Apr 22, 2011 0100 UTC Day 1 Convective Outlook
Updated: Fri Apr 22 01:03:07 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20110422 0100 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110422 0100 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
20110422 0100 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
20110422 0100 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 220059
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0759 PM CDT THU APR 21 2011
   
   VALID 220100Z - 221200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS SW TX TO SWRN OK...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS NERN OK/KS/AR/MO...
   
   ...SYNOPSIS...
   BROAD AREA OF CYCLONIC FLOW OVER NWRN CONUS IS ASSOCIATED WITH TWO
   SHORTWAVE TROUGHS...
   1. STRONGER PERTURBATION MOVING SLOWLY EWD ACROSS ERN PORTIONS
   WA/ORE TOWARD ID...AND
   2. LEADING/SRN TROUGH NOW APPARENT IN MOISTURE CHANNEL IMAGERY AND
   VWP/RAOB DATA OVER UT.
   AS HEIGHTS FALL TO ITS NW...LEADING TROUGH WILL MOVE EWD ACROSS
   CENTRAL ROCKIES TO ERN WY...BLACK HILLS AND NEB PANHANDLE REGION. 
   BY 12Z...LOW-AMPLITUDE TROUGHING...WITHOUT SIGNIFICANT VORTICITY
   CONCENTRATIONS...SHOULD EXTEND SWD ACROSS NM AND FAR W TX.
   
   AT SFC...QUASISTATIONARY FRONT WAS ANALYZED AT 23Z FROM SEA BREEZE
   INTERSECTION OVER SERN GA WWD OVER SRN AL...BECOMING DIFFUSED BY
   OUTFLOW FROM EARLIER CONVECTION OVER SRN PORTIONS MS/AL.  BOUNDARY
   THEN BECAME BETTER-DEFINED AGAIN AS WARM FRONT ACROSS EXTREME NRN
   LA...NE TX...JUST N OF DFW METROPLEX...THEN WSWWD TO JUST N ABI. 
   FRONT MERGED WITH DRYLINE NEAR SERN LYNN COUNTY TX.  BLENDED WARM
   FRONT/DRYLINE EXTENDED NWD ACROSS WRN SOUTH-PLAINS OF TX AND WRN
   PANHANDLE TO SFC LOW OVER SERN CO.  SECONDARY/FRONTOGENETIC ZONE WAS
   EVIDENT FROM NEAR ADM WNWWD NEAR LTS...THEN NWWD ACROSS N-CENTRAL
   PORTIONS TX PANHANDLE.  EXCEPT WHERE LOCALLY MODULATED BY
   OUTFLOW...SRN BOUNDARY SHOULD WEAKEN OVERNIGHT BENEATH STG LOW-LEVEL
   WAA...WHILE PRIMARY SYNOPTIC WARM FRONT DEVELOPS NWD INTO PORTIONS
   SRN/CENTRAL KS.  LOW SHOULD MOVE EWD ACROSS SWRN KS/NRN OK AREA. 
   DRYLINE...ANALYZED FROM NWRN COAHUILA NEAR FST THEN NNEWD TO
   FRONT...SHOULD RETREAT SLIGHTLY NWWD ACROSS PORTIONS PERMIAN BASIN.
   
   ...NERN OK/KS/AR/MO...
   LARGE COMPLEX OF MAINLY NON-SEVERE CONVECTION IS MOVING NEWD ACROSS
   OZARKS REGION ATTM...ALTHOUGH OCNL SVR HAIL CANNOT BE RULED OUT FROM
   CORES ALONG ITS SRN/WRN FRINGES WHERE ACCESS TO MOST
   BUOYANT/ELEVATED INFLOW WILL REMAIN.  REF SPC WW 175 AND
   ACCOMPANYING MESOSCALE DISCUSSIONS FOR NEAR-TERM GUIDANCE.
   
   OVERNIGHT...EXPECT COMBINATION OF HEIGHT FALLS...STRENGTHENING
   DEEP-LAYER SHEAR...AND INCREASING WAA/MOISTURE TRANSPORT INTO NRN
   PARTS OF THIS REGION...AHEAD OF APCHG SHORTWAVE TROUGH.  AS THIS
   OCCURS...ELEVATED WARM FRONTOGENETIC FORCING AND ISENTROPIC ASCENT
   TO LFC EACH SHOULD STRENGTHEN AS WELL...WITH CORRESPONDING
   DEVELOPMENT/INCREASE IN COVERAGE/INTENSITY OF TSTMS OVER LOWER MO
   VALLEY REGION.
   
   ...SW TX TO SWRN OK...
   SEVERAL STG-SVR TSTMS...INCLUDING A FEW SUPERCELLS CAPABLE OF VARY
   LARGE/DAMAGING HAIL AND TRANSIENT TORNADOES...ARE APPARENT  E OF
   DRYLINE OVER WW 176.  OPTIMAL COMBINATION OF BUOYANCY AND SHEAR
   SHOULD REMAIN INVOF WARM-FRONTAL ZONE FROM SNK/ABI AREAS EWD TOWARD
   SEP/MWL AREA...ALONG WITH EFFECTIVE SRH AND LOW-LEVEL VORTICITY IN
   SUPPORT OF SUPERCELLS.  INCREASING CAPPING WITH TIME...PER MODIFIED
   00Z FWD/DRT RAOBS FOR SFC COOLING...CASTS SOME UNCERTAINTY ON HOW
   FAR E ACTIVITY CAN PERSIST ACROSS/BEYOND WW AREA.  SRN COMPLEX MAY
   GROW UPSCALE SUFFICIENTLY TO ORGANIZE COLD POOL AND PERSIST ACROSS
   PORTIONS EDWARDS PLATEAU/SWRN HILL COUNTRY.  SEE WW AND ATTENDANT
   MESOSCALE DISCUSSIONS FOR NOWCAST INFORMATION ON SVR THREAT IN THIS
   REGION.
   
   MODIFIED RAOBS AND FCST SOUNDINGS SUGGEST ENVIRONMENT SUPPORTING
   ELEVATED SUPERCELLS AND LARGE HAIL POTENTIAL N OF SFC FRONT THROUGH
   MUCH OF TONIGHT...MAIN UNCERTAINTIES INVOLVING INITIATION AND
   COVERAGE.  CONVECTION NEAR TRIPLE POINT MAY MOVE ALONG OR N OF FRONT
   AS FRONT LIFTS NWD...AND/OR ADDITIONAL TSTMS MAY DEVELOP N OF FRONT.
   HODOGRAPHS APPEAR RATHER LARGE AND CURVED FOR SUSTAINED
   LEFT-SPLITS...AND ARE FCST TO GROW BIGGER OVERNIGHT AS LLJ
   STRENGTHENS TO 40-50 KT RANGE.  HOWEVER...PARCELS N OF WHAT NOW IS
   PRIMARY WARM FRONT SHOULD REMAIN ROOTED ABOVE SFC...WITH LARGE HAIL
   BEING MAIN THREAT FROM ANY TSTMS AFTER ABOUT 06Z.
   
   ...CENTRAL HIGH PLAINS...
   ISOLATED STG-SVR GUSTS ARE STILL POSSIBLE FOR ANOTHER COUPLE OF
   HOURS FROM HIGH-BASED CONVECTION MOVING OVER DEEPLY WELL-MIXED
   BOUNDARY LAYER.  HOWEVER...LARGE DEWPOINT DEPRESSIONS AT SFC WILL
   CONTRIBUTE TO SHARP DIABATIC COOLING/STABILIZATION AND WEAKENING OF
   WIND THREAT THIS EVENING.
   
   ..EDWARDS.. 04/22/2011
   
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