May 30, 2013 0600 UTC Day 1 Convective Outlook
Updated: Thu May 30 06:03:37 UTC 2013
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20130530 1200 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20130530 1200 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
20130530 1200 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
20130530 1200 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
SLIGHT 194,191 13,429,361 Oklahoma City, OK...Kansas City, MO...Omaha, NE...Tulsa, OK...Wichita, KS...
   SPC AC 300600

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0100 AM CDT THU MAY 30 2013

   VALID 301200Z - 311200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS IA TO PORTIONS NW TX...

   ...SYNOPSIS...
   AS SEVERAL VORTICITY LOBES PHASE/CONSOLIDATE OVER NRN
   PLAINS...MID-UPPER LEVEL CYCLONE IS FCST TO EVOLVE OVER BLACK HILLS
   REGION BY START OF PERIOD...DEEPENING SLIGHTLY AND PROCEEDING EWD
   ACROSS WRN/CENTRAL SD BEFORE 31/12Z.  NEGATIVELY TILTED SHORTWAVE
   TROUGH -- NOW APPARENT IN MOISTURE CHANNEL IMAGERY AND PROFILER/VWP
   DATA FROM NERN CO SSEWD OVER ERN HIGH PLAINS -- IS FCST TO SHIFT
   NEWD TO EXTEND FROM WRN IA ACROSS WRN OZARKS REGION BY 31/00Z...THEN
   NEWD OVER UPPER MS VALLEY REGION OVERNIGHT.  BEHIND THIS
   FEATURE...PRONOUNCED JET MAX ALOFT -- ALREADY APCHG 130 KT BASED ON
   30/00Z 250-MB ANALYSIS -- IS STRONGER THAN HAS BEEN PROGGED BY
   PREVIOUS RUNS OF OPERATIONAL NAM AND SIMILAR TO 30/12Z SPECTRAL
   FCST.  JET AXIS SHOULD SHIFT/EXPAND ESEWD OVER CENTRAL ROCKIES AND
   SRN KS THROUGH EVENING...WHILE DIRECTION OF MID-UPPER LEVEL FLOW
   BECOMES NEARLY ZONAL WITH GRADUAL CYCLONIC CURVATURE.

   AT SFC...NRN-PLAINS LOW IS FCST TO BECOME ESSENTIALLY VERTICALLY
   STACKED WITH CYCLONE ALOFT EARLY IN PERIOD...MIGRATING SLIGHTLY NEWD
   OVER ND AND N OF MID-UPPER LOW THROUGH 31/12Z.  SFC
   TROUGH/WIND-SHIFT LINE AND WEAK FRONT SHOULD ARC SWD/SWWD FROM THAT
   LOW DURING AFTERNOON...SUPPORTING SOME DIURNAL TSTM POTENTIAL ACROSS
   PORTIONS SD AND NRN/WRN NEB.  DRYLINE SHOULD MIX EWD DURING
   DAY...REACHING LATE-AFTN POSITION FROM NRN COAHUILA NNEWD ACROSS
   W-CENTRAL TX...W-CENTRAL OK AND S-CENTRAL KS...BEFORE RETREATING
   NWWD ACROSS NRN OK AND SRN KS DURING EVENING.

