Sep 2, 2012 1630 UTC Day 1 Convective Outlook
Updated: Sun Sep 2 16:33:26 UTC 2012
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20120902 1630 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20120902 1630 UTC Day 1 Tornado Probabilities Graphic
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Probabilistic Damaging Wind Graphic
20120902 1630 UTC Day 1 Damaging Wind Probabilities Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Probabilistic Large Hail Graphic
20120902 1630 UTC Day 1 Large Hail Probabilities Graphic
Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
   SPC AC 021629
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1129 AM CDT SUN SEP 02 2012
   
   VALID 021630Z - 031200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE LWR MS AND TN
   VLYS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE NRN PLNS/UPR
   MS VLY...
   
   ...SYNOPSIS...
   ZONAL FLOW WILL PREVAIL FROM THE PAC NW TO THE UPR MS VLY...ON SRN
   FRINGE OF PROGRESSIVE AB/SK UPR LOW. FARTHER S AND E...FLAT RIDGE
   WILL PERSIST FROM AZ/NM INTO THE CNTRL/SRN PLNS AS REMNANT
   CIRCULATION OF ISAAC BECOMES FURTHER ABSORBED WITHIN MODEST W TO NW
   FLOW OVER THE OH/TN VLYS. THE LOW-LVL CENTER OF ISAAC IS OVER FAR SE
   IL ATTM. THE CENTER SHOULD REMAIN JUST ABOUT STNRY OR DRIFT A BIT
   SWD TODAY. OF LIKELY GREATER IMPORTANCE TO SVR WEATHER POTENTIAL IS
   ASSOCIATED LOW-LVL CONFLUENCE ZONE THAT ARCS S THROUGH WRN KY/TN
   INTO NE AR. THIS FEATURE MAY SERVE AS A FOCUS FOR AFTN/EARLY EVE
   TSTMS...SOME OF WHICH COULD BECOME SVR...AS IT ADVANCES SEWD LATER
   TODAY. A CONDITIONAL RISK FOR SVR STORMS ALSO WILL EXIST OVER PARTS
   OF THE NRN PLNS/UPR MS VLY IN ASSOCIATION WITH DISTURBANCES WITHIN
   RELATIVELY FAST WSW FLOW OVER REGION.
   
   ...LWR MS/TN VLYS THIS AFTN INTO TNGT...
   RAOB AND VWP DATA INDICATE THAT BELT OF STRONGEST LOW TO
   MID-TROPOSPHERIC FLOW /WITH 700 MB SPEEDS OF 30-35 KTS/ ASSOCIATED
   WITH FORMER HRCN ISAAC HAS SHIFTED TO SRN SECTOR OF
   SYSTEM...EXTENDING ROUGHLY FROM AR EWD INTO THE TN VLY. THIS
   CONFIGURATION SHOULD REMAIN MORE OR LESS UNCHANGED THROUGH TNGT AS
   ISAAC CONTINUES TO SLOWLY BECOME ABSORBED IN THE WEAK WLYS OVER THE
   E CNTRL U.S.
   
   CLOUDS WILL SOMEWHAT LIMIT HEATING IN THE REGION...ESPECIALLY IN
   MIDDLE TN. NEVERTHELESS...AN AXIS OF RICH LOW-LVL MOISTURE REMAINS
   IN PLACE COINCIDENT WITH THE STRONGER FLOW...AND MID LVL TEMPS HAVE
   COOLED A BIT /500 MB TEMPS AROUND MINUS 4 TO 5 C/ RELATIVE TO RECENT
   DAYS. COUPLED WITH UPLIFT ALONG PREVIOUSLY-MENTIONED CONFLUENCE
   AXIS...SETUP SHOULD EVENTUALLY YIELD A BAND OF SCTD STRONG TO SVR
   STORMS ALONG AND POSSIBLY AHEAD OF THE CONFLUENCE ZONE FROM FAR ERN
   AR EWD INTO PARTS OF TN AND NRN MS/AL. THIS ACTIVITY SHOULD ACHIEVE
   GREATEST COVERAGE/STRENGTH VERY LATE THIS AFTN OR EARLY THIS
   EVE...AND CONTINUE THROUGH EARLY TNGT. IN THE MEANTIME...OTHER TSTMS
   MAY FORM EARLIER THIS AFTN OVER E TN...NE AL...N GA...AND THE SRN
   APPALACHIANS...IN AREA OF STRONGER SFC HEATING AHEAD OF REMNANT
   CONVECTION FROM OVERNIGHT STORMS.
   
