Jul 8, 2021 1730 UTC Day 2 Convective Outlook
Updated: Thu Jul 8 17:48:16 UTC 2021 (20210708 1730Z Day 2 shapefile | 20210708 1730Z Day 2 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20210708 1730 UTC Day 2 Outlook Graphic
Day 2 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 39,762 3,680,199 St. Louis, MO...Des Moines, IA...Columbia, MO...St. Charles, MO...West Des Moines, IA...
SLIGHT 154,053 8,021,559 Kansas City, MO...Omaha, NE...Lincoln, NE...Overland Park, KS...Kansas City, KS...
MARGINAL 222,544 45,148,018 New York, NY...Philadelphia, PA...Boston, MA...Newark, NJ...Jersey City, NJ...
Probabilistic Tornado Graphic
20210708 1730 UTC Day 2 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 2 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
5 % 53,443 3,034,298 Omaha, NE...Des Moines, IA...Columbia, MO...St. Charles, MO...Council Bluffs, IA...
2 % 62,533 14,475,947 Boston, MA...Kansas City, MO...St. Louis, MO...Lincoln, NE...Providence, RI...
Probabilistic Damaging Wind Graphic
20210708 1730 UTC Day 2 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 2 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SIG SEVERE 119,652 7,271,887 Omaha, NE...St. Louis, MO...Lincoln, NE...Des Moines, IA...Columbia, MO...
30 % 34,466 2,909,779 St. Louis, MO...Columbia, MO...St. Charles, MO...St. Peters, MO...Florissant, MO...
15 % 159,609 8,742,356 Kansas City, MO...Omaha, NE...Lincoln, NE...Des Moines, IA...Overland Park, KS...
5 % 222,045 45,173,433 New York, NY...Philadelphia, PA...Boston, MA...Newark, NJ...Jersey City, NJ...
Probabilistic Large Hail Graphic
20210708 1730 UTC Day 2 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 2 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SIG SEVERE 82,780 1,863,418 Des Moines, IA...Ames, IA...West Des Moines, IA...Quincy, IL...Ankeny, IA...
30 % 22,236 1,081,002 Des Moines, IA...West Des Moines, IA...Quincy, IL...Ankeny, IA...Urbandale, IA...
15 % 171,285 10,570,696 Kansas City, MO...Omaha, NE...St. Louis, MO...Lincoln, NE...Overland Park, KS...
5 % 176,693 5,522,606 Sioux Falls, SD...Topeka, KS...Evansville, IN...Peoria, IL...Billings, MT...
   SPC AC 081748

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1248 PM CDT Thu Jul 08 2021

   Valid 091200Z - 101200Z


   Thunderstorms, some with potentially significant severe weather, are
   expected Friday afternoon into Friday night across parts of the
   central Plains and Mid Missouri Valley. A tornado or two associated
   with Tropical Storm Elsa also is possible in the vicinity of the New
   England coast through Friday afternoon.

   Compact, low-amplitude shortwave trough currently moving through
   northern MT will turn southeast and continue through the middle MO
   Valley region Friday. By early Friday, a warm front should extend
   from a surface low in NE southeast through MO. A cold front will
   stretch southwestward from the low through southwest NE into
   northeast CO and will likely stall during the day.  

   ...Mid Missouri Valley...

   Thunderstorms will likely be in progress early Friday, primarily
   within the zone of isentropic ascent north of the warm front from
   southern MN through a portion of northern and eastern IA. The early
   activity should gradually shift southeast during the day, but will
   remain confined to the cool sector. Farther south in warm sector,
   dewpoints in the upper 60s to near 70 F will advect northward in
   wake of advancing warm front. This will contribute to moderate to
   strong instability with 2000-3000 J/kg possible as the boundary
   layer warms during the afternoon. The primary forcing for ascent
   associated with the southeast-advancing shortwave trough will
   probably remain confined to along and north of the warm front.
   However, additional storms may develop along this boundary by late
   afternoon and especially as the low-level jet strengthens by early
   evening. Strong effective shear from 45-50 kt will support some
   supercells, but storms may eventually evolve into lines and clusters
   as they spread southeast. All severe hazards are possible.

   ...Central Plains...

   Upslope flow regime is expected to evolve north of stalled front
   across the central plains maintaining a corridor of mid 50s to near
   60 F dewpoints beneath steep lapse rates and contributing to
   moderate instability with up to 2000 J/kg MLCAPE as the boundary
   layer destabilizes. Storms are expected to develop within this
   regime and spread east through the high Plains. A belt of stronger
   flow aloft will contribute to 50+ kt effective bulk shear supportive
   of supercells early in the evolution. However, storms may eventually
   evolve into one or more MCSs. Large hail and damaging wind will be
   the main threats.

   ..Dial.. 07/08/2021