[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 151630
SWODY1
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