SPC AC 151628
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1128 AM CDT SAT APR 15 2006
   
   VALID 151630Z - 161200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS OVER THE MID MO RIVER VALLEY...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CENTRAL PLAINS TO THE
   TIDEWATER/MID ATLANTIC COAST...
   
   ...PLAINS INTO THE MID MS RIVER VALLEY...
   WV IMAGERY DEPICTS SIGNIFICANT SYSTEM EJECTING QUICKLY NEWD INTO THE
   CENTRAL HIGH PLAINS THIS MORNING...WITH SUBSTANTIAL DRYING AND 40+
   KT WLY SURFACE WINDS OVER SERN CO SOUTH OF ASSOCIATED SURFACE LOW. 
   LOW CENTER NOW NEAR OGALLALA NEB WILL UNDERGO FURTHER DEEPENING AS
   IT SHIFTS ENEWD INTO CENTRAL NEB THIS AFTERNOON.  MORNING
   OPERATIONAL MODELS VERY CONSISTENT IN LOCATION OF LARGE SCALE
   FEATURES ASSOCIATED WITH THIS SYSTEM TODAY AND TONIGHT... WITH VERY
   FAVORABLE DYNAMIC SET-UP BECOMING ESTABLISHED INTO ERN NEB/ERN KS
   THIS AFTERNOON.  HOWEVER...BOUNDARY LAYER MOISTURE REMAINS QUITE
   MEAGER AND VERY STRONG CAP REMAINS FIRMLY ESTABLISHED UNDER
   WELL-MIXED ELEVATED AIR MASS OVER THE PLAINS.  OPERATIONAL MODELS
   CONTINUE TO OVER-FORECAST SURFACE DEW POINTS TODAY.  OBSERVED DEW
   POINTS AT 15Z REQUIRE SUBSTANTIAL INCREASES FROM NON-ADVECTIVE
   PROCESSES TO REACH THE MID 60S FORECAST BY THE NAM/ETA ACROSS MUCH
   OF MO...AND UPPER 60F EWD ALONG WARM FRONT TO THE LOWER OH RIVER
   VALLEY.  THE RUC APPEARS MORE REASONABLE IN BRINGING 60F-64F DEW
   POINTS INTO E-CENTRAL/NERN KS WITH MID 50S F DEW POINTS NWD ACROSS
   MUCH OF ERN NEB.  
   
   ATTM...APPEARS STRENGTH OF CAP WILL LIMIT DEVELOPMENT INTO WARM
   SECTOR UNTIL AFTER 21ZZ.  HOWEVER...NEAR 50F SURFACE DEW POINTS
   SHOULD WRAP NWWD NEAR/AROUND LOW CENTER UNDER MID LEVEL COLD POCKET
   DURING THE AFTERNOON.  SHOULD BOUNDARY LAYER MOISTURE SURVIVE
   MIXING...STORMS WILL LIKELY DEVELOP DURING THE MID/LATE AFTERNOON
   INTO WRN/CENTRAL NEB WITHIN STRONG AMBIENT VORTICITY WITH ATTENDANT
   ISOLATED TORNADO/LARGE HAIL THREAT.  PW/S ARE FORECAST TO REMAIN
   QUITE LOW AND SHOULD SUPPORT LP-SUPERCELLS AND HIGH BASED LINEAR
   STRUCTURES...INCREASING THE THREAT OF DAMAGING WINDS. THIS ACTIVITY
   MAY THEN CONSOLIDATE ALONG LEADING OUTFLOW/DEEP ASCENT EWD INTO
   RELATIVELY GREATER MOISTURE NEAR THE MID MO RIVER VALLEY. 
   SUBSTANTIAL LOW LEVEL SHEAR...ENHANCED BY INTENSE PRESSURE FALLS
   AHEAD OF ADVANCING LOW CENTER SHOULD ALSO MAINTAIN THE THREAT OF A
   FEW TORNADOES. FARTHER SOUTH ALONG THE DRY LINE DEVELOPMENT WILL
   BECOME LESS LIKELY INTO CENTRAL/ERN KS. HOWEVER...SUBSTANTIAL SHEAR
   AND PRESENCE OF LOWER 60F DEW POINTS/MLCAPE AROUND 2000 J/KG WILL
   REMAIN FAVORABLE FOR LONG-LIVED SUPERCELLS.  AFTER DARK...ONE OR
   MORE MCSS WILL EVOLVE ALONG NOSE OF STRONG SSWLY LLJ AND OVERSPREAD
   MUCH OF THE MID/NRN MS RIVER VALLEY.  ACTIVITY WILL LIKELY BECOME
   INCREASINGLY ELEVATED E-NE OF MID MO RIVER VALLEY WITH MAIN THREAT
   OF LARGE HAIL...THOUGH STRONG ASCENT NEAR WARM FRONT MAY SUSTAIN A
   NEAR SURFACE-BASED SEVERE THREAT WELL THROUGH THE EVENING INTO NRN
   MO INTO SERN IA/CENTRAL IL.
   
