SWODY2
SPC AC 021730
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT SAT APR 02 2011
VALID 031200Z - 041200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MIDWEST/MIDDLE MS
VALLEY TO THE SOUTH-CENTRAL PLAINS...
...MIDWEST/MIDDLE MS RIVER VALLEY TO SOUTH-CENTRAL PLAINS...
AN UPPER TROUGH...CURRENTLY OVER THE PACIFIC NORTHWEST...WILL
AMPLIFY/ADVANCE SOUTHEASTWARD IN A POSITIVE-TILT FASHION FROM THE
NORTHERN/CENTRAL ROCKIES EARLY SUNDAY TO THE UPPER MIDWEST AND
CENTRAL/SOUTHERN HIGH PLAINS BY LATE SUNDAY NIGHT. BENEATH A STRONG
ELEVATED MIXED LAYER/CAP...LOW LEVEL MOISTURE WILL AGGRESSIVELY
RETURN NORTHEASTWARD DURING THE DAY WITH AID OF A 50-70 KT
SOUTHWESTERLY LOW LEVEL JET. GENERALLY LOWER 60S F SURFACE DEWPOINTS
WILL BECOME ESTABLISHED BY MID/LATE AFTERNOON WITHIN THE PRE-COLD
FRONTAL WARM SECTOR ACROSS THE MIDWEST/LOWER MO VALLEY.
THE AFOREMENTIONED CAP SHOULD PRECLUDE SURFACE BASED TSTM
DEVELOPMENT THROUGH MUCH OF THE AFTERNOON. THAT SAID...INITIAL DEEP
CONVECTIVE DEVELOPMENT SEEMS PROBABLE BY LATE AFTERNOON/EARLY
EVENING IN VICINITY OF THE COLD FRONT ACROSS SOUTHEAST IA/NORTHWEST
IL AND NORTHERN MO...SOUTHWESTWARD TO NEAR A TRIPLE POINT/DRYLINE
INTERSECTION ACROSS EAST-CENTRAL/SOUTH-CENTRAL KS.
WITH MODERATE INSTABILITY/VERY STEEP LAPSE RATES ACROSS THE WARM
SECTOR...STRONG DEEP LAYER SHEAR AMID 50-60 KT SOUTHWESTERLY MID
LEVEL FLOW WILL SUPPORT AN INITIAL MODE OF SUPERCELLS CAPABLE OF
LARGE HAIL AND SOME TORNADOES...WITH THE RELATIVELY GREATEST
PROBABILITY OF TORNADOES APPEARING TO BE ACROSS PORTIONS OF FAR
EASTERN IA AND NORTHERN IL/NORTHEAST MO. A DAMAGING WIND THREAT WILL
UNFOLD AS WELL DURING THE EARLY/MID EVENING HOURS AS STORMS
CONGEAL/BOWS EVOLVE AMIDST NOCTURNALLY REINVIGORATED FLOW WITHIN THE
LOWEST FEW KM /70+ KT AT 850 MB/. WHILE A VERY STRONG WIND FIELD
WILL REMAIN FAVORABLE FOR SUSTAINED SUPERCELLS OR MORE LIKELY FAST
MOVING QUASI-LINEAR CONVECTION/BOWS SUNDAY NIGHT...MODEST BOUNDARY
LAYER MOISTURE/ASSOCIATED DECOUPLING IMPLIES AN INCREASINGLY MORE
ISOLATED/MARGINAL SEVERE THREAT BY LATE EVENING/OVERNIGHT ACROSS THE
MIDWEST.
FARTHER S/SW ACROSS THE SOUTH-CENTRAL PLAINS...DEEP CONVECTIVE
INITIATION PRE-EARLY EVENING/ROUGHLY PRE-03Z IS QUITE UNCERTAIN AMID
A STRONG ELEVATED MIXED LAYER/STOUT CAP. IN TERMS OF NUMERICAL
GUIDANCE...ONLY SOME WRF-ARW MEMBERSHIP OF THE 09Z SREF SUPPORTS
ISOLATED TSTM DEVELOPMENT IN VICINITY OF THE NORTH-SOUTH ORIENTED
DRYLINE ACROSS CENTRAL OK/NORTH TX...WITH OTHER/TRADITIONAL
DETERMINISTIC GUIDANCE INDICATIVE OF LITTLE OPPORTUNITY FOR PRE-DARK
INITIATION. IF STORMS DO INDEED FORM IN VICINITY OF THE DRYLINE
DURING THE LATE AFTERNOON/EARLY EVENING...RELATIVELY STRONG
INSTABILITY/HIGHLY FAVORABLE SHEAR PROFILES WOULD SUPPORT SUPERCELLS
CAPABLE OF VERY LARGE HAIL...WITH A TORNADO THREAT PROBABLY LIMITED
BY A RELATIVELY WELL-MIXED BOUNDARY LAYER. THE MOST LIKELY SCENARIO
IS FOR ISOLATED TSTMS TO DEVELOP LATE IN THE PERIOD AS THE SOUTHEAST
ADVANCING COLD FRONT OVERTAKES THE DRYLINE.
..GUYER.. 04/02/2011
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