National Weather Service Storm Prediction Center outlooks for September 18, 2026, placed only marginal severe thunderstorm risk across portions of the Carolinas, northern Georgia, Iowa, the central High Plains, and Intermountain West, with tornado probabilities limited to a 2% contour over parts of central Iowa near Ames and Des Moines. Forecasters cited modest instability and shear along a surface front, but emphasized primarily isolated wind and hail threats rather than organized supercells or significant tornado potential, consistent with late-summer climatology featuring lower shear and weaker low-level moisture gradients. Updated Day 1 products through the afternoon refined boundaries but maintained low tornado probabilities, while Day 2 outlooks shifted focus to wind and hail farther west. Traders monitoring these official probabilistic graphics and subsequent verification data from local National Weather Service offices would weigh any confirmed tornado reports against the narrow geographic and intensity thresholds typical for market resolution.
Résumé expérimental généré par IA à partir des données Polymarket. Ceci n'est pas un conseil de trading et ne joue aucun rôle dans la résolution de ce marché. · Mis à jourQuelles villes sont exposées au risque de tornade le 18 septembre ?
Chicago, IL
1%
Houston, TX
1%
San Antonio, TX
24%
Dallas, TX
1%
Austin, TX
2%
Fort Worth, TX
25%
Columbus, OH
24%
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%
La Nouvelle-Orléans, LA
1%
Tampa, FL
1%
Saint-Louis, MO
26%
Birmingham, AL
<1%
Des Moines, IA
<1%
Little Rock, AR
26%
$2,951 Vol.
Chicago, IL
1%
Houston, TX
1%
San Antonio, TX
24%
Dallas, TX
1%
Austin, TX
2%
Fort Worth, TX
25%
Columbus, OH
24%
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%
La Nouvelle-Orléans, LA
1%
Tampa, FL
1%
Saint-Louis, MO
26%
Birmingham, AL
<1%
Des Moines, IA
<1%
Little Rock, AR
26%
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.
Marché ouvert : Sep 18, 2026, 8:13 AM ET
Source de résolution
https://www.spc.noaa.gov/products/outlook/day1otlk.htmlRésolveur
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.
Source de résolution
https://www.spc.noaa.gov/products/outlook/day1otlk.htmlRésolveur
0x65070BE91...National Weather Service Storm Prediction Center outlooks for September 18, 2026, placed only marginal severe thunderstorm risk across portions of the Carolinas, northern Georgia, Iowa, the central High Plains, and Intermountain West, with tornado probabilities limited to a 2% contour over parts of central Iowa near Ames and Des Moines. Forecasters cited modest instability and shear along a surface front, but emphasized primarily isolated wind and hail threats rather than organized supercells or significant tornado potential, consistent with late-summer climatology featuring lower shear and weaker low-level moisture gradients. Updated Day 1 products through the afternoon refined boundaries but maintained low tornado probabilities, while Day 2 outlooks shifted focus to wind and hail farther west. Traders monitoring these official probabilistic graphics and subsequent verification data from local National Weather Service offices would weigh any confirmed tornado reports against the narrow geographic and intensity thresholds typical for market resolution.
Résumé expérimental généré par IA à partir des données Polymarket. Ceci n'est pas un conseil de trading et ne joue aucun rôle dans la résolution de ce marché. · Mis à jour


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