SPC AC 260818
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0218 AM CST THU FEB 26 2009
VALID 281200Z - 011200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER MUCH OF THE SOUTHEASTERN
U.S. SATURDAY AND SATURDAY NIGHT...
...SYNOPSIS...
MID/UPPER LEVEL LOW AND ASSOCIATED SHORTWAVE TROUGH OVER THE PAC NW
THURSDAY MORNING WILL MAINTAIN CONSIDERABLE AMPLITUDE AS IT DIGS
ACROSS THE CENTRAL PLAINS FRIDAY AND INTO THE MID SOUTH/LOWER MS
RIVER VALLEY SATURDAY. THIS SYSTEM WILL THEN TAKE ON A NEUTRAL OR
SLIGHT NEGATIVE TILT SATURDAY NIGHT/SUNDAY OVER THE SOUTHEASTERN
U.S. NAM...GFS AND ECMWF ARE IN SIMILAR AGREEMENT WITH THIS
SYSTEM...AND ALL DEVELOP A SURFACE LOW OVER CENTRAL AL BY SATURDAY
MORNING. LOW THEN TRACKS E-NEWD ALONG LIKELY WEDGE FRONT ACROSS
NRN/CENTRAL GA AND INTO WRN/CENTRAL SC DURING THE AFTERNOON...BEFORE
MOVING OFFSHORE SC/NC SATURDAY EVENING. STRENGTH OF SYSTEM
GENERATES LARGE MID LEVEL HEIGHT FALLS AND ENHANCED WIND FIELDS
ACROSS THE SOUTHEAST...WITH H5 SPEED MAX OF 80-100 KT ALONG BACK END
OF DIGGING TROUGH AND 50+ KT WLY MID LEVEL FLOW OVERSPREADING THE
WARM SECTOR.
SOME UNCERTAINTIES REMAIN /WHICH ARE COMMON WITH COOL SEASON SEVERE
WEATHER EVENTS 3+ DAYS OUT/ REGARDING QUALITY OF BOUNDARY LAYER
MOISTURE...EXTENT OF LOW CLOUDS/PRECIPITATION PRECEEDING SYSTEM AND
OVERALL TIMING. HOWEVER...MODELS ARE BEGINNING TO FAVOR POTENTIAL
FOR AN OUTBREAK OF SEVERE THUNDERSTORMS...INCLUDING TORNADOES...
SATURDAY INTO SATURDAY NIGHT OVER A LARGE PORTION OF THE
SOUTHEAST...AND HAVE BEEFED UP PROBABILITIES ACCORDINGLY.
EXPECT ONGOING STRONG/SEVERE ACTIVITY AT BEGINNING OF THE PERIOD
WHICH TO TRANSLATE QUICKLY EWD NEAR THE SURFACE LOW/COLD FRONT
ACROSS GA AND INTO SC THROUGH THE DAY. ACTIVITY WILL ALSO LIKELY
INTENSIFY NEAR AND AHEAD OF THE FRONT INTO SRN GA/NRN FL AS BOUNDARY
LAYER DESTABILIZES BY THE EARLY TO MID AFTERNOON. THREAT SHOULD
MANIFEST ITSELF AS BOTH FAST MOVING BOW SEGMENTS AND ISOLATED
TORNADIC SUPERCELLS.
..EVANS.. 02/26/2009
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0830Z
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