The Storm Prediction Center’s Day 1 outlook on September 11 placed a Slight Risk across the Upper Midwest, citing modest instability, 40-45 kt deep-layer shear, and strengthening low-level jet support for supercells capable of large hail and a couple of tornadoes, primarily late afternoon into evening. Cities and counties highlighted included Watertown and Aberdeen, South Dakota, plus Willmar, St. Cloud, Brainerd, Hibbing, and Duluth, Minnesota, where effective SRH values were forecast to reach 250-300 m²/s². No higher categorical risks or confirmed tornado reports emerged from official sources that day, keeping market-implied odds aligned with the limited, conditional threat rather than widespread activity. Updated model guidance and any local storm surveys released September 12 could further refine resolution criteria.
Resumen experimental generado por IA con datos de Polymarket. Esto no es asesoramiento de trading y no influye en cómo se resuelve este mercado. · Actualizado¿Qué ciudades enfrentan riesgo de tornado el 11 de septiembre?
$4,929 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
Indianápolis, 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
Nueva Orleans, LA
No
Tampa, FL
No
St. Louis, MO
No
Birmingham, AL
No
Des Moines, IA
No
Little Rock, AR
No
$4,929 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
Indianápolis, 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
Nueva 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.
Mercado abierto: Sep 11, 2026, 8:13 AM ET
Fuente de resolución
https://www.spc.noaa.gov/products/outlook/day1otlk.htmlResolver
0x65070BE91...Resultado propuesto: No
Sin disputa
Resultado final: 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.
Fuente de resolución
https://www.spc.noaa.gov/products/outlook/day1otlk.htmlResolver
0x65070BE91...Resultado propuesto: No
Sin disputa
Resultado final: No
The Storm Prediction Center’s Day 1 outlook on September 11 placed a Slight Risk across the Upper Midwest, citing modest instability, 40-45 kt deep-layer shear, and strengthening low-level jet support for supercells capable of large hail and a couple of tornadoes, primarily late afternoon into evening. Cities and counties highlighted included Watertown and Aberdeen, South Dakota, plus Willmar, St. Cloud, Brainerd, Hibbing, and Duluth, Minnesota, where effective SRH values were forecast to reach 250-300 m²/s². No higher categorical risks or confirmed tornado reports emerged from official sources that day, keeping market-implied odds aligned with the limited, conditional threat rather than widespread activity. Updated model guidance and any local storm surveys released September 12 could further refine resolution criteria.
Resumen experimental generado por IA con datos de Polymarket. Esto no es asesoramiento de trading y no influye en cómo se resuelve este mercado. · Actualizado


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