May 4, 2021 0100 UTC Day 1 Convective Outlook
Updated: Tue May 4 00:59:47 UTC 2021 (20210504 0100Z Day 1 shapefile | 20210504 0100Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20210504 0100 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 90,174 8,416,684 Dallas, TX...Plano, TX...Garland, TX...Irving, TX...Little Rock, AR...
SLIGHT 155,997 20,308,944 San Antonio, TX...Austin, TX...Memphis, TN...Fort Worth, TX...Nashville, TN...
MARGINAL 131,110 12,808,125 Tulsa, OK...Cincinnati, OH...Lexington-Fayette, KY...Lubbock, TX...Montgomery, AL...
Probabilistic Tornado Graphic
20210504 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.
Day 1 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
5 % 122,239 12,621,244 Dallas, TX...Fort Worth, TX...Arlington, TX...Plano, TX...Garland, TX...
2 % 85,717 11,045,269 Memphis, TN...Nashville, TN...St. Louis, MO...Louisville, KY...Lexington-Fayette, KY...
Probabilistic Damaging Wind Graphic
20210504 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.
Day 1 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SIG SEVERE 45,526 1,958,843 Fort Smith, AR...Fayetteville, AR...Jonesboro, AR...Conway, AR...Russellville, AR...
30 % 90,086 8,236,619 Dallas, TX...Plano, TX...Garland, TX...Irving, TX...Little Rock, AR...
15 % 141,937 19,036,593 San Antonio, TX...Austin, TX...Memphis, TN...Fort Worth, TX...Nashville, TN...
5 % 135,512 13,433,142 Cincinnati, OH...Lexington-Fayette, KY...Montgomery, AL...Knoxville, TN...Chattanooga, TN...
Probabilistic Large Hail Graphic
20210504 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.
Day 1 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SIG SEVERE 91,133 13,024,248 San Antonio, TX...Dallas, TX...Austin, TX...Fort Worth, TX...Arlington, TX...
30 % 14,257 4,073,527 Dallas, TX...Plano, TX...Garland, TX...Irving, TX...Grand Prairie, TX...
15 % 174,427 18,025,105 San Antonio, TX...Austin, TX...Memphis, TN...Fort Worth, TX...Arlington, TX...
5 % 140,637 12,639,753 Nashville, TN...Tulsa, OK...Louisville, KY...Lubbock, TX...Montgomery, AL...
   SPC AC 040059

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0759 PM CDT Mon May 03 2021

   Valid 040100Z - 041200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS EASTERN
   OKLAHOMA AND NORTH-CENTRAL TX INTO THE OZARKS AND LOWER OHIO
   VALLEY...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
   CENTRAL ALABAMA AND WEST-CENTRAL GEORGIA...

   ...SUMMARY...
   Scattered severe thunderstorms are likely this evening through
   tonight from parts of north-central Texas northeastward across the
   northern half of Arkansas and into the lower Ohio Valley.  Very
   large hail is possible mainly this evening over parts of Texas and
   Oklahoma.  The risk for intense severe gusts will increase this
   evening into the overnight from eastern Oklahoma to western
   Kentucky.

   ...OK-TX dryline northeast to the lower OH Valley...
   Severe thunderstorms this evening near the dryline from
   south-central TX northward into southeast OK are residing in a
   reservoir of rich low-level moisture and a very unstable airmass
   (3500 J/kg MLCAPE observed on the 7pm Fort Worth, TX raob). 
   Water-vapor imagery shows a mid-level shortwave trough over the
   southern High Plains and this feature will continue to move east
   towards the OK/TX I-35 corridor by daybreak Tuesday.  A belt of
   southwesterly 500 mb flow is forecast to strengthen this evening and
   into the overnight across the Red River Valley into southeast MO/AR.
    Upscale growth into a severe MCS is forecast with the transition
   from primarily a large-hail threat/tornado risk to a severe
   gust/tornado risk overnight.  Farther south along the dryline,
   boundary layer cooling will lead to increasing convective inhibition
   with time and gradual storm weakening by late evening.

   ...Parts of the TX Big Country...
   Strengthening mid-level forcing for ascent will overspread this
   region this evening and likely maintain a severe risk for the next
   several hours across the TX Big Country.  A cluster of
   quasi-discrete thunderstorms immediately north of a surface front
   will likely continue to ingest moist/unstable parcels above the
   surface through the evening hours and pose a large to very large
   hail risk.  

   ...Central AL east to the SC coast...
   Strong to severe thunderstorms may continue through the mid evening
   from central AL east to the SC Coast within a weak
   warm-air-advection regime.  A moist and moderately unstable
   environment may act to sustain organized storm structures with a
   localized hail/wind risk through 03 UTC.  Boundary-layer cooling
   will promote storm weakening and a cessation of the severe risk by
   late evening.

   ..Smith.. 05/04/2021

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