**SPC's 1300 UTC Day 1 convective outlook places a Marginal Risk for severe thunderstorms across the southern and central Plains into the Midwest today, driven by a cold front advancing into seasonably moist, unstable air ahead of an upper trough.** Primary threats center on isolated damaging winds from loosely organized clusters, with only limited supercell potential noted from eastern Kansas into Missouri where low-level lapse rates may steepen. Official probabilistic tornado graphics show no delineated risk areas, consistent with modest deep-layer shear and weak mid-level lapse rates that suppress organized rotation. Larger population centers within the broader marginal zone include Chicago, Indianapolis, Kansas City, Wichita, and St. Louis. Updated SPC outlooks and NWS local discussions through the afternoon will refine any short-term tornado potential as convection initiates.
Experimental AI-generated summary referencing Polymarket data. This is not trading advice and plays no role in how this market resolves. · UpdatedWhich cities face tornado risk on September 15?
Chicago, IL
2%
Houston, TX
2%
San Antonio, TX
2%
Dallas, TX
2%
Austin, TX
2%
Fort Worth, TX
3%
Columbus, OH
1%
Charlotte, NC
1%
Indianapolis, IN
2%
Denver, CO
1%
Nashville, TN
1%
Oklahoma City, OK
1%
Memphis, TN
2%
Louisville, KY
26%
Atlanta, GA
26%
Kansas City, MO
2%
Omaha, NE
2%
Minneapolis, MN
2%
Wichita, KS
2%
New Orleans, LA
1%
Tampa, FL
2%
St. Louis, MO
50%
Birmingham, AL
2%
Des Moines, IA
50%
Little Rock, AR
1%
$685 Vol.
Chicago, IL
2%
Houston, TX
2%
San Antonio, TX
2%
Dallas, TX
2%
Austin, TX
2%
Fort Worth, TX
3%
Columbus, OH
1%
Charlotte, NC
1%
Indianapolis, IN
2%
Denver, CO
1%
Nashville, TN
1%
Oklahoma City, OK
1%
Memphis, TN
2%
Louisville, KY
26%
Atlanta, GA
26%
Kansas City, MO
2%
Omaha, NE
2%
Minneapolis, MN
2%
Wichita, KS
2%
New Orleans, LA
1%
Tampa, FL
2%
St. Louis, MO
50%
Birmingham, AL
2%
Des Moines, IA
50%
Little Rock, AR
1%
The SPC Day 1 Convective Outlook assigns tornado probability percentages (2%, 5%, 10%, etc.) to geographic areas across the US. If the city's coordinates fall inside any area rated 2% or higher, that city resolves "Yes". If a city is outside all tornado probability areas, or only within areas rated below 2%, that city resolves "No".
The SPC outlook is published as machine-readable geographic data (GeoJSON) at spc.noaa.gov. Each city's coordinates and the polygon boundaries are publicly verifiable. Borderline cases can be independently confirmed using the polygon data (excluding the hatched SIGN overlay, which is not a probability rating) and the city's listed coordinates. The point-in-polygon test is performed on unprojected WGS84 (EPSG:4326) coordinates, which is the native coordinate system of the SPC GeoJSON data.
Resolution is based on the scheduled 01:00 UTC Day 1 Convective Outlook update issued on the following UTC calendar day. The SPC Day 1 outlook covers a 24-hour period from 12:00 UTC to 12:00 UTC the following day. Subsequent revisions published after that scheduled update will not be considered. If the SPC Day 1 Convective Outlook has not been published by the time the market closes, this market will resolve to "No".
The resolution source for this market is the NOAA Storm Prediction Center at spc.noaa.gov.
This market uses coordinates 41.8781, -87.6298 for Chicago, IL.
Market Opened: Sep 15, 2026, 8:13 AM ET
Resolution Source
https://www.spc.noaa.gov/products/outlook/day1otlk.htmlResolver
0x65070BE91...The SPC Day 1 Convective Outlook assigns tornado probability percentages (2%, 5%, 10%, etc.) to geographic areas across the US. If the city's coordinates fall inside any area rated 2% or higher, that city resolves "Yes". If a city is outside all tornado probability areas, or only within areas rated below 2%, that city resolves "No".
The SPC outlook is published as machine-readable geographic data (GeoJSON) at spc.noaa.gov. Each city's coordinates and the polygon boundaries are publicly verifiable. Borderline cases can be independently confirmed using the polygon data (excluding the hatched SIGN overlay, which is not a probability rating) and the city's listed coordinates. The point-in-polygon test is performed on unprojected WGS84 (EPSG:4326) coordinates, which is the native coordinate system of the SPC GeoJSON data.
Resolution is based on the scheduled 01:00 UTC Day 1 Convective Outlook update issued on the following UTC calendar day. The SPC Day 1 outlook covers a 24-hour period from 12:00 UTC to 12:00 UTC the following day. Subsequent revisions published after that scheduled update will not be considered. If the SPC Day 1 Convective Outlook has not been published by the time the market closes, this market will resolve to "No".
The resolution source for this market is the NOAA Storm Prediction Center at spc.noaa.gov.
This market uses coordinates 41.8781, -87.6298 for Chicago, IL.
Resolution Source
https://www.spc.noaa.gov/products/outlook/day1otlk.htmlResolver
0x65070BE91...**SPC's 1300 UTC Day 1 convective outlook places a Marginal Risk for severe thunderstorms across the southern and central Plains into the Midwest today, driven by a cold front advancing into seasonably moist, unstable air ahead of an upper trough.** Primary threats center on isolated damaging winds from loosely organized clusters, with only limited supercell potential noted from eastern Kansas into Missouri where low-level lapse rates may steepen. Official probabilistic tornado graphics show no delineated risk areas, consistent with modest deep-layer shear and weak mid-level lapse rates that suppress organized rotation. Larger population centers within the broader marginal zone include Chicago, Indianapolis, Kansas City, Wichita, and St. Louis. Updated SPC outlooks and NWS local discussions through the afternoon will refine any short-term tornado potential as convection initiates.
Experimental AI-generated summary referencing Polymarket data. This is not trading advice and plays no role in how this market resolves. · Updated

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