Official National Weather Service Storm Prediction Center outlooks for September 13, 2026, showed no tornado risk areas across the contiguous U.S., with only a marginal severe thunderstorm risk confined to parts of the Ohio Valley and Northeast. Limited buoyancy from poor mid-level lapse rates around 6–6.5 °C/km, combined with cloud cover, suppressed robust updrafts despite 35–45 kt of deep-layer shear ahead of a cold front. This environment favored isolated strong storms capable of marginal hail or wind but not organized supercells or significant tornadoes. Traders monitoring SPC updates and real-time mesoscale discussions would have seen the absence of any conditional tornado probabilities or watches as the dominant signal shaping market odds for that date.
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 13?
$3,419 Vol.
Chicago, IL
No
Houston, TX
No
San Antonio, TX
No
Dallas, TX
No
Austin, TX
No
Fort Worth, TX
No
Columbus, OH
No
Charlotte, NC
No
Indianapolis, IN
No
Denver, CO
No
Nashville, TN
No
Oklahoma City, OK
No
Memphis, TN
No
Louisville, KY
No
Atlanta, GA
No
Kansas City, MO
No
Omaha, NE
No
Minneapolis, MN
No
Wichita, KS
No
New Orleans, LA
No
Tampa, FL
No
St. Louis, MO
No
Birmingham, AL
No
Des Moines, IA
No
Little Rock, AR
No
$3,419 Vol.
Chicago, IL
No
Houston, TX
No
San Antonio, TX
No
Dallas, TX
No
Austin, TX
No
Fort Worth, TX
No
Columbus, OH
No
Charlotte, NC
No
Indianapolis, IN
No
Denver, CO
No
Nashville, TN
No
Oklahoma City, OK
No
Memphis, TN
No
Louisville, KY
No
Atlanta, GA
No
Kansas City, MO
No
Omaha, NE
No
Minneapolis, MN
No
Wichita, KS
No
New Orleans, LA
No
Tampa, FL
No
St. Louis, MO
No
Birmingham, AL
No
Des Moines, IA
No
Little Rock, AR
No
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 13, 2026, 8:13 AM ET
Resolution Source
https://www.spc.noaa.gov/products/outlook/day1otlk.htmlResolver
0x65070BE91...Outcome proposed: No
No dispute
Final outcome: No
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...Outcome proposed: No
No dispute
Final outcome: No
Official National Weather Service Storm Prediction Center outlooks for September 13, 2026, showed no tornado risk areas across the contiguous U.S., with only a marginal severe thunderstorm risk confined to parts of the Ohio Valley and Northeast. Limited buoyancy from poor mid-level lapse rates around 6–6.5 °C/km, combined with cloud cover, suppressed robust updrafts despite 35–45 kt of deep-layer shear ahead of a cold front. This environment favored isolated strong storms capable of marginal hail or wind but not organized supercells or significant tornadoes. Traders monitoring SPC updates and real-time mesoscale discussions would have seen the absence of any conditional tornado probabilities or watches as the dominant signal shaping market odds for that date.
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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