May 6, 2012 2000 UTC Day 1 Convective Outlook
Updated: Sun May 6 20:06:28 UTC 2012
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20120506 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20120506 2000 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
20120506 2000 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
20120506 2000 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 062003
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0303 PM CDT SUN MAY 06 2012
   
   VALID 062000Z - 071200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID TO
   UPPER MS VALLEY...OZARKS...CNTRL PLAINS AND SRN PLAINS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE GULF COAST
   STATES...
   
   SEVERAL CHANGES HAVE BEEN MADE TO THE OUTLOOK AT 20Z. THE FIRST
   CHANGE IS TO REMOVE THE SLIGHT RISK AREA FROM SRN WI AND CNTRL IA
   WHERE A COLD FRONT IS STABILIZING THE AIRMASS FROM NORTHWEST TO
   SOUTHEAST. THE SECOND CHANGE IS TO MAKE THE 30 PERCENT WIND DAMAGE
   PROBABILITY SMALLER AND CO-LOCATED WITH THE 5 PERCENT TORNADO
   PROBABILITY OVER NCNTRL IL JUST AHEAD OF A CLUSTER OF SEVERE STORMS.
   ANOTHER CHANGE IS TO REMOVE THE SLIGHT RISK AREA FROM NE MS...CNTRL
   AL AND SCNTRL GA WHERE ANALYSIS SHOWS WEAKER INSTABILITY THAN IN
   AREAS TO THE SOUTH AND WEST. ANOTHER CHANGE IS TO MOVE THE WRN EDGE
   OF THE SLIGHT OVER CNTRL OK TO AREAS EAST OF I-35 DUE TO A DRY SLOT
   THAT IS APPROACHING CNTRL OK FROM THE WEST. THE FINAL CHANGE IS TO
   ADD A NARROW 5 PERCENT WIND AND HAIL PROBABILITY OVER NW OK TO
   COINCIDE WITH A NARROW AXIS OF MODERATE INSTABILITY.
   
   ..BROYLES.. 05/06/2012
   
   .PREV DISCUSSION... /ISSUED 1119 AM CDT SUN MAY 06 2012/
   
   ...SYNOPSIS...
   
   UPPER LOW ALONG THE MT/SASKATCHEWAN BORDER WILL PROGRESS EWD INTO
   SRN MANITOBA WITH A TRAILING POSITIVE-TILT TROUGH EXTENDING SWWD
   INTO THE LOWER CO VALLEY.  ELSEWHERE...WEAK MIDLEVEL IMPULSES WILL
   CREST RIDGE AXIS OVER THE UPPER GREAT LAKES AND MIDWEST WHILE A WEAK
   PERTURBATION MOVES FROM THE CNTRL/SRN HIGH PLAINS ACROSS KS/OK
   TODAY.
   
   AT THE SURFACE...COLD FRONT FROM THE UPPER MS VALLEY THROUGH MID MO
   VALLEY INTO WRN TX WILL ADVANCE SWD/SEWD WHILE A WARM FRONT LIFTS
   NWD ACROSS PORTIONS OF THE OH VALLEY.  MEANWHILE...A DRYLINE WILL
   DEVELOP TODAY FROM THE INTERSECTION OF THE COLD FRONT SWD INTO THE
   EDWARDS PLATEAU OF TX.
   
   ...UPPER MIDWEST INTO OZARKS THIS AFTERNOON/EVENING...
   
   12Z WARM SECTOR SOUNDINGS SHOWED A VERY MOIST BOUNDARY LAYER BENEATH
   STEEP MIDLEVEL LAPSE RATES WITH MUCAPE VALUES ALREADY ON THE ORDER
   OF 3500-5000 J/KG.  THE STRONGEST HEIGHT FALLS ASSOCIATED WITH THE
   UPPER LOW MENTIONED ABOVE WILL REMAIN ACROSS POST-FRONTAL AIR MASS. 
   HOWEVER...INFLUENCE OF WEAKER MIDLEVEL PERTURBATIONS EMBEDDED WITHIN
   SWLY FLOW REGIME AND UPLIFT ALONG SYNOPTIC FRONTS AND EXISTING
   OUTFLOW BOUNDARIES WILL BE SUFFICIENT TO FOSTER AN INCREASE IN TSTM
   ACTIVITY TODAY.  VERTICAL SHEAR WILL REMAIN MARGINALLY SUPPORTIVE OF
   STORM ORGANIZATION.  BUT...THE DEGREE OF INSTABILITY MAY COMPENSATE
   WITH THE POTENTIAL FOR LARGE HAIL...DAMAGING WINDS...AND PERHAPS A
   BRIEF TORNADO.
   
   ...CNTRL/SRN PLAINS THIS AFTERNOON/EVENING...
   
   AS MENTIONED ABOVE...A WEAK MIDLEVEL IMPULSE WILL PROGRESS ACROSS
   THE REGION TODAY...PROVIDING A FAVORABLE BACKGROUND ENVIRONMENT FOR
   STORM FORMATION ALONG THE COLD FRONT AND PERHAPS DRYLINE.  HERE
   TOO...A MOIST BOUNDARY LAYER WILL COINCIDE WITH AN EML/STEEP
   MIDLEVEL LAPSE RATES TO YIELD AFTERNOON MLCAPE VALUES OF 2500-3500+
   K/JG.  STRONGER CAPPING ACROSS THE SRN PLAINS MAY TEND TO LIMIT
   STORM COVERAGE WITH SWD EXTENT ALONG THE COLD FRONT...WHILE
   GENERALLY WEAK VERTICAL SHEAR WILL MODULATE THE DEGREE OF STORM
   ORGANIZATION.  NONETHELESS...THE PRESENCE OF THE STEEP LAPSE RATES
   AND MODERATE-STRONG INSTABILITY SUGGEST THE POTENTIAL FOR VIGOROUS
   UP/DOWNDRAFTS WITH AN ASSOCIATED RISK FOR DAMAGING WINDS AND HAIL.
   
   ...CNTRL/ERN GULF STATES THIS AFTERNOON/EVENING...
   
   TSTMS HAVE ALREADY FORMED THIS MORNING ACROSS PORTIONS OF
   AL/GA...APPARENTLY IN ASSOCIATION WITH A COLD POOL WHICH HAS SURGED
   SWD OUT OF THE TN VALLEY.  12Z BMX SOUNDING REVEALED SEASONABLY COOL
   MIDLEVEL TEMPERATURES /I.E. AROUND -15 C AT 500 MB/ ATOP A MOIST
   BOUNDARY LAYER WITH MUCAPE ESTIMATED TO BE AROUND 3000 J/KG. 
   PRE-EXISTING CONVECTIVE OUTFLOW BOUNDARIES WILL LIKELY SERVE AS THE
   FOCUS FOR RENEWED TSTM DEVELOPMENT TODAY WITHIN THE
   MOIST...MODERATE-STRONGLY UNSTABLE ENVIRONMENT.  VERTICAL SHEAR WILL
   REMAIN WEAK...BUT THE PRESENCE OF THE STEEP LAPSE RATES AND DEGREE
   OF INSTABILITY WILL PROMOTE ORGANIZED MULTICELL CLUSTERS CAPABLE OF
   DAMAGING WINDS AND SEVERE HAIL.
   
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