Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS02 KWNS 051747
SWODY2
SPC AC 051732

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
ISSUED BY 15TH OWS SCOTT AIR FORCE BASE IL
1132 AM CST THU DEC 05 2013

VALID 061200Z - 071200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
A STRONG SHORTWAVE TROUGH/IMPULSE NOW ENTERING THE BASE OF A LARGER
SCALE POSITIVE-TILT TROUGH AXIS ACROSS WRN/SWRN U.S. IS FORECAST TO
DE-AMPLIFY AND ACCELERATE ENEWD FROM THE PLAINS TO MIDWEST THROUGH
EARLY FRIDAY. ONLY GRADUAL/WEAK HEIGHT FALLS ARE ANTICIPATED ACROSS
THE LOWER MS VALLEY AND GULF COAST THROUGH THE PERIOD AHEAD OF A
QUASI-STATIONARY FRONT THAT WILL SEPARATE A MARITIME TROPICAL
AIRMASS ACROSS THE SOUTH AND SOUTHEAST FROM A MUCH COLDER
CONTINENTAL POLAR AIRMASS DOMINATING MOST OF THE REST OF THE NATION.

SIMILAR TO THE DAY 1 PERIOD...A CORRIDOR OF LOW PROBABILITY BUT
NON-ZERO SEVERE TSTM POTENTIAL SHOULD PERSIST ALONG AND IMMEDIATELY
AHEAD OF THE TIGHT LOW LEVEL BAROCLINIC ZONE THAT DEFINES THE
QUASI-STATIONARY FRONT FROM DELTA REGION NEWD TO SRN APPALACHIANS.

...MS DELTA INTO NRN GA/ERN TN...
DEEP-LAYER ASCENT WITHIN/BENEATH RIGHT ENTRANCE REGION OF
STRENGTHENING MID-LEVEL JET IS FORECAST TO SPREAD NEWD FROM THE
MIDDLE/LOWER MS VALLEY TO OH VALLEY THROUGH THE DAY. THIS WILL
LIKELY MAINTAIN EXTENSIVE PRECIPITATION SHIELD ON THE COLDER SIDE OF
THE STALLED FRONT AND A MODEST WARM/MOIST CONVEYOR BELT FROM THE
GULF/SERN LA TO THE SRN APPALACHIANS WHERE SURFACE DEWPOINTS SHOULD
BE IN THE LOW-MID 60S F. A WEAK WAVE WILL DEVELOP ALONG THE FRONT
AND MOVE RAPIDLY TO THE NE AND WILL SERVE AS THE FOCAL POINT FOR ANY
SEVERE POTENTIAL. ALTHOUGH MLCAPE VALUES HAVE DECREASED IN THE RANGE
OF 500-750 J/KG, THERE WILL BE A WINDOW IN THE LATE MORNING/MIDDAY
WHERE THIS AXIS OF MLCAPES WILL COINCIDE WITH THE DEVELOPING WAVE
AND VERTICAL SHEAR OF 40-50KT TO SUPPORT THE POTENTIAL FOR AN
ORGANIZED STORM OR TWO AND POSSIBLY EVEN A TORNADO. PRIMARY LIMITING
FACTORS AT THIS TIME CONTINUE TO BE THE LACK OF STRONGER UPWARD
FORCING ACROSS THE REGION AND GENERALLY WEAK LAPSE RATES LIMITING
STORM UPDRAFT STRENGTH AND PERSISTENCE.

..15_OWS.. 12/05/2013
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