SPC AC 090600
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT WED JUN 09 2010
VALID 091200Z - 101200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE OH/TN VALLEYS TO THE
CENTRAL APPALACHIANS...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CENTRAL HIGH
PLAINS...
...SYNOPSIS...
MID-UPPER LEVEL FLOW FIELD IS EXPECTED TO BECOME MORE AMPLIFIED ON
WEDNESDAY AS A PACIFIC TROUGH MOVES INLAND ACROSS THE WRN STATES AND
A RIDGE BUILDS NNEWD THROUGH THE MID MO AND UPPER MS VALLEYS IN THE
WAKE OF A TROUGH SHIFTING EWD THROUGH THE GREAT LAKES TO NERN
STATES. FARTHER S...THE UPPER LOW/TROUGH CENTERED OVER CENTRAL TX
MAY BEGIN TO MOVE SLOWLY NEWD TOWARD NERN TX...WITH SEVERAL IMPULSES
SHEARING EWD FROM THIS LOW THROUGH THE MID SOUTH TO SRN APPALACHIANS
AND SRN ATLANTIC COAST THIS FORECAST PERIOD.
PRIMARY SYNOPTIC LOW ATTENDANT TO UPPER MS VALLEY TROUGH WILL TRACK
ESEWD THROUGH THE GREAT LAKES TO WRN NY TODAY...WHILE A SECONDARY
LOW MOVES EWD THROUGH THE OH VALLEY TO THE CENTRAL APPALACHIANS BY
10/00Z. THIS LOW WILL THEN DEEPEN OFF THE MID ATLANTIC/SRN NEW
ENGLAND COASTS LATE IN THE FORECAST PERIOD. COLD FRONT TRAILING
SWWD FROM SECONDARY SURFACE LOW WILL ADVANCE ESEWD THROUGH THE OH
VALLEY WITH THE ERN EXTENT SHIFTING OFF THE MID ATLANTIC COAST THIS
EVENING. THE WRN EXTENT OF THIS BOUNDARY WILL SETTLE SLOWLY SWD AND
WEAKEN FROM AR INTO OK AND OK/TX PANHANDLES. MEANWHILE...LOW LEVEL
TROUGH IN LEE OF THE ROCKIES IS EXPECTED TO STRENGTHEN TODAY.
...KY/TN TO THE CENTRAL APPALACHIANS...
WSWLY LOW LEVEL FLOW INTO THE OH/TN VALLEYS WILL ADVECT MOISTURE
NEWD ACROSS THE SLIGHT RISK AREA WITH SURFACE DEWPOINTS IN THE 60S
REACHING THE CENTRAL APPALACHIANS AND LOWER 70S F INTO WRN KY/TN.
DESPITE WEAK MIDLEVEL LAPSE RATES WITH EWD EXTENT INTO THIS
REGION...THE HIGHER DEWPOINTS AND SOME SURFACE HEATING WILL
CONTRIBUTE TO MLCAPE VALUES OF 1000-2000 J/KG. SHOWERS AND TSTMS
SHOULD BE ONGOING AT 12Z TODAY ALONG THE EXTENT OF THE COLD FRONT
FROM CENTRAL OH SWWD TO SRN MO. NEW TSTM DEVELOPMENT WILL BE LIKELY
INTO THE AFTERNOON ALONG THE FRONT. STRONGEST DEEP LAYER SHEAR IS
EXPECTED TO REMAIN CONFINED TO THE NRN HALF OF THE SLIGHT RISK AREA
WHERE STRONGER FLOW ALOFT WILL SUPPORT EFFECTIVE BULK SHEAR 35-50
KT. THESE SHEAR VALUES WILL SUPPORT SUPERCELL STRUCTURES...WITH
ATTENDANT THREATS OF HAIL...STRONG WIND GUSTS AND HAIL. DEEP LAYER
WLY WINDS WITH UP TO 40 KT AT 850-700 MB WILL ENHANCE THE WIND
THREAT.
ACTIVITY WILL LIKELY REACH THE APPALACHIANS BY LATE AFTERNOON/EARLY
EVENING AND WEAKEN SOME AS THOSE MOVE E INTO THE MID ATLANTIC STATES
WHERE INSTABILITY IS FORECAST TO BE WEAKER.
FARTHER S ACROSS TN AND NRN EXTENT OF CENTRAL GULF COAST STATES...
