Aug 15, 2020 0600 UTC Day 1 Convective Outlook
Updated: Sat Aug 15 05:23:08 UTC 2020 (20200815 1200Z Day 1 shapefile | 20200815 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20200815 1200 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 76,842 474,386 Garden City, KS...Hibbing, MN...Bemidji, MN...Sterling, CO...Guymon, OK...
MARGINAL 259,350 29,328,079 Chicago, IL...St. Louis, MO...Fort Wayne, IN...Grand Rapids, MI...Amarillo, TX...
Probabilistic Tornado Graphic
20200815 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
2 % 44,084 575,980 Duluth, MN...Superior, WI...Hibbing, MN...Brainerd, MN...Bemidji, MN...
Probabilistic Damaging Wind Graphic
20200815 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 % 50,194 233,419 Garden City, KS...Sterling, CO...Guymon, OK...Lamar, CO...
5 % 285,885 29,406,136 Chicago, IL...St. Louis, MO...Fort Wayne, IN...Grand Rapids, MI...Amarillo, TX...
Probabilistic Large Hail Graphic
20200815 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 28,487 117,986 Sterling, CO...
15 % 77,419 475,804 Garden City, KS...Hibbing, MN...Bemidji, MN...Sterling, CO...Guymon, OK...
5 % 257,919 28,942,305 Chicago, IL...St. Louis, MO...Fort Wayne, IN...Grand Rapids, MI...Amarillo, TX...
   SPC AC 150523

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1223 AM CDT Sat Aug 15 2020

   Valid 151200Z - 161200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER THE CENTRAL
   HIGH PLAINS AND NORTHERN MINNESOTA...

   ...SUMMARY...
   Isolated severe storms capable of large hail and damaging winds will
   be possible over the central High Plains as well as northern
   Minnesota. A more marginal risk for a few severe storms will exist
   from the Great Lakes into the Midwest region.

   ...Central High Plains...

   A modest west to northwest upper flow regime will reside across the
   central High Plains Saturday. In the low levels an east-southeast
   post-frontal flow regime will become established. This will result
   in advection of higher theta-e air beneath steep mid-level lapse
   rates, contributing to a corridor of moderate to strong instability
   with 2000-3000 J/kg MLCAPE. Weak forcing aloft and a modest capping
   inversion may limit thunderstorm coverage. However, at least
   isolated storms are expected to develop in this regime and activity
   will subsequently spread southeast. Effective bulk shear from 30-40
   kt will support potential for some supercell structures with
   isolated large hail and locally strong to damaging gusts the main
   threats. A few storms might evolve into clusters as they develop
   southeast into the evening before weakening.  

   ...Northern Minnesota...

   Post frontal low-level moisture with dewpoints only in the 50s F
   will reside across this region. However, cool temperatures aloft
   with -14 C at 500 mb along with diabatic warming of the boundary
   layer will contribute to 500-1000 J/kg MLCAPE. A shortwave trough
   embedded in the northern stream will approach this area during the
   afternoon, and at least isolated storms will develop. Effective bulk
   shear from 40-50 kt will support potential for some supercell
   structures with large hail and a few strong to damaging gusts the
   main threat through early evening.  

   ...Great Lakes through the Midwest...

   Widely scattered to scattered thunderstorms will likely once again
   develop along an eastward-advancing cold front from the Great Lakes
   into the Ohio Valley and Midwest regions Saturday afternoon. The
   environment will be characterized by moderate instability, but the
   stronger winds aloft will remain north and west of the warm sector
   with weak vertical shear supportive of multicells. A few storms may
   produce locally strong wind gusts and hail through early evening.

   ..Dial/Bentley.. 08/15/2020

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