Probabilistic Outlook

The Probabilistic Outlook is the part of the Storm Prediction Center (SPC) Day 1, 2 and 3 Convective Outlooks that gives the chance of severe weather occurring within 25 miles of any point. Day 1 and Day 2 show separate probabilities for tornadoes, wind and hail, while Day 3 shows one combined severe probability.

What the numbers mean

Each contour marks a probability of severe weather within 25 miles of a point. SPC compares that distance to the size of a major metropolitan area.

The number applies to each point inside the contour, not to the area as a whole. A 30 percent hail contour does not mean 30 percent of the region will see severe hail.

Which days show which hazards

Day 1 carries separate tornado, wind and hail maps. SPC began issuing individual hazard graphics for the Day 2 outlook with the 1730Z issuance on 01/30/20.

Day 3 still combines all three hazards into one probability. SPC cites greater uncertainty at that range.

What changed in 2026

Starting 03/03/26, the Day 1 to 3 outlooks pair the probabilities with Conditional Intensity Groups, labeled CIG1 to CIG3. The groups replaced the older 10 percent significant severe area and describe how intense a hazard could be if it occurs.

SPC also added 75 and 90 percent levels to the Day 1 and Day 2 wind probabilities. In the current conversion tables, tornado probabilities start at 2 percent, while wind and hail start at 5 percent.

How forecasters read them

Without an intensity group, SPC converts both a 15 percent and a 30 percent tornado probability to Enhanced Risk. The number carries detail the color cannot.

The shape of the contours matters too. A tight area of high numbers focuses concern, while a broad area of low numbers points to scattered potential over a wide region.

Common misreadings

Probability describes coverage, not strength. SPC notes a wind event with many reports but few significant ones could have high coverage probabilities and a lower conditional intensity forecast, while a day with one or two high-end storms could show the reverse.

So read the probability, the intensity group and the category together. Each answers a different question.

How Probabilistic Outlook connects

Leads to 1

Categorical Outlook
Each risk category is converted from the hazard probabilities, so the color on the map builds on the probability forecast behind it.

Part of 1

SPC Convective Outlook
The Probabilistic Outlook is the probability side of the SPC Day 1, 2 and 3 Convective Outlooks, shown by hazard on Days 1 and 2.

Contrasts with 3

Conditional Intensity
Outlook probabilities describe how likely a hazard is near a point, while Conditional Intensity describes how strong it could be if it occurs.
Day 4-8 Outlook
The Day 4-8 Outlook uses two probability contours for all severe weather combined, while the Day 1 and Day 2 probabilistic outlooks show tornado, wind and hail separately.
Ensemble Forecast
An ensemble probability counts agreeing members, while an outlook probability is a forecaster's chance of severe weather near a point.