SPC AC 191256
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0756 AM CDT WED APR 19 2006
   
   VALID 191300Z - 201200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM S CNTRL TX THROUGH THE LWR
   MS VLY TO SRN APLCNS...
   
   ...SYNOPSIS...
   OMEGA BLOCK WILL PROGRESS SLOWLY E ACROSS THE CNTRL/ERN U.S. THIS
   PERIOD AS SRN CA UPR VORT CONTINUES E TOWARD THE FOUR CORNERS. AT
   THE SURFACE...COLD FRONT ASSOCIATED WITH NRN PLNS LOW EXPECTED TO
   BECOME MORE OR LESS STATIONARY FROM S CNTRL TX E/NE ACROSS SRN AR
   INTO THE UPR TN VLY.  A BIT FARTHER S AND E...WEAK BACK-DOOR
   BOUNDARY THAT MOVED INTO AL YESTERDAY SHOULD RETREAT E ACROSS GA
   TODAY IN RESPONSE TO WLY LLJ AND SURFACE WAVE MOVING E ACROSS TN.
   
   ...UPR TN VLY INTO GA/WRN CAROLINAS...
   RESIDUAL WLY LLJ WILL IMPINGE UPON RETREATING BACK-DOOR FRONT OVER
   THE SRN APPALACHIAN REGION TODAY.  LARGE SCALE FORCING FOR ASCENT
   WILL BE WEAK OVER THE AREA AS HEIGHTS SLIGHTLY REBOUND WITH THE
   CONTINUED PROGRESSION OF AFOREMENTIONED OMEGA PATTERN. BUT
   COMBINATION OF SURFACE HEATING...UPSLOPE COMPONENTS AND CONVERGENCE 
   ALONG FRONT AN/OR OUTFLOW FROM OVERNIGHT CONVECTION LIKELY TO RESULT
   IN RENEWED AND/OR STRENGTHENED STORM DEVELOPMENT OVER PARTS OF SE
   TN/NRN AL/GA AND THE WRN CAROLINAS BY MIDDAY.
   
   HEATING BENEATH RESIDUAL EML SHOULD YIELD SBCAPE AOA 2000 J/KG W OF
   BACK-DOOR FRONT IN SRN TN/AL AND WRN GA...WITH VALUES DECREASING TO
   AROUND 1000 J/KG IN THE WRN CAROLINAS. COUPLED WITH DEEP NWLY SHEAR
   OF 35-40 KTS ORIENTED ROUGHLY PARALLEL BACK-DOOR BOUNDARY...SETUP
   MAY SUPPORT A FEW SUPERCELLS WITH HAIL AND POSSIBLY A COUPLE
   TORNADOES IN GA AND THE WRN CAROLINAS. FARTHER W...DEEP SHEAR
   LIKELY WILL BE ORIENTED MORE PERPENDICULAR TO COMPOSITE STORM
   OUTFLOW BOUNDARY IN TN.  COUPLED WITH STEEP LOW TO MID LEVEL LAPSE
   RATES /PER BHM 12Z RAOB/...POSSIBILITY WILL BE GREATER FOR A
   FORWARD-PROPAGATING MCS/SQUALL LINE.  EMBEDDED BOWS MAY YIELD BOTH
   HIGH WIND AND HAIL.
   
   ALL OF THE STORMS IN THIS REGION SHOULD BE STRONGLY DIURNAL...WITH
   LITTLE IF ANY SEVERE THREAT CONTINUING INTO THE NIGHT.
   
   ...S CNTRL TX INTO THE ARKLATEX AND THE LWR MS VLY...
   STALLING COLD FRONT WILL BE FOCUS OF TSTM DEVELOPMENT LATE TODAY
   INTO TONIGHT FROM S CNTRL TX NEWD INTO THE ARKLATEX AND THE LWR MS
   VLY.  BY EARLY AFTERNOON...FRONT SHOULD EXTEND FROM MIDDLE TN/NRN MS
   WSWWD INTO NERN TX AND THEN TO THE RIO GRANDE NEAR DRT.  MODERATE
   INSTABILITY /SBCAPE 0F 1500-2000 J PER KG/ WILL DEVELOP ALONG/S OF
   THE BOUNDARY GIVEN STRONG HEATING...MOIST PREFRONTAL AIR MASS AND
   STEEP MID-LEVEL LAPSE RATES.
   
   30-40 KT SWLY MID-LEVEL FLOW ROUGHLY PARALLEL TO FRONT WILL EXTEND
   FROM S CNTRL TX INTO AR AND THE LWR MS VLY.  THE STRONGEST FLOW
   ALOFT OVER THE TN VLY SHOULD REMAIN IN THE POST-FRONTAL ENVIRONMENT.
    THIS SHOULD LIMIT DURATION/ORGANIZATION OF ANY STORMS THAT DO FORM
   OVER THAT REGION IN WAKE OF ON-GOING MORNING STORMS. 
   HOWEVER...GIVEN DEGREE OF AFTERNOON CAPE /AROUND 2000 J PER KG/...A
   CONDITIONAL THREAT WILL EXIST FOR A FEW SPOTS OF SEVERE HAIL/LOCALLY
   DAMAGING WIND THROUGH EARLY EVENING.
   
   FARTHER SW...SOMEWHAT GREATER DEEP WSWLY SHEAR WILL BE PRESENT INVOF
   FRONT FROM THE ARKLATEX REGION SW TO THE TX BIG BEND.  COMBINATION
   OF STRONG SURFACE HEATING AND FRONTAL UPLIFT MAY INITIATE MORE
   ORGANIZED STORMS/SUPERCELLS.  GIVEN FAIRLY RICH BOUNDARY LAYER
   MOISTURE AND STEEP MID LEVEL LAPSE RATES...THIS ACTIVITY WILL BE
   CAPABLE OF LARGE HAIL AND DAMAGING WIND.
   
   STORM COVERAGE EXPECTED TO INCREASE FROM THE TX HILL COUNTRY N/NE
   INTO PARTS OF CNTRL/NE TX TONIGHT...AND ACROSS SRN AR/NRN LA EARLY
   THURSDAY...AS ISENTROPIC ASCENT INCREASES N OF STALLED FRONT. 
   STRENGTHENING SWLY MID-LEVEL WIND FIELD AHEAD OF CA SHORTWAVE
   IMPULSE WILL YIELD SUFFICIENT CLOUD LAYER SHEAR FOR ELEVATED
   STORMS/POSSIBLE SUPERCELLS WITH HAIL AND HEAVY RAIN.  OTHER ELEVATED
   STORMS/POSSIBLE SUPERCELLS WITH HAIL MAY FORM VERY LATE IN THE
   PERIOD OVER THE PERMIAN BASIN OF W TX...IN AREA OF RAPID MOISTURE
   INFLUX/UPR DIVERGENCE AHEAD SAME UPR DISTURBANCE.
   
   ...WRN/CNTRL WI...
   A SMALL AREA WITH THE POTENTIAL FOR NON-SUPERCELL FUNNELS MAY EVOLVE
   INVOF OLD OCCLUSION MOVING NE ACROSS THE UPR MS VLY THIS AFTERNOON. 
   STEEP LOW LEVEL LAPSE RATE PLUME WILL BE ADJACENT TO BOUNDARY LAYER
   MOISTURE/VERTICAL VORTICITY AXIS NEAR SURFACE OCCLUSION...AND MAY
   YIELD A BRIEF SPINUP OR TWO FOLLOWING MAX HEATING.
   
   ..CORFIDI/JEWELL.. 04/19/2006
   
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