Mar 25, 2021 0600 UTC Day 1 Convective Outlook
Updated: Thu Mar 25 05:59:15 UTC 2021 (20210325 1200Z Day 1 shapefile | 20210325 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20210325 1200 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
HIGH 22,996 1,353,214 Decatur, AL...Madison, AL...Tupelo, MS...Florence, AL...Columbus, MS...
MODERATE 55,711 7,162,512 Memphis, TN...Nashville, TN...Birmingham, AL...Jackson, MS...Huntsville, AL...
ENHANCED 77,339 6,137,074 Evansville, IN...Jonesboro, AR...Owensboro, KY...Bowling Green, KY...Hattiesburg, MS...
SLIGHT 178,207 18,581,024 New Orleans, LA...Atlanta, GA...Cincinnati, OH...Louisville, KY...Lexington-Fayette, KY...
MARGINAL 143,331 20,224,530 Indianapolis, IN...Columbus, OH...Akron, OH...Columbus, GA...Dayton, OH...
Probabilistic Tornado Graphic
20210325 1200 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 155,650 14,632,153 Memphis, TN...Nashville, TN...Birmingham, AL...Jackson, MS...Huntsville, AL...
30 % 22,891 1,347,449 Decatur, AL...Tupelo, MS...Florence, AL...Columbus, MS...Starkville, MS...
15 % 55,650 7,165,067 Memphis, TN...Nashville, TN...Birmingham, AL...Jackson, MS...Huntsville, AL...
10 % 77,008 6,127,445 Chattanooga, TN...Evansville, IN...Jonesboro, AR...Owensboro, KY...Bowling Green, KY...
5 % 137,073 14,783,913 Atlanta, GA...Cincinnati, OH...Louisville, KY...Lexington-Fayette, KY...Baton Rouge, LA...
2 % 154,084 21,795,161 Indianapolis, IN...Columbus, OH...New Orleans, LA...Akron, OH...Mobile, AL...
Probabilistic Damaging Wind Graphic
20210325 1200 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 155,779 14,525,922 Memphis, TN...Nashville, TN...Birmingham, AL...Jackson, MS...Huntsville, AL...
45 % 79,025 8,499,688 Memphis, TN...Nashville, TN...Birmingham, AL...Jackson, MS...Huntsville, AL...
30 % 76,836 6,138,446 Chattanooga, TN...Evansville, IN...Jonesboro, AR...Owensboro, KY...Bowling Green, KY...
15 % 178,402 18,636,037 New Orleans, LA...Atlanta, GA...Cincinnati, OH...Louisville, KY...Lexington-Fayette, KY...
5 % 142,799 20,043,834 Indianapolis, IN...Columbus, OH...Akron, OH...Columbus, GA...Dayton, OH...
Probabilistic Large Hail Graphic
20210325 1200 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 81,653 5,793,661 Memphis, TN...Jackson, MS...Huntsville, AL...Tuscaloosa, AL...Jackson, TN...
30 % 81,730 5,798,426 Memphis, TN...Jackson, MS...Huntsville, AL...Tuscaloosa, AL...Jackson, TN...
15 % 116,602 9,417,577 Nashville, TN...Birmingham, AL...Little Rock, AR...Chattanooga, TN...Clarksville, TN...
5 % 160,967 16,066,734 New Orleans, LA...Louisville, KY...Lexington-Fayette, KY...Baton Rouge, LA...Montgomery, AL...
   SPC AC 250559

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1259 AM CDT Thu Mar 25 2021

   Valid 251200Z - 261200Z

   ...THERE IS A HIGH RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   CENTRAL...EASTERN AND NORTHERN MISSISSIPPI INTO NORTHWESTERN ALABAMA
   AND SOUTHERN TENNESSEE...

   ...SUMMARY...
   A tornado outbreak is expected today into early this evening across
   parts of the Southeast northward into the Tennessee Valley. Several
   long-track strong tornadoes, destructive winds and very large hail
   are forecast from the Lower Mississippi Valley, eastward across
   parts of the Southeast and northward into the Tennessee and Ohio
   Valleys.

   ...Tornado Outbreak Expected Across Parts of the Southeast and
   Tennessee Valley Today into Early This Evening...

   ...Southeast/Tennessee and Ohio Valleys...
   A potent shortwave trough and an associated 75 to 90 kt mid-level
   jet will eject quickly northeastward across the southern Plains
   today. At the surface, a low will move northeastward and deepen
   across the Arklatex and mid Mississippi Valley today. Strong
   moisture advection will take place in the lower Mississippi Valley
   as a 50 to 65 kt low-level jet strengthens. Surface dewpoints will
   increase into the 65 to 70 F degree range by late morning throughout
   much of eastern Louisiana, Mississippi and western Alabama. The
   low-level moisture combined with surface heating will result in a
   moderately unstable and volatile airmass by late morning. A band of
   strong large-scale ascent, in advance of the shortwave trough, will
   move quickly northeastward across the Arklatex this morning.
   Convection appears likely to initiate around midday ahead of this
   band of ascent from southeast Arkansas southward into northeast
   Louisiana and eastward into southwest Mississippi. This cluster of
   thunderstorms is expected to organize and rapidly intensify, moving
   northeastward across central and northern Mississippi into
   northwestern Alabama during the afternoon. Moderate instability,
   strong deep-layer shear and impressive amount of lift on a large
   scale will be favorable for widespread severe thunderstorm
   development, and a tornado outbreak is expected.

   RAP and NAM Forecast soundings this afternoon across the warm sector
   from central Mississippi northeastward into northwest Alabama show
   an impressive environment for severe storms. MLCAPE is forecast to
   increase into the 2000 to 3000 J/kg range across much of central and
   northern Mississippi by midday. Surface winds are forecast to become
   backed to the south-southeast across the eastern half of
   Mississippi. This combined with 60 kt of flow near 850 mb will
   result in 0-3 km storm relative helicities in the 400 to 500 m2/s2
   range. In addition, the progressive nature of the mid-level jet will
   be optimal for the development of tornadic storms. Supercells are
   forecast to develop rapidly after initiation across central
   Mississippi early this afternoon and move quickly
   north-northeastward into northeast Mississippi. Significant tornado
   parameter is forecast to increase to near ten across northeast
   Mississippi and northwest Alabama by 21Z, making conditions very
   favorable for long-track strong tornadoes. As the low-level jet
   consolidates and couples with the progressive mid-level jet, a
   violent long-track tornado will be possible.

   The cluster of severe thunderstorms is expected to move from parts
   of northern Mississippi and northern Alabama into the Tennessee
   Valley late this afternoon and early this evening. Supercells and
   bowing line segments will likely be severe, producing wind damage,
   tornadoes and large hail. Hailstones greater than 2 inches in
   diameter may occur with the stronger updraft cores. The wind damage
   threat is forecast to become more widespread as a squall line
   organizes along a cold front in the Mississippi Valley. This line of
   severe storms is forecast to move quickly eastward across the Ohio
   and Tennessee Valleys this evening, producing widespread wind
   damage. Wind gusts of greater than 65 knots will be possible.

   Further north in areas near the Ohio River, instability is forecast
   to be considerably weaker than in areas to the south. In spite of
   the weaker instability, enhanced lift and strong deep-layer shear
   will make severe storms possible. As storms move north-northeastward
   across the Ohio Valley this evening, isolated large hail and wind
   damage will accompany supercells and bow echoes. An isolated tornado
   threat will also exist.

   ..Broyles/Cook.. 03/25/2021

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