172 
ACUS01 KWNS 131959
SWODY1
SPC AC 131957

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0157 PM CST SAT MAR 13 2010

VALID 132000Z - 141200Z

...NO SVR TSTM AREAS FORECAST...

...NC/VA INTO THE EVENING...
THE 5 PERCENT HAIL PROBABILITY HAS BEEN REDUCED IN AREAL COVERAGE
AND NOW EXTENDS FROM NERN NC INTO SERN VA.  TRENDS IN SURFACE
OBSERVATIONS INDICATED DEWPOINTS HAVE BEEN FALLING TODAY AS SWLY
WINDS ADVECT A DRIER CP AIR MASS INTO THIS REGION...WITH VALUES IN
THE MID 50S NOW CONFINED TO NERN NC TO ERN VA/DELMARVA.  DESPITE
CONTINUED COOLING OF MID LEVEL TEMPERATURES WITH THE APPROACH OF THE
LARGE CLOSED LOW...NOW CENTERED OVER NRN AL/SRN MIDDLE TN...GREATER
INSTABILITY VALUES SHOULD BE CONFINED TO NERN NC/SERN VA WHERE
STRONGER SURFACE HEATING AND DEWPOINTS RESIDE. THE LEADING EDGE OF
STRONGER ASCENT ATTENDANT TO A SHORTWAVE TROUGH TRACKING NEWD FROM
GA/SC MAY SUPPORT NEW TSTM DEVELOPMENT INTO NERN NC/SERN VA LATER
THIS AFTERNOON.  AS FORECAST EARLIER...THE COLD TEMPERATURES ALOFT
AND MODEST INSTABILITY COULD SUPPORT ISOLATED STORMS WITH HAIL NEAR
THE 1 INCH CRITERION.

..PETERS.. 03/13/2010

.PREV DISCUSSION... /ISSUED 1015 AM CST SAT MAR 13 2010/

...SYNOPSIS...
TWO PRIMARY SYNOPTIC SYSTEMS WILL AFFECT THE CONUS THIS PERIOD -- A
BROAD CLOSED LOW WILL MOVE EWD FROM THE MID SOUTH TO THE
CAROLINAS...AND AN UPSTREAM SHORTWAVE TROUGH WILL PROGRESS ESEWD
FROM THE GREAT BASIN TO THE FOUR CORNERS.  THE LATTER WAVE WILL BE
ACCOMPANIED BY CONDITIONALLY UNSTABLE LAPSE RATES AND A FEW
THUNDERSTORMS IN THE LEFT EXIT REGION OF THE MID-UPPER JET. 
HOWEVER...THE THREAT FOR DAMAGING WINDS APPEARS TO BE MINIMAL GIVEN
VERY WEAK INSTABILITY WITH MARGINAL LOW-MIDLEVEL MOISTURE. 
ADDITIONALLY...THE POTENTIAL FOR MOMENTUM TRANSFER WILL BE LIMITED
BY MEAN LOW-LEVEL FLOW AOB 25 KT THIS AFTERNOON IN THE AREA OF
EXPECTED THUNDERSTORM DEVELOPMENT.

...NC/VA THIS AFTERNOON/EVENING...
THE CLOSED LOW CENTERED OVER WRN TN AS OF MID MORNING WILL CONTINUE
EWD TO CAROLINAS THIS EVENING/TONIGHT.  RESIDUAL BOUNDARY LAYER
DEWPOINTS IN THE LOW-MID 50S...DAYTIME HEATING...AND COOLING MID
LEVEL TEMPERATURES /NEAR -24 C AT 500 MB/ WILL CONTRIBUTE TO THE
DEVELOPMENT OF SBCAPE VALUES ON THE ORDER OF 500-1000 J/KG THIS
AFTERNOON ACROSS NC/SRN VA.  THUNDERSTORM DEVELOPMENT WILL BE
FOCUSED THIS AFTERNOON IN NC AS AN EMBEDDED SPEED MAX PIVOTS NEWD
FROM GA...WITH CONVECTION EXPECTED TO SPREAD NEWD TO SRN VA THIS
EVENING.  THOUGH VERTICAL SHEAR WILL WEAKEN WITH TIME IN PROXIMITY
TO THE MID LEVEL LOW...THE COLD TEMPERATURES ALOFT AND MODEST
INSTABILITY COULD SUPPORT ISOLATED STORMS WITH HAIL NEAR THE 1 INCH
CRITERION.