH THE MID-UPPER 60S ACROSS A BROAD WARM SECTOR.  LATEST
   THINKING IS MODERATE-EXTREME INSTABILITY SHOULD DEVELOP ALONG ERN
   PLUME OF STEEP LAPSE RATES FROM WCNTRL TX...NWD INTO SCNTRL KS
   SATURDAY WHERE MUCAPE COULD APPROACH 4000 J/KG.  IF THERMODYNAMIC
   ENVIRONMENT EVOLVES AS LATEST GUIDANCE SUGGESTS THEN POTENTIALLY
   SIGNIFICANT SUPERCELL DEVELOPMENT WITH VERY LARGE HAIL AND TORNADOES
   CAN BE EXPECTED.  CONVECTION SHOULD INITIATE ALONG DRYLINE FROM SWRN
   TX...NWD INTO WRN KS SATURDAY THEN REDEVELOP AGAIN SUNDAY FROM SERN
   KS...SWD INTO CNTRL TX AS MID-LEVEL SPEED MAX EJECTS INTO THE SRN
   PLAINS.  SEVERE TSTMS SHOULD SPREAD INTO THE MS VALLEY BY EARLY
   MONDAY.  ORGANIZED SEVERE MAY CONTINUE INTO THE DAY7 PERIOD BUT
   SUBSTANTIAL CONVECTION DURING THE DAY5-6 TIME FRAME COULD
   POTENTIALLY DISRUPT THERMODYNAMIC ENVIRONMENT...THUS CONFIDENCE IS
   NOT AS HIGH.