   ...PLAINS STATES TO UPPER MS VALLEY AND UPPER MIDWEST...
   PRIMARY CONCERN ATTM IS FOR ISOLATED TO WIDELY SCATTERED TSTMS TO
   DEVELOP INVOF DRYLINE DURING LATE AFTN AFTER STG/SUSTAINED SFC
   HEATING AND MOVE EWD...OFFERING RISK OF VERY LARGE/DAMAGING HAIL AND
   TORNADOES.  NARROW SECTOR OF VERY FAVORABLE SUPERCELL-SUPPORTING
   PARAMETER SPACE IS APPARENT FROM ABOUT E-CENTRAL KS SWWD TO RED
   RIVER REGION OF OK AND N TX...FOR ANY TSTMS THAT CAN FORM AND
   PERSIST TO MATURITY.  ROBUST MOIST-SECTOR AIR IS FCST AHEAD OF
   DRYLINE...WITH SFC DEW POINTS RANGING FROM MID-60S TO LOW-70S F
   SUPPORTING MLCAPE IN 3000-5000 J/KG RANGE...LYING BENEATH 55-65 KT
   EFFECTIVE SHEAR MAGNITUDES.  HODOGRAPHS ARE EXPECTED TO ENLARGE
   CONSIDERABLY IN 00Z-03Z TIME FRAME OVER AREA OF LARGEST HAIL/TORNADO
   PROBABILITIES...AS LLJ STRENGTHENS. UNLIKE PREVIOUS DAY...GEOMETRY
   OF FLOW RELATED TO NEGATIVELY TILTED SHORTWAVE WILL RENDER
   DEEP-SHEAR AND MEAN-WIND VECTORS NEARLY ORTHOGONAL TO
   DRYLINE...INDICATING GREATER POTENTIAL FOR DISCRETE STORM CHARACTER
   AND SUPERCELL MODE.

   HOWEVER...SOME CAVEATS ARE EVIDENT THAT MAKE THREAT TOO CONDITIONAL
   TO INTRODUCE MDT-RISK PROBABILITIES YET...AND WHICH ALSO CAST GREAT
   UNCERTAINTY ON SVR POTENTIAL FARTHER N OVER MO VALLEY..NRN PLAINS
   AND CORN BELT.  THESE INCLUDE...
   1. ABUNDANT PRIOR AND ONGOING CONVECTION FROM ERN OK/OZARKS AREA NWD
   ACROSS MO VALLEY AND NWWD OVER PORTIONS KS...EARLY IN PERIOD.  THIS
   ACTIVITY HAS OVERTURNED AIR MASS ACROSS MUCH OF THAT
   REGION...LOWERING DEW POINTS.  RESULTING MODIFIED BOUNDARY LAYER
   WILL ADVECT NWD ACROSS CENTRAL PLAINS...IA...DAKOTAS AND MO VALLEY
   REGION WITH FRAGMENTED AND MODULATED MOISTURE FIELD...CHARACTERIZED
   BY EMBEDDED RIBBONS AND POCKETS OF LOW-THETAE AIR.
   2. LACK OF WELL-DEFINED FOCI FOR INITIATION IN THAT AIR
   MASS...ESPECIALLY FROM ABOUT I-70 NWD.
   3. HEIGHT RISES ARE EXPECTED BEHIND SHORTWAVE TROUGH THROUGHOUT
   AFTERNOON OVER SRN PLAINS...WITH WEAK MID-UPPER LEVEL VERTICAL
   MOTIONS.
   4. CAPPING WILL INHIBIT TSTM COVERAGE...ESPECIALLY FROM RED RIVER
   AREA SWD ACROSS W-CENTRAL/SW TX.  ANY TSTM THAT DOES DEVELOP OFF
   DRYLINE OVER TX STILL WILL POSE SVR WIND/HAIL RISK BEFORE NOCTURNAL
   DISSIPATION.
   5. NARROWNESS OF MOST FAVORABLE MOIST SECTOR MAY LIMIT TIME WINDOW
   FOR SUPERCELLS.  STILL...GIVEN RECOVERY EXPECTED OVER OK AND
   PROBABLY SERN KS...VERY LARGE CAPE WILL SUPPORT ENHANCED
   TORNADO/HAIL PROBABILITIES FOR NOW WITHIN SLGT-RISK FRAMEWORK.

   AS SOME OF THESE UNCERTAINTIES GET BETTER RESOLVED TODAY...NARROW
   AREA OF SIGNIFICANT-TORNADO AND/OR LARGER-HAIL PROBABILITIES MAY
   BECOME NECESSARY...ESPECIALLY OVER PORTIONS OK AND KS.

   ..EDWARDS/BUNTING.. 05/30/2013

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