May 26, 2021 1300 UTC Day 1 Convective Outlook
Updated: Wed May 26 12:51:02 UTC 2021 (20210526 1300Z Day 1 shapefile | 20210526 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20210526 1300 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MODERATE 39,649 337,495 Kearney, NE...North Platte, NE...Hastings, NE...Hays, KS...Lexington, NE...
ENHANCED 73,242 1,431,846 Lincoln, NE...Topeka, KS...Salina, KS...Manhattan, KS...Grand Island, NE...
SLIGHT 304,662 56,413,803 New York, NY...Philadelphia, PA...Baltimore, MD...Washington, DC...Kansas City, MO...
MARGINAL 318,124 35,808,737 Columbus, OH...Boston, MA...Cleveland, OH...Virginia Beach, VA...Cincinnati, OH...
Probabilistic Tornado Graphic
20210526 1300 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 39,614 302,897 Garden City, KS...Dodge City, KS...Hays, KS...Great Bend, KS...
15 % 13,018 79,403 Hays, KS...
10 % 48,736 436,833 Kearney, NE...Garden City, KS...Dodge City, KS...North Platte, NE...Hastings, NE...
5 % 82,401 1,365,991 Lubbock, TX...Amarillo, TX...Salina, KS...Grand Island, NE...Hutchinson, KS...
2 % 246,460 45,224,132 Philadelphia, PA...Baltimore, MD...Washington, DC...Kansas City, MO...Wichita, KS...
Probabilistic Damaging Wind Graphic
20210526 1300 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 50,750 1,053,462 Lincoln, NE...Salina, KS...Manhattan, KS...Grand Island, NE...Kearney, NE...
45 % 18,745 218,083 Kearney, NE...Hastings, NE...Hays, KS...Lexington, NE...
30 % 65,665 1,326,937 Lincoln, NE...Topeka, KS...Salina, KS...Manhattan, KS...Grand Island, NE...
15 % 317,293 56,514,713 New York, NY...Philadelphia, PA...Baltimore, MD...Washington, DC...Kansas City, MO...
5 % 323,018 35,805,383 Columbus, OH...Boston, MA...Cleveland, OH...Virginia Beach, VA...Cincinnati, OH...
Probabilistic Large Hail Graphic
20210526 1300 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 130,431 1,742,297 Lubbock, TX...Amarillo, TX...Salina, KS...Grand Island, NE...Hutchinson, KS...
45 % 33,042 263,638 Kearney, NE...North Platte, NE...Hays, KS...Lexington, NE...
30 % 57,626 557,284 Salina, KS...Grand Island, NE...Garden City, KS...Dodge City, KS...Hastings, NE...
15 % 128,800 3,097,657 Wichita, KS...Lincoln, NE...Lubbock, TX...Amarillo, TX...Topeka, KS...
5 % 345,768 60,430,392 New York, NY...Philadelphia, PA...Columbus, OH...Baltimore, MD...Washington, DC...
   SPC AC 261251

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0751 AM CDT Wed May 26 2021

   Valid 261300Z - 271200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS
   NORTHWEST/NORTH-CENTRAL KS AND SOUTHWEST/SOUTH-CENTRAL NE...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NORTHEAST
   STATES...

   ...SUMMARY...
   A regional outbreak of severe thunderstorms is expected across the
   central Great Plains this afternoon through tonight. The greatest
   tornado threat, including the potential for strong tornadoes, is
   expected between 5 to 11 PM CDT. Intense damaging winds and very
   large hail are expected as well.

   ...Central Great Plains...
   A shortwave trough over the northern Rockies should reach the
   Dakotas by 12Z tomorrow. An attendant belt of enhanced mid-level
   southwesterlies should overspread WY to the Dakotas this afternoon.
   Meanwhile, a confluent belt of enhanced southwesterlies in the
   southern stream will become centered from AZ/NM to the central High
   Plains. A surface cyclone will initially deepen over southeast WY as
   a warm front advances north across KS and NE. Early afternoon
   thunderstorm development is expected in advance of the shortwave
   trough across north-central WY and far southeast MT, with additional
   development a couple hours later farther east-southeast in eastern
   WY near the surface low. An initially narrow surface-based buoyancy
   plume should broaden on continued low-level moist advection from the
   southeast, yielding development and intensification of supercells
   across the WY/SD/NE border area by late afternoon.

   Farther south, the most likely scenario is for discrete supercells
   developing across parts of northeast CO and at the apex of the
   thermal ridge along the dryline near the southeast CO/west-central
   KS border by late afternoon. This activity should impinge on a plume
   of large buoyancy with MLCAPE of 2500-3500 J/kg. In addition, a
   strengthening low-level jet between 00-03Z renders substantial
   concern for potential long-track supercells capable of significant
   tornadoes centered on the northwest KS vicinity this evening. With
   time, numerous supercell structures will likely grow upscale as they
   mature along/south of the warm frontal zone, aided by the strong
   low-level jet. An intense MCS may evolve by late evening with bowing
   structures, yielded an increasing threat for significant severe wind
   gusts across portions of KS and southern NE into the overnight. This
   wind threat may spread as far east-southeast as the Lower MO Valley
   by 12Z tomorrow.

   Variance in CAM guidance appears greater-than-normal regarding the
   aforementioned potential convective evolution. The 00Z HRW-NSSL and
   HRW-ARW both suggest that surface-based convection may develop by
   early to mid-afternoon across parts of western to central KS,
   overturning the air mass prior to substantial strengthening of the
   low-level jet. This would limit the likelihood of significant
   tornado/wind potential and coverage of all severe probabilities as
   far north as indicated by the current forecast. This scenario may be
   unlikely in the presence of mid-level ridging but appears plausible
   given persistent low-level theta-e advection and weak MLCIN.

   ...Southern High Plains...
   Isolated severe thunderstorms will develop south along the dryline
   through west TX where strong diabatic heating will once again allow
   surface parcels to reach their convective temperatures by late
   afternoon. Modest southwesterly flow aloft will support a few
   supercells, and large hail/severe wind are the greatest threats.

   ...Northeast...
   A low-amplitude shortwave trough over the Upper Great Lakes should
   quickly progress towards the Saint Lawrence Valley by tonight. While
   the bulk of strong 500-mb west-southwesterlies will remain prevalent
   across Ontario and Quebec, moderately enhanced 700-mb flow will
   persist across much of the Northeast States through this afternoon.
   Scattered thunderstorms will develop this afternoon ahead of the
   warm conveyor from OH across the central to northern Appalachians as
   robust boundary-layer heating occurs. Weak mid-level lapse rates and
   unidirectional wind profiles will largely support scattered damaging
   winds as the primary hazard, with multicell clusters spreading
   toward the coastal plain.

   ..Grams/Mosier.. 05/26/2021

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