Jun 20, 2021 1630 UTC Day 1 Convective Outlook
Updated: Sun Jun 20 16:22:19 UTC 2021 (20210620 1630Z Day 1 shapefile | 20210620 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20210620 1630 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 51,079 18,458,412 Chicago, IL...Detroit, MI...Toledo, OH...Fort Wayne, IN...Aurora, IL...
SLIGHT 204,119 25,588,384 Milwaukee, WI...Kansas City, MO...Cleveland, OH...Minneapolis, MN...St. Paul, MN...
MARGINAL 266,324 37,034,178 Jacksonville, FL...Indianapolis, IN...Columbus, OH...Baltimore, MD...Wichita, KS...
Probabilistic Tornado Graphic
20210620 1630 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 % 129,500 26,945,895 Chicago, IL...Detroit, MI...Toledo, OH...Fort Wayne, IN...Grand Rapids, MI...
2 % 180,629 24,378,674 Jacksonville, FL...Milwaukee, WI...Kansas City, MO...Cleveland, OH...Minneapolis, MN...
Probabilistic Damaging Wind Graphic
20210620 1630 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
30 % 50,891 18,409,756 Chicago, IL...Detroit, MI...Toledo, OH...Fort Wayne, IN...Aurora, IL...
15 % 203,743 25,558,360 Milwaukee, WI...Kansas City, MO...Cleveland, OH...Minneapolis, MN...St. Paul, MN...
5 % 265,871 36,933,068 Jacksonville, FL...Indianapolis, IN...Columbus, OH...Baltimore, MD...Wichita, KS...
Probabilistic Large Hail Graphic
20210620 1630 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 50,187 4,158,843 Aurora, IL...Rockford, IL...Cedar Rapids, IA...Peoria, IL...Davenport, IA...
15 % 162,597 30,431,676 Chicago, IL...Detroit, MI...Milwaukee, WI...Kansas City, MO...Toledo, OH...
5 % 178,056 18,933,331 Indianapolis, IN...Cleveland, OH...Minneapolis, MN...Wichita, KS...St. Louis, MO...
   SPC AC 201622

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1122 AM CDT Sun Jun 20 2021

   Valid 201630Z - 211200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
   EXTREME EASTERN IOWA ACROSS CHICAGOLAND TO NORTHWEST OHIO AND
   SOUTHERN LOWER MICHIGAN...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OF SEVERE
   THUNDERSTORMS SURROUNDING THE ENHANCED RISK...AND ALSO OVER PARTS OF
   GEORGIA AND THE CAROLINAS...

   ...SUMMARY...
   Scattered severe storms are expected across the Midwest into the
   lower Great Lakes/upper Ohio Valley. Large hail, severe/damaging
   winds, and a few tornadoes are possible. Damaging winds and a couple
   of tornadoes are also possible across the Southeast.

   ...MO to OH...
   Current water vapor loop shows a convectively augmented vort max
   over northern MO.  New thunderstorm development has occurred in the
   past couple of hours in this region, with a corridor of rapid
   heating/destabilization occurring to the east from northeast MO into
   northern IL.  Storms will likely intensify through the afternoon
   along this axis, with the risk of damaging winds, large hail, and
   isolated tornadoes.  12z CAM solutions differ on the handling of
   this cluster, but the potential appears to exist for a longer-lived
   bowing structure that would track all the way into northern OH this
   evening.  Please refer to MCD #1032 for short-term details.

   ...MN/WI/IA/IL...
   Latest surface analysis shows a low over west-central MN.  clearing
   skies ahead of the low, along with southerly low-level winds, will
   help to warm/moisten and destabilize this area by mid-afternoon.  A
   consensus of model guidance shows intense thunderstorm development
   later today over southeast MN, southwest WI, and parts of
   northern/eastern IA.  Large hail and damaging winds will be possible
   with these storms.  A combination of remnant cloud debris and
   outflow boundaries complicate the scenario, but also increase the
   conditional risk of supercells and perhaps a few tornadoes this
   evening.  If the storms over MO do not materialize into a
   longer-lived bow, then this area of storms may persist for several
   hours and track eastward across the ENH risk area.

   ...GA/SC/NC...
   The remnants of Claudette continue to affect parts of GA and the
   Carolinas today, with relatively strong low-level winds from
   southeast GA into southern SC.  Considerable daytime heating and
   ample low level moisture will provide favorable thermodynamics for a
   few intense afternoon thunderstorms capable of damaging wind gusts
   and a few tornadoes.

   ...Southeast CO into southern KS late tonight...
   A surface cold front will extend from eastern CO into southern KS
   tonight, providing the focus for a few evening/overnight
   thunderstorms.  Sufficient CAPE/shear along this zone will pose a
   risk of hail in the strongest storms.

   ..Hart/Bentley.. 06/20/2021

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