Resolution criteria

This market resolves to the total number of distinct convective outlook products issued by the NOAA/NWS Storm Prediction Center (SPC) during the month of December 2026 that include an Enhanced Risk (Level 3), Moderate Risk (Level 4), or High Risk (Level 5) category for any part of the contiguous United States.

• Time Period: Outlooks issued between 00:00:00 UTC on December 1, 2026, and 23:59:59 UTC on December 31, 2026 (based on the issuance timestamp on the SPC product).

• Included Products: Standard Day 1, Day 2, and Day 3 Convective Outlook issuances and updates. Each officially issued outlook update (e.g., standard Day 1 update cycles at 0100Z, 0600Z, 1300Z, 1630Z, 2000Z) that contains at least one area designated as Enhanced (ENH), Moderate (MDT), or High (HIGH) counts as one issuance towards the total.

• Exclusions: Days 4–8 outlooks (which use generic probability percentages rather than categorical ENH/MDT/HIGH risk levels), mesoscale convective discussions (MCDs), watches, and fire weather outlooks do not count.

• Source of Truth: Official archives published by the NOAA Storm Prediction Center via the SPC Convective Outlook Archive or the Iowa Environmental Mesonet (IEM) SPC Archive.

• If the market is intended to count the number of unique calendar days with an Enhanced or higher risk rather than the count of individual outlook text/graphic issuances, the creator should edit this description prior to significant trading activity.

Background

The NOAA Storm Prediction Center categorizes severe convective storm risk into five categorical levels:

1. Marginal (MRGL)

2. Slight (SLGT)

3. Enhanced (ENH)

4. Moderate (MDT)

5. High (HIGH)

December is climatologically one of the quietest months of the year for severe convective weather across North America. However, high-shear, low-CAPE environments in the Deep South, Gulf Coast, and Mississippi Valley occasionally support severe tornado and wind events in late autumn and early winter. While widespread Enhanced or higher risks in December are relatively uncommon compared to the spring months, winter outbreaks (such as December 10–11, 2021, and December 15, 2021) have previously triggered multiple high-end outlooks across consecutive update cycles.

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