SPC 1200Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1254 AM CDT TUE JUL 30 2013 VALID 301200Z - 311200Z ...THERE IS A SLGT RISK OF SVR TSTMS NRN PLAINS... ...CNTRL AND NRN PLAINS... AN UPPER-LEVEL RIDGE WILL BUILD NWD ACROSS THE INTERMOUNTAIN WEST TODAY AS A SHORTWAVE TROUGH MOVES EWD ACROSS THE NRN HIGH PLAINS. AT THE SFC...A LOW SHOULD DEEPEN AND MOVE SEWD INTO SWRN SD AS A COLD FRONT ADVANCES SWD ACROSS THE NRN HIGH PLAINS. THUNDERSTORMS ARE FORECAST TO DEVELOP FROM THE SFC LOW NWD ACROSS THE WRN DAKOTAS THIS AFTERNOON WITH SEVERAL CLUSTERS OF CONVECTION MOVING SEWD ACROSS THE SLIGHT RISK AREA DURING THE LATE AFTERNOON AND EARLY EVENING. MORE ISOLATED STORM DEVELOPMENT COULD OCCUR SOUTH OF THE SFC LOW ACROSS WRN NEB AND NW KS. FORECAST SOUNDINGS AT 00Z/WED FOR PIERRE AND MOBRIDGE SD SHOW SFC DEWPOINTS IN THE MID TO UPPER 50S F WITH MLCAPE OF 1000 TO 1500 J/KG. THIS COMBINED WITH 50 KT OF DEEP LAYER SHEAR MAY SUPPORT SUPERCELL DEVELOPMENT IF CELLS CAN PREDOMINATELY REMAIN DISCRETE. THE STRONG SHEAR AND STEEP MID-LEVEL LAPSE RATES SHOULD BE FAVORABLE FOR LARGE HAIL WITH THE MORE DOMINANT CELLS. FORECAST SOUNDINGS ALSO SHOW LOW-LEVEL LAPSE RATES AROUND 8.5 C/KM WHICH ALSO MAY BE FAVORABLE FOR DAMAGING WIND GUSTS ESPECIALLY IF A COLD POOL CAN BE GENERATED. ...SRN PLAINS/OZARKS... AN MCS MAY BE LOCATED ACROSS THE ARKLATEX AT THE START OF THE PERIOD. THIS CONVECTIVE SYSTEM SHOULD LEAVE AN OUTFLOW BOUNDARY ACROSS SRN OK EXTENDING EWD INTO WRN AR...ALONG WHICH THUNDERSTORM DEVELOPMENT MAY OCCUR THIS AFTERNOON. FORECAST SOUNDINGS AT 21Z FROM LAWTON OK EWD TO NEAR FT SMITH AR SHOW SFC DEWPOINTS IN THE UPPER 60S TO LOWER 70S F WITH MLCAPE IN THE 2000 TO 2500 J/KG RANGE. THE ABUNDANT LOW-LEVEL MOISTURE IN THE BOUNDARY LAYER COMBINED WITH STEEP LOW-LEVEL LAPSE RATES MAY BE ENOUGH FOR A MARGINAL WIND DAMAGE THREAT WITH CELLS THAT CAN DEVELOP IN SPITE OF THE WARM AIR ALOFT. ...SRN ATLANTIC SEABOARD... AN AXIS OF MODERATE INSTABILITY IS FORECAST TO DEVELOP TODAY FROM SERN GA NEWD INTO ERN SC AND SERN NC. SCATTERED THUNDERSTORMS MAY INITIATE ALONG THIS CORRIDOR THIS AFTERNOON DUE TO SFC HEATING. FORECAST SOUNDINGS AT 21Z FOR CHARLESTON SC SHOW SFC DEWPOINTS IN THE LOWER 70S F WITH SBCAPE NEAR 2000 J/KG. THIS COMBINED WITH STEEP LOW-LEVEL LAPSE RATES MAY BE ENOUGH FOR A MARGINAL WIND DAMAGE THREAT. ..BROYLES/COHEN.. 07/30/2013
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_1200.html
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