Sep 17, 2012 1730 UTC Day 2 Convective Outlook
Updated: Mon Sep 17 17:32:44 UTC 2012
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20120917 1730 UTC Day 2 Outlook Graphic
Probabilistic Graphic
20120917 1730 UTC Day Probabilitic Graphic
Probability of severe weather within 25 miles of a point.
Hatched Area: 10% or greater probability of significant severe within 25 miles of a point.
   SPC AC 171731
   
   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1231 PM CDT MON SEP 17 2012
   
   VALID 181200Z - 191200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM A PORTION OF THE SERN
   STATES THROUGH THE MID ATLANTIC AND NERN U.S....
   
   ...SYNOPSIS...
   
   SYNOPTIC UPPER PATTERN IS IN THE PROCESS OF AMPLIFICATION...AND THIS
   TREND WILL CONTINUE INTO EARLY TUESDAY. A NRN STREAM UPPER TROUGH
   FROM SCNTRL CANADA INTO THE NRN PLAINS/UPPER MS VALLEY WILL AMPLIFY
   ACROSS THE OH VALLEY AND GREAT LAKES. THIS FEATURE WILL SUBSEQUENTLY
   EJECT NEWD THROUGH THE NERN STATES AND SERN CANADA TUESDAY NIGHT. AS
   NRN BRANCH TROUGH AMPLIFIES...THE SRN STREAM UPPER LOW OVER TX /AS
   WELL AS THE LEAD IMPULSE OVER LA/ WILL SHEAR NEWD AND DEAMPLIFY
   WHILE ACCELERATING INTO THE SRN APPALACHIANS AND THE MID ATLANTIC
   REGION. PRIMARY SFC LOW WILL DEEPEN OVER THE LOWER GREAT LAKES AND
   LIFT NWD INTO QUEBEC WHILE TRAILING COLD FRONT ADVANCES THROUGH THE
   ERN STATES...REACHING THE ATLANTIC SEABOARD LATER TUESDAY NIGHT. A
   WARM FRONT SHOULD LIFT NWD THROUGH THE MID ATLANTIC...REACHING SRN
   NEW ENGLAND BY TUESDAY EVENING.  
   
   
   ...MID ATLANTIC THROUGH PORTIONS OF THE NERN STATES...
   
   IN WAKE OF NWD ADVANCING WARM FRONT...RICH GULF MOISTURE WITH UPPER
   60S TO NEAR 70F DEWPOINTS WILL ADVECT THROUGH WARM SECTOR ALONG
   STRENGTHENING 50+ KT LLJ. WIDESPREAD CLOUDS WITH AREAS OF RAIN AND
   THUNDERSTORMS WILL LIKELY BE ONGOING ALONG WARM CONVEYOR BELT AND
   WITHIN PLUME OF DEEPER SUBTROPICAL MOISTURE...ESPECIALLY IN WRN
   PORTION OF WARM SECTOR. SOME OF THIS ACTIVITY COULD POSE A THREAT OF
   MAINLY ISOLATED DAMAGING WIND FROM THE WRN CAROLINAS INTO WRN VA.
   CLOUDS AND AREAS OF RAIN WILL CONTRIBUTE TO WEAK MID LEVEL LAPSE
   RATES AND INSTABILITY...POSSIBLY SERVING AS A LIMITING FACTOR. THE
   MOST FAVORABLE SHEAR/INSTABILITY PARAMETER SPACE FOR SEVERE STORMS
   IS EXPECTED EVOLVE OVER THE MID ATLANTIC REGION ALONG STRENGTHENING
   LLJ AND WHERE A FEW CLOUD BREAKS WILL PROMOTE AT LEAST MODEST
   BOUNDARY LAYER DESTABILIZATION WITH 500-1000 J/KG MLCAPE POSSIBLE. 
   
   STORMS ARE EXPECTED TO INTENSIFY AS THEY DEVELOP EWD THROUGH THE
   DESTABILIZING WARM SECTOR. MIXED CONVECTIVE MODES ARE LIKELY
   INCLUDING LINES WITH EMBEDDED SUPERCELLS/BOWING SEGMENTS. A FEW
   DISCRETE SUPERCELLS MAY ALSO OCCUR IF SUFFICIENT BOUNDARY LAYER
   WARMING OCCURS. DAMAGING WIND AND A FEW TORNADOES WILL BE THE
   PRIMARY THREATS. THIS REGION WILL CONTINUE TO BE MONITORED FOR A
   POSSIBLE MODERATE RISK IF IT BEGINS TO APPEAR THAT MORE INSTABILITY
   WILL DEVELOP THAN CURRENTLY ANTICIPATED.
   
   ...SERN STATES...
   
   OTHER STORMS WILL LIKELY CONTINUE DEVELOPING IN PRE-FRONTAL WARM
   SECTOR WHERE DEEP SHEAR WILL REMAIN AT LEAST MARGINALLY SUFFICIENT
   FOR ORGANIZED STORMS...BUT LOW LEVEL FLOW/SHEAR WILL BE MUCH WEAKER
   THAN FARTHER NE AS THE LLJ LIFTS INTO THE MID ATLANTIC AREA.
   DEPENDING ON AMOUNT OF CLOUD BREAKS AND DIABATIC WARMING...SOME OF
   THIS ACTIVITY MAY INTENSIFY AND POSE A THREAT OF ISOLATED STRONG TO
   DAMAGING WIND GUSTS.
   
   ..DIAL.. 09/17/2012
   
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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z