DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 150557
SWODY2
SPC AC 150555

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1255 AM CDT FRI MAR 15 2013

VALID 161200Z - 171200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF SRN VA AND NRN
NC...

...CNTRL APPALACHIAN MTNS/NRN NC/SRN VA...
A WEST TO WEST-NORTHWEST FLOW PATTERN WILL BE IN PLACE ACROSS THE
CONUS ON SATURDAY WITH SEVERAL IMPULSES EMBEDDED IN THE FLOW. A
MINOR SHORTWAVE TROUGH IS FORECAST TO MOVE ESEWD FROM THE MID MS
VALLEY INTO THE CNTRL APPALACHIANS ON SATURDAY WITH ANOTHER
SHORTWAVE TROUGH MOVING ACROSS VA. THUNDERSTORMS COULD BE ONGOING
AHEAD OF THE LEADING SHORTWAVE TROUGH ACROSS THE CNTRL APPALACHIANS
SATURDAY MORNING. THIS ACTIVITY SHOULD BE LOCATED NEAR A SFC LOW
MOVING EWD ALONG A QUASI-STATIONARY FRONTAL BOUNDARY. THE MORNING
CONVECTION COULD HAVE A HAIL THREAT DUE TO STEEP MID-LEVEL LAPSE
RATES. HOWEVER...FORECAST SOUNDINGS BEFORE NOON SHOW A SFC INVERSION
SUGGESTING THE CONVECTION WILL BE ELEVATED HELPING TO LIMIT THE WIND
DAMAGE POTENTIAL.

THE TRAILING SHORTWAVE TROUGH IS FORECAST TO MOVE EWD ACROSS THE
OHIO VALLEY INTO THE CNTRL APPALACHIAN MTNS SATURDAY AFTERNOON. SFC
HEATING ALONG THE FRONTAL BOUNDARY ALONG WITH INCREASING LARGE-SCALE
ASCENT SHOULD ALLOW A CLUSTER OF SFC-BASED THUNDERSTORMS TO INITIATE
AND INCREASE IN COVERAGE FROM ERN KY/ERN TN EWD ACROSS SRN VA AND
NRN NC. FORECAST SOUNDINGS AT 21Z AT JACKSON KY AND RICHMOND VA SHOW
ABOUT 1000 J/KG OF SBCAPE WITH 60 TO 65 KT OF DEEP LAYER SHEAR. THIS
ENVIRONMENT SHOULD BE SUPPORTIVE OF AT LEAST AN ISOLATED SEVERE
THREAT. IF STORMS CAN EXHIBIT ROTATION...THEN A THREAT FOR ISOLATED
LARGE HAIL MAY DEVELOP. AS LOW-LEVEL LAPSE RATES STEEPEN...A WIND
DAMAGE THREAT MAY ALSO DEVELOP ACROSS THE REGION. THE MAIN CONCERN
IS INSTABILITY. SFC DEWPOINTS ARE FORECAST TO ONLY BE AROUND 50 F
ALONG THE FRONTAL BOUNDARY. IN SPITE OF THIS FACTOR...A STRONG WIND
FIELD WILL BE PRESENT AND LOW-LEVEL LAPSE RATES WILL BE STEEP DURING
THE AFTERNOON. FOR THESE REASONS...WILL ADD A SMALL SLIGHT RISK AREA
ACROSS SRN VA AND NRN NC.

..BROYLES.. 03/15/2013

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