WEAKER DEEP LAYER SHEAR SUGGESTS STORM MODE SHOULD PRIMARILY BE
MULTICELL WITH AN ATTENDANT THREAT FOR HAIL AND STRONG WIND GUSTS.
ACTIVITY ACROSS THIS REGION MAY BE AIDED BY FORCING FOR ASCENT AS
SEVERAL WEAK IMPULSES TRACK EWD TOWARD THE SRN APPALACHIANS/SRN
ATLANTIC COAST.
...CENTRAL AND NRN HIGH PLAINS INTO PARTS OF NEB/WRN DAKOTAS...
SSELY LOW LEVEL WINDS DEVELOPING ALONG THE CENTRAL HIGH PLAINS WILL
ADVECT MOISTURE NWWD TODAY WITH SURFACE DEWPOINTS IN THE UPPER
50S-LOWER 60S REACHING NERN CO/SERN WY AND WRN NEB. STEEP LAPSE
RATES ATOP THIS MOISTURE WILL CONTRIBUTE TO MODERATE INSTABILITY BY
PEAK HEATING WITH VALUES RANGING FROM 1500-2500 J/KG. DESPITE WEAK
UPPER FORCING...TSTMS ARE EXPECTED TO DEVELOP IN THE UPSLOPE FLOW
REGIME FROM ERN CO INTO SERN WY THIS AFTERNOON WITH VEERING WIND
PROFILES WITH HEIGHT RESULTING IN EFFECTIVE BULK SHEAR TO AROUND 50
KT. THIS WILL SUPPORT SUPERCELLS WITH AN ATTENDANT THREAT FOR
HAIL...DAMAGING WINDS AND AN ISOLATED TORNADO CANNOT BE RULED OUT.
FARTHER NW...STRONGER FORCING FOR ASCENT IS EXPECTED TO SPREAD ENEWD
ACROSS THE NRN ROCKIES TO NRN HIGH PLAINS AHEAD OF A LEAD SHORTWAVE
TROUGH TRACKING INTO THIS REGION. HOWEVER...WEAKER INSTABILITY
SHOULD LIMIT THE COVERAGE OF STRONGER/SEVERE STORMS. HOWEVER...
THOSE STORMS THAT DO DEVELOP MAY ROTATE GIVEN STRONG DEEP LAYER
SHEAR...WITH ISOLATED HAIL AND STRONG WIND GUSTS BEING THE PRIMARY
THREATS.
INCREASING LOW LEVEL WAA ALONG STRENGTHENING SSELY LLJ /TO 45+ KT/
FROM WRN KS TO THE WRN DAKOTAS WEDNESDAY NIGHT/EARLY THURSDAY AND
MODERATE INSTABILITY SUGGEST ONE OR MORE MCS/S WILL DEVELOP AND
SPREAD INTO PARTS OF NEB AND THE WRN DAKOTAS LATER IN THE FORECAST
PERIOD. AN ISOLATED SEVERE THREAT MAY ACCOMPANY THE STRONGER
STORMS.
...NRN LOWER MI...
COLD MIDLEVEL TEMPERATURES AND STEEP LAPSE RATES ACCOMPANYING THE
GREAT LAKES TROUGH WILL SUPPORT TSTM DEVELOPMENT ALONG THE TRACK OF
THIS SYSTEM TODAY. EFFECTIVE BULK SHEAR UP TO 30-35 KT ACROSS NRN
LOWER MI SUGGEST A MULTICELLS WILL BE POSSIBLE WITH ISOLATED HAIL
AND STRONG WIND GUSTS.
...PARTS OF S/E TX INTO LOWER MS VALLEY/MID SOUTH...
HIGH PRECIPITABLE WATER VALUES /2+ INCHES/ EXTENDING FROM SRN/ERN TX
INTO THE LOWER MS VALLEY/MID SOUTH AND POCKETS OF SURFACE HEATING
WILL CONTRIBUTE TO MODERATE INSTABILITY ACROSS THIS REGION. WEAK
DEEP LAYER SHEAR SUGGESTS ANY TSTMS DEVELOPING WITHIN THIS
ENVIRONMENT BENEATH MID-UPPER LEVEL LOW/TROUGH SHOULD BE PULSE-TYPE
AND COULD PRODUCE ISOLATED STRONG WIND GUSTS.
..PETERS/SMITH.. 06/09/2010
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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