SWODY2
SPC AC 221729
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1229 PM CDT SUN MAY 22 2011
VALID 231200Z - 241200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS PORTIONS OF CENTRAL AND
NRN OK...
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CNTRL/SRN PLAINS NEWD
INTO THE MIDDLE MS...TN AND OH VALLEYS AND LWR GREAT LAKES....
...SYNOPSIS...
UPPER LOW...LOCATED OVER THE UPPER MS VALLEY TODAY...WILL SHIFT
ENEWD INTO ONTARIO AND QUEBEC DURING THE FORECAST PERIOD. ASSOCIATED
SURFACE FRONT IS FORECAST TO STRETCH FROM LOWER MI SWWD THROUGH THE
MIDDLE MS VALLEY INTO SRN KS/NRN OK LATE MONDAY AFTERNOON. AN UPPER
LEVEL TROUGH WILL AMPLIFY IN THE WRN STATES AND PROGRESS RAPIDLY EWD
THROUGH THE SWRN STATES. AHEAD OF THIS TROUGH...AN UPPER
IMPULSE...CURRENTLY LOCATED OVER NV/SRN CA... WILL BE EJECTED EWD
AHEAD OF THE MAIN TROUGH AND MOVE ACROSS OK/TX MONDAY AFTERNOON.
DEEPENING TROUGH IN THE WEST SHOULD MAINTAIN DRYLINE FURTHER WEST
TOMORROW THAN TODAY AND IS EXPECTED TO EXTEND NEAR A P28-LTS-EAST OF
ABI LINE AT LATE AFTERNOON. LARGE AREA OF WARM UNSTABLE AIR MASS IS
LIKELY TO RESULT IN ANOTHER ACTIVE SEVERE WEATHER DAY ACROSS A LARGE
AREA...WITH THE INGREDIENTS ACROSS PORTIONS OF OK MOST FAVORABLE FOR
GREATER SEVERE WEATHER COVERAGE.
...CENTRAL/SRN PLAINS EWD INTO THE MIDDLE MS VALLEY...
MODELS SUGGEST CONVECTION/MCS MAY BE ONGOING PORTIONS OF SRN OK/NRN
KS AT THE START OF THE PERIOD AS STRENGTHENING LOW LEVEL JET
INTERACTS WITH QUASI-STATIONARY FRONT. EXPECT THIS ACTIVITY TO SHIFT
MOSTLY EWD WITHIN MODERATELY STRONG WLY FLOW ALOFT AS LOW LEVEL JET
VEERS INTO AR/MO. GIVEN AT LEAST MODERATE INSTABILITY AND 30-40 DEEP
LAYER SHEAR...CLUSTER MAY PRODUCE SEVERE WEATHER DURING THE
MORNING/EARLY AFTERNOON HOURS.
CONVECTION IS EXPECTED TO REINFORCE FRONT...WITH EFFECTIVE
CONVECTIVE OUTFLOW BOUNDARY LOCATED IN NRN OK. AS CONVECTION SHIFTS
EWD INTO AR/MO...AIR MASS SHOULD RECOVER QUICKLY GIVEN LARGE SOURCE
OF MOIST UNSTABLE AIR MASS SOUTH OF CONVECTION. WITH
HEATING...EXTREMELY UNSTABLE AIR MASS WILL BE IN PLACE AS UPPER
TROUGH APPROACHES FROM THE WEST DURING THE AFTERNOON. THIS WILL
RESULT IN STORMS REDEVELOPING NEAR THE OUTFLOW BOUNDARY/FRONT AND
EAST OF DRYLINE IN OK AND SRN KS. THE MOISTENED BOUNDARY LAYER FROM
OVERNIGHT CONVECTION COMBINED WITH EXTREME INSTABILITY AND 40-50 KT
DEEP LAYER SHEAR WILL BE FAVORABLE FOR SUPERCELLS WITH VERY LARGE
HAIL. THE GREATEST COVERAGE OF STORMS IS EXPECTED IN THE MODERATE
RISK AREA...AND THE MOISTENED BOUNDARY LAYER AND VEERED LOW LEVEL
WINDS ALSO SUGGEST A FEW TORNADOES...SOME STRONG...ARE ALSO
POSSIBLE. STORMS ARE EXPECTED TO DEVELOP SWD ALONG THE DRYLINE IN
NRN TX DURING THE LATE AFTERNOON HOURS...WITH VERY LARGE HAIL AND
PERHAPS A TORNADO OR TWO POSSIBLE. STORMS THAT DEVELOP IN NRN
TX/OK/SRN KS ARE EXPECTED TO SHIFT EWD OVERNIGHT AS AN MCS OR
TWO...WITH THE POTENTIAL FOR WIND DAMAGE AND HAIL INTO AR AND MO.
...TN AND OH VALLEYS...
MORNING CLUSTERS OF WEAKENING STORMS ARE EXPECTED TO MOVE EWD
ACROSS PORTIONS OF THE REGION IN THE MORNING. HOWEVER...THE STORMS
SHOULD BE LOCATED WELL EAST OF THE FRONT AND STRONG DESTABILIZATION
SHOULD OCCUR NEAR THE COLD FRONT FROM WRN OH SWWD INTO CENTRAL
INDIANA AND SRN IL BY AFTERNOON. THIS SHOULD SUPPORT RENEWED
THUNDERSTORMS DEVELOPING NEAR THE FRONT AND SHIFTING EWD THROUGH THE
OH/TN VALLEYS. THE SHEAR WILL BE SUPPORTIVE OF SUPERCELLS...WITH A
TORNADO OR TWO POSSIBLE IN THE MORE DISCRETE STORMS. HOWEVER...THE
MODELS HINT AT MORE WIDESPREAD CONVECTION DEVELOPING ALONG/AHEAD OF
THE FRONT AND SHIFTING EWD INTO THE EVENING HOURS. THIS APPEARS
REASONABLE GIVEN THE FORECAST OF DEEP WSWLY FLOW ABOVE THE BOUNDARY
LAYER...WITH WIND DAMAGE THE MOST LIKELY THREAT.
..IMY.. 05/22/2011
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