SPC AC 121252

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0752 AM CDT SUN OCT 12 2014

   VALID 121300Z - 131200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS CENTRAL/SRN HIGH
   PLAINS TO OZARKS AND ARLKATEX...

   ...SUMMARY...
   STRONG TO SEVERE THUNDERSTORMS ARE FORECAST TO DEVELOP ACROSS THE
   CENTRAL AND SOUTHERN HIGH PLAINS THIS AFTERNOON.  THIS ACTIVITY WILL
   EXPAND AND BECOME MORE INTENSE WITH TIME THIS EVENING AND OVERNIGHT
   WHILE MOVING ACROSS PARTS OF NORTH TEXAS AND OKLAHOMA...EVENTUALLY
   REACHING ARKANSAS BY TOMORROW MORNING.  DAMAGING WINDS ARE LIKELY. 
   LARGE HAIL AND A FEW TORNADOES ALSO SHOULD BE EXPECTED.

   ...SYNOPSIS...
   FALLING HEIGHTS AND MORE PRONOUNCED CYCLONIC FLOW ARE EXPECTED IN
   MIDDLE-UPPER LEVELS OVER MOST OF CENTRAL CONUS THROUGH PERIOD. 
   SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE-CHANNEL IMAGERY OVER UT
   -- IS EXPECTED TO DIG SEWD AND STRENGTHEN CONSIDERABLY...REACHING
   SERN CO AND ERN NM BY 00Z AND SRN KS...W-CENTRAL OK AND W-CENTRAL TX
   BY 12Z.  BY THEN...CLOSED 500-MB LOW AND WELL-DEFINED PV ANOMALY
   SHOULD EXIST ALONG OK SEGMENT OF SHORTWAVE TROUGH. 

   AT SFC...11Z ANALYSIS SHOWED WAVY/QUASISTATIONARY FRONTAL ZONE FROM
   ERN SC ACROSS NRN PORTIONS GA/AL THEN ARCHING ACROSS SERN AR...NWRN
   LA...E TX...TX COASTAL BEND...AND DEEP S TX.  OUTFLOW BOUNDARIES ARE
   EVIDENT S OF FRONT FROM WRN GA ACROSS CENTRAL AL TO CENTRAL MS AND
   NRN LA.  ONGOING CONVECTION IS OR RECENTLY HAS BEEN REINFORCING
   PARTS OF THOSE OUTFLOW BOUNDARIES.  NONETHELESS...WARM FRONT IS
   EXPECTED TO MOVE NWD ACROSS MID SOUTH AND LOWER OH VALLEY REGION
   THROUGH PERIOD WHILE BECOMING MORE DIFFUSE.  WRN PORTION OF FRONTAL
   ZONE ALSO SHOULD BECOME ILL-DEFINED TODAY AND TONIGHT AS INTENSE
   LOW-LEVEL RETURN-FLOW/WAA REGIME SETS UP IN ADVANCE OF NEXT COLD
   FRONT.

   SFC CYCLOGENESIS/FRONTOGENESIS IS EXPECTED THROUGH EARLY AFTN OVER
   S-CENTRAL HIGH PLAINS...WITH DEEPENING SFC LOW REACHING ERN/NRN TX
   PANHANDLE BY 00Z...NWRN/N-CENTRAL OK BY 06Z...TO NEAR ERN PORTIONS
   KS/OK BORDER BY 12Z.  INTENSIFYING COLD FRONT WILL SWEEP SEWD S AND
   SW OF THAT LOW...REACHING SERN OK AND CENTRAL/SW TX BY END OF
   PERIOD.  

   ...CENTRAL/SRN HIGH PLAINS TO OZARKS AND ARLKATEX...
   SCATTERED TO LOCALLY NUMEROUS TSTMS SHOULD FORM AND MOVE/EXPAND FROM
   W-E AND NW-SE ACROSS OUTLOOK AREA FROM LATE AFTN ONWARD...OFFERING
   DAMAGING GUSTS AND SPORADIC HAIL.  ONCE SUBSTANTIAL RETURN-FLOW
   MOISTURE SUFFUSES FOREGOING WARM SECTOR TONIGHT...MOST LIKELY OVER
   SRN/ERN OK AND N-CENTRAL/NE TX...SLGT TORNADO RISK SHOULD COMMENCE
   -- ESPECIALLY WITH ANY RELATIVELY DISCRETE/PRE-FRONTAL CONVECTION
   ROOTED AT SFC OR WITH QLCS MESOVORTICES.  