   ...MID MS RIVER VALLEY ACROSS THE OH RIVER VALLEY...
   LARGE SCALE ASCENT WILL REMAIN WEAK/LACKING OVER MUCH OF THIS REGION
   TODAY. HOWEVER...AIR MASS WILL BECOME MODERATELY UNSTABLE AND
   REMAIN UNDER MODEST WNWLY FLOW ALOFT.  RIDGING WILL BUILD ACROSS THE
   MID MS RIVER VALLEY THOUGH THE DAY AHEAD OF PLAINS SYSTEM. 
   HOWEVER...CONVERGENCE NEAR WARM FRONT/RESIDUAL OUTFLOW BOUNDARIES
   SUGGEST ANY THUNDERSTORM CLUSTER WHICH CAN FORM WILL LIKELY BECOME
   SEVERE.  OVERALL THREAT SHOULD DIMINISH THIS EVENING WITH LOSS OF
   HEATING.
   
   ...CENTRAL APPALACHIANS INTO THE MID ATLANTIC/TIDEWATER...
   STRONG HEATING AND HIGHER THETA-E AIR MASS FROM ERN WV/PA ACROSS THE
   DELMARVA AND SRN NJ WILL CONTRIBUTE TO INCREASING DESTABILIZATION
   THIS AFTERNOON. LARGE SCALE DYNAMIC FORCING FOR ASCENT ACROSS THESE
   AREAS APPEARS TO REMAIN SOMEWHAT AMBIGUOUS/WEAK BASED ON LATEST
   WATER VAPOR SATELLITE LOOP AND SHORT-TERM GUIDANCE. HOWEVER...COLD
   FRONT...NOW DEVELOPING SLOWLY SOUTH FROM OH/PA...AND LEE-TROUGHING
   EAST OF THE APPALACHIAN FOOTHILLS...SHOULD PROVIDE IMPETUS FOR STORM
   DEVELOPMENT. BAND OF 60KT NWLY MID LEVEL FLOW AND STEEPENING LOW
   THROUGH MID LEVEL LAPSE RATES WILL PROMOTE STORM ORGANIZATION AND
   INTENSIFICATION THROUGH LATE AFTERNOON. STRONG
   DEEP-LAYER...PRIMARILY UNIDIRECTIONAL...SHEAR INDICATES FAST MOVING
   STORMS WITH SUPERCELL STRUCTURES POSSIBLE. ACTIVITY MAY BECOME
   CONCENTRATED NEAR/ALONG LEE-TROUGH/COLD FRONT INTERSECTION FROM SERN
   PA INTO NRN VA...AND PERHAPS NEAR RESIDUAL/WEAK OUTFLOW BOUNDARY
   FROM TIP OF DELMARVA PENINSULA WNWWD ACROSS THE TIDEWATER. DAMAGING
   WIND GUSTS AND HAIL ARE EXPECTED WITH THESE STORMS THROUGH EARLY
   EVENING WITH SEVERE WEATHER POTENTIAL DIMINISHING RAPIDLY HEREAFTER.
   
   ..EVANS/CARBIN/GUYER.. 04/15/2006
   
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