SWODY1
SPC AC 290552
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1252 AM CDT WED SEP 29 2010
VALID 291200Z - 301200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS ERN NC TO SERN VA...
...SYNOPSIS...
AMPLIFIED UPPER FLOW REGIME WILL CONTINUE TODAY FEATURING A
TROUGH/LOW CENTERED OVER AL/GA AND A RIDGE ACROSS THE WRN PORTIONS
OF THE COUNTRY. A SECONDARY DISTURBANCE WILL DIG SEWD INTO THE
UPPER MS VALLEY/WRN GREAT LAKES REGION...ACTING TO REINFORCE THE
MEAN TROUGH IN THE EAST. AT THE SAME TIME...A TROPICAL CYCLONE WILL
TRACK NNE FROM THE NRN SIDE OF CUBA...ACROSS SERN FL THIS
AFTERNOON...TO OFF THE NERN FL/GA COAST BY LATE IN THE PERIOD.
MEANWHILE...00Z NAM/GFS SUGGEST A SECONDARY AREA OF LOW PRESSURE
SHOULD DEVELOP N OF THE SERN FL TROPICAL CYCLONE...WITH THE SECOND
LOW FORMING E OF FL/N OF THE BAHAMAS THIS AFTERNOON. THIS SECONDARY
AREA OF LOW PRESSURE APPEARS TO BE ATTENDANT TO A MIDLEVEL
DISTURBANCE EXPECTED TO TRACK NWD TOWARD THE CAROLINAS/VA THIS
FORECAST PERIOD. IF THIS LOW DOES DEVELOP...IT IS FORECAST TO MOVE
ONSHORE ACROSS NERN SC/SERN NC LATE THIS EVENING/EARLY TONIGHT. THE
28/12Z ECMWF HAS LESS SURFACE REFLECTION OF THIS LOW MOVING TOWARD
THE CAROLINA COAST TONIGHT...SINCE IT IS SLOWER WITH NWD SPEED OF
THE ATTENDANT MIDLEVEL IMPULSE.
...ERN CAROLINAS TO SERN VA...
ALTHOUGH OPERATIONAL MODELS DIFFER IN THE DEVELOPMENT OF A SURFACE
LOW TRACKING INLAND LATER IN THE FORECAST PERIOD...THE 28/12Z ECMWF
IS IN AGREEMENT WITH THE 29/00Z NAM/GFS SHOWING A SIGNIFICANT
INCREASE OF DEEP SLY WIND FIELDS /50-60 KT/ FROM OFF THE SRN
ATLANTIC COAST TO THE MID ATLANTIC STATES BETWEEN 30/00-12Z.
SLY LOW LEVEL WINDS THROUGH THE DAY WILL DRAW RICH MOISTURE INLAND
ACROSS THE ERN CAROLINAS TO MID ATLANTIC STATES WITH SURFACE
DEWPOINTS IN THE LOWER 70S EXPECTED INTO THESE AREAS AFTER 30/00Z.
DESPITE WEAK LAPSE RATES...THE INFLUX OF HIGH THETAE AIR IS EXPECTED
TO SUPPORT MUCAPE GENERALLY BELOW 500 J/KG ACROSS ERN NC/ FAR SERN
VA. ALTHOUGH INSTABILITY WILL BE MARGINAL...THE INCREASE IN WIND
FIELDS WITH EFFECTIVE BULK SHEAR /35-40 KT/ AND LARGE HODOGRAPH
CURVATURE ACROSS THE SLIGHT RISK AREA SUGGEST A POTENTIAL FOR AN
AFTER DARK TORNADO THREAT. THUS...THIS OUTLOOK HAS INTRODUCED A
SLIGHT RISK FOR ERN NC INTO FAR SERN VA.
...SE FL/UPPER KEYS...
NHC IS CURRENTLY INDICATING A TROPICAL STORM WILL HAVE FORMED BY 12Z
TODAY ALONG THE N SIDE OF CUBA...WITH THIS SYSTEM TRACKING THROUGH
THE FAR SERN PART OF FL THIS AFTERNOON. GIVEN THIS TRACK...MUCH OF
THE ERN QUADRANT OF THE TS WILL REMAIN OFFSHORE. THUS...THIS
OUTLOOK IS ONLY INCLUDING A VERY LOW TORNADO PROBABILITY ACROSS THE
UPPER KEYS TO SERN FL FROM THIS MORNING INTO THE AFTERNOON.
..PETERS/HURLBUT.. 09/29/2010
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