May 21, 2024 0100 UTC Day 1 Convective Outlook
Updated: Tue May 21 00:59:09 UTC 2024 (20240521 0100Z Day 1 shapefile | 20240521 0100Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20240521 0100 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 42,971 1,645,382 Omaha, NE...Lincoln, NE...Council Bluffs, IA...Bellevue, NE...Grand Island, NE...
SLIGHT 91,884 2,740,992 Des Moines, IA...Rochester, MN...Sioux City, IA...Waterloo, IA...Ames, IA...
MARGINAL 206,902 25,748,224 Detroit, MI...Denver, CO...Kansas City, MO...Minneapolis, MN...Aurora, CO...
Probabilistic Tornado Graphic
20240521 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
SIG SEVERE 4,684 26,001 No Major Population Center in Risk Area
10 % 6,799 33,252 No Major Population Center in Risk Area
5 % 21,013 210,931 Kearney, NE...Hastings, NE...Sterling, CO...Lexington, NE...
2 % 120,946 6,374,488 Kansas City, MO...Omaha, NE...Lincoln, NE...Des Moines, IA...Overland Park, KS...
Probabilistic Damaging Wind Graphic
20240521 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 27,142 301,394 Grand Island, NE...Kearney, NE...Hastings, NE...Lexington, NE...
30 % 30,963 1,547,531 Omaha, NE...Lincoln, NE...Council Bluffs, IA...Bellevue, NE...Grand Island, NE...
15 % 79,362 2,267,415 Des Moines, IA...Sioux City, IA...Waterloo, IA...Ames, IA...West Des Moines, IA...
5 % 200,678 24,258,807 Detroit, MI...Kansas City, MO...Minneapolis, MN...Aurora, CO...St. Paul, MN...
Probabilistic Large Hail Graphic
20240521 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 39,660 342,441 Kearney, NE...North Platte, NE...Sterling, CO...Fort Morgan, CO...Lexington, NE...
30 % 22,593 148,960 North Platte, NE...Sterling, CO...
15 % 109,249 4,217,618 Omaha, NE...Lincoln, NE...Des Moines, IA...Rochester, MN...Sioux City, IA...
5 % 196,293 24,027,042 Detroit, MI...Denver, CO...Kansas City, MO...Minneapolis, MN...Aurora, CO...
   SPC AC 210059

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0759 PM CDT Mon May 20 2024

   Valid 210100Z - 211200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE CENTRAL
   HIGH PLAINS ACROSS SOUTHERN NE...

   ...SUMMARY...
   Scattered severe thunderstorms are expected through tonight from the
   central High Plains to parts of the Upper Midwest. The greatest
   concentration of tornadoes, large hail, and severe wind is expected
   over northeast Colorado into southern Nebraska, and far northwest
   Kansas. This will include potential for a strong tornado, very large
   hail, and significant severe gusts.

   ...01Z Update...
   Primary concern is with ongoing convection developing across
   northeast CO into the southwest NE Panhandle. With a current of east
   to southeast 0-1 km winds expected to increase during the next few
   hours, afternoon CAM guidance along with recent WoFS runs are
   insistent on long-lived supercell development along the southern
   flank of the thunderstorm plume. This appears likely to emanate out
   of the Akron, CO vicinity and move east towards the CO/KS/NE border
   area. With low 60s surface dew points across northwest KS marking
   the northwest extent of MLCAPE in excess of 1500 J/kg, a supercell
   or two impinging on the increasingly buoyant airmass downstream, may
   become intense. In addition to the risk for very large hail,
   enlarging low-level hodographs will support potential for cyclic
   tornadogenesis, especially in the 02-05Z time frame. Transition from
   tornadic supercell to a bow will likely occur during the late
   evening to early morning, with probable movement along the
   pronounced MLCAPE gradient into at least south-central NE.
   Increasingly large MLCIN is anticipated overnight across KS,
   suggesting that the severe wind swath will remain latitudinally
   confined. Downstream convection, ongoing across southeast NE,
   suggests the upstream severe wind threat may wane somewhat near dawn
   as the MCS approaches the Mid-MO Valley. But the potential for a
   well-organized MCS to persist across much of southern NE is apparent
   and warrants expansion of the level 3-ENH risk.

   Elsewhere, scattered large hail and sporadic severe wind gusts
   should occur this evening into the early overnight from southeast NE
   to southeast MN. A lower-end QLCS across Lower MI into northwest IN
   may produce locally damaging winds with strong gusts through the
   rest of this evening. But this convection will likely diminish
   overnight.

   ..Grams.. 05/21/2024

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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z