Oct 31, 2013 1300 UTC Day 1 Convective Outlook
Updated: Thu Oct 31 12:54:44 UTC 2013 (20131031 1300Z Day 1 shapefile | 20131031 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20131031 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20131031 1300 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
20131031 1300 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
20131031 1300 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.
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 346,096 41,301,437 Indianapolis, IN...Columbus, OH...Memphis, TN...Nashville, TN...Louisville, KY...
   SPC AC 311250

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0750 AM CDT THU OCT 31 2013

   VALID 311300Z - 011200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS WRN GULF COAST TO
   MID-SOUTH...LOWER-MID MS RIVER VALLEY AND LAKE ERIE REGION...

   ...SYNOPSIS...
   MAIN SYNOPTIC-SCALE FEATURE FOR THIS OUTLOOK WILL REMAIN
   WELL-DEFINED TROUGH -- LOCATED INITIALLY FROM ERN DAKOTAS SSWWD
   ACROSS SRN HIGH PLAINS.  TWO EMBEDDED/PRIMARY VORTICITY MAXIMA AND
   RELATED MESOSCALE CIRCULATIONS ALOFT ARE EVIDENT IN MOISTURE CHANNEL
   IMAGERY...
   1. OVER ERN SD AT 31/12Z -- FCST TO MOVE EWD ACROSS UPPER MS VALLEY
   TO WI BY 1/00Z AND ACCELERATE ENEWD ACROSS LH TO NECK OF ONT BY
   1/12Z.
   2. OVER OK PANHANDLE AS 31/12Z...WITH SHORTWAVE TROUGH SWD ACROSS
   MERIDIONAL SEGMENT OF TX/NM BORDER. THIS PERTURBATION SHOULD WEAKEN
   SLIGHTLY UNTIL MOVING ENEWD OVER OZARKS BY 1/00Z...THEN
   ACCELERATE/WEAKEN CONSIDERABLY WHILE EJECTING OVER IL/INDIANA/OH/LE
   REGION OVERNIGHT.

   ASSOCIATED SFC LOW OVER SERN WI SHOULD BECOME BETTER-DEFINED
   THROUGHOUT DAYLIGHT HOURS...AS IT CROSSES REMAINDER WI AND WRN/NRN
   LM.  BY 00Z...COLD FRONT SHOULD EXTEND FROM LOW ACROSS NWRN
   INDIANA...NEAR WRN TIP OF KY...NWRN LA...AND DEEP S TX.  BY END OF
   PERIOD...LOW SHOULD BECOME SUBSTANTIALLY OCCLUDED AND VERTICALLY
   STACKED WITH NRN PERTURBATION OVER ONT.  COLD FRONT SHOULD BE
   CROSSING PORTIONS CENTRAL APPALACHIANS...AL...AND SERN LA BY 1/12Z.

   ...WRN GULF COAST...LOWER MS VALLEY TO LOWER GREAT LAKES...
   WRN GULF COAST REGION IS EXPERIENCING PERIPHERAL INFLUENCE OF
   MID-UPPER LEVEL PERTURBATION IN FORM OF STRENGTHENING DEEP SHEAR AND
   DEEP-LAYER LIFT...JUXTAPOSED WITH VERY RICHLY MOST BOUNDARY LAYER --
   E.G. SFC DEW POINTS INTO MID-70S F.  SUCH MOISTURE IS NEEDED TO
   OFFSET WEAK LAPSE RATES ALOFT TO MAINTAIN BUOYANCY ROOTED IN
   BOUNDARY LAYER.  ACCORDINGLY...CONVECTION HAS BEEN GETTING BETTER
   ORGANIZED IN BROAD LOW-LEVEL CONFLUENCE ZONE ACROSS PORTIONS SE TX
   AND LA.  OCNL DAMAGING GUSTS ARE POSSIBLE...AND A FEW TORNADOES
   CANNOT BE RULED OUT GIVEN LARGE SIZE OF LOW-LEVEL VWP/RAOB
   HODOGRAPHS E OF MAIN CONFLUENCE/CONVECTIVE AXIS.  REF SPC MESOSCALE
   DISCUSSION 1989 AND WW 551 FOR ADDITIONAL NEAR-TERM GUIDANCE.

   WITH NWD EXTENT...BOUNDARY-LAYER THETAE WILL DIMINISH WHILE
   STRENGTHENING WIND FIELDS ALOFT WILL YIELD MORE SUBSTANTIAL
   DEEP-LAYER SHEAR.  AS SUCH...OUTLOOK BECOMES MORE CONDITIONAL. 
   ANTECEDENT CLOUDS/PRECIP ACROSS MUCH OF PREFRONTAL CORRIDOR FROM
   MID-SOUTH REGION NWD SUGGEST LOW-LEVEL LAPSE RATES WILL REMAIN
   WEAK...ALTHOUGH FCST SOUNDINGS CAN PRODUCE EFFECTIVELY SFC-BASED
   INFLOW PARCELS WITH ONLY A FEW DEG F ADJUSTMENT OF SFC TEMPS
   RESULTING FROM POCKETS OF MUTED INSOLATION.  ONE OR MORE
   QUASI-LINEAR CONVECTIVE BANDS MAY DEVELOP ALONG OR AHEAD OF SFC COLD
   FRONT -- SOMETIMES WITHOUT LIGHTNING DUE TO STUNTED CAPE DEPTH WITH
   RESPECT TO OPTIMAL ICING LAYER -- BUT STILL WITH POTENTIAL TO
   TRANSFER STG-SVR GUSTS TO SFC OR SPAWN A BRIEF QLCS TORNADO.

   ADDITIONAL SVR POTENTIAL MAY ARISE OVER OZARKS REGION AS SERN
   PORTIONS OF STRONGEST MIDLEVEL ASCENT/COOLING...RELATED TO DCVA
   REGION OF SHORTWAVE PERTURBATION -- JUXTAPOSE WITH AREAS OF SFC
   DIABATIC HEATING.  RESULTANT STEEPENING OF LOW-MIDDLE LEVEL LAPSE
   RATES...RESIDUAL MOISTURE WITH DEW POINTS 60S F...AND STG DEEP SHEAR
   MAY YIELD ENVIRONMENT FAVORABLE FOR STG/DAMAGING WINDS AND ISOLATED
   HAIL.

   ..EDWARDS/COHEN.. 10/31/2013

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