   RESIDUAL BAND OF ENHANCED LOW TO MID-LVL FLOW SHOULD BE SUFFICIENT
   TO POSE A RISK FOR SUSTAINED STORMS/SUPERCELLS IN SLGT RISK AREA...A
   FEW OF WHICH COULD CONTAIN LOW-LVL MESOS WITH A TORNADO RISK GIVEN
   RICH LOW-LVL MOISTURE. DMGG WIND ALSO WILL BE POSSIBLE...WITH
   LARGELY UNIDIRECTIONAL CLOUD-LAYER FLOW POSSIBLY FOSTERING THE
   DEVELOPMENT OF SMALL BOWS. THE SVR THREAT SHOULD DIMINISH WITH
   DIURNAL COOLING LATER TNGT.
   
   ...NRN PLNS/UPR MS VLY LATE THIS AFTN INTO TNGT...
   A CONDITIONAL RISK FOR SVR STORMS WILL EXIST OVER PARTS OF THE NRN
   PLNS/UPR MS VLY...WHERE A STRONGLY-CAPPED/MODERATELY-SHEARED
   ENVIRONMENT WILL BE PRESENT DOWNSTREAM FROM UPR IMPULSE SKIRTING SE
   QUADRANT OF AB/SK UPR LOW. THE DISTURBANCE IS OVER WRN NEB/SD
   ATTM...AND SHOULD BE FAVORABLY TIMED TO ASSIST UPLIFT ALONG
   PROGRESSIVE COLD FRONT NOW OVER ERN ND/N CNTRL SD.
   
   NARROW LOW-LVL MOIST AXIS SHOULD LIMIT OVERALL EXTENT/DURATION OF
   SVR THREAT. BUT SUSTAINED UPLIFT SHOULD PROVE SUFFICIENT TO SUPPORT
   AT LEAST WDLY SCTD STORMS ALONG AND AHEAD OF FRONT INTO WRN/NRN MN
   BY LATE IN THE DAY GIVEN LIKELIHOOD FOR FAIRLY STRONG SFC HEATING.
   40-50 KT WSWLY DEEP SHEAR AND PRESENCE OF EML WILL BE FAVORABLE FOR
   SUPERCELLS WITH A RISK FOR HAIL AND HIGH WINDS. SWD DEVELOPMENT OF
   STORMS LIKELY WILL BE LIMITED BY CAP.
   
   ...MID ATLANTIC/CAROLINAS THIS AFTN/EARLY EVE...
   MODERATE TO STRONG SFC HEATING OF VERY MOIST /PW AROUND 2
   INCHES/...MODESTLY-SHEARED ENVIRONMENT MAY YIELD A FEW
   LOOSELY-ORGANIZED CLUSTERS OF STRONG PULSE STORMS FROM THE CNTRL/SRN
   APPALACHIANS TO THE MID ATLANTIC CST THROUGH EARLY EVE. WITH FORCING
   FOR ASCENT REMAINING WEAK...EXPECT THAT DEVELOPMENT WILL BE GOVERNED
   LARGELY BY TERRAIN INFLUENCES AND/OR BAY/SEA BREEZE BOUNDARIES.
   LOCALLY DMGG WIND SHOULD BE THAT MAIN SVR THREAT.
   
   ..CORFIDI/HURLBUT.. 09/02/2012
   
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