SWODY2
SPC AC 121726
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1226 PM CDT WED OCT 12 2011
VALID 131200Z - 141200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MODELS INDICATE THAT A BELT OF STRONG FLOW WILL PERSIST ON THE
NORTHERN PERIPHERY OF BROAD UPPER RIDGING EXTENDING FROM THE EASTERN
PACIFIC INTO THE INTERMOUNTAIN WEST AND ROCKIES. AND A SERIES OF
SHORT WAVE IMPULSES EMERGING FROM THIS JET WILL CONTINUE TO DIG INTO
LARGER-SCALE TROUGH OVER THE CENTRAL AND EASTERN UNITED STATES.
ONE OF THE MORE SIGNIFICANT IMPULSES IS PROGGED TO DIG INTO THE
EASTERN GULF STATES BY EARLY THURSDAY...BEFORE TURNING
EASTWARD...THEN GRADUALLY TAKING ON A NEGATIVE TILT ACROSS THE SOUTH
ATLANTIC COAST STATES AS IT BEGINS TO LIFT NORTHEASTWARD LATE IN THE
PERIOD...AHEAD OF ANOTHER SIGNIFICANT IMPULSE DIGGING ACROSS THE
UPPER MISSISSIPPI VALLEY. PRECEDING THE FORMER FEATURE...GUIDANCE
IS SUGGESTIVE THAT A WEAKER IMPULSE MAY LIFT OUT OF THE BASE OF THE
EASTERN TROUGH THROUGH THE SOUTHERN AND MID ATLANTIC COAST STATES
DURING THE DAY THURSDAY...ENHANCING UPPER DIVERGENCE WITHIN A
BROADER SCALE DIFLUENT REGIME DOWNSTREAM OF THE LARGE-SCALE TROUGH
AXIS.
FAVORABLE MID/UPPER FORCING FOR ASCENT...AND RESIDUAL LOW-LEVEL
MOISTURE ALONG AND AHEAD OF AN ASSOCIATED OCCLUDING SURFACE LOW AND
FRONT...PARTICULARLY TO THE EAST OF THE APPALACHIANS...ARE EXPECTED
TO SUPPORT CONSIDERABLE THUNDERSTORM ACTIVITY DURING THIS PERIOD.
HOWEVER...IT APPEARS THAT MID-LEVEL LAPSE RATES WILL NOT STEEPEN
SUFFICIENTLY TO SUPPORT MUCH BEYOND WEAK DESTABILIZATION...WITH
CONSIDERABLE EARLY DAY CLOUD COVER ALSO SLOWING DAYTIME HEATING.
WITH GENERALLY WEAK LOW-LEVEL FLOW FIELDS ALSO A LIMITING
FACTOR...THE RISK FOR SEVERE STORMS REMAINS SOMEWHAT UNCERTAIN...AND
SEEMS LOW MOST AREAS...WITH PERHAPS THE POSSIBLE EXCEPTION OF
PORTIONS OF THE SOUTHERN MID ATLANTIC COAST STATES.
...CNTRL/ERN NORTH CAROLINA INTO SRN VIRGINIA...
SOME GUIDANCE...THE NAM IN PARTICULAR...HAS BEEN INCREASINGLY
SUGGESTIVE OF A STRONGER LEAD IMPULSE LIFTING OUT OF THE BASE OF THE
EASTERN TROUGH...TO THE LEE OF THE SOUTHERN APPALACHIANS... DURING
THE DAY THURSDAY. IT APPEARS THAT THIS COULD BE ACCOMPANIED BY A
500 MB SPEED MAXIMUM IN EXCESS OF 50 KT...AND STRENGTHENING OF
SOUTHERLY 850 MB FLOW FIELDS IN EXCESS OF 30 KT ACROSS PARTS OF THE
PIEDMONT AND COASTAL PLAIN BY PEAK AFTERNOON HEATING. GIVEN THE
POTENTIAL FOR SIZABLE CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS...STRONG
DEEP LAYER SHEAR...AND A LINGERING MOIST BOUNDARY LAYER
CHARACTERIZED BY MID/UPPER 60S DEW POINTS... IT DOES NOT APPEAR OUT
OF THE QUESTION THAT THE ENVIRONMENT COULD BECOME CONDUCIVE FOR
SUPERCELLS WITH A RISK FOR TORNADOES. UNCERTAINTY REMAINS TOO LARGE
FOR SLIGHT RISK PROBABILITIES AT THE PRESENT TIME...BUT THIS COULD
CHANGE IN FORTHCOMING OUTLOOKS FOR THIS TIME PERIOD.
..KERR.. 10/12/2011
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