Oct 11, 2010 1630 UTC Day 1 Convective Outlook
Updated: Mon Oct 11 16:09:46 UTC 2010
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20101011 1630 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20101011 1630 UTC Day 1 Tornado Probabilities Graphic
Torndao Legend Image
Probabilistic Damaging Wind Graphic
20101011 1630 UTC Day 1 Damaging Wind Probabilities Graphic
Wind Legend Image
Probabilistic Large Hail Graphic
20101011 1630 UTC Day 1 Large Hail Probabilities Graphic
Hail Legend Image
   SPC AC 111606
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1106 AM CDT MON OCT 11 2010
   
   VALID 111630Z - 121200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ERN OK/WRN AR INTO EASTERN
   TX...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF PA AND NJ SWD
   INTO DELMARVA...
   
   ...SYNOPSIS...
   COLD UPPER LOW NCENTRAL KS CONTINUES SLOWLY SEWD INTO NERN OK 12Z
   TUE. AIR MASS REMAINS MOIST IN ADVANCE OF THE LOW ACROSS ERN OK INTO
   WRN AR.  OVERNIGHT MCS NOW WEAKENING OVER NERN TX AND CLEARING IN
   ITS WAKE WILL ALLOW INSTABILITY TO REDEVELOP AHEAD OF UPPER LOW THIS
   AFTERNOON.
   
   STALLED FRONTAL BOUNDARY WNW/ESE ACROSS PA/NJ IN CONFLUENT FLOW
   BETWEEN TROUGH DROPPING SEWD FROM GREAT LAKES AND WESTERLIES IN SRN
   BRANCH ACROSS THE MID ATLANTIC STATES.  STEEP LAPSE RATES...MDT
   SHEAR AND INSTABILITY SUFFICIENT FOR A SEVERE THUNDERSTORM THREAT
   VICINITY AND JUST S OF FRONTAL ZONE.
   
   ...SRN PLAINS...
   WITH THE CLEARING IN THE WAKE OF THE MCS OVER NERN TX...AND THE COOL
   STEEP LAPSE RATES/7-8C/KM/ IN PLACE IN ADVANCE OF THE UPPER
   LOW...SURFACE HEATING AND NEAR ONE INCH PWAT SHOULD LEAD TO
   SCATTERED THUNDERSTORMS BY MID AFTERNOON.  WHILE MLCAPES WILL BE
   LIMITED WITH AND JUST AHEAD OF THE UPPER LOW ITSELF...FURTHER SE
   ACROSS ERN OK INTO WRN AR BOTH THE INSTABILITY AND SHEAR EXPECTED TO
   SUPPORT A FEW SEVERE THUNDERSTORMS AS MLCAPE CLIMBS TO 1500 J/KG AND
   DEEP LAYER SHEAR FROM 30-40KT WILL BE IN PLACE. PRIMARY THREAT WILL
   BE LARGE HAIL THIS AREA WITH HAIL STILL LIKELY FURTHER N WITH UPPER
   LOW...BUT LESS RISK OF SEVERE.
   
   FURTHER S THE OUTFLOW FROM THE MORNING MCS WILL BE FOCUS FOR RENEWAL
   OF ACTIVE THUNDERSTORMS ERN TO SCENTRAL TX WHERE LOW LEVEL
   MOISTURE...I.E. DEWPOINTS INTO THE LOW/MID 60S...COUPLED WITH LAPSE
   RATES IN EXCESS OF 7C/KM...WILL PROVIDE MDT INSTABILITY.
   
   LOW/MID LEVEL SHEAR WILL BE MARGINAL FOR ORGANIZED STORMS...HOWEVER
   WITH THE LOW LEVEL CONVERGENCE ALONG OUTFLOW
   BOUNDARY...THUNDERSTORMS SHOULD BECOME QUITE ACTIVE BY MID/LATE
   AFTERNOON WITH A FEW SEVERE.  PRIMARY THREAT GIVEN THE LIMITED SHEAR
   WOULD BE LARGE HAIL.
   
   ...PA AND DELMARVA...
   HAVE EXPANDED THE SLIGHT RISK SWD INTO THE DC AREA GIVEN THE
   OBSERVED AIR MASS CHARACTERISTICS ON THE 12Z IAD SOUNDING AND
   CURRENT OBJECTIVE ANALYSES OF THE PRE FRONTAL AIR MASS ACROSS PA
   INTO DELMARVA. OVERALL MOISTURE IS LIMITED...HOWEVER...INCREASED
   DIABATIC WARMING IN THE BOUNDARY LAYER COUPLED WITH 500 MB
   TEMPERATURES COOLING TO -16 TO -17 C WILL CONTRIBUTE TO STEEP LAPSE
   RATES WITH AFTERNOON MLCAPE VALUES APPROACHING 500-1000 J/KG WITH A
   DECREASING CAP.  LATEST MESOSCALE AND CONVECTION-RESOLVING MODEL
   GUIDANCE ARE IN GENERALLY GOOD AGREEMENT IN SUGGESTING THAT
   SURFACE-BASED STORM DEVELOPMENT WILL BECOME INCREASINGLY LIKELY BY
   21Z ALONG THE COLD FRONT OVER WRN AND CNTRL PARTS OF PA.  STORMS
   SHOULD INCREASE IN COVERAGE THROUGH THE REMAINDER OF THE AFTERNOON
   INTO TONIGHT WHILE MOVING/DEVELOPING EWD TO OFF THE NJ COAST.
   PRIMARY THREAT WILL BE WIND DAMAGE AND HAIL AS STORMS EVOLVE INTO
   SHORT LINE SEGMENTS/ BOWS IN THE 40-45KT WLY SHEAR ENVIRONMENT.
   
   FURTHER S THE PRIMARY CONCERN IS STORM INITIATION AS LOW LEVEL
   CONVERGENCE IS WEAK IN WLY FLOW.  A FEW STORMS HOWEVER COULD DEVELOP
   OFF THE HIGHER TERRAIN NRN VA/WRN MD BY PEAK HEATING AND MOVE
   EASTWARD WHERE INSTABILITY AND SHEAR WILL BE FAVORABLE FOR SEVERE
   STORMS.
   
   ..HALES/GARNER.. 10/11/2010
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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