DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 251719
SWODY2
SPC AC 251717

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1217 PM CDT FRI MAY 25 2007

VALID 261200Z - 271200Z

..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE UPPER MS
VALLEY AND CNTRL PLAINS....

..UPPER MIDWEST...
AN UPPER-LEVEL TROUGH OVER THE NRN PLAINS TONIGHT WILL DRIFT EWD
INTO THE UPPER MS VALLEY SATURDAY. LARGE-SCALE ASCENT WILL INCREASE
ACROSS THE REGION AS THIS FEATURE APPROACHES SATURDAY AFTERNOON. AT
THE SFC...A WELL-DEVELOPED LOW WILL LIFT NEWD INTO NRN MN AS A COLD
FRONT MOVES SEWD INTO ERN MN AND IA BY LATE AFTERNOON. ALTHOUGH
LOW-LEVEL CONVERGENCE ALONG THE FRONT SHOULD NOT BE THAT
STRONG...ENOUGH INSTABILITY AND LIFT SHOULD BE PRESENT FOR THE
DEVELOPMENT TO SCATTERED TO NUMEROUS THUNDERSTORMS LATE SATURDAY
AFTERNOON INTO THE EVENING ACROSS THE REGION.

CONCERNING THE SEVERE THREAT...MODEL FORECASTS MOVE AND INTENSIFY A
60-70 KT MID-LEVEL JET EWD INTO THE UPPER MIDWEST DURING THE DAY.
THIS WILL CREATE MODERATE TO STRONG VERTICAL SHEAR PROFILES ACROSS
THE WARM SECTOR. A THREAT FOR ORGANIZED THUNDERSTORMS APPEARS LIKELY
FROM NE KS EXTENDING NEWD INTO WI AND NRN IL WITH SUPERCELLS
POSSIBLE WHERE MODERATE INSTABILITY DEVELOPS. THE GREATEST THREAT
FOR SUPERCELLS WITH LARGE HAIL SHOULD EXIST ACROSS ERN IA...SW WI
AND NW IL WHERE FORECAST SOUNDINGS SHOW ADEQUATE THERMODYNAMIC AND
SHEAR PROFILES FOR ROTATING STORMS. MULTICELL LINE SEGMENTS MAY ALSO
DEVELOP DUE TO THE STRONG LOW-LEVEL FLOW AND UNIDIRECTIONAL WIND
PROFILES SHOWN ON FORECAST SOUNDINGS. DUE TO THESE FACTORS...THE
STRONGER LINE SEGMENTS MAY HAVE WIND DAMAGE AND HAIL POTENTIAL
ESPECIALLY WHERE LOW-LEVEL LAPSE RATES LOCALLY STEEPEN SATURDAY
AFTERNOON. THIS MAY FAVOR THE DEVELOPMENT OF A LINEAR MCS OR TWO
ALONG THE BOUNDARY DURING THE EVENING. A SEVERE THREAT MAY CONTINUE
WITH ORGANIZED STORM CLUSTERS THROUGH PART OF THE EVENING.

..WRN PART OF THE CNTRL AND SRN PLAINS...
AN UPPER-LEVEL TROUGH OVER THE NRN AND CNTRL PLAINS WILL MOVE EWD
SATURDAY INTO THE UPPER MIDWEST. AT THE SFC...A COLD FRONT WILL
LIKELY BE LOCATED IN THE VICINITY OF SW IA...SE NEB AND NRN KS.
SCATTERED TO NUMEROUS THUNDERSTORMS WILL LIKELY DEVELOP ALONG THE
BOUNDARY SATURDAY AFTERNOON AS DESTABILIZATION OCCURS AND A CAP
WEAKENS. FORECAST SOUNDINGS RIGHT ALONG THE BOUNDARY DURING THE
AFTERNOON SHOW 0-6 KM SHEAR VALUES FROM 30-35 KT. ALTHOUGH THIS IS
TOWARD THE LOW-END FOR SUPERCELL DEVELOPMENT...AN ISOLATED SUPERCELL
THREAT MAY STILL EXIST ESPECIALLY WHERE MODERATE INSTABILITY
DEVELOPS. LAPSE RATES ON FORECAST SOUNDINGS APPEAR STEEP ESPECIALLY
ACROSS NCNTRL KS...SW KS AND ERN CO SUGGESTING THAT LARGE HAIL WILL
BE THE PRIMARY THREAT.

THUNDERSTORMS WILL ALSO LIKELY DEVELOP SWD ALONG THE AXIS OF
INSTABILITY ACROSS THE SRN PLAINS SATURDAY AFTERNOON. ALTHOUGH
POCKETS OF MODERATE INSTABILITY WILL LIKELY DEVELOP...FORECAST
SOUNDINGS SHOW A WEAK SHEAR ENVIRONMENT. THIS SHOULD KEEP ANY
SEVERE THEAT MARGINAL ACROSS THE REGION DURING THE LATE AFTERNOON.

.BROYLES.. 05/25/2007

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