SPC AC 151731
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1231 PM CDT WED AUG 15 2007
VALID 161200Z - 171200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE
NORTHEAST/OH VALLEY...
...SYNOPSIS...
STRONG UPPER RIDGE ACROSS THE WRN HALF OF THE CONUS WILL BE
SUPPRESSED SOMEWHAT THIS PERIOD ACROSS THE PAC NW/WRN CANADA...AS
UPPER LOW INITIALLY OFF THE W COAST ROTATES NEWD TOWARD VANCOUVER
ISLAND THROUGH THE PERIOD. MEANWHILE...RELATIVELY LOW-AMPLITUDE
TROUGH OVER THE ERN CONUS WILL AMPLIFY -- PARTICULARLY ACROSS THE
NORTHEAST...AS MAIN UPPER VORTEX MOVES EWD ACROSS ONTARIO/QUEBEC
THROUGH THE PERIOD. FINALLY...T.S. ERIN IS FORECAST TO MAKE
LANDFALL OVER THE LOWER/MIDDLE TX COAST EARLY IN THE PERIOD.
AT THE SURFACE...THE MAIN FEATURE -- ASIDE FROM T.S. ERIN -- WILL BE
THE COLD FRONT ASSOCIATED WITH THE NERN U.S. UPPER TROUGH. THIS
FRONT -- INITIALLY FORECAST FROM ONTARIO SWD ACROSS LOWER MI AND
THEN WSWWD INTO THE CENTRAL PLAINS -- IS FORECAST TO APPROACH THE
NEW ENGLAND AND MID ATLANTIC COASTS...AND CROSS THE SRN
APPALACHIANS/TN VALLEY REGION...THROUGH THE END OF THE PERIOD.
...SRN NEW ENGLAND WSWWD ACROSS THE OH VALLEY REGION...
STORMS ARE EXPECTED TO BE ONGOING ACROSS PARTS OF THE GREAT
LAKES/UPPER OH VALLEY REGION AT THE START OF THE PERIOD...AHEAD OF
COLD FRONT/INVOF WEAK LEAD SHORT-WAVE TROUGH. EWD EXPANSION OF THIS
CONVECTION AND ASSOCIATED CLOUD COVER ACROSS THE LOWER LAKES/NEW
ENGLAND THROUGH THE FIRST HALF OF THE PERIOD RENDERS DETERMINING THE
NRN FRINGE OF DESTABILIZATION POTENTIAL -- AND THUS SEVERE THREAT --
DIFFICULT ATTM. HOWEVER...GIVEN STRONG DEEP-LAYER WIND FIELD
FORECAST TO SPREAD ACROSS NEW YORK/NEW ENGLAND -- AND ASSOCIATED
POTENTIAL FOR DAMAGING WINDS DESPITE THE LIKELIHOOD OF LIMITED
INSTABILITY...WILL EXPAND THE SLIGHT RISK NWD.
FURTHER S -- FROM THE MID-ATLANTIC REGION WWD ACROSS THE OH
VALLEY...GREATER DESTABILIZATION SHOULD SUPPORT THE DEVELOPMENT OF
VIGOROUS STORMS -- ALONG/AHEAD OF FRONT AND PERHAPS NEAR ANY OUTFLOW
BOUNDARY ASSOCIATED EARLIER CONVECTION. THOUGH DEEP-LAYER WIND
FIELD WILL BE WEAKER ACROSS THIS REGION...ROUGHLY UNIDIRECTIONAL
NATURE OF THE LOWER TROPOSPHERIC FLOW SHOULD SUPPORT A THREAT FOR
DAMAGING WINDS WITH LINEAR/BOWING CONVECTIVE STRUCTURES.
...SRN/SERN TX...
TD 5 HAS BEEN UPGRADED IN INTENSITY TO TROPICAL STORM ERIN...PER
LATEST GUIDANCE FROM TPC/NHC -- AND IS EXPECTED TO MAKE LANDFALL
AROUND 16/12Z N OF BRO/S OF CRP. WITH SUFFICIENT LOW-LEVEL
VEERING/SHEAR ACROSS AREAS N OF THE CENTER OF CIRCULATION
ANTICIPATED...WILL MAINTAIN A LOW-PROBABILITY SEVERE THREAT --
MAINLY FOR ISOLATED/BRIEF TORNADOES.
...ERN WY/SWRN SD/THE NEB PANHANDLE/NERN CO...
UPSLOPE FLOW WITHIN POST-FRONTAL AIRMASS AND MODEST DESTABILIZATION
MAY SUPPORT THE DEVELOPMENT OF ISOLATED AFTERNOON STORMS ACROSS THIS
REGION. LOW-LEVEL SELYS BENEATH MODEST /AOB 25 KT/ NWLYS AT MID
LEVELS MAY RESULT IN SUFFICIENT SHEAR FOR A FEW ORGANIZED/ROTATING
STORMS...AND ASSOCIATED THREAT FOR LOCALLY DAMAGING WINDS AND/OR
HAIL.
..GOSS.. 08/15/2007
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NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0800Z
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