Oct 6, 2013 1300 UTC Day 1 Convective Outlook
Updated: Sun Oct 6 12:45:48 UTC 2013 (20131006 1300Z Day 1 shapefile | 20131006 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20131006 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20131006 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
20131006 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
20131006 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
No Risk Areas Forecast
   SPC AC 061241

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0741 AM CDT SUN OCT 06 2013

   VALID 061300Z - 071200Z

   ...NO SVR TSTM AREAS FORECAST...

   ...SYNOPSIS...
   MAIN UPPER-AIR CONTRIBUTOR TO THIS OUTLOOK WILL BE WELL-DEFINED
   CYCLONE...CENTER OF WHICH IS EVIDENT IN MOISTURE CHANNEL IMAGERY AND
   INTERPOLATED 12Z RAOB DATA OVER WRN IA.  RELATED 500-MB LOW IS FCST
   TO MOVE ESEWD TO BETWEEN DBQ-MLI BY 00Z...THEN PIVOT EWD ACROSS NRN
   IL THROUGH EVENING/OVERNIGHT HOURS.  CONSIDERABLE SPREAD IS EVIDENT
   IN BOTH OPERATIONAL AND SREF MODEL MEMBERS AFTER ABOUT
   06Z...REGARDING WHETHER THIS LOW PROCEEDS EWD OVER NRN INDIANA OR
   EJECTS NEWD ACROSS LM AND LOWER MI BY 12Z.  SUCH SHORT-TERM SPREAD
   IS UNUSUAL FOR A SYSTEM WITH SHARP DEFINITION AND ORGANIZATION
   EMBEDDED WITHIN DOMESTIC RAOB NETWORK...AND APPEARS TO BE RELATED TO
   DISCREPANCIES IN AMPLIFICATION OF INITIALLY SEPARATE BUT
   STRENGTHENING SHORTWAVE TROUGH OVER MB THAT WILL CROSS NRN ONT
   THROUGH PERIOD.

   AT SFC...11Z ANALYSIS SHOWED COLD FRONT EXTENDING FROM NRN LM SSEWD
   OVER PORTIONS NRN/CENTRAL INDIANA...THEN SSWWD OVER WRN PORTIONS
   KY/TN/MS TO W-CENTRAL COAST OF LA...THEN ARCHING SWWD ACROSS NWRN
   GULF TO LOWER RIO GRANDE VALLEY REGION OF DEEP S TX.  BY AROUND
   00Z...FRONT SHOULD REACH CENTRAL OH...ERN TN...AND CENTRAL/SWRN AL. 
   BY END OF PERIOD...FRONT SHOULD EXTEND OVER WRN PORTIONS
   NY...VA...NC AND GA.

   ...LOWER GREAT LAKES TO TN VALLEY AND SRN APPALACHIANS...
   SCATTERED TO WIDELY SCATTERED TSTMS ARE EXPECTED TO DEVELOP
   EPISODICALLY THROUGHOUT PERIOD...BUT ESPECIALLY FROM LATE MORNING
   INTO EVENING...IN BROAD PREFRONTAL SWATH.  AT LEAST MRGL SVR
   POTENTIAL...PRIMARILY FOR DAMAGING GUSTS...WILL AFFECT THIS
   CORRIDOR.  ANY HAIL IS EXPECTED TO BE MRGL/LOW-END SVR IN SIZE. 
   EARLIER NORTHERN 15%/CATEGORICAL WIND RISK HAS BEEN REDUCED DUE TO
   CONCERNS OVER ONGOING CLOUD/PRECIP AND EFFECTS ON DIURNAL
   DESTABILIZATION.  STILL...AS YET-TO-DEVELOP MESOSCALE TRENDS MAY
   WARRANT...RELATIVELY CONCENTRATED/SMALL AREA OF ENHANCED SVR
   POTENTIAL MAY DEVELOP SOMEWHERE WITHIN REMAINING 5% SWATH TODAY...SO
   A PARTIAL-AREA UPGRADE IS NOT OUT OF THE QUESTION.

   35-45 KT EFFECTIVE SHEAR MAGNITUDES ARE POSSIBLE FOR ANY CONVECTION
   THAT DEVELOPS ALONG OR JUST AHEAD OF COLD FRONT...BASED ON MODIFIED
   FCST SOUNDINGS AND PLANAR PROGS SHOWING STRONGER MID-UPPER LEVEL
   WINDS BARELY OVERLAPPING WARM SECTOR.  THIS CONCEPTUAL MODEL IS
   PREDICATED ON WEAKENING AND/OR DECELERATION OF ONGOING
   CONVECTIVE/PRECIP BAND...SUCH THAT PREFRONTAL OUTFLOW/DIFFERENTIAL
   HEATING BOUNDARY DOES NOT STAY AHEAD OF THAT INCREASE IN FLOW ALOFT.
    THOUGH CHARACTERIZED BY PERSISTENT WEAKENING TREND...ONGOING PRECIP
   PLUME IS ORIENTED FARTHER E AND FARTHER AHEAD OF COLD FRONT WITH NWD
   EXTENT...CASTING CONSIDERABLE UNCERTAINTY ON AMOUNT OF DIABATIC
   HEATING AND RELATED DESTABILIZATION THAT WILL OCCUR OVER LOWER MI
   AND WESTERN/CENTRAL OH.  FARTHER S...WINDS ALOFT GENERALLY WILL BE
   WEAKER...BUT STILL MRGL FOR MULTICELLULAR/QUASI-LINEAR SVR POTENTIAL
   AND JUXTAPOSED WITH MORE SUSTAINED SFC HEATING.  POCKETS OF SUCH
   HEATING...WITH SFC DEW POINTS UPPER 60S TO NEAR 70 F...SHOULD OFFSET
   WEAK LAPSE RATES ALOFT ENOUGH FOR AROUND 300-800 J/KG MLCAPE.

   ...CENTRAL/SRN APPALACHIANS OVERNIGHT...
   SHORTWAVE TROUGH EXTENDING SWD FROM MID-UPPER LEVEL LOW WILL BECOME
   MORE NEGATIVELY TILTED OVERNIGHT.  AS THIS OCCURS...MORE VIGOROUS
   LOW-LEVEL MASS/MOISTURE RESPONSE TO STRENGTHENING LARGE-SCALE
   ASCENT...ALONG WITH GREATER MID-UPPER LEVEL FLOW...COULD OVERLAP
   WARM SECTOR OVER PORTIONS CENTRAL/SRN APPALACHIANS.  SOME
   ORGANIZATION AND NEWD ACCELERATION OF PREFRONTAL CONVECTIVE BAND
   ACROSS THIS AREA MAY OCCUR...BUT INTO AIR MASS WITH VERY LIMITED
   INSTABILITY.  AS SUCH...UNCONDITIONAL WIND PROBABILITIES ARE KEPT
   MRGL FOR NOW...BUT EXTENDED SOMEWHAT EWD OVER HIGHER TERRAIN.

   ..EDWARDS/LEITMAN.. 10/06/2013

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