SWODY1
SPC AC 180558
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1158 PM CST SUN FEB 17 2008
VALID 181200Z - 191200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF ERN NC AND FAR
ERN SC...
..ERN NC/ERN SC...
THE LATEST WATER VAPOR IMAGERY SHOWS A LARGE UPPER-LEVEL TROUGH OVER
THE CNTRL US WITH SWLY FLOW IN PLACE ALONG THE ERN SEABOARD. A COLD
FRONT IS MOVING EWD IN THE OH AND TN VALLEYS WITH A PREFRONTAL
TROUGH ORIENTED NNE TO SSW IN THE APPALACHIANS. A LARGE AREA OF
SHOWERS AND THUNDERSTORMS EXISTS AHEAD OF THE SFC TROUGH FROM THE FL
PANHANDLE NEWD INTO THE CAROLINAS. THIS ACTIVITY WILL CONTINUE TO
SPREAD NEWD LATE TONIGHT AS THE AXIS OF A STRONG LOW-LEVEL JET
SHIFTS EWD. AHEAD OF THE CONVECTION...SFC DEWPOINTS WILL CONTINUE TO
SLOWLY INCREASE IN ERN NC AND MODEL FORECASTS DEVELOP ABOUT 500 TO
1000 J/KG OF SBCAPE BY 12Z INLAND TO ABOUT 100 MILES OF THE COAST.
THIS COMBINED WITH VERY STRONG SHEAR PROFILES SUGGEST A SEVERE
THREAT MAY DEVELOP BY EARLY IN THE DAY 1 PERIOD. FORECAST SOUNDINGS
AT 12Z IN ERN NC SHOW 40 TO 50 KT OF FLOW AT 1 KM AND THIS COULD BE
ENOUGH FOR ISOLATED WIND DAMAGE IF THE FASTER MOVING LINE SEGMENTS
CAN EFFECTIVELY MIX THE HIGHER WINDS TO THE SFC. THE GREATEST
POTENTIAL FOR SEVERE WOULD BE IN THE COASTAL AREAS WHERE INSTABILITY
WILL LIKELY BE MAXIMIZED IN THE 12Z TO 15Z TIMEFRAME. CONVECTION
WILL ALSO DEVELOP FURTHER NORTH ALONG THE COASTAL SECTIONS OF THE
MID-ATLANTIC. STRONG LARGE-SCALE ASCENT AND COLDER AIR ALOFT IN THE
THIS AREA MAY BE ENOUGH FOR HAIL WITH THE STRONGER THUNDERSTORMS
MAINLY BEFORE 18Z.
..NRN AND CNTRL FL...
A LARGE MCS CURRENTLY OVER THE FL PANHANDLE WILL BEGIN TO ACCELERATE
EWD THIS MORNING AS A COLD FRONT ADVANCES EWD INTO NRN FL PENINSULA
BY MIDDAY. LOW-LEVEL CONVERGENCE ALONG THE BOUNDARY AND SFC HEATING
SHOULD ALLOW THE LINE TO REMAIN SUSTAINED OR REINTENSIFY SOME LATE
THIS MORNING. STRONG LOW-LEVEL FLOW WILL BE IN PLACE ACROSS NRN FL
DUE TO THE SRN EXTENT OF A LOW-LEVEL JET. THIS COULD BE ENOUGH FOR
AN ISOLATED WIND DAMAGE THREAT WITH THE STRONGER CELLS EMBEDDED IN
THE LINE THROUGH EARLY THIS AFTERNOON. HOWEVER...THE STRONGER
LARGE-SCALE ASCENT WITH AN UPPER-LEVEL TROUGH IN THE MS VALLEY IS
FORECAST TO LIFT NEWD AWAY FROM THE REGION THIS AFTERNOON. THIS
ALONG WITH DECREASING LOW-LEVEL SHEAR SHOULD KEEP THE SEVERE THREAT
MARGINAL THROUGH LATE AFTERNOON.
.BROYLES.. 02/18/2008
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