SWODY1
SPC AC 151940
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0240 PM CDT SAT MAR 15 2008
VALID 152000Z - 161200Z
..THERE IS A HIGH RISK OF SVR TSTMS ACROSS PARTS OF NRN GA AND
SC...
..THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF NRN AND CNTRL
GA...SC AND SRN NC...
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE TN
VALLEY...SRN APPALACHIAN MTNS AND CAROLINAS...
..REGIONAL TORNADO OUTBREAK IS IN PROGRESS ACROSS NRN GA AND SC
WILL CONTINUE FOR THE REMAINDER OF THE AFTERNOON INTO THE EARLY
EVENING...
..SRN ATLANTIC SEABOARD/ERN TN VALLEY...
LATEST WATER VAPOR IMAGERY SHOWS A LOW AMPLITUDE PROGRESSIVE
SHORTWAVE TROUGH LOCATED ACROSS THE LOWER MS VALLEY. A MORE SUBTLE
LEAD SHORTWAVE TROUGH IS ALSO EVIDENT OVER THE UPPER TN VALLEY AND
LIFT ASSOCIATED WITH THIS FEATURE IS AIDING INTENSE CONVECTIVE
DEVELOPMENT ACROSS NRN GA AND FAR WRN SC. THE THUNDERSTORMS ARE
LOCATED ALONG A QUASI-STATIONARY FRONT EXTENDING EWD FROM THE
ATLANTA METRO AREA TO JUST SOUTH OF GREENVILLE SC. A CLUSTER OF
SUPERCELLS WILL CONTINUE TO MOVE EWD ALONG THE BOUNDARY AND REACH
THE COLUMBIA SC AREA BY LATE AFTERNOON. SOUTH OF THE BOUNDARY...RUC
ANALYSIS INDICATES A SLIGHT CAPPING INVERSION EXISTS ACROSS ECNTRL
GA AND THIS CAP SHOULD WEAKEN QUICKLY OVER THE NEXT 1 TO 2 HOURS. AS
THIS HAPPENS...CONVECTIVE INITIATION WILL CONTINUE TO OCCUR BETWEEN
ATLANTA AND MACON GA THIS AFTERNOON WITH A SEVERE CONVECTIVE CLUSTER
MOVING EWD INTO ECNTRL GA LATE THIS AFTERNOON INTO EARLY THIS
EVENING. SHORT-TERM MODEL FORECASTS AND RECENT RADAR TRENDS ARE IN
GENERAL AGREEMENT WITH THIS SCENARIO AND SEVERE STORM COVERAGE
SHOULD GRADUALLY INCREASE ACROSS THE REGION OVER THE NEXT 3 TO 6
HOURS.
CONCERNING THE SHEAR ENVIRONMENT...LATEST RUC ANALYSIS HAS A 50 TO
60 KT LOW-LEVEL JET EXTENDING NEWD FROM THE FL PANHANDLE INTO CNTRL
GA. THIS FEATURE WILL MOVE EWD ACROSS SCNTRL GA THIS AFTERNOON
INCREASING LOW-LEVEL SHEAR ACROSS THE HIGH RISK AREA. FORECAST
SOUNDINGS AT AUGUSTA GA SHOW CURVED HODOGRAPHS AND INCREASE 0-3 KM
STORM RELATIVE HELICITIES FROM ABOUT 300 M2/S2 AT 19Z TO ABOUT 450
M2/S2 AT 21Z SUGGESTING LOW-LEVEL SHEAR WILL BECOME INCREASINGLY
FAVORABLE FOR TORNADOES OVER THE NEXT FEW HOURS. IN
ADDITION...SHORT-TERM MODEL FORECASTS SUGGEST LCL HEIGHTS WILL DROP
ACROSS THE HIGH RISK AREA AS MOISTURE ADVECTION BRINGS SFC DEWPOINTS
INTO THE MID 60S F MAKING CONDITIONS MORE FAVORABLE FOR STRONG
TORNADOES. STRONG TORNADOES WILL BE POSSIBLE IN THE CORRIDOR FROM
ATHENS GA SEWD TO THE AUGUSTA GA AREA AND EWD TO NEAR COLUMBIA SC
LATE THIS AFTERNOON INTO EARLY THIS EVENING. SUPERCELLS AND BOW
ECHOES WILL ALSO BE CAPABLE OF PRODUCING VERY LARGE HAIL AND
DAMAGING WIND GUSTS OVER 80 KT. MODEL FORECASTS GRADUALLY DRIVE THE
MCS EWD INTO ERN SC AND ACROSS NC SUGGESTING THE TORNADO...WIND
DAMAGE AND LARGE HAIL THREAT SHOULD EXPAND EWD INTO THE I-95
CORRIDOR BY EARLY TO MID EVENING.
..TN VALLEY...
A LINE OF CONVECTION IS ONGOING ACROSS MIDDLE TN AND NRN AL WHICH IS
ASSOCIATED WITH THE MAIN UPPER-LEVEL TROUGH EXITING THE LOWER MS
VALLEY ATTM. AS SFC DEWPOINTS GRADUALLY INCREASE AND MODERATE
INSTABILITY DEVELOPS ACROSS NRN AL...THE SEVERE THREAT SHOULD
GRADUALLY EXPAND EWD ACROSS THE I-65 CORRIDOR. STRONG VERTICAL SHEAR
SHOWN BY RUC ANALYSIS AND COLD AIR ALOFT ON FORECAST SOUNDINGS
SUGGESTS THE PRIMARY THREAT WITH THE ACTIVITY WILL BE LARGE HAIL.
.BROYLES.. 03/15/2008
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