SPC Day 1 convective outlooks for September 16, 2026, assigned no tornado risk areas across the U.S., reflecting weak deep-layer shear, modest MLCAPE values, and disorganized multicell clusters that favored isolated damaging winds or hail rather than rotation. Marginal severe probabilities focused on the Ohio Valley and northern Utah, where steep low-level lapse rates and precipitable water near 2 inches supported wet microbursts amid a subtropical ridge and weak mid-level impulses. No tornado reports were logged that day per NWS summaries, consistent with September climatology of sparse activity absent tropical cyclone influence. Traders monitoring resolution criteria can watch for final Storm Data verification and any late local storm reports that might alter city-specific outcomes.
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 16?
Chicago, IL
<1%
Houston, TX
<1%
San Antonio, TX
<1%
Dallas, TX
<1%
Austin, TX
<1%
Fort Worth, TX
<1%
Columbus, OH
<1%
Charlotte, NC
<1%
Indianapolis, IN
<1%
Denver, CO
<1%
Nashville, TN
<1%
Oklahoma City, OK
<1%
Memphis, TN
<1%
Louisville, KY
<1%
Atlanta, GA
<1%
Kansas City, MO
<1%
Omaha, NE
<1%
Minneapolis, MN
<1%
Wichita, KS
<1%
New Orleans, LA
<1%
Tampa, FL
<1%
St. Louis, MO
<1%
Birmingham, AL
<1%
Des Moines, IA
<1%
Little Rock, AR
<1%
$2,355 Vol.
Chicago, IL
<1%
Houston, TX
<1%
San Antonio, TX
<1%
Dallas, TX
<1%
Austin, TX
<1%
Fort Worth, TX
<1%
Columbus, OH
<1%
Charlotte, NC
<1%
Indianapolis, IN
<1%
Denver, CO
<1%
Nashville, TN
<1%
Oklahoma City, OK
<1%
Memphis, TN
<1%
Louisville, KY
<1%
Atlanta, GA
<1%
Kansas City, MO
<1%
Omaha, NE
<1%
Minneapolis, MN
<1%
Wichita, KS
<1%
New Orleans, LA
<1%
Tampa, FL
<1%
St. Louis, MO
<1%
Birmingham, AL
<1%
Des Moines, IA
<1%
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 16, 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 Day 1 convective outlooks for September 16, 2026, assigned no tornado risk areas across the U.S., reflecting weak deep-layer shear, modest MLCAPE values, and disorganized multicell clusters that favored isolated damaging winds or hail rather than rotation. Marginal severe probabilities focused on the Ohio Valley and northern Utah, where steep low-level lapse rates and precipitable water near 2 inches supported wet microbursts amid a subtropical ridge and weak mid-level impulses. No tornado reports were logged that day per NWS summaries, consistent with September climatology of sparse activity absent tropical cyclone influence. Traders monitoring resolution criteria can watch for final Storm Data verification and any late local storm reports that might alter city-specific outcomes.
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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