Apr 21, 2010 1630 UTC Day 1 Convective Outlook
Updated: Wed Apr 21 16:18:15 UTC 2010
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20100421 1630 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20100421 1630 UTC Day 1 Tornado Probabilities Graphic
Torndao Legend Image
Probabilistic Damaging Wind Graphic
20100421 1630 UTC Day 1 Damaging Wind Probabilities Graphic
Wind Legend Image
Probabilistic Large Hail Graphic
20100421 1630 UTC Day 1 Large Hail Probabilities Graphic
Hail Legend Image
   SPC AC 211615
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1115 AM CDT WED APR 21 2010
   
   VALID 211630Z - 221200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY
   TONIGHT FROM EXTREME NW TX INTO SE CO...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS THROUGH LATE EVENING FOR
   UT...WRN CO...SE ID...SW WY...
   
   ...SE TX PANHANDLE TO SE CO THIS AFTERNOON THROUGH EARLY TONIGHT...
   LOW-LEVEL MOISTURE IS RETURNING NWD ACROSS W/NW TX WITH BOUNDARY
   LAYER DEWPOINTS NOW IN THE MID-UPPER 50S INTO THE PVW-ABI-SPS
   AREA...AND A SLOW INCREASE IS EXPECTED THIS AFTERNOON WITH CONTINUED
   MOISTURE ADVECTION AND LATENT HEAT FLUX FROM THE MOIST GROUND. 
   MEANWHILE...CLOUD EROSION AND DAYTIME HEATING FROM S TO N WILL
   CONTRIBUTE TO DIFFERENTIAL HEATING AND HELP CONSOLIDATE A
   SLOW-MOVING WARM FRONT ALONG THE CAO-AMA-CDS-SPS CORRIDOR...ROUGHLY
   ALONG THE RED RIVER INTO PALO DURO CANYON.  THIS SURFACE BOUNDARY
   WILL SERVE TO FOCUS THUNDERSTORM DEVELOPMENT AS CONVECTIVE
   INHIBITION WEAKENS THIS AFTERNOON.
   
   MODERATE INSTABILITY /MLCAPE OF 1000-2000 J PER KG/ IS EXPECTED THIS
   AFTERNOON ALONG THE FRONT AND E OF A DIFFUSE DRYLINE.  THIS
   INSTABILITY...IN COMBINATION WITH A GRADUAL INCREASE IN LOW-MIDLEVEL
   FLOW...WILL CONTRIBUTE TO AN ENVIRONMENT FAVORABLE FOR SUPERCELLS
   THIS AFTERNOON INTO EARLY TONIGHT...ESPECIALLY IN THE AREA BETWEEN
   PVW-AMA-CDS.  FORECAST HODOGRAPHS SHOW FAVORABLE VERTICAL WIND SHEAR
   FOR PERSISTENT STORMS...AND AN INCREASE IN LOW-LEVEL SHEAR LATE THIS
   EVENING WITH A DEVELOPING 25-35 KT SLY/SSELY LLJ.  A COUPLE OF
   TORNADOES...LARGE HAIL...AND ISOLATED DAMAGING WINDS WILL ALL BE
   POSSIBLE FROM MID-LATE AFTERNOON THROUGH AT LEAST EARLY TONIGHT.
   
   FARTHER NW INTO SE CO...LOW-LEVEL UPSLOPE FLOW WILL DRAW UPPER 40S
   TO LOWER 50S BOUNDARY LAYER DEWPOINTS NWWD...AND A FEW CLOUD BREAKS
   WILL ALLOW SURFACE HEATING IMMEDIATELY E OF THE MOUNTAINS. 
   THUNDERSTORMS WILL LIKELY DEVELOP THIS AFTERNOON OVER THE HIGH
   TERRAIN IN CO AND THEN SPREAD SEWD ALONG THE BAROCLINIC ZONE NEAR
   THE RATON MESA.  THOUGH INSTABILITY WILL BE WEAKER COMPARED TO AREAS
   FARTHER SE IN THE TX PANHANDLE...VERTICAL SHEAR WILL BE SUFFICIENT
   FOR SUPERCELLS CAPABLE OF PRODUCING AT LEAST ISOLATED LARGE HAIL AND
   DAMAGING GUSTS.  OVERNIGHT...CLUSTERS OF ELEVATED THUNDERSTORMS WILL
   CONTINUE AND SPREAD EWD/NEWD ACROSS WRN/NRN OK INTO KS IN
   ASSOCIATION WITH LOW-LEVEL WAA.
   
   ...GREAT BASIN THROUGH LATE EVENING...
   A STRONG MIDLEVEL LOW AND ASSOCIATED COLD FRONT WILL CONTINUE TO
   MOVE SLOWLY EWD ACROSS UT/AZ THROUGH EARLY TONIGHT.  A FOCUSED BELT
   OF ASCENT ALONG THE FRONT...COMBINED WITH 7-8 C/KM MIDLEVEL LAPSE
   RATES AND STEEPENING LOW-LEVEL LAPSE RATES WITH DAYTIME
   HEATING...WILL SUPPORT A BAND OF THUNDERSTORMS WHICH WILL SPREAD EWD
   ACROSS UT/SE ID INTO SW WY/WRN CO THROUGH THIS EVENING.  THOUGH
   INSTABILITY WILL NOT BE PARTICULARLY STRONG...SUBSTANTIAL DEEP-LAYER
   SLY SHEAR AND INVERTED-V PROFILES IN THE LOW LEVELS WILL SUPPORT
   EMBEDDED BOWING SEGMENTS AND/OR ROTATING STORMS WITH THE POTENTIAL
   FOR A FEW DAMAGING GUSTS.
   
   ..THOMPSON/ROGERS.. 04/21/2010
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z