DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 040555
SWODY1
SPC AC 040553

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1253 AM CDT SUN NOV 04 2012

VALID 041200Z - 051200Z

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON FOR PART OF
ERN/SERN GA...CENTRAL AND ERN SC...AND FAR SERN NC...

...SYNOPSIS...
A RELATIVELY LOW-AMPLITUDE FLOW REGIME CURRENTLY ANALYZED ACROSS THE
LOWER 48 STATES IS EXPECTED TO AMPLIFY THIS FORECAST PERIOD...WITH A
BROAD LONGWAVE TROUGH FORMING E OF THE ROCKIES WHILE AN UPPER RIDGE
BUILDS E INTO THE WRN STATES. A SHORTWAVE TROUGH WILL AMPLIFY SEWD
THROUGH THE OH/TN VALLEYS TODAY...AND THEN TURN EWD REACHING THE MID
ATLANTIC STATES BY 12Z MON. MEANWHILE...AN UPSTREAM TROUGH WILL
AMPLIFY SSEWD ACROSS THE NRN TO CENTRAL PLAINS AIDING IN THE
EVOLUTION OF THE BROAD CENTRAL/ERN U.S. LONGWAVE TROUGH.

AN AREA OF LOW PRESSURE /ATTENDANT TO A LEAD SHORTWAVE TROUGH
CURRENTLY CROSSING THE CENTRAL APPALACHIANS/ SHOULD BE LOCATED OVER
UPSTATE SC/NC AT 12Z TODAY...WITH A COLD FRONT TRAILING SWWD THROUGH
NRN GA TO THE LOWER MS VALLEY. THIS LOW WILL TRACK EWD ALONG A WARM
FRONT REACHING SERN NC BY EARLY AFTERNOON BEFORE MOVING OFFSHORE.
AND...THE COLD FRONT WILL ADVANCE SSEWD THROUGH THE CENTRAL GULF
COAST STATES/GA. MEANWHILE...A SECONDARY FRONTAL WAVE/SURFACE LOW
IS EXPECTED TO DEVELOP BY AFTERNOON OVER CENTRAL/SRN SC ALONG A
LEE/THERMAL TROUGH. THIS TROUGH WILL EXTEND SWD INTO ERN/SERN GA
AND NEWD TO FAR SERN NC. THE GREATEST COVERAGE OF TSTMS IS FORECAST
ACROSS THE SLIGHT RISK AREA DURING THE MID AFTERNOON TO EARLY
EVENING.

...FAR SERN NC/CENTRAL AND ERN SC/PART OF ERN/SERN GA...
ALTHOUGH DEEP WLY WIND FIELDS WILL TEND TO LIMIT THE RETURN OF
GREATER MOISTURE INTO THE WARM SECTOR TODAY...SURFACE DEWPOINTS IN
THE MIDDLE 50S F AND ABOVE NORMAL SURFACE TEMPERATURES ARE EXPECTED
TO RESULT IN MARGINAL-MODERATE INSTABILITY. MLCAPE VALUES BY PEAK
HEATING SHOULD RANGE FROM 500 TO AROUND 1000 J/KG. EFFECTIVE BULK
SHEAR OF 25-35 KT ACROSS THE SLIGHT RISK AREA AND STRAIGHT
HODOGRAPHS GIVEN DEEP WLY WINDS SUGGEST THE POTENTIAL FOR MULTICELLS
AND SUPERCELLS...WITH SPLITTING STORMS POSSIBLE. AN INCREASE IN LOW
LEVEL CONVERGENCE INVOF THE SECONDARY FRONTAL WAVE AND THE LEE
TROUGH...AND AN INCREASE IN UVVS WITHIN A COUPLED MID-UPPER LEVEL
JET STRUCTURE SHOULD SUPPORT TSTM DEVELOPMENT THIS AFTERNOON. THIS
SCENARIO IS SUPPORTED BY THE 00Z NAM/GFS AND 00Z WRF-NMM. THE
AFOREMENTIONED THERMODYNAMICS/DYNAMICS AND STEEP LOW LEVEL LAPSE
RATES SUGGEST DAMAGING WINDS AND HAIL WILL BE THE MAIN THREATS. THE
SEVERE WEATHER POTENTIAL SHOULD DIMINISH THIS EVENING AS THE STORMS
MOVE OFFSHORE AND INSTABILITY WEAKENS.

FARTHER S INTO SRN GA...A FEW STRONGER STORMS WILL BE POSSIBLE WHERE
THE AIR MASS WILL BECOME MODERATELY UNSTABLE...BUT EFFECTIVE BULK
SHEAR SHOULD BE WEAKER...LIMITING THE OVERALL SEVERE WEATHER THREAT.

..PETERS/SMITH.. 11/04/2012

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