**SPC's latest Day 1 convective outlook shows no tornado risk areas across the continental U.S. for the period valid through 24/1200Z, with only a marginal (level 1/5) severe thunderstorm area confined to the southern Appalachians.** Isolated damaging wind gusts and hail remain possible this afternoon near a surface trough from central Alabama into eastern Tennessee, where dewpoints in the mid-to-upper 60s support MLCAPE of 1000–1500 J/kg and 0–6 km shear of 30–40 knots. Model soundings favor multicell clusters rather than organized supercells, limiting tornadic potential. No watches or mesoscale discussions are active, and the next update is scheduled for 1300Z. Day 2 and longer-range outlooks indicate even lower severe probabilities.
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 23?
Chicago, IL
2%
Houston, TX
2%
San Antonio, TX
2%
Dallas, TX
2%
Austin, TX
2%
Fort Worth, TX
2%
Columbus, OH
2%
Charlotte, NC
2%
Indianapolis, IN
2%
Denver, CO
2%
Nashville, TN
2%
Oklahoma City, OK
2%
Memphis, TN
2%
Louisville, KY
2%
Atlanta, GA
2%
Kansas City, MO
2%
Omaha, NE
2%
Minneapolis, MN
2%
Wichita, KS
2%
New Orleans, LA
2%
Tampa, FL
2%
St. Louis, MO
2%
Birmingham, AL
2%
Des Moines, IA
2%
Little Rock, AR
2%
$315 Vol.
Chicago, IL
2%
Houston, TX
2%
San Antonio, TX
2%
Dallas, TX
2%
Austin, TX
2%
Fort Worth, TX
2%
Columbus, OH
2%
Charlotte, NC
2%
Indianapolis, IN
2%
Denver, CO
2%
Nashville, TN
2%
Oklahoma City, OK
2%
Memphis, TN
2%
Louisville, KY
2%
Atlanta, GA
2%
Kansas City, MO
2%
Omaha, NE
2%
Minneapolis, MN
2%
Wichita, KS
2%
New Orleans, LA
2%
Tampa, FL
2%
St. Louis, MO
2%
Birmingham, AL
2%
Des Moines, IA
2%
Little Rock, AR
2%
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 23, 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 latest Day 1 convective outlook shows no tornado risk areas across the continental U.S. for the period valid through 24/1200Z, with only a marginal (level 1/5) severe thunderstorm area confined to the southern Appalachians.** Isolated damaging wind gusts and hail remain possible this afternoon near a surface trough from central Alabama into eastern Tennessee, where dewpoints in the mid-to-upper 60s support MLCAPE of 1000–1500 J/kg and 0–6 km shear of 30–40 knots. Model soundings favor multicell clusters rather than organized supercells, limiting tornadic potential. No watches or mesoscale discussions are active, and the next update is scheduled for 1300Z. Day 2 and longer-range outlooks indicate even lower severe probabilities.
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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