Jul 12, 2014 1300 UTC Day 1 Convective Outlook

DAY 1 CONVECTIVE OUTLOOK  

   NWS STORM PREDICTION CENTER NORMAN OK
   0758 AM CDT SAT JUL 12 2014

   VALID 121300Z - 131200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS CENTRAL PLAINS TO SRN
   LM AND ADJACENT LAND AREAS...

   ...SUMMARY...
   ISOLATED TO SCATTERED SEVERE STORMS ARE ANTICIPATED FROM PARTS OF
   THE MID-MISSOURI VALLEY TO THE SOUTHERN LAKE MICHIGAN REGION DURING
   THE LATE AFTERNOON INTO TONIGHT. DAMAGING WINDS SHOULD BE THE
   PRIMARY HAZARD...BUT SEVERE HAIL AND A TORNADO OR TWO WILL BE
   POSSIBLE.

   --- TECHNICAL DISCUSSION ---

   ...SYNOPSIS...
   IN MID-UPPER LEVELS...SYNOPTIC-SCALE RIDGE IS FCST TO AMPLIFY ACROSS
   ERN NORTH AMERICA...WITH 500-MB ANTICYCLONE BUILDING OVER GREAT
   BASIN.  DOWNSTREAM CYCLONE IS FCST TO MEANDER ACROSS NRN/NERN
   AB...AS STG/ATTACHED SHORTWAVE TROUGH MOVES SEWD FROM CURRENT
   POSITION OVER NRN SK.  LATTER TROUGH SHOULD REACH SERN MB AND NERN
   ND BY 00Z...THEN PIVOT CYCLONICALLY TO NWRN ONT AND LS BY END OF
   PERIOD.  SMALL SHORTWAVE TROUGH -- INITIALLY LOCATED OVER SRN SD/NRN
   NEB -- SHOULD MOVE EWD ACROSS UPPER MS VALLEY TO WI/LM BY 00Z.  THIS
   FEATURE THEN WILL ACCELERATE NEWD AND WEAKEN CONSIDERABLY...AS
   HEIGHTS FALL IN ADVANCE OF MUCH MORE INTENSE CANADIAN PERTURBATION.

   AT SFC...COLD FRONTOGENESIS IS EXPECTED OVER CANADIAN PRAIRIE
   PROVINCES...WITH RESULTING BOUNDARY MOVING QUICKLY SEWD OVER
   PORTIONS ND/ERN MT BY 00Z.  MEANWHILE...WAVY...MOSTLY
   QUASISTATIONARY FRONT WAS EVIDENT IN 12Z ANALYSIS FROM LS SWWD
   ACROSS SRN MN...N-CENTRAL NEB...THROUGH WEAK FRONTAL-WAVE LOW OVER
   SWRN NEB...TO ANOTHER WEAK LOW IN SERN CO.  ERN LOW SHOULD MOVE EWD
   TO ERN NEB/SWRN IA BY 00Z...THEN TO NEAR SRN LM AT 12Z.  BY THAT
   TIME...FRONTS MAY MERGE OVER LOWER MI...WITH SRN BOUNDARY EXTENDING
   SWWD ACROSS NRN MO...ERN KS AND OK PANHANDLE...AND STRONGER/NRN
   FRONT ACROSS WI...SRN MN/NRN IA...SD AND CENTRAL/ERN MT.

   ...CENTRAL PLAINS TO SRN LM AND ADJACENT LAND AREAS...
   DECAYING CONVECTION IS ONGOING FROM PARTS OF DAKOTAS TO
   IL...EXTENDING WNWWD FROM MERIDIONAL BAND OF ELEVATED TSTMS OVER ERN
   IL ATTM.  STG INSOLATION IS EXPECTED S OF ASSOCIATED CLOUD COVER
   TODAY...WHICH SHOULD THIN AND BREAK UP THROUGHOUT AFTN PERMITTING
   AIR MASS RECOVERY N OF CURRENT OUTFLOW/BAROCLINIC BOUNDARY OVER SRN
   IA.  SCATTERED TSTMS ARE EXPECTED TO DEVELOP THIS AFTN OVER PORTIONS
   NEB/IA...MOVING EWD TO ESEWD WITH EARLY WIND/HAIL THREAT BEFORE
   CONGEALING INTO ONE OR TWO PRIMARY COMPLEXES.  LATTER CONVECTION
   THEN WILL OFFER DAMAGING GUSTS AND ISOLATED LARGE HAIL.

   SFC ANALYSIS SHOWS AXIS OF UPPER 60S TO 70S F SFC DEW POINTS...FROM
   WRN GULF NNEWD ACROSS MO TO WRN IL THEN NWWD ACROSS IA TO SUX/FSD
   REGION.  ACCOMPANYING BOUNDARY-LAYER MOIST PLUME CONTRIBUTES TO
   1.75-2 INCH PW...WITH ISOLATED VALUES EXCEEDING 2 INCHES.  THIS WILL
   SUPPORT PRECONVECTIVE MLCAPE IN 1500-3000 J/KG RANGE BY LATE
   AFTN...WITH STRONGEST LOW-LEVEL SHEAR...LARGEST HODOGRAPHS AND
   GREATEST STORM-RELATIVE INFLOW VECTORS LOCATED ALONG AND N OF
   RESIDUAL BOUNDARY.  45-55 KT EFFECTIVE-SHEAR MAGNITUDES AND 0-3 KM
   SRH 200-300 J/KG MAY DEVELOP...THOUGH WEAK SFC WINDS SHOULD LIMIT
   0-1-KM HODOGRAPH SIZE.  STILL...SOME SUPERCELLS ARE POSSIBLE BEFORE
   CONVECTION AGGREGATES INTO MCS MODE.

   CLOUD COVER/PRECIP RELATED TO MORNING CONVECTION WILL CAUSE ERN
   PORTIONS CATEGORICAL OUTLOOK AREA TO TAKE LONGER TO DESTABILIZE. 
   NONETHELESS...PRIND SUFFICIENT THETAE ADVECTION AND RELATED 
   MOISTURE/BUOYANCY RECOVERY WILL OCCUR BY LATE/EVENING/OVERNIGHT
   HOURS...SUPPORTING POTENTIAL EWD MOVEMENT OF MCS ACROSS SRN LM
   REGION.