Sep 21, 2024 0600 UTC Day 1 Convective Outlook
Updated: Sat Sep 21 05:50:26 UTC 2024 (20240921 1200Z Day 1 shapefile | 20240921 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20240921 1200 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 38,224 624,706 Amarillo, TX...Roswell, NM...Clovis, NM...Hobbs, NM...Carlsbad, NM...
MARGINAL 253,404 16,502,732 Albuquerque, NM...Kansas City, MO...Omaha, NE...Lincoln, NE...Lubbock, TX...
Probabilistic Tornado Graphic
20240921 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
5 % 18,551 129,475 Clovis, NM...Hereford, TX...Portales, NM...Tucumcari, NM...
2 % 34,070 631,624 Amarillo, TX...Roswell, NM...Hobbs, NM...Carlsbad, NM...Plainview, TX...
Probabilistic Damaging Wind Graphic
20240921 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
15 % 37,942 624,027 Amarillo, TX...Roswell, NM...Clovis, NM...Hobbs, NM...Carlsbad, NM...
5 % 254,478 16,685,679 Albuquerque, NM...Kansas City, MO...Omaha, NE...Lincoln, NE...Lubbock, TX...
Probabilistic Large Hail Graphic
20240921 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
15 % 38,011 624,201 Amarillo, TX...Roswell, NM...Clovis, NM...Hobbs, NM...Carlsbad, NM...
5 % 253,742 16,617,000 Albuquerque, NM...Kansas City, MO...Omaha, NE...Lincoln, NE...Lubbock, TX...
   SPC AC 210550

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1250 AM CDT Sat Sep 21 2024

   Valid 211200Z - 221200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
   SOUTHERN HIGH PLAINS...

   ...SUMMARY...
   Scattered severe storms are expected this afternoon and evening
   across the southern High Plains. Isolated strong to severe
   thunderstorms are also possible from the mid Missouri Valley to the
   Upper Midwest, and also from western Pennsylvania into
   northern/central Virginia.

   ...Southern High Plains...

   Notable upper trough has advanced into the lower CO River Valley
   early this morning. Strong 500mb speed max will soon round the base
   of the trough and eject across southern AZ into southern NM by late
   afternoon. This feature will greatly influence convective
   development/intensity across the southern High Plains by peak
   heating. Northern-stream short-wave trough will shift east today
   which will allow a sharp surface cold front to surge south across
   the High Plains into eastern CO by early afternoon, likely arcing
   across the northern TX Panhandle into northeast NM by 22/00z. Strong
   boundary-layer heating is expected across southern NM with more
   modest warming forecast within southeasterly upslope flow from the
   TX/NM border into the Sangre de Cristo range, just southwest of the
   cold front. Forecast soundings suggest convective temperatures will
   be breached fairly early, aided in part by frontal/orographic
   influences. Scattered convection will easily develop ahead of the
   short wave, and this activity will be strongly sheared as the speed
   max approaches. Supercells are expected to evolve within this
   environment as 0-6km shear will be on the order of 50kt, along with
   veering winds with height. Large hail should develop with this
   activity along with some risk for a few tornadoes.

   ...Upper Midwest to Mid MO Valley...

   Northern-stream short-wave trough is progressing across SK/eastern
   MT into the northern Plains, in line with latest model guidance.
   This feature is forecast to suppress the height field immediately
   downstream across eastern ND into northern MN, though the strongest
   falls will remain north of the international border. Even so,
   notable surface front will advance into MN-western IA-southern NE by
   18z, then steadily surge east into the early evening hours. This
   boundary will serve as the focus for potential convective
   development during the late afternoon, though surface heating is not
   expected to be particularly strong ahead of the wind shift. With the
   strongest forcing expected to spread across northwest ON, convection
   may be more isolated along the front trailing across the Upper
   Midwest. Even so, some hail/wind threat will exist with this
   activity which should peak in intensity during the early evening.

   ...Western PA into western VA...

   Weak short-wave trough will dig southeast across the upper OH Valley
   later this afternoon with modest mid-level northwesterly flow
   expected to extend across western PA/VA. This feature will encourage
   scattered convection later this afternoon along a frontal zone that
   will be draped across the Delmarva-western PA into western NY.
   Convection that evolves near this wind shift will move southeast
   with an attendant risk for gusty winds and some hail.

   ..Darrow/Thornton.. 09/21/2024

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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z