Apr 13, 2012 1630 UTC Day 1 Convective Outlook
Updated: Fri Apr 13 17:28:24 UTC 2012
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20120413 1630 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20120413 1630 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
20120413 1630 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
20120413 1630 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.
   SPC AC 131725
   
   DAY 1 CONVECTIVE OUTLOOK CORR 1
   NWS STORM PREDICTION CENTER NORMAN OK
   1225 PM CDT FRI APR 13 2012
   
   VALID 131630Z - 141200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS SRN KS/MUCH OF OK AND
   INTO PORTIONS OF NRN AND NWRN TX...
   
   CORRECTED SIG AREA ON THE TORNADO GRAPHIC
   
   ...SYNOPSIS...
   A LEAD SHORT-WAVE TROUGH CROSSING THE MID MO VALLEY ATTM WILL
   CONTINUE SHIFTING NNEWD WITH TIME...WHILE THE MAIN SYNOPTIC SYSTEM
   DIGS SEWD ACROSS CENTRAL AND SRN CA AND REACHES THE LOWER CO VALLEY
   BY THE END OF THE PERIOD.  IN BETWEEN...A BROAD ZONE OF FAST/FLAT
   SWLY FLOW ALOFT WILL PREVAIL ACROSS THE CENTRAL AND SRN PLAINS.
   
   AT THE SURFACE...A COLD FRONT WILL CROSS SRN CA AND SHIFT
   INTO/ACROSS THE DESERT SW AHEAD OF THE MAIN UPPER SYSTEM. 
   MEANWHILE...THE SURFACE PATTERN ACROSS THE N CENTRAL CONUS IS
   PROGGED TO BECOME MORE ILL-DEFINED WITH TIME...AS A DEVELOPING LEE
   CYCLONE IN THE ERN CO VICINITY BECOMES THE MAIN SURFACE FEATURE OVER
   THE PLAINS THROUGH THE SECOND HALF OF THE PERIOD.  
   
   ...NRN AND WRN OK/KS AND VICINITY...
   A SLOWLY WARMING/MOISTENING BOUNDARY LAYER IS OBSERVED ACROSS THE
   TX/OK VICINITY...AHEAD OF A DRYLINE MIXING SLOWLY EWD INTO WRN OK
   ATTM.  HOWEVER...DRYLINE ADVANCE IS PROGGED TO REMAIN LIMITED...WITH
   SOME RETREAT EXPECTED LATER THIS AFTERNOON AND EVENING AS SURFACE
   PRESSURE FALLS INCREASE ACROSS THE HIGH PLAINS.  
   
   WITH ONLY WEAK CAPPING INDICATED BY MORNING RAOBS WITHIN AN
   OTHERWISE VERY FAVORABLE KINEMATIC AND THERMODYNAMIC
   ENVIRONMENT...THE FORECAST REMAINS CHALLENGING -- AS ANY
   SURFACE-BASED STORM WHICH DOES DEVELOP WOULD BE LIKELY TO RAPIDLY
   ORGANIZE INTO A LARGE SUPERCELL STORM.  SOME POTENTIAL EXISTS THAT
   THE SUBTLE AREA OF WEAK MID-LEVEL ASCENT EVIDENT IN WV IMAGERY NOW
   MOVING ENEWD ACROSS SERN CO AND NERN/CENTRAL NM COULD SUPPORT
   EARLIER -- AND POSSIBLY MORE WIDESPREAD -- INITIATION THAN CURRENTLY
   EXPECTED.  HOWEVER...THE MORE LIKELY SCENARIO REMAINS THAT
   DEVELOPMENT WILL REMAIN CONFINED TO THIS AFTERNOON -- INVOF THE
   AFOREMENTIONED DRYLINE...WITHIN A ZONE FROM NWRN TX ACROSS THE ERN
   TX PANHANDLE AND INTO WRN OK.
   
   AS MENTIONED...STORMS WHICH DEVELOP WILL RAPIDLY ORGANIZE...AS 1500
   TO 2000 J/KG MIXED-LAYER CAPE COMBINED WITH A PARTICULARLY FAVORABLE
   WIND PROFILE /VEERING AND INCREASING RAPIDLY WITH HEIGHT FROM SSELY
   AT LOW LEVELS TO WSWLY AT 50 KT AT MID LEVELS/ WILL FAVOR
   LARGE/LONG-LIVED SUPERCELLS.  AGAIN -- WITH GENERALLY WEAK/SUBTLE
   FORCING FOR ASCENT...STORMS SHOULD REMAIN FAIRLY ISOLATED INITIALLY
   -- AND THUS WILL MAINTAIN ONLY SLIGHT RISK CATEGORICAL FORECAST
   ATTM.  HOWEVER...ANY STORM WHICH DOES DEVELOP WILL BE CAPABLE OF
   PRODUCING VERY LARGE HAIL...DAMAGING WINDS...AND POTENTIALLY
   STRONG/LONG-LIVED TORNADOES.
   
   DURING THE EVENING...AS THE INITIAL STORMS SHIFT NEWD TOWARD NRN
   OK/SRN KS...AN EXPANSION IN CONVECTIVE COVERAGE IS EXPECTED AS SLY
   LOW-LEVEL JET INTENSIFIES TO NEAR 50 KT.  WHILE AN EVENTUAL LARGE
   CLUSTER OF STORMS -- ACCOMPANIED BY POTENTIAL FOR LARGE HAIL AND
   LOCALLY DAMAGING WINDS -- SHOULD EVOLVE AND SHIFT ENEWD ACROSS KS
   AND INTO MO WITH TIME...A PERIOD OF HEIGHTENED TORNADO POTENTIAL MAY
   EXIST FOR A FEW HOURS INVOF SUNSET AND INTO EARLY EVENING AS THE
   LOW-LEVEL WIND PROFILE BECOMES PARTICULARLY SUPPORTIVE.
   
   ...SRN CA...
   A BAND OF CONVECTION CONTINUES MOVING EWD/SEWD ACROSS SRN CA...INVOF
   THE SURFACE COLD FRONT AND JUST AHEAD OF THE STRONG SHORT-WAVE
   SYSTEM DIGGING SEWD JUST OFF THE CA COAST.  WITH A FAIRLY STRONG
   DEEP-LAYER WIND FIELD BUT VERY MODEST INSTABILITY...STORMS SHOULD
   REMAIN GENERALLY SUB-SEVERE.  HOWEVER...GUSTY WINDS OR EVEN A
   BRIEF/WEAK TORNADO WILL BE POSSIBLE WITH ANY STRONGER CONVECTIVE
   CELL/BAND -- PRIMARILY INVOF THE COAST.
   
   FARTHER N INTO THE CENTRAL VALLEY...COLD AIR ALOFT/STEEP LAPSE RATES
   NEARER TO THE CENTER OF THE UPPER SYSTEM SHOULD -- WITH LIMITED
   BOUNDARY-LAYER HEATING -- SUPPORT INCREASING AFTERNOON SHOWERS AND
   ISOLATED THUNDERSTORMS.  GIVEN THE STEEP LAPSE RATES/COLD MID
   LEVELS...MARGINAL HAIL WILL BE POSSIBLE WITH A STRONGER CELL OR TWO.
   
   ..GOSS.. 04/13/2012
   
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