SPC AC 091735
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1235 PM CDT SUN MAY 09 2010
VALID 101200Z – 111200Z
…THERE IS A MDT RISK OF SVR TSTMS ACROSS PORTIONS OF KS/OK TO
SOUTHWEST MO…
…THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CENTRAL/SOUTHERN
PLAINS TO MIDDLE MS RIVER VALLEY…
…SUPERCELLS WITH STRONG TORNADOES AND VERY LARGE HAIL ARE EXPECTED
MONDAY LATE AFTERNOON AND EVENING ACROSS PARTS OF OK/KS INTO
SOUTHWEST MO…
…CENTRAL/SOUTHERN PLAINS TO MIDWEST/MIDDLE MS RIVER VALLEY…
WITHIN A PROGRESSIVE/RELATIVELY STRONG BELT OF WESTERLIES…A
SHORTWAVE TROUGH CURRENTLY ALONG THE NORTHERN CA COAST IS EXPECTED
TO ADVANCE EAST-NORTHEASTWARD FROM THE FOUR CORNERS VICINITY TO THE
LOWER/MIDDLE MO RIVER VALLEY AND MIDWEST MONDAY/MONDAY NIGHT.
OWING TO A 50+ SOUTHWESTERLY LOW LEVEL JET AND ROBUST ELEVATED
MOISTURE TRANSPORT REGIME…EARLY DAY ELEVATED TSTMS…WITH AT LEAST
SOME THREAT FOR SEVERE STORMS CAPABLE OF HAIL…WILL LIKELY BE
ONGOING MONDAY MORNING ACROSS EASTERN NEB/EASTERN KS/NORTHEAST OK TO
ADJACENT PORTIONS OF IA/MO/AR. ON THE EDGE OF AN EASTWARD BUILDING
ELEVATED MIXED LAYER…THESE EARLY DAY STORMS COULD CONTINUE TO
PRODUCE SEVERE HAIL THROUGH THE MORNING AS THIS ACTIVITY TRANSITIONS
EAST-NORTHEASTWARD ACROSS THE REGION.
OTHERWISE…BENEATH THE STRENGTHENING ELEVATED MIXED LAYER…MAINLY
MIDDLE 60S F SURFACE DEWPOINTS WILL BECOME WELL ESTABLISHED IN THE
PRE-DRYLINE WARM SECTOR FROM PORTIONS OF WEST/NORTH TX INTO OK AND
SOUTHERN KS. THERE IS SOME CONCERN THAT EARLY DAY STORMS/CLOUD COVER
COULD IMPEDE APPRECIABLE DESTABILIZATION WITH NORTH EXTENT ACROSS
KS…BUT SUCH DETAILS WILL BE MORE READILY RESOLVED IN THE DAY 1
TIME FRAME.
OWING TO SHORTWAVE TROUGH ASSOCIATED DVCA AND STRONG HEATING/MIXING
IN VICINITY OF THE DRYLINE…THE CAP IS EXPECTED TO GRADUALLY ERODE
THROUGH MID/LATE AFTERNOON. CURRENT THINKING IS THAT SURFACE BASED
SEVERE TSTM DEVELOPMENT COULD FIRST OCCUR ACROSS WEST CENTRAL KS BY
MID AFTERNOON…WITH SUBSEQUENT DEVELOPMENT PROBABLE ALONG THE
DRYLINE /AUGMENTED PERHAPS BY EFFECTIVE WARM FRONT INTERSECTION OR
EARLY DAY CONVECTIVE OUTFLOW/ FROM SOUTH CENTRAL KS INTO CENTRAL OK
BY LATE AFTERNOON/EARLY EVENING.
DRYLINE PERPENDICULAR DEEP LAYER WIND VECTORS…WARM/MOIST SECTOR
MLCAPE VALUES OF 2000-3500 J/KG…AND EFFECTIVE SHEAR OF 50-70 KT
WILL SUPPORT DISCRETE SUPERCELLS WITH THE POSSIBILITY OF VERY LARGE
HAIL. AS LOW LEVEL/NEAR-1 KM FLOW RE-INTENSIFIES DURING THE EARLY
EVENING HOURS…FORECAST SOUNDINGS ALSO REFLECT 300-400 M2/S2 OF 0-1
KM/EFFECTIVE SRH AHEAD OF THE DRYLINE…WHICH SUPPORTS THE
POSSIBILITY OF SOME STRONG TORNADOES…PARTICULARLY FROM THE OK
PORTION OF I-40/44 INTO SOUTH CENTRAL KS EITHER SIDE OF I-35/135.
EVENTUALLY MONDAY NIGHT…ACTIVITY WILL TRANSITION INTO
LINES/CLUSTERS WITH DAMAGING WINDS…ISOLATED TORNADOES…AND LARGE
HAIL AS FAR EAST AS THE MIDDLE MS RIVER VALLEY BY EARLY TUESDAY.
FARTHER SOUTH…IT SEEMS PROBABLE THAT STORM DEVELOPMENT MAY BE A
BIT MORE ISOLATED WITH SOUTH-SOUTHWESTWARD EXTENT ALONG THE DRYLINE
FROM SOUTHERN OK TO WEST CENTRAL TX. NONETHELESS…SHEAR/INSTABILITY
WILL AT LEAST CONDITIONALLY SUPPORT A RISK OF SUPERCELLS WITH LARGE
HAIL AND PERHAPS A TORNADO OR TWO…MAINLY DURING THE LATE
AFTERNOON/EARLY EVENING HOURS.
..GUYER.. 05/09/2010