Will Chicago, IL face tornado risk on September 29?

This market will resolve to "Yes" if Chicago, IL falls within a tornado probability area rated ≥2% in the NOAA Storm Prediction Center Day 1 Convective Outlook on September 29, 2026. Otherwise, this market will resolve to "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. That scheduled update is the revisions cutoff; subsequent revisions published after it 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". In the case that the Resolution Source publishes data, sufficient to settle a Market, that is clearly erroneous and the result of technical or operational error, or of unauthorized interference with the Resolution Source or its data, the Market may remain open for a period of up to seven (7) calendar days (ET) from the time of the original release, in anticipation of a correction by the Resolution Source. If the Resolution Source publishes a corrected value within that period, that value will be eligible for resolution. If no corrected value is published within that period, Polymarket will issue a Clarification to determine whether the originally published value may be eligible for resolution, or whether other action is required to preserve the orderly functioning of the Market. Revisions remain subject to the cutoff above. The only exception is a correction of a clearly erroneous print under the preceding paragraph, which will be used even if published after the cutoff. 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.

Sourcehttps://www.spc.noaa.gov/products/outlook/day1otlk.html