   CONVECTION THAT DEVELOPS THIS AFTN AND EARLY EVENING OVER
   CENTRAL/SRN HIGH PLAINS IS EXPECTED TO BE RELATIVELY HIGH-BASED WITH
   AT LEAST ISOLATED SVR DOWNDRAFTS AND HAIL POSSIBLE.  ACTIVITY WILL
   BE OCCURRING IN ENVIRONMENT OF MRGL LOW-LEVEL MOISTURE...BUT ALSO
   STG DCVA/COOLING ALOFT...INTENSIFYING MID-UPPER WINDS AND DEEP
   SHEAR...AND STRENGTHENING FRONTOGENETIC FORCING.  THIS ACTIVITY
   SHOULD BECOME MORE FRONTALLY TIED WITH TIME...EXPAND LATERALLY ON
   EITHER SIDE OF SFC LOW...AND IMPROVE ITS ORGANIZATION TONIGHT. 
   FORCED ASCENT WILL PENETRATE OTHERWISE STG CAPPING TO LIFT
   INCREASINGLY HIGH-THETAE BOUNDARY-LAYER PARCELS INTO INCREASINGLY
   UNSTABLE MIDLEVELS AND GROW/MAINTAIN SVR MCS.

   E OF STRONGEST CAPPING...SEPARATE AREA OF WIDELY SCATTERED TO
   SCATTERED TSTMS MAY DEVELOP OVERNIGHT FROM CENTRAL TX TO SERN OK/WRN
   AR...WITHIN ONE OR MORE PREFRONTAL/LOW-LEVEL CONFLUENCE ZONES.  THIS
   ACTIVITY...WHILE INITIALLY ROOTED ABOVE SFC...COULD BECOME SFC-BASED
   RATHER QUICKLY GIVEN FCST SOUNDINGS SHOWING 
   1. LACK OF SUBSTANTIAL MLCINH ATOP MID-UPPER-60S F SFC DEW POINTS
   WITH PW NEAR 1.5 INCHES...AND  
   2. EFFECTIVELY SFC-BASED INFLOW PARCELS DURING 06-12Z TIME FRAME
   WHEN STRENGTHENING MOISTURE BOOSTS MLCAPE FROM NEAR 1000 TO AOA 1500
   J/KG. 
   STRENGTHENING DEEP SHEAR AND LLJ-ENHANCED LOW-LEVEL HODOGRAPHS WILL
   SUPPORT SUPERCELLULAR AND BOWING STRUCTURES.  THIS ENVIRONMENT WILL
   ALSO BE AVAILABLE TO EXPANSIVE FRONTAL SQUALL LINE LATE IN
   PERIOD...AS IT OVERTAKES SOME OF THAT WARM-SECTOR CONVECTION. 

   ...TN VALLEY REGION...
   STRENGTHENING LOW-LEVEL WAA/MOIST-ADVECTION PLUME...DIURNAL/DIABATIC
   HEATING...CORRIDORS OF LOW-LEVEL CONFLUENCE/CONVERGENCE...AND
   INCREASING MOISTURE WILL SUPPORT SFC-BASED TSTM DEVELOPMENT OVER
   THIS AREA THIS AFTERNOON.  TSTM CONCENTRATION AND AVAILABLE
   LOW-LEVEL LIFT/SHEAR EACH ARE LIKELY TO MAXIMIZE NEAR WARM FRONT AND
   OUTFLOW BOUNDARIES.  AS HEIGHT GRADIENT ALOFT INCREASES ACROSS THIS
   REGION...AMIDST MORE CYCLONIC MID-UPPER WINDS...EFFECTIVE-SHEAR
   MAGNITUDES OF 30-40 KT AND EFFECTIVE SRH IN 150-250 J/KG RANGE MAY
   APPEAR IN POCKETS.  THIS WILL SUPPORT BLEND OF MULTICELLULAR AND
   OCNL SUPERCELLULAR TSTM MODES.  ISOLATED DAMAGING GUSTS AND HAIL
   NEAR SVR LEVELS ARE POSSIBLE...AND A TORNADO CANNOT BE RULED OUT
   DEPENDING ON MESOSCALE/STORM-SCALE PROCESSES.

   ..EDWARDS/MOSIER.. 10/12/2014

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z