Storm Report Glossary

SPC (Storm Prediction Center): The NOAA center in Norman, Oklahoma responsible for severe thunderstorm and tornado forecasting nationwide. SPC also compiles Local Storm Reports of hail, wind, and tornadoes into the public storm report record used on these pages.
NWS (National Weather Service): The NOAA agency that issues weather warnings. Its 122 local forecast offices issue the Severe Thunderstorm and Tornado Warnings that appear on IDOLCheck pages.
Local Storm Report (LSR): A report of observed severe weather — hail size, wind gust, tornado, or storm-related effects — filed by an NWS office from spotters, emergency managers, law enforcement, or the public. LSRs are what SPC aggregates into its storm reports.
SPC verified report: IDOLCheck's label for an SPC storm report: an observed hazard with a magnitude, time, and location. Distinct from a warning, which is a forecast that a hazard is imminent or occurring.
Severe Thunderstorm Warning: An NWS warning issued when a storm is producing or is about to produce hail of 1 inch or larger and/or wind gusts of 58 mph or greater. Warnings are issued for a polygon, not a whole county.
Tornado Warning: An NWS warning issued when a tornado has been sighted or indicated by radar. Like severe thunderstorm warnings, it covers a specific polygon.
Severe weather mention: IDOLCheck's label for hail size or wind speed cited in the text of an NWS warning — for example “quarter size hail and 60 mph wind gusts.” It reflects what the forecaster expected, not a ground measurement.
Radar-indicated vs. observed: A warning is radar-indicated when the hazard is inferred from radar signatures; it is observed when a spotter, chaser, or official has confirmed it on the ground. Both appear on IDOLCheck pages, labeled.
Warning polygon: The geographic boundary an NWS warning applies to. Since 2007 warnings are storm-based polygons rather than whole counties. IDOLCheck shows the authoritative polygon and can test whether a specific address was inside it.
Severe threshold: The NWS criteria for a severe thunderstorm: hail 1 inch or larger, or wind gusts 58 mph or greater. Significant severe is 2-inch hail or 75 mph gusts.
EF scale (Enhanced Fujita): The rating system for tornado intensity, EF0 through EF5, assigned by NWS survey teams after a ground survey based on observed effects. Preliminary SPC reports rarely carry a rating; final ratings appear later in NOAA's Storm Events database.
Derecho: A widespread, long-lived windstorm associated with a fast-moving line of thunderstorms. A single derecho can generate hundreds of wind reports across several states in one day, which is why raw report counts alone can overstate a state's activity.
Mesoscale Discussion (MD): A short SPC bulletin describing a developing severe weather situation and whether a watch is likely. Haily's Briefing summarizes active MDs alongside current warnings.
Convective Outlook: SPC's daily forecast of severe thunderstorm risk across the US, issued in categories from Marginal to High. The Day 1 outlook map appears on state pages as context — it is a forecast, not a record.
NEXRAD: The national network of Doppler weather radars operated by NWS. Radar snapshots on IDOLCheck pages are NEXRAD composites rendered by the Iowa Environmental Mesonet for the time of the event.
Storm exposure: Whether a specific location was inside a warning polygon or near a verified report. The IDOLCheck app checks storm exposure for any US address.
Rolling window: IDOLCheck pages cover a rolling period ending today — currently 12 months — so the record rolls forward every day rather than resetting on a calendar date.
County-level (gated) view: For events in the last 30 days, public pages show counts and peak magnitudes by county and month only. Exact dates, locations, and warning text unlock after 30 days, or immediately in the app.

See these terms in a real record