ACUS02 KWNS 241754
SWODY2
SPC AC 241753
DAY 2 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
1253 PM CDT THU JUN 24 2010
VALID 251200Z - 261200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE NRN PLAINS TO THE
UPPER MS VALLEY/WRN GREAT LAKES...
CORRECTED GENERAL TSTM LINE IN NERN IL/NWRN IND
...SYNOPSIS...
A CORRIDOR OF STRONG WLY MID-UPPER LEVEL FLOW WILL PERSIST THROUGH
DAY 2 ACROSS THE NRN TIER OF STATES BETWEEN A LARGE VORTEX CENTERED
OVER HUDSON BAY/NRN QUEBEC AND AN ELONGATED RIDGE ANCHORED OVER THE
SRN UNITED STATES. SEVERAL SHORTWAVE TROUGHS EMANATING FROM TROUGH
IN THE WRN STATES WILL TRACK EWD THROUGH THE STRONGER FLOW ALOFT
PROVIDING A FOCUS FOR TSTM/SEVERE WEATHER THREAT OVER THE UPPER MS
VALLEY/WRN GREAT LAKES AND NRN PLAINS ON FRIDAY.
IN THE LOW LEVELS...A BAROCLINIC ZONE SHOULD REMAIN NEARLY
STATIONARY FROM SRN ALBERTA/SASKATCHEWAN ESEWD THROUGH FAR NRN MN TO
THE NRN EXTENT OF THE GREAT LAKES ON FRIDAY. WIND SHIFT/FRONT
ATTENDANT TO A MORE PROMINENT NRN PLAINS SHORTWAVE TROUGH WILL SHIFT
ESEWD WITH THE TROUGH FROM THE DAKOTAS THROUGH THE UPPER MS
VALLEY...WHILE AN UPSTREAM SURFACE FRONT MOVES INTO THE NRN HIGH
PLAINS LATE IN THE PERIOD WITH THE NEXT IMPULSE. IN THE EAST...A
COLD FRONT LOCATED OVER CENTRAL/ERN NC/SC INTO CENTRAL GA FRIDAY
MORNING SHOULD HAVE LITTLE MOVEMENT DURING DAY 2.
...NRN PLAINS/UPPER MS VALLEY...
AT 12Z FRIDAY...TSTMS SHOULD BE ONGOING FROM PARTS OF ERN ND THROUGH
NRN MN TO POSSIBLY UPPER MI WITHIN WAA REGIME ALONG BAROCLINIC ZONE.
WEAK INSTABILITY AND INCREASING DEEP LAYER WLY SHEAR FROM FAR NRN MN
ESEWD THROUGH THE NRN GREAT LAKES TO ADJACENT PARTS OF ONTARIO MAY
SUPPORT A FEW STRONG TO SEVERE STORMS AS ACTIVITY MOVES/DEVELOPS
ALONG BAROCLINIC ZONE WITHIN WAA REGIME.
MEANWHILE...SLY LOW LEVEL FLOW WITHIN THE WARM SECTOR ACROSS THE MID
MO TO UPPER MS VALLEYS WILL RESULT IN MOISTURE RETURN BENEATH THE
ERN EXTENT OF STEEP LAPSE RATES/EML SPREADING EWD WITHIN WLY FLOW
ALOFT. THIS AND SURFACE HEATING WILL RESULT IN A MODERATELY
UNSTABLE PRE-FRONTAL AIR MASS SUPPORTING TSTM DEVELOPMENT AS DEEP
LAYER ASCENT SPREADS ACROSS THE ERN DAKOTAS/UPPER MS VALLEY FRIDAY
AFTERNOON/EVENING. GIVE THE DEGREE OF INSTABILITY WITH VALUES UP TO
2500-3500 J/KG FROM SERN SD/NERN NEB EWD ACROSS SRN MN/NRN IA FRIDAY
AFTERNOON AND DEEP LAYER SHEAR SUFFICIENT FOR SUPERCELLS...SEVERE
PROBABILITIES HAVE BEEN INCREASED TO 30 PERCENT ACROSS THIS REGION
WHERE COVERAGE COULD BE GREATER.
INCREASING AND VEERING LLJ ACROSS THE UPPER MS VALLEY INTO THE GREAT
LAKES FRIDAY EVENING/OVERNIGHT SUGGESTS ONE OR MORE MCS/S SHOULD
DEVELOP AND SPREAD EWD ACROSS THE ERN EXTENT OF THE SLIGHT RISK
AREA.
FARTHER WEST...STRONG HEATING ACROSS THE HIGH PLAINS FROM THE NEB
PANHANDLE INTO THE BLACK HILLS REGION OF SD/WY SHOULD REMOVE ANY
CAPPING FOR SOLID UPDRAFT DEVELOPMENT...WITH ADDITIONAL DEVELOPMENT
POSSIBLE OVER CENTRAL/ERN MT. 40-50KT OF WLY MID LEVEL FLOW WILL
SUPPORT SHEAR PROFILES FAVORABLE FOR SUPERCELLS WHILE AN ELY LOW
LEVEL COMPONENT OVER WRN SD/NEB WILL ENHANCE THE SHEAR PROFILES.
SCATTERED LATE AFTERNOON/EARLY EVENING THUNDERSTORMS ACROSS THIS
REGION MAY EVOLVE INTO A SMALL MCS AS THEY MERGE AND PROPAGATE ESEWD
INTO PORTIONS OF THE WRN DAKOTAS AFTER DARK.
...NC/SC
SURFACE HEATING WITHIN A MOIST BOUNDARY LAYER WILL SUPPORT A
MODERATELY UNSTABLE AIR MASS ON FRIDAY ACROSS THE SERN STATES. THE
LACK OF STRONGER UPPER FORCING MAY TEND TO LIMIT GREATER STORM
COVERAGE/ORGANIZATION AND THE NEED FOR A CATEGORICAL OUTLOOK.
HOWEVER...FOR NOW...DEEP LAYER WLY SHEAR UP TO 30 KT OVER SRN VA/NRN
NC MAY SUPPORT A FEW ORGANIZED STORMS AS CONVECTION SHOULD DEVELOP
ALONG THE SURFACE FRONT...SEA BREEZE BOUNDARY AND INTERACTIONS
THEREOF. ADDITIONAL DEVELOPMENT IS POSSIBLE ACROSS THE HIGHER
TERRAIN AND PIEDMONT REGION. ISOLATED STRONG WIND GUSTS AND HAIL
SHOULD BE THE PRIMARY THREATS. THOUGH...GIVEN BOUNDARY INTERACTIONS
WITH ENHANCED LOW LEVEL SHEAR...AN ISOLATED/BRIEF TORNADO CANNOT BE
RULED OUT.
..PETERS.. 06/24/2010
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