SPC has placed a good chunk of the region under a moderate risk for severe weather today! Main threats look to be Tornadoes, and Large Hail!
Tornado Threat!
Large Hail threat!
Damaging winds threat!
SPC Discussion!
...SYNOPSIS...
POWERFUL UPPER TROUGH LOCATED OVER NRN TX LATE TONIGHT WILL RACE
NEWD ACROSS THE MIDDLE MS VALLEY THROUGH WEDNESDAY AFTERNOON...AND
THEN ACROSS THE OH VALLEY THROUGH EARLY THANKSGIVING DAY. IN
RESPONSE TO VERY INTENSE DYNAMIC FORCING FOR ASCENT WITHIN LEFT EXIT
REGION OF 90-100KT MID LEVEL JET...DEEPENING SURFACE CYCLONE WILL
DEVELOP RAPIDLY NEWD FROM THE MO BOOTHEEL TO SRN QUEBEC DURING THIS
FORECAST PERIOD. WARM/MOIST AIR MASS PRECEEDING A STRONG COLD FRONT
AND INTENSIFYING SURFACE LOW WILL BE CHANNELED RAPIDLY NORTH TO THE
OH VALLEY THROUGH THIS AFTERNOON AIDED BY LOW LEVEL SLY FLOW OF
50-60KT. PREFRONTAL SQUALL LINE SHOULD CONTINUE TO CONSOLIDATE OVER
MS/AL THIS MORNING AND THEN SWEEP EAST ACROSS THE REST OF THE DEEP
SOUTH AND EXTEND FROM THE PIEDMONT OF NC TO NRN FL BY THIS EVENING.
WITH THE EXCEPTION OF PARTS OF THE NORTHEAST...ENTIRE PREFRONTAL
CONVECTIVE BAND SHOULD BE ON OR JUST OFFSHORE MOST OF THE ERN
SEABOARD BY EARLY THURSDAY.
...OH VALLEY...
DEEPENING SURFACE CYCLONE WILL TRACK NEWD ACROSS SRN IL AND IND
COINCIDENT WITH WEAK DIURNAL DESTABILIZATION WITHIN PRONOUNCED MID
LEVEL DRY SLOT. SUFFICIENT INSTABILITY /MLCAPE 300-800 J PER KG/ IS
FORECAST BY LATEST SREF AND ETA FOR SCATTERED SURFACE-BASED TSTM
DEVELOPMENT IN THE LOWER OH VALLEY AREA BETWEEN 18-21Z. INTENSE
FORCING FOR ASCENT AHEAD OF THE SURFACE LOW...COUPLED WITH VERY
STRONG LOW LEVEL AND DEEP LAYER SHEAR...WILL CONTRIBUTE TO FAVORABLE
ENVIRONMENT FOR FAST MOVING LOW-TOPPED SUPERCELLS. IN ADDITION TO
LARGE HAIL...A FEW TORNADOES WILL BE POSSIBLE ACROSS THE MDT RISK
AREA DURING THE AFTERNOON. THIS ACTIVITY MAY CONSOLIDATE INTO SHORT
LINE SEGMENTS WITH WIND DAMAGE/HAIL AND ISOLATED TORNADO POTENTIAL
SPREADING NEWD INTO OH DURING THE EVENING...AND POSSIBLY AS FAR EAST
AS WRN PA OVERNIGHT.
...TN VALLEY....SOUTH AND SOUTHEAST...
EXTENSIVE SQUALL LINE SHOULD CONTINUE DEVELOPING EWD ACROSS THE
SOUTH THROUGH THE DAY. LAPSE RATES ARE NOT PARTICULARLY STEEP AND
PRE-CONVECTIVE ENVIRONMENT IS NOT EXPECTED TO BECOME HIGHLY UNSTABLE
DUE TO CLOUD COVER. HOWEVER...STRONG LARGE SCALE FORCING FOR ASCENT
IN THE FORM OF 60-90M HEIGHT FALLS PER 12H...MID LEVEL DRY
SLOT...AND INCREASINGLY STRONG TROPOSPHERIC FLOW WILL ALL CONTRIBUTE
TO A CONTINUING SEVERE WIND AND ISOLATED TORNADO THREAT SPREADING
EAST WITH TIME. GREATEST POTENTIAL FOR DAMAGING WINDS FROM BOWING
LINE SEGMENTS...AND POSSIBLY EMBEDDED TORNADIC SUPERCELLS...WILL
EXIST FROM CNTRL/WRN AL INTO WRN GA DURING THE AFTERNOON WHERE
RICHER BOUNDARY LAYER MOISTURE AND GREATER DESTABILIZATION IS
POSSIBLE.
ISOLATED ACTIVITY...POSSIBLY SUPERCELLS...COULD DEVELOP ACROSS PARTS
OF ERN SC/NC WELL AHEAD OF THE LARGER SCALE SQUALL LINE AS LOW LEVEL
FLOW BACKS AND TRANSPORTS GULF STREAM AIRMASS INLAND. WHILE VERTICAL
SHEAR IS FORECAST TO STRENGTHEN WITH TIME ACROSS THESE
AREAS...FORECAST SOUNDINGS DEPICT A MID LEVEL WARM LAYER WHICH MAY
TEMPER UPDRAFT STRENGTH THUS LIMITING SEVERE POTENTIAL.
