SWODY2
SPC AC 110559
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CDT WED MAY 11 2011
VALID 121200Z - 131200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SOUTHERN
PLAINS/ARKLATEX TO THE LOWER MO VALLEY AND MIDDLE MS VALLEY...
...SYNOPSIS...
A RELATIVELY AMPLIFIED/BLOCKY LONGWAVE PATTERN WILL CONTINUE INTO
THURSDAY. THE UPPER TROUGH CURRENTLY OVER THE SOUTHERN ROCKIES IS
FORECAST TO ADVANCE NORTHEASTWARD...AND ULTIMATELY SLOWLY MIGRATE
EAST-SOUTHEASTWARD AS A CLOSED LOW OVER THE CENTRAL PLAINS ON
THURSDAY.
...SOUTHERN PLAINS/ARKLATEX TO THE OZARKS/MIDDLE MS VALLEY...
GIVEN THE LARGE SCALE SCENARIO AS PREVIOUSLY DESCRIBED...A PLUME OF
STEEP LAPSE RATES ALOFT...ACCOMPANIED BY 50-80 KT MID/UPPER LEVEL
FLOW ON THE SOUTHERN/EASTERN PERIPHERY OF THE ADVANCING UPPER
LOW...WILL OVERSPREAD A BROAD PRE-DRYLINE/COLD FRONT MOIST SECTOR
ACROSS THE SOUTHERN PLAINS/OZARKS/ARKLATEX ON THURSDAY. MODEST
CONFIDENCE EXISTS WITH RESPECT TO SOME OF THE DETAILS...BUT IT SEEMS
LIKELY THAT AMPLE DESTABILIZATION WILL OCCUR INTO THE AFTERNOON
NEAR/EAST OF THE DRYLINE...AND AHEAD OF A COLD FRONT THAT WILL
GRADUALLY OVERTAKE THE SOUTHERN PLAINS DRYLINE THURSDAY LATE
AFTERNOON AND NIGHT. WITH THE INFLUENCE OF DPVA AND A WEAKLY
CAPPED/UNSTABLE MOIST SECTOR...SCATTERED CORRIDORS OF TSTMS SHOULD
FORM/INCREASE THROUGH THE AFTERNOON ALONG PRE-FRONTAL BOUNDARIES
AND/OR NEAR/EAST OF THE DRYLINE/COLD FRONT THROUGH THE
AFTERNOON...INCLUDING A GENERAL CORRIDOR FROM SOUTHEAST KS/SOUTHERN
MO AND EASTERN OK/ARKLATEX TO EAST-CENTRAL/SOUTH-CENTRAL TX. A
COMBINATION OF SUPERCELLS AND ORGANIZED MULTICELLULAR CLUSTERS ARE
LIKELY. OVERALL...LARGE HAIL IS EXPECTED TO BE THE PRIMARY RISK
DURING THE PERIOD...BUT DAMAGING WINDS WILL BE POSSIBLE AS WELL.
WHILE A COUPLE OF TORNADOES MAY BE POSSIBLE...THE TORNADIC POTENTIAL
SHOULD GENERALLY BE TEMPERED BY WHAT IS EXPECTED TO BE A MODEST LOW
LEVEL WIND FIELD NEAR/EAST OF THE DRYLINE/COLD FRONT.
...CENTRAL PLAINS/LOWER MO VALLEY...
A SEPARATE REGION OF RELATIVELY LOWER TOPPED TSTMS ARE EXPECTED TO
DEVELOP ACROSS THE REGION THURSDAY AFTERNOON...INCLUDING PORTIONS OF
EASTERN KS/SOUTHEAST NEB TO IA/WESTERN MO. WHILE MID LEVEL FLOW WILL
BE COMPARATIVELY WEAKER...MID LEVELS WILL BE COOLER/LAPSE RATES WILL
BE VERY STEEP IN CLOSE PROXIMITY TO THE UPPER LOW...WITH THE
POTENTIAL FOR RELATIVELY STRONG DESTABILIZATION BY AFTERNOON.
MULTICELL STORMS...AND POTENTIALLY SOME MINI-SUPERCELLS ESPECIALLY
EAST-NORTHEAST OF THE SURFACE LOW...WILL BE CAPABLE OF SEVERE HAIL
IN ADDITION TO THE POSSIBILITY OF A FEW BRIEF TORNADOES.
...OH VALLEY AND CENTRAL/SOUTHERN APPALACHIANS TO SOUTHEAST
STATES...
ISOLATED TO SCATTERED TSTMS SHOULD DIURNALLY INCREASE THURSDAY
AFTERNOON...ESPECIALLY IN VICINITY OF A WAVY NNW-SSE ORIENTED
FRONTAL ZONE FROM THE OH VALLEY TO THE SOUTHEAST STATES...WITH
ADDITIONAL DEVELOPMENT POSSIBLE WITHIN A WEAKLY CAPPED WARM SECTOR
ACROSS THE OH/TN VALLEYS. WHILE A RELATIVELY UNSTABLE BOUNDARY LAYER
WILL BE IN PLACE...RELATIVELY WEAK MID/UPPER FLOW IN CLOSE PROXIMITY
TO THE UPPER RIDGE GENERALLY IMPLIES ONLY A MODESTLY ORGANIZED
AND/OR PULSE-TYPE SEVERE MODE IS MOST PROBABLE. WHILE ISOLATED BOUTS
OF SEVERE HAIL/WINDS WILL BE POSSIBLE MAINLY THURSDAY
AFTERNOON/EARLY EVENING...A CATEGORICAL SLIGHT RISK DOES NOT SEEM
WARRANTED.
..GUYER.. 05/11/2011
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