Apr 7, 2021 1630 UTC Day 1 Convective Outlook
Updated: Wed Apr 7 16:05:51 UTC 2021 (20210407 1630Z Day 1 shapefile | 20210407 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20210407 1630 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 65,439 4,726,900 Memphis, TN...Shreveport, LA...Little Rock, AR...Jackson, MS...Bossier City, LA...
SLIGHT 142,768 8,030,931 Baton Rouge, LA...Springfield, MO...Lafayette, LA...Columbia, MO...Longview, TX...
MARGINAL 182,678 20,808,865 Kansas City, MO...New Orleans, LA...Minneapolis, MN...St. Louis, MO...St. Paul, MN...
Probabilistic Tornado Graphic
20210407 1630 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
10 % 59,337 4,518,768 Memphis, TN...Shreveport, LA...Little Rock, AR...Jackson, MS...Bossier City, LA...
5 % 77,680 3,437,735 Columbia, MO...Alexandria, LA...Meridian, MS...Texarkana, TX...Tupelo, MS...
2 % 129,674 12,114,689 New Orleans, LA...St. Louis, MO...Birmingham, AL...Baton Rouge, LA...Des Moines, IA...
Probabilistic Damaging Wind Graphic
20210407 1630 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 % 65,918 4,766,237 Memphis, TN...Shreveport, LA...Little Rock, AR...Jackson, MS...Bossier City, LA...
15 % 141,942 7,924,563 Baton Rouge, LA...Springfield, MO...Lafayette, LA...Columbia, MO...Longview, TX...
5 % 165,622 17,826,271 Kansas City, MO...New Orleans, LA...St. Louis, MO...Birmingham, AL...Des Moines, IA...
Probabilistic Large Hail Graphic
20210407 1630 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
15 % 121,853 5,950,090 Shreveport, LA...Little Rock, AR...Springfield, MO...Columbia, MO...Longview, TX...
5 % 187,034 20,430,511 Memphis, TN...Kansas City, MO...Minneapolis, MN...St. Louis, MO...St. Paul, MN...
   SPC AC 071605

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1105 AM CDT Wed Apr 07 2021

   Valid 071630Z - 081200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PORTIONS
   OF ARKANSAS...NORTHERN LOUISIANA...CENTRAL AND NORTHERN
   MISSISSIPPI...AND SOUTHWEST TN...

   ...SUMMARY...
   Scattered severe thunderstorms are expected from this afternoon into
   the evening across parts of the lower Mississippi Valley, Mid-South,
   Arklatex and Ozarks.  Wind damage, hail and tornadoes will be
   possible.

   ...Lower MS Valley...
   An upper low is evident this morning over central KS, with a
   shortwave trough rotating through the base of the low into parts of
   OK/TX.  Strong forcing for ascent ahead of this trough will
   overspread a cold front currently over eastern OK, leading to
   thunderstorm development by early afternoon.  Abundant clouds have
   limited daytime heating ahead of the front over parts of AR/LA, but
   dewpoints in the 60s and rather steep lapse rates will yield
   afternoon MLCAPE values of 1500+ J/kg.  South-southwesterly
   low-level winds of 40+ knots will result in favorable vertical shear
   profiles (0-3km SRH values of 150-300 m2/s2) for supercell storms
   capable of large hail, damaging winds, and tornadoes.  Messy storm
   modes are likely to evolve through the afternoon, but a continued
   risk of damaging winds and tornadoes will persist into parts of west
   TN and much of MS before storms move out of primary
   moisture/instability axis this evening.

   ...Mid MS Valley...
   A surface low is currently analyzed over eastern KS, with a cold
   front extending southeastward into western MO.  An area of
   precipitation has affected much of MO during the morning, but is
   moving away and allowing some air mass recovery.  Present
   indications are that scattered thunderstorms will form early this
   afternoon along the front and move across much of MO before
   weakening as they track into more stable air over IL this evening. 
   The strongest cells will be capable of hail, damaging winds, and
   isolated tornadoes.  Please refer to recent MCD #321 for further
   details.

   ...MN/WI...
   Most 12z CAM solutions suggest the development of a cluster of
   thunderstorms this afternoon over parts of eastern MN/western WI. 
   This would be in vicinity of a retreating warm front, where broken
   cloudiness and dewpoints in the 50s will result in MLCAPE values
   around 1000 J/kg.  A strong storm or two is possible for a few hours
   this afternoon, capable mainly of hail.

   ..Hart/Cook.. 04/07/2021

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