Categorical Graphic
Probabilistic 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 171730
   
   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1230 PM CDT WED OCT 17 2012
   
   VALID 181200Z - 191200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS THUR INTO THUR EVE ACROSS PARTS
   OF THE LOWER GREAT LAKES AND UPPER OHIO VALLEY SOUTHWARD THROUGH THE
   SOUTHERN MID ATLANTIC COAST STATES...
   
   ...SYNOPSIS...
   A BROAD AND DEEP MID-LEVEL CYCLONE STILL APPEARS LIKELY TO FORM OVER
   THE CENTRAL U.S. LATER TODAY THROUGH TONIGHT...BECOMING CENTERED
   OVER THE UPPER MISSISSIPPI VALLEY BY 12Z THURSDAY.  ALTHOUGH MODELS
   SUGGEST THIS FEATURE MAY BEGIN AN EASTWARD/NORTHEASTWARD
   ACCELERATION LATE THURSDAY NIGHT INTO FRIDAY...AS ANOTHER STRONG MID
   LATITUDE PACIFIC UPPER JET BEGINS TO NOSE INTO THE PACIFIC
   NORTHWEST...MOVEMENT THROUGH MUCH OF THIS PERIOD IS EXPECTED TO BE
   IN RESPONSE TO SHORT WAVE IMPULSES PIVOTING AROUND THE CIRCULATION
   CENTER.  VARIABILITY EXISTS AMONG THE MODELS CONCERNING THESE
   SMALLER SCALE FEATURES...BUT...IN GENERAL...IT APPEARS LIKELY THAT
   ONE IMPULSE WILL BE IN THE PROCESS OF PIVOTING NORTHWARD THROUGH THE
   UPPER OHIO VALLEY/LOWER GREAT LAKES REGION EARLY THURSDAY...FOLLOWED
   BY AT LEAST ONE MORE SIGNIFICANT IMPULSE THROUGH THE CENTRAL
   APPALACHIANS/UPPER OHIO VALLEY DURING THE AFTERNOON AND EVENING.
   
   IN LOWER LEVELS...AN ASSOCIATED SURFACE CYCLONE IS EXPECTED TO
   GRADUALLY OCCLUDE AND WEAKEN OVER THE UPPER MISSISSIPPI VALLEY...
   WHILE THE COLD FRONT SLOWLY APPROACHES AND ADVANCES ACROSS THE
   APPALACHIANS.  IN THE WAKE OF SURFACE RIDGING SHIFTING EAST OF THE
   ATLANTIC SEABOARD...GUIDANCE IS SUGGESTIVE THAT SUBSTANTIVE
   PRE-FRONTAL RETURN FLOW OF MOISTURE FROM THE GULF OF MEXICO MAY BE
   INITIALLY CUT-OFF...ACROSS THE EASTERN GULF STATES.  EVENTUALLY...
   THOUGH...MODEST MOISTENING MAY OCCUR ON SOUTHERLY LOW-LEVEL FLOW
   THROUGH MUCH OF THE SOUTHERN AND MID ATLANTIC SEABOARD BY LATE
   THURSDAY NIGHT.
   
   ...WESTERN SLOPES OF THE APPALACHIANS INTO ATLANTIC SEABOARD...
   IN ADVANCE OF THE LEADING EDGE OF THE MID-LEVEL COLD POOL ASSOCIATED
   WITH THE CLOSED LOW...WHICH MAY NOT REACH ATLANTIC COASTAL AREAS
   UNTIL THE END OF THE PERIOD...OR LATER...MODEST MOISTURE RETURN AND
   WEAK MID-LEVEL LAPSE RATES ARE EXPECTED TO LIMIT DESTABILIZATION. 
   IN FACT...ACROSS THE LOWER GREAT LAKES AND UPPER OHIO VALLEY
   REGION...LOW-LEVEL MOISTENING MAY REMAIN MARGINAL AT BEST FOR
   SIGNIFICANT CONVECTIVE DEVELOPMENT.  BUT STRONG FORCING FOR UPWARD
   VERTICAL MOTION MAY BECOME SUFFICIENT TO SUPPORT A LOW TOPPED LINE
   OF STORMS IN THE PRESENCE OF 30-50 KT SOUTHWESTERLY LOWER/MID
   TROPOSPHERIC MEAN WIND FIELDS.  WHILE THE EXTENT OF LIGHTNING
   POSSIBLE WITH THIS ACTIVITY REMAINS UNCLEAR...POTENTIAL CERTAINLY
   APPEARS TO EXISTS FOR CONVECTIVELY ENHANCED SURFACE GUSTS CAPABLE OF
   PRODUCING DAMAGE.
   
   FARTHER SOUTH...ALONG AND TO THE EAST OF THE CENTRAL AND SOUTHERN
   APPALACHIANS...MODELS ARE MORE UNCLEAR CONCERNING THE STRENGTH AND
   POSSIBLE TIMING OF STRONGER PRE-FRONTAL FORCING FOR UPWARD VERTICAL
   MOTION.  HOWEVER...MOISTURE WILL BE MORE FAVORABLE FOR VIGOROUS
   CONVECTIVE DEVELOPMENT...AND AT LEAST NAM/SREF ARE SUGGESTIVE THAT
   THIS COULD OCCUR DURING AFTERNOON/EARLY EVENING HOURS...PARTICULARLY
   ACROSS PARTS OF THE WESTERN CAROLINAS AND SOUTHWEST INTO CENTRAL
   VIRGINIA.  DAMAGING WINDS WITH A POSSIBLE SQUALL LINE APPEARS THE
   PRIMARY SEVERE WEATHER THREAT AT THE PRESENT TIME.
   
   ..KERR.. 10/17/2012
   
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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z