SPC AC 091628
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1128 AM CDT THU SEP 09 2010
   
   VALID 091630Z - 101200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY
   TONIGHT FOR THE NRN HIGH PLAINS...
   
   ...NRN HIGH PLAINS THIS AFTERNOON INTO EARLY TONIGHT...
   NO SUBSTANTIAL CHANGES TO THE PRIOR OUTLOOK AREA AND REASONING.  A
   HIGH-AMPLITUDE TROUGH WILL MOVE EWD FROM THE NRN ROCKIES/GREAT BASIN
   TO THE NRN HIGH PLAINS BY EARLY FRIDAY.  THE MIDLEVEL TROUGH WILL BE
   PRECEDED BY A LEE CYCLONE THAT WILL DEVELOP NEWD FROM SE MT TO WRN
   ND...WHILE S OF THE CYCLONE A LEE TROUGH WILL MOVE SLOWLY EWD THIS
   EVENING ACROSS THE NRN AND CENTRAL HIGH PLAINS.  BOUNDARY LAYER
   DEWPOINTS IN THE LOW-MID 60S ARE RETURNING NNWWD IN A CORRIDOR FROM
   NEB TOWARD WRN ND TO THE E OF THE LEE TROUGH AND S OF A WARM
   FRONT...AND BENEATH A PLUME OF 7-7.5 C/KM MIDLEVEL LAPSE RATES. 
   WITH ADDITIONAL SURFACE HEATING THROUGH THE AFTERNOON... MLCAPE
   VALUES WILL LIKELY INCREASE TO THE 1000-2000 J/KG RANGE... WITH
   MINIMAL CONVECTIVE INHIBITION BY LATE AFTERNOON ALONG THE LEE
   TROUGH.
   
   THUNDERSTORM DEVELOPMENT IS EXPECTED BY 21-23Z NEAR THE SURFACE LOW
   CLOSE TO THE MT/ND BORDER...AND SWD ALONG THE LEE TROUGH NEAR THE
   WY/SD BORDER.  DEEP-LAYER VERTICAL SHEAR AND INSTABILITY WILL BE
   FAVORABLE FOR SUPERCELLS AND ORGANIZED LINE SEGMENTS...WITH AN
   ACCOMPANYING RISK FOR LARGE HAIL AND DAMAGING WINDS.  A COUPLE OF
   TORNADOES WILL ALSO BE POSSIBLE THIS EVENING...PRIMARILY ACROSS NW
   SD/SW ND IN PROXIMITY TO THE WARM FRONT WHERE THE INITIAL STORMS
   WILL BE SUPERCELLULAR AND SOMEWHAT STRONGER LOW-LEVEL SHEAR WILL
   CORRESPOND WITH THE LOW-LEVEL MOISTURE/INSTABILITY AXIS.  THE SEVERE
   STORM THREAT WILL BEGIN TO DIMINISH TONIGHT TOWARD THE CENTRAL
   DAKOTAS. 
   
   ...CENTRAL/NRN AR THIS AFTERNOON...
   THE REMNANTS OF TROPICAL DEPRESSION HERMINE ARE MOVING ENEWD FROM NE
   OK/SE KS TO NW AR AND SW MO...ALONG AND N OF SURFACE WARM FRONT NEAR
   I-40 ACROSS AR.  SURFACE-BASED STORMS CAN BE EXPECTED NEAR THE
   INTERSECTION OF THE WARM FRONT AND THE PRIMARY CONFLUENCE BAND WHICH
   EXTENDS FROM SE OK INTO NW AR...WHICH ALSO COINCIDES WITH THE BELT
   OF STRONGER LOW-LEVEL SLY/SWLY FLOW AND EFFECTIVE SRH IN EXCESS OF
   200 M2/S2.  THERE WILL BE A WINDOW OF OPPORTUNITY FOR A FEW ROTATING
   STORMS THIS AFTERNOON...AND PERHAPS A BRIEF TORNADO ...ALONG THE
   WARM FRONT WITH THE REMNANTS OF HERMINE...BEFORE THE SYSTEM WEAKENS
   AND THE BOUNDARY LAYER STABILIZES BY LATE EVENING.  AT THIS
   TIME...THE TORNADO THREAT APPEARS TO BE REDUCED A LITTLE FROM PRIOR
   DAYS...SO WILL MAINTAIN 2% TORNADO PROBABILITY AREA.
   
   ..THOMPSON/ROGERS.. 09/09/2010
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z