SPC AC 201630
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1130 AM CDT MON MAY 20 2013
   
   VALID 201630Z - 211200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS FOR ERN/CNTRL OK...N-CNTRL
   TX...NWRN AR...SRN MO...FAR SERN KS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE UPPER MS VALLEY/CNTRL
   GREAT LAKES TO THE SRN PLAINS...
   
   ...SRN PLAINS TO OZARK PLATEAU...
   OVERALL FORECAST SCENARIO REMAINS SIMILAR TO EARLIER OUTLOOKS WITH
   ONLY MINOR OVERALL CHANGES TO INDIVIDUAL HAZARD PROBABILITIES.
   MID-LEVEL SPEED MAX /65 KT AT 500 MB IN THE 12Z ABQ RAOB/ ATTENDANT
   TO THE SHORTWAVE IMPULSE OVER THE LEE OF THE SRN ROCKIES WILL
   OVERSPREAD MOST OF OK TO THE LOWER MO VALLEY BY EARLY EVENING.
   TRAILING PORTION OF COLD FRONT HAS BECOME SLOW-MOVING FROM SERN KS
   TO SWRN OK...INTERSECTING A DRYLINE THAT WILL BECOME WELL
   ESTABLISHED S/SWWD ACROSS THE TX BIG COUNTRY TO THE ERN EDWARDS
   PLATEAU BY LATE AFTERNOON. SCATTERED TSTMS WILL INITIATE ALONG THESE
   BOUNDARIES BY MID-AFTERNOON. MORNING CONVECTION-ALLOWING MODEL
   GUIDANCE ARE INSISTENT THAT THIS ACTIVITY WILL RAPIDLY GROW UPSCALE
   INTO NUMEROUS LINE SEGMENTS...SURGING EWD THIS EVENING WITHIN A
   STRONGLY UNSTABLE ENVIRONMENT.
   
   INITIAL TSTMS WILL BECOME SUPERCELLUAR QUICKLY WITH VERY LARGE HAIL
   LIKELY AS HODOGRAPHS/INSTABILITY WILL BE QUITE FAVORABLE...ALONG
   WITH A FEW TORNADOES. THE GREATEST RISK FOR A COUPLE OF STRONG
   TORNADOES SHOULD EXIST FROM S-CNTRL INTO E-CNTRL OK. BUT WITH
   PREDOMINANT SWLY COMPONENT TO LOW-LEVEL FLOW AND MODERATE 0-1 KM
   SHEAR...OVERALL TORNADO INTENSITY/LONGEVITY MAY BE
   TEMPERED...ESPECIALLY WITH CONVECTION EXPECTED TO GROW UPSCALE SO
   QUICKLY. NEVERTHELESS...THIS GROWTH SHOULD YIELD BOWING LINEAR
   SEGMENTS CAPABLE OF SWATHS OF WIDESPREAD DAMAGING WINDS...LARGE HAIL
   AND A FEW TORNADOES.
   
   ...MID/UPPER-MS VALLEY TO CNTRL GREAT LAKES...
   PRIMARY CHANGE HAS BEEN TO EXPAND DAMAGING WIND PROBABILITIES E/NEWD
   FOR THIS AFTERNOON AND EVENING. IN THE WAKE OF CONVECTION
   YESTERDAY...LOW-LEVEL MOISTURE PLUME HAS BECOME CONFINED FROM LOWER
   MI S/SSWD TO THE CONFLUENCE OF THE MS/OH RIVERS. BUT PLENTIFUL
   HEATING IS OCCURRING TO THE N OF THIS PLUME WILL YIELD A RECOVERING
   AIR MASS DOWNSTREAM OF A TSTM CLUSTER APPROACHING CNTRL MO. THIS
   ACTIVITY SHOULD GROW UPSCALE ALONG THE EDGE OF THE INSTABILITY
   AXIS...WITH ADDITIONAL LINEAR SEGMENTS EMANATING E/NEWD FROM THE
   OZARK PLATEAU LATER TODAY. SWATHS OF DAMAGING WINDS...LARGE HAIL AND
   A COUPLE OF TORNADOES WILL BE POSSIBLE.
   
   FARTHER N/NW...SCATTERED TSTMS ARE EXPECTED TO FORM OVER LOWER MI
   AND IN PARTS OF THE UPPER MIDWEST IN ASSOCIATION WITH AN UPPER-LEVEL
   LOW CENTERED OVER ERN SD. BUOYANCY WILL BE STRONGEST OVER LOWER MI
   WITHIN THE LOW-LEVEL MOISTURE PLUME CHARACTERIZED BY MIDDLE TO UPPER
   60S SURFACE DEW POINTS. IN THE UPPER MIDWEST...POCKETS OF ROBUST
   SURFACE HEATING WILL SUPPORT AT LEAST MODEST INSTABILITY AND WITH
   STRONG UNIDIRECTIONAL WIND PROFILES...SETUP COULD A FEW ORGANIZED
   TSTM CLUSTERS. A MIX OF ISOLATED SEVERE HAIL/WIND SHOULD BE THE
   PRIMARY THREATS.
   
   ..GRAMS/ROGERS.. 05/20/2013
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z