SWODY2
SPC AC 301728
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1228 PM CDT SUN MAY 30 2010
VALID 311200Z - 011200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS A SMALL PART OF THE
CENTRAL AND SOUTHERN HIGH PLAINS...
...SYNOPSIS...
THE UPPER FLOW REGIME WILL BECOME MORE ZONAL ON MONDAY AS THE WRN
STATES TROUGH TOPS THE UPPER RIDGE AND CONTINUES DOWNSTREAM ALONG
THE NRN TIER OF THE COUNTRY. THE ASSOCIATED COLD FRONT CURRENTLY
OVER THE PLAINS WILL MOVE THROUGH THE GREAT LAKES REGION...REACHING
THE NERN STATES BY MONDAY NIGHT. TAIL-END OF THE BOUNDARY WILL
SUBSEQUENTLY REDEVELOP NWD AS A WARM FRONT INTO THE CNTRL PLAINS. A
NEW COLD FRONT IS FORECAST TO MORE SEWD THROUGH THE NRN
PLAINS...REACHING THE UPPER MS VALLEY BY MONDAY NIGHT.
...CNTRL HIGH PLAINS AREA...
FORECAST UNCERTAINTY IS HIGH WITH FRONT/OUTFLOW BOUNDARY PLACEMENTS
BY MONDAY AFTERNOON. SHORT-TERM MODELS/ENSEMBLES ARE CLUSTERING
AROUND THE SOLUTION THAT BOUNDARY LAYER SELYS WILL INCREASE MONDAY
AFTERNOON IN WAKE OF MORNING CONVECTION AND THE WARM FRONT SHOULD
DEVELOP QUICKLY NWD INTO NRN OK/SRN KS. MEANWHILE...A WEAK LEE
TROUGH WILL BECOME ESTABLISHED OVER FAR ERN CO AND NM AMIDST ZONAL
FLOW ALOFT AND A TRIPLE POINT SHOULD EVOLVE OVER SERN CO/NERN NM.
A RESERVOIR OF MODEST MOISTURE WILL BE TRANSPORTED NW TO THE TRIPLE
POINT WITH LOWER/MIDDLE 60S SURFACE DEW POINTS ACROSS WRN/CNTRL
KS/OK AND NEAR 50F INTO EXTREME ERN CO/NM. THE MOISTURE WILL RESIDE
BENEATH STEEP LAPSE RATES AND STRONG DIABATIC HEATING WILL
CONTRIBUTE TO 1500-2500 J/KG MLCAPE BY MID-AFTERNOON. BUILDING
HEIGHTS AND STRENGTH OF THE ELEVATED MIXED LAYER WILL PROBABLY
MAINTAIN A SIZABLE CAP IN THE LOWER PLAINS THROUGH THE AFTERNOON.
BUT...HIGH-BASED STORMS ARE EXPECTED TO FORM ALONG THE HIGHER SERN
CO/NERN NM TERRAIN AND ALONG THE LEE TROUGH/DRYLINE/TRIPLE POINT BY
LATE AFTERNOON. ADDITIONAL STORMS MAY FORM NEAR/AFTER SUNSET
ALONG/NORTH OF THE WARM FRONT ACROSS CNTRL/SRN KS AS THE LOW-LEVEL
JET STRENGTHENS DURING THE EVENING.
EFFECTIVE VERTICAL SHEAR WILL BE SUFFICIENT FOR SUPERCELLS...
ESPECIALLY WITH THE INITIAL STORMS OVER THE HIGHER PLAINS. BUT...AS
THE EVENING APPROACHES...EVOLUTION INTO ONE OR MORE MESOSCALE
CONVECTIVE COMPLEXES COULD OCCUR...MOST LIKELY OVER SWRN KS/NWRN OK
EWD TOWARD CNTRL/ERN KS. ISOLATED LARGE HAIL AND HIGH WINDS WILL BE
THE PRIMARY THREATS.
...NEB AND SD...
THE ATMOSPHERE WILL DESTABILIZE NWD THROUGH THE PLAINS ALONG AXIS OF
THETA-E ADVECTION ASSOCIATED WITH THE STRENGTHENING LOW LEVEL JET.
ELEVATED STORMS COULD DEVELOP OVERNIGHT WITHIN THE ZONE OF
INCREASING ISENTROPIC LIFT. MODERATE INSTABILITY...STEEP MID LEVEL
LAPSE RATES...AND EFFECTIVE SHEAR OF 40 KT WILL SUPPORT A THREAT FOR
ISOLATED LARGE HAIL.
...LOWER GREAT LAKES THROUGH PORTIONS OF NERN STATES...
IMPULSE EJECTING ENEWD THROUGH THE GREAT LAKES AND SERN CANADA AHEAD
OF MAIN UPPER TROUGH WILL RESULT IN DEAMPLIFICATION OF UPPER RIDGE
OVER THE GREAT LAKES AND OH VALLEY. A COLD FRONT ACCOMPANYING THIS
FEATURE IS FORECAST TO INITIALLY EXTEND FROM THE UPPER GREAT LAKES
SWWD INTO THE SRN PLAINS...AND FROM NERN U.S. SWWD INTO THE OH
VALLEY BY THE END OF THE PERIOD. LOW-MID 60S F DEWPOINTS WILL ADVECT
THROUGH WARM SECTOR...BUT MODEST LAPSE RATES SHOULD LIMIT MLCAPE TO
GENERALLY AOB 1500 J/KG. STORMS ARE EXPECTED TO DEVELOP ALONG AND
AHEAD OF FRONT AS THE ATMOSPHERE DESTABILIZES. IT STILL APPEARS THAT
STRONGER VERTICAL SHEAR WILL REMAIN POST FRONTAL...WITH MODEST
UNIDIRECTIONAL DEEP LAYER WINDS SUPPORTIVE OF MULTICELLS. A FEW
STORMS COULD BECOME CAPABLE OF PRODUCING MAINLY ISOLATED STRONG WIND
GUSTS THROUGH EARLY EVENING. EXPECTED MODEST SHEAR/INSTABILITY
PARAMETER SPACE PRECLUDES INTRODUCING MORE THAN 5% SEVERE
PROBABILITIES AT THIS TIME.
...SERN STATES...
CUTOFF UPPER LOW IS FORECAST TO BECOME AN OPEN WAVE TROUGH AND SHIFT
EWD THROUGH THE SERN STATES. ATMOSPHERE WILL LIKELY ONCE AGAIN
BECOME MODERATELY UNSTABLE AS THE BOUNDARY LAYER WARMS. WEAK
VERTICAL SHEAR WILL SUPPORT MULTICELL AND PULSE STORMS...A FEW OF
WHICH COULD PRODUCE ISOLATED MARGINALLY SEVERE HAIL AND DOWNBURST
WINDS.
..RACY.. 05/30/2010
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