Apr 24, 2015 2000 UTC Day 1 Convective Outlook
Updated: Fri Apr 24 20:01:43 UTC 2015 (20150424 2000Z Day 1 shapefile | 20150424 2000Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20150424 2000 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 94,375 10,778,280 Dallas, TX...Fort Worth, TX...Arlington, TX...Plano, TX...Garland, TX...
SLIGHT 249,585 21,332,169 Houston, TX...San Antonio, TX...Austin, TX...Oklahoma City, OK...New Orleans, LA...
MARGINAL 292,458 16,045,255 Memphis, TN...Kansas City, MO...Birmingham, AL...Mobile, AL...Little Rock, AR...
Probabilistic Tornado Graphic
20150424 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.
Day 1 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SIG SEVERE 44,249 6,383,739 Dallas, TX...Arlington, TX...Garland, TX...Shreveport, LA...Irving, TX...
10 % 48,948 8,429,815 Dallas, TX...Fort Worth, TX...Arlington, TX...Plano, TX...Garland, TX...
5 % 153,777 11,975,411 San Antonio, TX...Austin, TX...New Orleans, LA...Baton Rouge, LA...Jackson, MS...
2 % 172,966 14,077,405 Houston, TX...Kansas City, MO...Wichita, KS...Corpus Christi, TX...Laredo, TX...
Probabilistic Damaging Wind Graphic
20150424 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.
Day 1 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
30 % 54,371 7,916,043 Dallas, TX...Fort Worth, TX...Arlington, TX...Garland, TX...Shreveport, LA...
15 % 287,417 23,453,371 Houston, TX...San Antonio, TX...Austin, TX...Oklahoma City, OK...Tulsa, OK...
5 % 281,884 16,111,395 Memphis, TN...Kansas City, MO...New Orleans, LA...Birmingham, AL...Mobile, AL...
Probabilistic Large Hail Graphic
20150424 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.
Day 1 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SIG SEVERE 65,584 11,424,649 San Antonio, TX...Dallas, TX...Austin, TX...Fort Worth, TX...Arlington, TX...
30 % 76,110 10,113,323 Dallas, TX...Fort Worth, TX...Arlington, TX...Plano, TX...Garland, TX...
15 % 236,514 19,812,750 Houston, TX...San Antonio, TX...Austin, TX...Oklahoma City, OK...Tulsa, OK...
5 % 312,045 17,689,394 Memphis, TN...Kansas City, MO...New Orleans, LA...Birmingham, AL...Mobile, AL...
   SPC AC 242001

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0301 PM CDT FRI APR 24 2015

   VALID 242000Z - 251200Z

   ...THERE IS AN ENH RISK OF SVR TSTMS FROM CNTRL TX TO THE LOWER MS
   VALLEY...

   ...THERE IS AN ENH RISK OF SVR TSTMS FOR CNTRL KS...

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER MUCH OF KS AND PARTS OF
   CNTRL AND WRN OK...

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM W-CNTRL TX EWD INTO THE
   LOWER MS VALLEY...

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL
   STATES AND CNTRL GULF COAST...

   ...SUMMARY...
   SEVERE THUNDERSTORMS ARE LIKELY THIS AFTERNOON INTO TONIGHT FROM
   TEXAS TO THE LOWER MISSISSIPPI VALLEY. OTHER SEVERE STORMS ARE
   EXPECTED OVER PARTS OF THE CENTRAL GREAT PLAINS THIS AFTERNOON AND
   EVENING. STORMS WILL BE CAPABLE OF VERY LARGE HAIL...DAMAGING
   WINDS...AND TORNADOES. A COUPLE STRONG TORNADOES ARE POSSIBLE FROM
   NORTHEAST TEXAS TO NORTHERN LOUISIANA.

   A FEW CHANGES HAVE BEEN MADE TO THE EXISTING OUTLOOK AND ARE
   DESCRIBED BELOW.  OTHERWISE THE FORECAST APPEARS ON TRACK.
     
   1. CONSIDERABLE CLOUD COVER AND CONVECTIVE SHOWERS INVOF THE RED
   RIVER VALLEY HAVE IMPEDED GREATER DIURNAL DESTABILIZATION THAN
   PREVIOUSLY THOUGHT.  DUE TO EXISTING CONVECTION ACTING TO REINFORCE
   THE EFFECTIVE BAROCLINIC ZONE/OUTFLOW BOUNDARY ACROSS N-CNTRL
   TX...HAVE REDUCED SEVERE PROBABILITIES N OF THIS REGION OVER
   PORTIONS OF SRN OK NEWD INTO NWRN AR AND AREAS DOWNSTREAM.  
   2. BASED ON VISIBLE SATELLITE IMAGERY AND SURFACE
   OBSERVATIONS...HAVE INCLUDED ADDITIONAL AREAS OF NWRN KS INTO SLIGHT
   RISK AND ENHANCED RISK CATEGORIES.  STEEP TO VERY STEEP LAPSE RATES
   AND SUFFICIENT SHEAR WILL PROBABLY PROVE ADEQUATE AS STORMS DEVELOP
   AND MOVE INTO THE MOIST AXIS.  LARGE TO VERY LARGE HAIL APPEARS TO
   BE THE PRIMARY THREAT BUT A TORNADO OR TWO IS POSSIBLE WITH STORMS
   THAT CAN FAVORABLY INTERACT TO AMBIENT LOW-LEVEL VORTICITY ALONG THE
   BOUNDARY.

