Sep 14, 2010 1630 UTC Day 1 Convective Outlook
Updated: Tue Sep 14 16:24:44 UTC 2010
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20100914 1630 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20100914 1630 UTC Day 1 Tornado Probabilities Graphic
Torndao Legend Image
Probabilistic Damaging Wind Graphic
20100914 1630 UTC Day 1 Damaging Wind Probabilities Graphic
Wind Legend Image
Probabilistic Large Hail Graphic
20100914 1630 UTC Day 1 Large Hail Probabilities Graphic
Hail Legend Image
   SPC AC 141621
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1121 AM CDT TUE SEP 14 2010
   
   VALID 141630Z - 151200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT FOR
   PARTS OF THE CENTRAL PLAINS...
   
   ...SYNOPSIS...
   A LARGELY ZONAL FLOW REGIME EXISTS OVER THE NRN TWO THIRDS OF THE
   CONUS...WITH SEVERAL EMBEDDED SHORTWAVE TROUGHS TRAVERSING THE GREAT
   LAKES/NEW ENGLAND...AND A WEAK SPLIT FLOW PATTERN OVER THE PAC COAST
   AND ROCKIES.  WITHIN THE SRN BRANCH...ONE SHORTWAVE TROUGH OVER NV
   THIS MORNING WILL PROGRESS ENEWD TO THE CENTRAL HIGH PLAINS
   OVERNIGHT...AND A DOWNSTREAM WAVE OVER MO WILL MOVE ESEWD AND
   WEAKEN.  THE PRIMARY SEVERE STORM THREAT ACROSS THE CONUS LATER
   TODAY INTO TONIGHT WILL BE FOCUSED ACROSS THE CENTRAL PLAINS IN
   ADVANCE OF THE EJECTING GREAT BASIN TROUGH.
   
   ...CENTRAL PLAINS REGION THROUGH TONIGHT...
   THE REMNANTS OF OVERNIGHT CONVECTION CONTINUE TO DEVELOP SWD/SEWD
   OVER ERN OK ALONG THE ERN EDGE OF THE LOW-LEVEL MOISTURE AND
   INSTABILITY CORRIDOR.  THIS CONVECTION HAS BEEN ASSOCIATED WITH A
   SHORTWAVE TROUGH OVER MO AND WAA WITH A SWLY NOCTURNAL LLJ.  SINCE
   THE MO TROUGH WILL MOVE ESEWD AWAY FROM THE INSTABILITY CORRIDOR
   TODAY AND THE NOCTURNAL LLJ WILL WEAKEN THROUGH MIDDAY...IT APPEARS
   THAT THE ONLY FOCUS FOR CONTINUED THUNDERSTORM DEVELOPMENT ACROSS OK
   WILL BE LOW-LEVEL ASCENT ALONG THE OUTFLOW BOUNDARY ACROSS CENTRAL
   AND E/SE OK.  GIVEN MODERATE INSTABILITY...WEAKENING LOW-LEVEL SHEAR
   WITH TIME AND WEAKENING DEEP-LAYER SHEAR WITH SWD EXTENT...ONLY
   ISOLATED DAMAGING WINDS AND MARGINALLY SEVERE HAIL ARE EXPECTED WITH
   THE OK STORMS THIS AFTERNOON.
   
   A ZONE OF MID 60S BOUNDARY LAYER DEWPOINTS EXTENDS NNWWD ACROSS
   CENTRAL KS/NEB TO THE W OF THE OUTFLOW WITH THE ONGOING OK
   STORMS...AND S OF WEAK LOW IN S CENTRAL SD.  LEE CYCLOGENESIS IS
   EXPECTED THIS AFTERNOON FARTHER TO THE W ACROSS THE CENTRAL HIGH
   PLAINS /IN ADVANCE OF THE GREAT BASIN MIDLEVEL TROUGH/.  BASED ON
   MODIFIED 12Z REGIONAL SOUNDINGS...SURFACE TEMPERATURES WILL NEED TO
   WARM INTO THE 90S ACROSS WRN KS/NEB TO REMOVE CONVECTIVE INHIBITION
   AND ALLOW THUNDERSTORM DEVELOPMENT ALONG THE LEE TROUGH THIS
   AFTERNOON.  THE WARMER EML AND STRONGER CAP RESIDES OVER
   KS/NEB...WITH A WEAKER CAP AND RICHER LOW-LEVEL MOISTURE ACROSS WRN
   OK...WHERE ISOLATED THUNDERSTORM DEVELOPMENT WILL ALSO BE POSSIBLE
   THIS AFTERNOON.  THE STRENGTH OF THE CAP AND LACK OF LARGE SCALE
   SUPPORT FOR ASCENT SUGGESTS THAT THUNDERSTORM COVERAGE WILL REMAIN
   RATHER SPARSE ACROSS THE HIGH PLAINS THIS AFTERNOON/EVENING.  WHAT
   STORMS DO FORM COULD BECOME SUPERCELLS CAPABLE OF PRODUCING LARGE
   HAIL AND DAMAGING WINDS...GIVEN STEEP MIDLEVEL LAPSE RATES AND
   EFFECTIVE BULK SHEAR OF 40-50 KT.
   
   STRONGER LOW-LEVEL SHEAR WILL BE PRESENT ALONG THE STALLED FRONT
   NEAR THE SD/NEB BORDER THIS AFTERNOON/EVENING...WHERE AT LEAST WEAK
   LOW-LEVEL ASCENT WILL BE PRESENT.  HOWEVER...THE WARM UPSTREAM EML
   MAY ALSO SERVE TO INHIBIT SURFACE-BASED THUNDERSTORM DEVELOPMENT
   ALONG THIS BOUNDARY DURING THE AFTERNOON.  IF STORMS
   FORM...SUPERCELLS WILL CERTAINLY BE POSSIBLE.  OTHERWISE...THE MORE
   PROBABLE SCENARIO APPEARS TO BE FOR CONVECTION TO INCREASE TONIGHT
   ACROSS NEB/SD AS LOW-LEVEL WAA INCREASES IN CONJUNCTION WITH A 35-45
   KT LLJ...AND WITH THE ARRIVAL OF THE GREAT BASIN MIDLEVEL TROUGH. 
   ONE OR MORE THUNDERSTORM CLUSTERS SHOULD EVOLVE FROM THE OVERNIGHT
   CONVECTION ACROSS SD/NEB...WITH THE POTENTIAL FOR A FEW DAMAGING
   WIND AND LARGE HAIL EVENTS.
   
   ..THOMPSON/ROGERS.. 09/14/2010
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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