SWODY1
SPC AC 301621
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1121 AM CDT MON MAY 30 2011
VALID 301630Z - 311200Z
...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY
TONIGHT FROM CENTRAL NEB TO ERN SD...WRN MN...AND EXTREME SE ND...
...THERE IS A SLGT RISK OF SVR TSTMS FROM NORTHWEST OK NORTHWARD
ACROSS MUCH OF THE CENTRAL/NORTHERN PLAINS...
A BROAD UPPER TROUGH IS PRESENT TODAY OVER THE WESTERN STATES...WITH
A SHORTWAVE TROUGH EVIDENT IN WATER VAPOR IMAGERY ROUNDING THE BASE
OF THE TROUGH OVER NM. THIS FEATURE WILL LIFT NORTHWARD ACROSS THE
HIGH PLAINS THIS AFTERNOON AND EVENING...LEADING TO AN ACTIVE ZONE
OF SEVERE THUNDERSTORMS FROM CENTRAL KS INTO THE DAKOTAS AND WESTERN
MN.
...NEB/DAKOTAS/MN...
A WEAK SURFACE COLD FRONT CURRENTLY EXTENDS FROM SOUTHEAST ND INTO
NORTH CENTRAL NEB. THIS FRONT WILL MOVE ONLY SLOWLY SOUTHEASTWARD
TODAY...AND WILL LIKELY RETREAT NORTHWARD LATER TODAY OVER ND/MN AS
CYCLOGENESIS OCCURS OVER THE REGION. THE FRONT WILL SERVE AS THE
PRIMARY FOCUS FOR THUNDERSTORM INITIATION THIS AFTERNOON AS FULL
SUNSHINE OCCURS IN THE WARM SECTOR. AFTERNOON MLCAPE VALUES OF
3000+ J/KG ARE EXPECTED...ALONG WITH A NARROW AXIS OF WEAK CINH
ALONG THE FRONT.
PRESENT INDICATIONS ARE THAT STORMS WILL FORM ON THE FRONT AROUND
21Z FROM THE TRIPLE POINT OVER CENTRAL NEB NORTHWARD INTO THE
EASTERN DAKOTAS. STRONG WINDS THROUGH THE TROPOSPHERE WILL PROMOTE
SUPERCELL STORM STRUCTURES. HOWEVER...ORIENTATION OF FRONT TO UPPER
WINDS MAKE STORM-MODE FORECASTS COMPLEX. INITIAL STORMS MAY POSE A
RISK OF TORNADOES. BUT A RATHER QUICK EVOLUTION TO A SQUALL LINE
APPEARS LIKELY WITH EMBEDDED BOWS POSSIBLE. THROUGH THE
EVENING...LARGE HAIL AND DAMAGING WINDS ARE EXPECTED ALONG THE
SQUALL LINE AS IT MOVES INTO WESTERN NEB AND NORTHWEST IA.
...KS SOUTHWARD ACROSS THE HIGH PLAINS...
THE DRYLINE WILL EXTEND FROM CENTRAL NEB SOUTHWARD INTO WESTERN OK
AND WEST TX. THE POTENTIAL FOR CONVECTIVE INITIATION THIS AFTERNOON
AND EVENING IS HIGHEST NEAR THE TRIPLE POINT OVER NEB/NORTHERN
KS...AND DECREASES WITH SOUTHWARD EXTENT. STORMS THAT FORM OVER
NEB/KS WILL POSE A RISK OF LARGE HAIL...DAMAGING WINDS...AND PERHAPS
A TORNADO. HOWEVER...THERE REMAINS CONSIDERABLE UNCERTAINTY
REGARDING COVERAGE AND LONGEVITY OF STORMS. FROM WESTERN OK INTO
WEST TX...ONLY VERY ISOLATED DRYLINE STORMS ARE EXPECTED.
..HART/GRAMS.. 05/30/2011
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