NOAA/NCEI Storm Events Database
The historical archive uses the NOAA National Centers for Environmental Information Storm Events Database bulk files. Peak Country selects records identified as Hail, validates required fields, and retains the official event identifiers and source links. The public history uses the latest five-calendar-year window, 2022–2026. Completed NOAA/NCEI archive records currently cover 2022–2025; the current 2026 season remains provisional in the live tracker and is not mixed into completed historical totals.
NOAA can correct or revise historical Storm Events records after publication. The repository retains the broader source archive and precise annual filenames so results can be reproduced and later reconciled against corrected releases. Only the five-year public subset is loaded into the history interface. Peak Country does not rewrite an observation to fill a missing magnitude or location.
Download the approved public derivative as CSV or JSON. Both distributions use the same source-backed observations as the human-readable hail-history resource.
National Weather Service
The National Weather Service active-alert API provides severe-weather information, including warning geometry and affected areas where supplied. The live tracker prioritizes relevant alert polygons near the Greeley-centered area instead of depending entirely on county-name matching. Broader Colorado alerts remain secondary so distant warnings do not dominate the Northern Colorado view.
Always follow official NWS warnings and local emergency instructions during severe weather. Peak Country’s site is an informational repair and hail-report resource, not an emergency warning system.
Storm Prediction Center
The NOAA Storm Prediction Center preliminary hail-report feed provides current context. These observations can be useful soon after a storm, but preliminary reports may be delayed, updated, or corrected. The tracker labels its source and refresh status and does not invent a report when the feed is unavailable or empty.
Greeley anchor and 50-mile filter
The historical process uses the Greeley city geographic reference point at latitude 40.41566 and longitude -104.7721515. This is a calculation anchor, not a Peak Country address or shop location. Qualifying observations must have valid coordinates and fall within 50 statute miles.
Distance is calculated with the Haversine formula, a great-circle calculation using latitude and longitude on the Earth’s surface. This produces a consistent straight-line geographic distance. A 50-mile circle crosses municipal and county boundaries, so regional records are not automatically labeled as belonging to Greeley or Weld County. The Weld County view uses NOAA’s source area field for county attribution.
Reports, hail days, and storm episodes
A hail report is one qualifying official observation. A hail day is one calendar date with at least one qualifying observation. Several reports can occur on the same day, and several observations can belong to one NOAA episode. Peak Country therefore does not present report count as storm count. Annual and five-year public summaries are calculated from the same source-backed records used by the plot and report table.
How cached and unavailable data is handled
Official feeds can fail temporarily. When retained data is shown, the tracker labels its timestamp and stale condition rather than presenting it as current. A source failure produces an unavailable state instead of simulated observations. Meaningful page text and source explanations remain available even when a live request cannot be completed.
Freshness and limitations
Live pages display source status and distinguish current, stale cached, and unavailable data. Reports can be delayed or incomplete, and location accuracy varies by observer and source. An empty feed does not prove that no hail occurred. A nearby hail report confirms only that hail was reported in the area; it does not prove that a specific vehicle was exposed or damaged. A direct vehicle inspection is required.
Explore the Live Hail Tracker, search the verified historical archive, or review the Hail Size Guide. Technical details are preserved in the archive source manifest and repository validation tests.
Published September 5, 2026 · Last reviewed October 6, 2026 · Historical dataset generated September 6, 2026