Understanding Storm Prediction Center (SPC) Outlooks
By StormAuditor Editorial Team · Published 2026-07-20 · Updated 2026-08-10
Based on public NOAA and National Weather Service records, published under StormAuditor's methodology and data-source standards. Radar-derived hail sizes are estimates unless attributed to a ground report.
Damage-threshold ranges in this article are general guidance synthesized from industry and federal research — IBHS building-performance research, NWS severe criteria, and product standards such as UL 2218 (hail impact resistance) and ASTM D3161/D7158 (shingle wind ratings). Actual performance depends on product rating, age, installation quality, exposure, and impact characteristics — thresholds describe when damage becomes possible, not when it occurs.
Storm Prediction Center (SPC) outlooks provide a forecast of severe weather threats, including hail, damaging winds, and tornadoes, across the United States. These outlooks are crucial for understanding potential storm impacts ranging from general thunderstorms to high-risk events.
Storm Prediction Center (SPC) outlooks are key forecasts from NOAA. They assess the chance of severe weather across the contiguous United States. They help the public, first responders, and many industries get ready for major storms. StormAuditor uses data like the data the SPC uses to give detailed storm history. So it helps to understand these forecasts.
What Are SPC Outlooks and What Do They Forecast?
An SPC outlook forecasts organized severe weather. It shows where thunderstorms are expected to produce:
- hail 1.00" (quarter size) or larger,
- wind gusts of 58 mph (50 knots) or more, or
- tornadoes.
The SPC ranks risk from "Marginal" to "High" to show how likely and how strong the severe weather may be. Outlooks are usually issued several times a day, up to 8 days ahead. Near-term forecasts have more detail.
The SPC's main forecast products are:
- Convective Outlooks: The best-known outlooks. They forecast severe thunderstorms and tornadoes for today (Day 1), tomorrow (Day 2), and Days 3-8.
- Mesoscale Discussions: Short-term, focused notes on smaller regions. They come out hours before or during severe weather.
- Public Swath Forecasts: General public guidance on where severe weather is possible.
Outlooks weigh instability, wind shear, and lift in the air to predict where and when severe weather is most likely. For StormAuditor, they set the scene for the detailed storm history we provide.
How StormAuditor Uses SPC Data
SPC outlooks are forecasts. StormAuditor focuses on storms that already happened.
- We use final SPC storm reports to anchor our history of hail, wind, and tornadoes.
- Our methods, SAHE-2 for hail and SAWE-2 for wind, use data reported to and cataloged by NOAA and the SPC.
- That includes SPC reports of hail sizes and wind gusts seen by people. (Data Sources)
For example, say an SPC outlook gave an area a "Moderate" risk. Later, StormAuditor could give a detailed report for one property in that area. It would show whether 1.00" hail or 58 mph winds (or more) were reported, or whether a tornado occurred.
We also analyze NOAA NWS severe thunderstorm warnings. SPC outlooks often lead to these warnings, and the warnings are the official alert record for the areas hit.
Practical Guidance for Reading SPC Outlooks
For property owners:
- Watch the SPC outlooks for your area. A "Slight" risk or higher means be prepared.
- At "Moderate" or "High," secure outdoor items, park vehicles under cover, and have a severe weather plan.
- After a storm, if you suspect damage, StormAuditor can give a property-level historical weather report to document the conditions.
For contractors and adjusters:
- SPC outlooks are an excellent early warning of storms. They help you plan crews and resources.
- Risk levels hint at where claims or repairs will rise.
- After the storm, StormAuditor reports add to SPC data. They pinpoint hail sizes and wind gusts at one location, such as 1.75" golf-ball hail, which commonly breaks windows. This helps with date-of-loss research (Date of Loss Weather Research).
For attorneys and researchers:
- SPC outlooks give a big-picture view of severe weather risk.
- For a date-of-loss case, pair that forecast with StormAuditor's detailed history. Together they show how strong the storms were at one location. (Sample Report)
Limitations
- SPC outlooks are forecasts. They do not say what will happen.
- Severe weather can be very local. A property in a "High" risk area did not always get severe weather. It only means conditions were very favorable.
- Severe weather can also form outside outlook areas when conditions change.
- Our reports show what happened, not what was forecast. They use radar estimates (MESH) and storm reports. These have limits too: radar can under-estimate wet hail, and stations may miss a microburst.
Related StormAuditor Tools
- Historical Weather by Address: Get a detailed report for any property.
- Hail Explorer: See historical hail swaths and reports.
- Wind Explorer: Look at historical wind gusts and warnings.
- Date of Loss Weather Research: Research specific dates.
- Our Methodology: Hail: Learn about SAHE-2.
- Our Methodology: Wind: Learn about SAWE-2.
FAQ
Q: What is a Storm Prediction Center outlook?
A: It is a NOAA forecast of the chance of severe thunderstorms across the United States, including hail, damaging wind, and tornadoes. It ranks risk from Marginal to High.
Q: What are the SPC risk categories?
A: Marginal, Slight, Enhanced, Moderate, and High. Each step means a higher chance of stronger severe weather. "Slight" means scattered severe storms are possible. "High" means widespread, long-lived, intense severe weather is likely.
Q: What types of severe weather do SPC outlooks cover?
A: Mainly hail 1.00" (quarter size) or larger, wind gusts of 58 mph (50 knots) or more, and tornadoes.
Q: How far ahead do SPC outlooks forecast?
A: For today (Day 1), tomorrow (Day 2), and Days 3-8. Near-term forecasts are more detailed and updated more often.
Q: Can StormAuditor confirm whether severe weather from an SPC outlook happened at my property?
A: Yes. StormAuditor's history reports use radar estimates (MRMS MESH) and SPC-reported observations. They show the hail sizes (such as 2.00" hen-egg hail) and wind gusts (such as 75 mph) that occurred at one location, as opposed to the SPC's forecast.
Q: Where can I find official SPC outlooks?
A: On the SPC website: Storm Prediction Center (spc.noaa.gov).