SPC Storm Reports: What They Are & How to Use Them
By StormAuditor Editorial Team · Published 2026-07-14 · Updated 2026-08-20
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.
SPC (Storm Prediction Center) storm reports are vital pieces of information that document severe weather occurrences like hail, high winds, and tornadoes, often submitted by trained spotters or emergency managers.
Understanding SPC Storm Reports
After severe weather, it can be hard to confirm what hit where. One of the best resources for past storms is the set of Storm Prediction Center (SPC) storm reports. They give a ground-truth view of what actually happened in a severe storm.
What Are SPC Storm Reports?
SPC storm reports are real-time reports of severe weather that people saw: hail, damaging wind, and tornadoes. They come from:
- trained weather spotters,
- emergency managers,
- police, and
- at times, the public.
They matter because they give the place, type, and strength of an event. Radar alone does not always capture those details.
What a report usually says:
- Hail: the size seen (for example, "1.00 inch hail").
- Wind: an estimated gust speed, or the damage seen (for example, "trees down" or "power poles snapped").
- Tornadoes: the location, and sometimes a first damage assessment.
The SPC, a part of the National Weather Service (NWS) that forecasts severe storms, compiles the reports. They are a key source. But they are reports of what people saw, not official NWS warnings. Their accuracy can vary with the observer and the conditions.
How StormAuditor Uses SPC Storm Reports
StormAuditor builds SPC storm reports into its weather history, mainly in our Hail Explorer and Wind Explorer tools. They are a key part of our method because they show conditions on the ground.
- Hail: In our StormAuditor Hail Estimate v2 (SAHE-2), SPC hail reports back up the radar estimates from MRMS MESH (Maximum Estimated Size of Hail). If an SPC report shows 1.75-inch (golf ball) hail near a property, it strengthens the case for severe hail in that area.
- Wind: In our SAWE-2, the StormAuditor Wind Estimate, SPC wind reports of fallen trees or estimated gusts add context to the daily peak readings from weather stations. They are more evidence of severe wind at a place.
When you request a property report at Address Lookup, StormAuditor checks your address against nearby SPC storm reports. That gives a fuller picture of severe weather in your area on a given date in our DOL research workflow.
Limitations
SPC storm reports are very valuable, but they have limits. StormAuditor accounts for them:
- Gaps in space: A report exists only where someone saw and reported the event. Coverage can have large gaps, so severe weather can happen without a report.
- Timing: A report is a snapshot. The time may not be exact to the minute. It is usually when the observation was made or the event happened.
- Observer differences: Many reporters are trained, but different people may judge hail size or wind damage a little differently. Accuracy can vary.
- Under-reporting: Not all severe weather gets reported, mainly in rural areas or at night. No SPC report does not mean no severe weather.
StormAuditor combines SPC reports with other sources: NWS severe weather warnings, radar products like MRMS MESH, and station wind data. Together they give a fuller estimate of conditions. Using many sources offsets the weak spots of any one. See our Limitations page for more.
Related StormAuditor Tools
- Address Lookup: Get property-level weather history, including nearby SPC reports.
- Hail Explorer: See hail swaths and SPC hail reports across a state.
- Wind Explorer: Map wind gusts and SPC wind reports.
- StormAuditor Methodology: How SAWE-2 uses SPC reports.
- StormAuditor Methodology: How SAHE-2 uses SPC reports.
- Data Sources: The full list of data sources StormAuditor uses.
FAQ: SPC Storm Reports
Q: What's the difference between an SPC storm report and an NWS warning?
A: An NWS severe thunderstorm or tornado warning is an official alert. It says severe weather is about to happen or is happening in an area. An SPC storm report is a sighting of severe weather that already happened. It gives ground-truth confirmation. StormAuditor uses both.
Q: Does every severe weather event get an SPC report?
A: No. Many do, mainly in populated areas or where spotters are active. But some severe events go unreported. That is why StormAuditor uses many data sources: to give the most complete picture possible, even with no report.
Q: How accurate are hail sizes in SPC reports?
A: They are usually judged by eye. Many observers are trained, but estimates can vary. For scale: 1.00" is quarter size, 1.75" is golf ball size, and 2.00" is hen-egg size. StormAuditor combines these reports with radar data for a more refined estimate.
Q: Can I use SPC reports to prove damage?
A: SPC reports show what severe weather was seen in an area. They are a strong sign of severe conditions, but StormAuditor cannot prove what caused damage. We give the weather context. Qualified damage assessors decide the cause. See our Sample Report and Limitations pages for more.
Q: Where can I see raw SPC storm reports?
A: The Storm Prediction Center's website has raw storm reports and archives. So do the Iowa Environmental Mesonet (IEM) archives. StormAuditor uses these public sources. SPC Storm Reports (spc.noaa.gov) and Iowa Environmental Mesonet