SPC AC 071248
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0748 AM CDT SUN APR 07 2013
   
   VALID 071300Z - 081200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF KS AND NRN
   OK INTO CNTRL MO THIS AFTERNOON INTO TONIGHT...
   
   ...SYNOPSIS...
   
   AN INITIALLY QUASI-ZONAL PATTERN WILL UNDERGO AMPLIFICATION DURING
   THE D1 PERIOD IN RESPONSE TO THE EQUATORWARD PROGRESSION OF MID AND
   UPPER-LEVEL JET STREAKS FROM THE NERN PACIFIC INTO THE LOWER CO
   RIVER VALLEY.  THIS WILL RESULT IN THE FORMATION OF A SUBSTANTIAL
   TROUGH FROM THE NRN INTERMOUNTAIN REGION INTO GREAT BASIN WHERE
   12-HR HEIGHT FALLS AT 500 MB WILL EXCEED 100-150 M.  FARTHER E...A
   SERIES OF WEAK VORTICITY MAXIMA WILL PROGRESS THROUGH THE CNTRL
   CONUS...AIDING IN THE DEVELOPMENT OF STRONG TO SEVERE TSTMS LATER
   TODAY INTO TONIGHT.
   
   IN THE LOW LEVELS...A SURFACE CYCLONE OVER THE UPPER GREAT LAKES
   WILL DEVELOP NEWD INTO THE CANADIAN MARITIMES WHILE A TRAILING COLD
   FRONT SETTLES SEWD THROUGH THE LOWER GREAT LAKES.  THE WRN EXTENSION
   OF THIS FRONT WILL REMAIN QUASI-STATIONARY OR RETREAT SLOWLY NWD
   OVER THE MIDWEST INTO NRN PLAINS IN RESPONSE TO UPSTREAM CYCLONE
   DEVELOPMENT IN THE NRN HIGH PLAINS.  FARTHER S...A WEAK
   FRONT/MOISTURE DISCONTINUITY CURRENTLY FROM CNTRL MO TO ALONG THE
   KS-OK BORDER WILL SLOWLY MOVE NWD IN RESPONSE TO THE NRN HIGH PLAINS
   CYCLOGENESIS.  A DRYLINE WILL STRENGTHEN TODAY FROM WRN KS SWD
   THROUGH A DEEPENING THERMAL LOW OVER NWRN TX INTO W-CNTRL TX.
   
   ...CNTRL/SRN PLAINS INTO THE OZARKS THIS AFTERNOON INTO TONIGHT...
   
   A BIFURCATED LLJ PRESENT E OF THE ROCKIES WILL TEMPORARILY WEAKEN
   THIS MORNING BEFORE CONSOLIDATING ACROSS LOWER ELEVATIONS OF THE
   CNTRL/SRN PLAINS THIS AFTERNOON INTO EVENING.  THIS FEATURE WILL
   HASTEN THE NWD FLUX OF A MODIFIED CP AIR MASS THROUGH THE
   REGION...AND BENEATH A PRONOUNCED EML AS SAMPLED BY 12Z REGIONAL
   SOUNDINGS.  THE CO-LOCATION OF THE STEEP LAPSE RATES AND INCREASING
   BOUNDARY LAYER MOISTURE IS EXPECTED TO YIELD A MODERATELY UNSTABLE
   WARM SECTOR BY MID TO LATE AFTERNOON WITH MLCAPE APPROACHING
   1000-2000 J/KG.
   
   THE EARLY PASSAGE OF A LEAD VORTICITY MAXIMUM THROUGH KS THIS
   MORNING CASTS SOME UNCERTAINTY ON SPECIFIC TIMING OF STORM
   DEVELOPMENT LATER TODAY.  HOWEVER...MODEL GUIDANCE...AND TO A LESSER
   EXTENT...WV IMAGERY SUGGEST THE PRESENCE OF WEAKER UPSTREAM IMPULSES
   WHICH WILL AFFECT THE REGION DURING THE PEAK OF THE DIURNAL HEATING
   CYCLE.  FORCING FOR ASCENT ATTENDANT TO THESE FEATURES WILL COMBINE
   WITH LOW-LEVEL CONVERGENCE ALONG THE EXISTING SURFACE BOUNDARIES TO
   FOSTER WIDELY SCATTERED TSTMS...INCLUDING SUPERCELLS...BY MID
   AFTERNOON ACROSS PORTIONS OF KS WITH AN ATTENDANT RISK FOR LARGE
   HAIL AND PERHAPS A TORNADO OR TWO.
   
   THE STRENGTHENING LLJ SHOULD SUPPORT UPSCALE GROWTH OF STORMS INTO
   MULTIPLE CLUSTERS WITH A LARGE HAIL AND DAMAGING WIND THREAT
   SPREADING EWD INTO WRN AND CNTRL PARTS OF MO LATE THIS AFTERNOON
   INTO TONIGHT.  FARTHER S...A CONDITIONAL RISK FOR SEVERE WEATHER
   WILL EXIST ALONG THE DRYLINE OVER WRN OK AND NWRN TX THIS AFTERNOON
   AND EVENING.  HOWEVER...GIVEN A PROGRESSIVELY STRONGER CAP AND
   WEAKER FORCING FOR ASCENT WITH SWD EXTENT...UNCERTAINTY IN STORM
   INITIATION AND SUSTENANCE REMAINS QUITE HIGH.
   
   ..MEAD/ROGERS.. 04/07/2013
   
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