SPC AC 301955

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0255 PM CDT TUE JUL 30 2013

   VALID 302000Z - 311200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FOR PARTS OF THE NRN/CNTRL
   PLAINS INTO THIS EVENING...

   ...NRN/CNTRL PLAINS...
   SURFACE-BASED TSTM INITIATION IS UNDERWAY OVER WRN SD /REF WW 452/.
   PREVIOUS FORECAST REASONING IS LARGELY ON-TRACK...WITH CHANGES TO
   SPATIAL EXTENT OF PROBABILITIES BASED PRIMARILY ON EXTRAPOLATED
   THERMODYNAMIC ENVIRONMENT AND 12Z WRF-NSSL/NMM GUIDANCE. HAVE
   INTRODUCED A NARROW 5 PERCENT TORNADO PROBABILITY ALONG THE COOL
   SIDE OF THE SURFACE FRONT/LEE TROUGH IN PARTS OF WRN SD GIVEN THE
   EXPECTATION OF SUPERCELLS DEVELOPING SEWD ALONG THIS CORRIDOR. 

   ...ERN OK TO THE MID-SOUTH...
   ABUNDANT CLOUD COVERAGE AND STRATIFORM RAINFALL HAS LIMITED
   DESTABILIZATION INVOF THE MCV CENTERED OVER SERN MO. AS SUCH...MORE
   ROBUST HEATING HAS REMAINED DIVORCED FROM THE STRONGER ASCENT
   ASSOCIATED WITH THE MCV. NEVERTHELESS...POTENTIAL DOES REMAIN FOR
   SURFACE-BASED STORMS TO FORM BY EARLY EVENING ALONG THE MS/AL BORDER
   AND OVER ERN OK. ANY ACTIVITY OVER ERN OK IS MOST LIKELY TO PERSIST
   THIS EVENING INTO THE OVERNIGHT WITH A MODEST WLY LLJ SUPPORTING
   ISENTROPIC LIFT ACROSS THE MID-SOUTH. LOCALIZED MICROBURSTS WILL BE
   THE PRIMARY HAZARD WITHIN A HIGH PW ENVIRONMENT.

   ..GRAMS.. 07/30/2013

   .PREV DISCUSSION... /ISSUED 1124 AM CDT TUE JUL 30 2013/

   ...SYNOPSIS...

   THE LARGE-SCALE PATTERN WILL REMAIN CHARACTERIZED BY A PROMINENT
   UPPER-LEVEL ANTICYCLONE CENTERED OVER THE SRN ROCKIES INTO SRN HIGH
   PLAINS WITH A BELT OF ENHANCED MID TO UPPER-LEVEL FLOW ALONG THE NRN
   PERIPHERY OF THIS FEATURE ACROSS THE NRN TIER OF STATES.  A SERIES
   OF LOW-AMPLITUDE PERTURBATIONS WILL TRANSLATE EWD WITHIN THIS
   HIGH-MOMENTUM AIR STREAM FROM THE NRN INTERMOUNTAIN REGION AND NRN
   HIGH PLAINS INTO THE GREAT LAKES...AHEAD OF AN AMPLIFYING MIDLEVEL
   TROUGH OVER CNTRL CANADA.  

   IN THE LOW LEVELS...A WEAK COLD FRONT WILL CONTINUE EWD INTO THE
   UPPER GREAT LAKES WITH THE TRAILING EXTENSION OF THIS BOUNDARY
   SETTLING SWD THROUGH THE NRN HIGH PLAINS.  A SURFACE LOW CURRENTLY
   JOINED WITH THE FRONT OVER NERN WY WILL DEVELOP EWD INTO WRN SD
   TODAY WHILE A LEE TROUGH STRENGTHENS ACROSS THE CNTRL HIGH PLAINS. 
   FARTHER TO THE SOUTH...A WEAK COLD FRONT WILL SLOWLY ADVANCE SWD
   ACROSS THE SRN PLAINS.  

   ...NRN/CNTRL PLAINS THIS AFTERNOON INTO TONIGHT...

   12Z REGIONAL SOUNDINGS SHOWED THE PRESENCE OF A RELATIVELY MOIST
   BOUNDARY LAYER /I.E. LOWEST 100-MB MEAN-MIXING RATIOS OF 11-12 G PER
   KG/ BENEATH STEEP MIDLEVEL LAPSE RATES WHICH WILL CONTRIBUTE TO A
   MODERATELY UNSTABLE AIR MASS BY AFTERNOON WITH MLCAPE OF 1000-1500
   J/KG.  CONVERGENCE ALONG THE COLD FRONT AND LEE TROUGH COUPLED WITH
   THE INFLUENCE OF MIGRATORY MIDLEVEL PERTURBATIONS MOVING OUT OF THE
   NRN HIGH PLAINS WILL FOSTER WIDELY SCATTERED TSTMS LATER TODAY
   AMIDST A KINEMATIC ENVIRONMENT FEATURING A VERTICALLY VEERING WIND
   PROFILE WITH 40-50 KT OF DEEP-LAYER SHEAR.  AS SUCH...THE POTENTIAL
   WILL EXIST FOR SUPERCELLS CAPABLE OF LARGE HAIL AND DAMAGING WINDS. 
   STORMS MAY COALESCE INTO SEWD-MOVING CLUSTERS BY THIS EVENING WITH A
   CONTINUED RISK FOR HAIL AND HIGH WINDS.

   OTHER ISOLATED STORMS MAY FORM OFF THE HIGH TERRAIN OF SRN MT/NRN WY
   WITHIN THE POST-FRONTAL ENVIRONMENT THIS AFTERNOON AND EVENING.
   WHILE INSTABILITY WILL BE LIMITED...VERTICAL SHEAR WILL BE
   RELATIVELY STRONG AND SUPPORTIVE OF UPDRAFT ROTATION WITH A RISK FOR
   HAIL AND STRONG WIND GUSTS.

   ...OK INTO THE MID SOUTH AND CNTRL GULF COAST STATES THIS AFTERNOON
   AND EVENING...

   A FAIRLY WELL-DEFINED MCV IS APPARENT THIS MORNING OVER S-CNTRL MO
   WITH THIS FEATURE CONTINUING EWD ACROSS THE MID SOUTH TODAY. 
   FORCING ASSOCIATED WITH THIS FEATURE WILL COMBINE WITH LOW-LEVEL
   CONVERGENCE ALONG A WARM FRONT LIFTING NWD ACROSS THE MID SOUTH TO
   PROMOTE WIDELY SCATTERED AFTERNOON TSTMS.  THOUGH VERTICAL SHEAR
   WILL NOT BE PARTICULARLY STRONG...THE PRESENCE OF A MOIST AND
   MODERATE TO STRONGLY UNSTABLE AIR MASS WILL BE SUPPORTIVE OF STRONG
   TO MARGINALLY SEVERE STORMS CAPABLE OF LOCALLY DAMAGING WIND GUSTS. 
   OTHER INTENSE STORMS WILL BE POSSIBLE THIS AFTERNOON ALONG THE
   TRAILING COLD FRONT AND OUTFLOW BOUNDARY ACROSS THE OZARK PLATEAU. 
   HERE TOO...THE PRIMARY HAZARD WILL BE ISOLATED DAMAGING WIND GUSTS.

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z