The Storm Prediction Center's Day 1 convective outlook for September 13, 2026, places a Slight Risk of severe thunderstorms across the upper Ohio Valley into the Northeast, driven by a mid-level jet and cold front, but with tornado probabilities remaining low or absent as strong deep-layer shear favors linear bowing segments and damaging winds over discrete supercells. Marginal severe potential also exists over the central and northern High Plains amid weaker instability. Authoritative SPC and NOAA guidance note that while 30+ knot effective shear could support transient rotation, poor lapse rates and frontal forcing limit organized tornado risk today, consistent with climatologically lower September activity. Traders should monitor the Day 2 outlook update and any NWS watches for potential shifts in the Nebraska-Iowa corridor tomorrow, where higher CAPE and streamwise vorticity may elevate discrete storm chances.
Eksperimental na AI-generated summary na nire-reference ang Polymarket data. Hindi ito trading advice at wala itong papel sa kung paano nire-resolve ang market na ito. · Na-updateWhich cities face tornado risk on September 13?
Chicago, IL
1%
Houston, TX
1%
San Antonio, TX
50%
Dallas, TX
1%
Austin, TX
3%
Fort Worth, TX
1%
Columbus, OH
3%
Charlotte, NC
50%
Indianapolis, IN
1%
Denver, CO
26%
Nashville, TN
50%
Oklahoma City, OK
1%
Memphis, TN
50%
Louisville, KY
1%
Atlanta, GA
50%
Kansas City, MO
26%
Omaha, NE
3%
Minneapolis, MN
1%
Wichita, KS
1%
New Orleans, LA
1%
Tampa, FL
3%
St. Louis, MO
26%
Birmingham, AL
25%
Des Moines, IA
3%
Little Rock, AR
3%
$1,549 Vol.
Chicago, IL
1%
Houston, TX
1%
San Antonio, TX
50%
Dallas, TX
1%
Austin, TX
3%
Fort Worth, TX
1%
Columbus, OH
3%
Charlotte, NC
50%
Indianapolis, IN
1%
Denver, CO
26%
Nashville, TN
50%
Oklahoma City, OK
1%
Memphis, TN
50%
Louisville, KY
1%
Atlanta, GA
50%
Kansas City, MO
26%
Omaha, NE
3%
Minneapolis, MN
1%
Wichita, KS
1%
New Orleans, LA
1%
Tampa, FL
3%
St. Louis, MO
26%
Birmingham, AL
25%
Des Moines, IA
3%
Little Rock, AR
3%
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.
Binuksan ang Market: Sep 13, 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...The Storm Prediction Center's Day 1 convective outlook for September 13, 2026, places a Slight Risk of severe thunderstorms across the upper Ohio Valley into the Northeast, driven by a mid-level jet and cold front, but with tornado probabilities remaining low or absent as strong deep-layer shear favors linear bowing segments and damaging winds over discrete supercells. Marginal severe potential also exists over the central and northern High Plains amid weaker instability. Authoritative SPC and NOAA guidance note that while 30+ knot effective shear could support transient rotation, poor lapse rates and frontal forcing limit organized tornado risk today, consistent with climatologically lower September activity. Traders should monitor the Day 2 outlook update and any NWS watches for potential shifts in the Nebraska-Iowa corridor tomorrow, where higher CAPE and streamwise vorticity may elevate discrete storm chances.
Eksperimental na AI-generated summary na nire-reference ang Polymarket data. Hindi ito trading advice at wala itong papel sa kung paano nire-resolve ang market na ito. · Na-update

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