SPC AC 201939
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0239 PM CDT TUE MAY 20 2008
VALID 202000Z - 211200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF SRN VA...THE
CAROLINAS...TN...GA AND AL...
...SRN VA/CAROLINAS/TN/GA AND AL...
THE LATEST WATER VAPOR IMAGERY SHOWS A BROAD UPPER-LEVEL TROUGH OVER
THE CNTRL AND SRN APPALACHIAN MTNS WITH ABUNDANT MID-LEVEL MOISTURE
OVER THE CAROLINAS AND GA. AT THE SFC...A 995 MB SFC LOW IS LOCATED
JUST OFFSHORE FROM SRN MD AND A COLD FRONT EXTENDS WSWWD ACROSS SRN
VA INTO NRN NC. A LINE OF THUNDERSTORMS IS LOCATED ALONG THE
BOUNDARY AND STORM COVERAGE SHOULD INCREASE OVER THE NEXT FEW HOURS
WSWWD INTO ACROSS NC INTO WRN SC. A LARGE LINEAR MCS APPEARS LIKELY
TO DEVELOP ALONG THE COLD FRONT THIS EVENING IN SRN NC AND SC WITH
THE LINE MOVING SSEWD INTO THE WRN ATLANTIC. THIS IDEA IS SUPPORTED
BY THE LATEST MODEL RUNS OF THE GFS...NAM AND NAMKF. ADDITIONAL
THUNDERSTORMS SHOULD INITIATE ACROSS NRN AL AND NRN GA AND MOVE SWD
AHEAD OF THE APPROACHING COLD FRONT LATE THIS AFTERNOON INTO EARLY
THIS EVENING.
CONCERNING THE SEVERE POTENTIAL...THE LATEST RUC ANALYSIS SHOW
STRONG VERTICAL SHEAR PROFILES IN PLACE ACROSS THE ENTIRE SLIGHT
RISK AREA. IN ADDITION...FORECAST SOUNDINGS SHOW VEERED SFC WINDS
WITH UNIDIRECTIONAL WLY WINDS IN THE LOWER TO MID-LEVELS. THIS
COMBINED WITH A FAST ELY STORM MOTION SUGGESTS WIND DAMAGE WILL BE
LIKELY WITH THE STRONGER CELL ELEMENTS EMBEDDED IN THE LINE. A FEW
VERY STRONG WIND GUSTS ABOVE 65 KT MAY OCCUR WITH BOWING SEGMENTS IN
THE LINE ACROSS ERN NC AND NRN SC. THE THERMODYNAMIC ENVIRONMENT
ALSO APPEARS FAVORABLE FOR LARGE HAIL. ACCORDING TO OBJECTIVE
ANALYSIS...MID-LEVEL LAPSE RATES EXCEED 7.0 C/KM FROM SRN NC WSWWD
ACROSS CNTRL GA AND CNTRL AL. THIS COMBINED WITH THE STRONG VERTICAL
SHEAR AND MODERATE TO STRONG INSTABILITY MAY BE SUFFICIENT FOR A FEW
SUPERCELLS WITH VERY LARGE HAIL.
...HIGH PLAINS AND NRN ROCKIES...
AN UPPER-LEVEL TROUGH WILL MOVE ONSHORE ACROSS THE WEST COAST TODAY
AS AN UPPER-LEVEL RIDGE MOVES EWD FROM THE ROCKIES INTO THE HIGH
PLAINS. AT THE SFC...A TROUGH WILL ORGANIZE FROM WCNTRL MT SSEWD
ACROSS WY INTO CO. INCREASING LARGE-SCALE ASCENT ACROSS WRN MT WILL
SUPPORT SCATTERED THUNDERSTORM DEVELOPMENT BY EARLY EVENING. FURTHER
SSEWD...LIMITED LARGE-SCALE ASCENT SHOULD KEEP THUNDERSTORM
DEVELOPMENT ISOLATED FROM ERN WY SWD ACROSS ECNTRL CO.
CONCERNING THE SEVERE POTENTIAL...SFC OBSERVATIONS SHOW A DRY
BOUNDARY LAYER ALONG THE SFC TROUGH WITH DEWPOINTS MAINLY FROM THE
MID 30S TO THE MID 40S F. TEMPS IN THE 70S F WILL CREATE LARGE
TEMP-DEWPOINT SPREADS RESULTING IN HIGH STORM BASES. IN SPITE OF THE
DRY AIR...FORECAST SOUNDINGS SHOW ENOUGH VERTICAL SHEAR FOR ISOLATED
SUPERCELL DEVELOPMENT. THE DRY AIR MAY EVEN ENHANCE THE WIND GUST
POTENTIAL WITH THE STRONGER CELLS. HAIL WILL ALSO BE POSSIBLE
ESPECIALLY WHERE INSTABILITY BECOMES MAXIMIZED LATE THIS AFTERNOON.
..BROYLES.. 05/20/2008
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
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