   ..SMITH.. 04/24/2015

   .PREV DISCUSSION... /ISSUED 1132 AM CDT FRI APR 24 2015/

   ...TX TO LOWER MS VALLEY...
   SEVERE WEATHER SCENARIO REMAINS COMPLICATED BY ONGOING SCATTERED
   TSTMS...ALONG WITH A NUMBER OF CONVECTIVE OUTFLOWS FROM EARLIER
   OVERNIGHT CONVECTIVE COMPLEXES...THE STABILIZING EFFECTS OF WHICH
   WERE MOST EVIDENT IN 12Z CRP/BRO RAOBS. THESE RENDER TOO MUCH
   UNCERTAINTY IN FURTHER UPGRADING SEVERE TSTM PROBABILITIES. 

   THE GREATEST DIURNALLY-DRIVEN RISK WILL PROBABLY EVOLVE WHERE A
   POCKET OF STRONGER INSOLATION IS APPARENT ACROSS N-CNTRL TO E-CNTRL
   TX. THIS SHOULD YIELD MORE ROBUST DESTABILIZATION ALONG THE
   PERIPHERY OF UPPER 60S TO MIDDLE 70S SURFACE DEW POINTS. AS
   MID-LEVEL HEIGHTS CONTINUE TO FALL IN RESPONSE TO THE VORT
   MAX/CIRCULATION CENTER SHIFTING NEWD ACROSS NM...ONGOING ELEVATED
   CONVECTION ACROSS THE TX BIG COUNTRY SHOULD INTENSIFY IN THE EARLY
   AFTERNOON AS THEY BECOME INCREASINGLY ROOTED IN THE DESTABILIZING
   BOUNDARY LAYER.  

   WITH 60 TO 70 KT SWLY MID-LEVEL FLOW ACCOMPANYING THE NM VORT MAX
   CONTINUING TO SPREAD ACROSS TX...THE KINEMATIC ENVIRONMENT WILL BE
   QUITE SUPPORTIVE OF ORGANIZED STORMS. A MIXED CONVECTIVE MODE IS
   EXPECTED...WITH LIKELY TENDENCY FOR SUPERCELLS IN SOME AREAS TO
   GROW UPSCALE INTO MULTIPLE LINE SEGMENTS/BOWS. THUS...LARGE HAIL
   AND DAMAGING WINDS CAN BE EXPECTED...ALONG WITH TORNADOES
   WHERE CELLULAR CONVECTIVE MODE CAN BE MAINTAINED /A COUPLE OF WHICH
   COULD BE STRONG/. 

   ADDITIONAL MORE ISOLATED TSTM ACTIVITY SHOULD DEVELOP S ALONG THE
   DRYLINE AS IT MIXES E ACROSS THE EDWARDS PLATEAU. ALTHOUGH LOW-LEVEL
   SHEAR WILL BE WEAKER RELATIVE TO FARTHER NE...VERY STRONG DEEP SHEAR
   WILL SUPPORT SUPERCELLS WITH RISKS FOR VERY LARGE HAIL..SEVERE WINDS
   AND A COUPLE TORNADOES.

   GIVEN STRENGTHENING SWLY LOW-LVL FLOW ASSOCIATED WITH THE
   EJECTING UPR TROUGH...AFTERNOON TSTMS WILL PROBABLY CONSOLIDATE INTO
   A FAIRLY EXTENSIVE QLCS THIS EVENING INTO TONIGHT. EMBEDDED
   SUPERCELLS WITHIN THIS ACTIVITY COULD CONTAIN BOWS AND LEWPS POSING
   A CONTINUING SEVERE THREAT TOWARDS THE LOWER MS VALLEY. 
     
   ...KS AREA...
   A POCKET OF MORE ROBUST SURFACE HEATING IS BECOMING APPARENT ACROSS
   WRN KS TO THE W OF THE EXTENSIVE STRATUS AND THICKER CIRRUS PLUMES.
   MODIFICATION OF THE 12Z DDC RAOB SUGGESTS A  FAVORABLE SUPERCELL
   ENVIRONMENT SHOULD DEVELOP BY AFTERNOON. BUT THE SURFACE LOW WILL
   REMAIN RATHER LOOSELY-ORGANIZED THROUGH THE DAY...AND THE STRONGEST
   MID/UPPER-LEVEL FLOW WILL REMAIN S OF THE REGION. COUPLED WITH
   MODIFIED MOISTURE RETURN DUE TO CONTINUING PRESENCE OF STORMS OVER N
   TX...STORM COVERAGE WILL PROBABLY BE CONFINED MAINLY TO CNTRL KS.
   HERE...A FEW SUPERCELLS APPEAR LIKELY WITH ALL SEVERE MODES
   POSSIBLE.

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