Sep 9, 2010 2000 UTC Day 1 Convective Outlook
Updated: Thu Sep 9 23:32:46 UTC 2010
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20100909 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20100909 2000 UTC Day 1 Tornado Probabilities Graphic
Torndao Legend Image
Probabilistic Damaging Wind Graphic
20100909 2000 UTC Day 1 Damaging Wind Probabilities Graphic
Wind Legend Image
Probabilistic Large Hail Graphic
20100909 2000 UTC Day 1 Large Hail Probabilities Graphic
Hail Legend Image
   SPC AC 092329
   
   DAY 1 CONVECTIVE OUTLOOK AMEND 1
   NWS STORM PREDICTION CENTER NORMAN OK
   0629 PM CDT THU SEP 09 2010
   
   VALID 092330Z - 101200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS INTO EARLY TONIGHT FOR THE NRN
   HIGH PLAINS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FOR THE MID-SOUTH EARLY THIS
   EVENING...
   
   AMENDED FOR SLIGHT RISK MID-SOUTH
   
   ...MID-SOUTH...
   AMD FOR TORNADO WATCH PARTS OF MID-SOUTH.
   
   ...NRN HIGH PLAINS...
   NO CHANGES NEEDED AS OBJECTIVE ANALYSES SHOWED AIR MASS
   DESTABILIZING ACROSS WRN NEB/SD INTO SERN MT...ALONG AND E OF LEE
   TROUGH AND INVOF DEEPENING SURFACE LOW OVER SERN MT.  EFFECTIVE BULK
   SHEAR IS STRENGTHENING /35-50 KT/ ACROSS THE CENTRAL/NRN HIGH PLAINS
   THIS AFTERNOON AS STRONGER JET CORE ATTENDANT TO ID SHORTWAVE TROUGH
   SPREADS NEWD.
   
   ...CENTRAL ND...
   ONGOING ELEVATED TSTMS /LOCATED N-E OF BIS/ MAY PRODUCE AN ISOLATED
   HAIL THREAT THIS AFTERNOON GIVEN EFFECTIVE BULK SHEAR /30-35 KT/...
   MARGINAL INSTABILITY AND MIDLEVEL LAPSE RATES NEAR 7 C/KM.  THIS
   AREA CONTINUES TO WARRANT LOW SEVERE PROBABILITIES.
   
   ...CENTRAL/NRN AR...
   NO CHANGES NEEDED WITH THIS OUTLOOK MAINTAINING A LOW TORNADO
   PROBABILITY /2 PERCENT/ ACROSS NRN HALF OF AR...WITH GREATEST
   POTENTIAL...THOUGH STILL A LOW THREAT...ACROSS NWRN AR WHERE THE LOW
   LEVEL SW-NE ORIENTED CONFLUENCE ZONE INTERSECTS THE WARM FRONT. 
   SUFFICIENT DEEP LAYER SHEAR SUPPORTING ORGANIZED STORMS RESIDES N/NE
   OF THE WARM FRONT WHICH EARLY THIS AFTERNOON EXTENDED FROM SWRN TN
   WNWWD THROUGH NRN AR TO A WEAKENING SURFACE LOW /ATTENDANT TO TC
   HERMINE/ OVER FAR SERN KS.  HOWEVER...CURRENT LOW LEVEL EFFECTIVE
   SRH /200-300 M2 PER S2/ EXTENDING INTO NWRN AR INVOF THE WARM FRONT
   SUGGESTS A NON-ZERO TORNADO THREAT THROUGH THE AFTERNOON.  FURTHER
   WEAKENING AND VEERING OF THE SWLY LLJ INTO WRN/NRN AR SHOULD REDUCE
   THIS LOW SEVERE WEATHER THREAT BY THIS EVENING. 
   
   ...DOWNEAST MAINE...
   COLD MIDLEVEL TEMPERATURES...ATTENDANT TO CLOSED LOW MOVING ACROSS
   MAINE...COMBINED WITH SURFACE HEATING AND DEWPOINTS IN THE UPPER 50S
   HAS RESULTED IN MARGINAL INSTABILITY IN ADVANCE OF A WIND SHIFT.  A
   FEW LIGHTNING STRIKES REMAIN POSSIBLE YET THIS AFTERNOON...PRIOR TO
   SURFACE BOUNDARY...WHICH CURRENTLY EXTENDED FROM NRN WASHINGTON TO
   LINCOLN COUNTIES...MOVES OFFSHORE.  LIMITED POTENTIAL FOR STRIKES
   AND EXPECTED SHORT DURATION PRECLUDES THE INCLUSION OF A GENERAL
   TSTM AREA FOR THIS REGION.
   
   ..JPR.. 09/09/2010
   
   .PREV DISCUSSION... /ISSUED 1128 AM CDT THU SEP 09 2010/
   
   ...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.
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z