SWODY2
SPC AC 261711
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1111 AM CST MON DEC 26 2011
VALID 271200Z - 281200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER SERN GA...THE ERN
CAROLINAS AND EXTREME SERN VA...
...SYNOPSIS...
LATEST WATER VAPOR IMAGERY SHOWS UPPER LOW OVER W TX BEGINNING TO
MOVE EWD IN RESPONSE TO UPPER SHORT WAVE TROUGH PROGRESSING EWD
ACROSS THE NRN PLAINS. MODELS INDICATE THE UPPER LOW WILL OPEN INTO
A NEWD MOVING SHORT WAVE TROUGH OVER THE LOWER MS VALLEY LATE
TONIGHT. THIS SYSTEM IS FORECAST TO DEAMPLIFY AS IT CONTINUES NEWD
ACROSS THE CENTRAL APPALACHIANS AND NERN STATES TOMORROW...WHILE THE
CURRENT NRN PLAINS TROUGHS DIGS ESEWD TOWARD THE ATLANTIC COAST
IMMEDIATELY IN THE WAKE OF THE FIRST SYSTEM.
AT THE SURFACE...INCREASING PRESSURE FALLS WILL SPREAD EWD ACROSS
THE ERN STATES IN THE WAKE OF THE RETREATING HIGH CURRENTLY CENTERED
OVER THE CENTRAL APPALACHIANS. A COMPLEX SERIES OF LOW CENTERS
ASSOCIATED WITH THE AFOREMENTIONED UPPER TROUGHS ARE FORECAST OVER
THE ERN STATES. A SRN LOW OVER THE TN VALLEY AT 27/12Z IS EXPECTED
TO MOVE NEWD ALONG THE LEE OF THE APPALACHIANS REACHING THE DELMARVA
REGION BY 28/00Z...BEFORE CONSOLIDATING WITH THE NRN LOW AND
DEEPENING OVER THE NERN STATES TOMORROW NIGHT. A RAPIDLY MOVING
COLD FRONT WILL SURGE EWD ACROSS THE SERN STATES AND MIDDLE/SRN
ATLANTIC COAST BY EVENING...WHILE A WARM FRONT LIFTS NWD ALONG THE
SRN ATLANTIC COAST DURING THE DAY. STRONG DYNAMIC FORCING FOR LARGE
SCALE ASCENT COUPLED WITH MESOSCALE CONVERGENCE ALONG THE COLD FRONT
AND VERY STRONG LOW- AND DEEP-LAYER VERTICAL SHEAR WILL SUPPORT A
RISK FOR STRONG/SEVERE STORMS...BUT WEAK LAPSE RATES AND MINIMAL
INSTABILITY ARE EXPECTED TO LIMIT THE OVERALL SEVERE THREAT.
...NRN FL/SRN GA...ERN CAROLINAS INTO EXTREME SERN VA...
STRONG THUNDERSTORMS ARE EXPECTED TO BE ONGOING AT THE START OF THE
PERIOD OVER PARTS OF NWRN FL AND SWRN GA ALONG/AHEAD OF THE COLD
FRONT. THIS ACTIVITY IS EXPECTED TO SHIFT EWD ACROSS NRN FL AND
GRADUALLY WEAKEN BY MID/LATE MORNING AS IT MOVES INTO A LESS
UNSTABLE AIR MASS. HOWEVER...LOW LEVEL MOISTURE IN ADVANCE OF THE
FRONT WILL BE AUGMENTED BY AN INFLUX OF ATLANTIC MOISTURE AS A VERY
STRONG /60-70 KT/ 850 MB JET INTENSIFIES AND LIFTS NEWD FROM GA
ACROSS THE CAROLINAS AND ERN VA DURING THE DAY...WITH 60-64F SURFACE
DEW POINTS SPREADING INTO SERN GA AND THE ERN CAROLINAS. OVERALL
INSTABILITY WILL BE TEMPERED BY INTENSE SYNOPTIC SCALE ASCENT/NEAR
MOST-ADIABATIC LAPSE RATES...WITH MLCAPE VALUES GENERALLY AOB 500
J/KG. HOWEVER...A FEW BREAKS IN CLOUD COVER FROM SERN GA INTO THE
ERN CAROLINAS MAY PERMIT AREAS OF LOCALLY STRONGER DIURNAL
DESTABILIZATION TO OCCUR INTO THE AFTERNOON.
THERE WILL BE POTENTIAL FOR LOW TOP STORMS TO INTENSIFY BY MID-LATE
MORNING INTO THE AFTERNOON...WITH CONVECTION POSSIBLY DEVELOPING
INTO SHORT LINE SEGMENTS. THE VERY STRONG VERTICAL SHEAR ALSO MAY
SUPPORT EMBEDDED ROTATING STRUCTURES...WITH A THREAT FOR DAMAGING
WIND GUSTS ASSOCIATED WITH RAPIDLY MOVING LINE SEGMENTS AND ISOLATED
SUPERCELLS. THERE WILL ALSO BE POTENTIAL FOR A FEW BRIEF
TORNADOES...ESPECIALLY OVER THE ERN CAROLINAS WHERE LOW LEVEL
MOISTURE WILL BE GREATER. THE SEVERE THREAT IS EXPECTED TO END BY
LATE AFTERNOON/EVENING FROM THE WEST AS THE COLD FRONT MOVES
OFFSHORE.
..WEISS.. 12/26/2011
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