BTV WARNING VERIFICATION

What this is: a warning verification browser for Tornado (TOR), Severe Thunderstorm (SVR), Flash Flood (FFW), and Snow Squall (SQW) warnings, built on top of the Iowa Environmental Mesonet's IEM Cow service. IEM Cow automatically checks each storm-based warning polygon against Local Storm Reports (LSRs) to determine whether it verified.

Verification status shown here is computed as: Verified if IEM found a matching LSR of the right type, within the time window, inside the buffered warning polygon. Needs Verification if the warning has fully expired with no matching LSR found. Pending if the warning is still active (verification isn't final until it expires or a report comes in).

Calendar day: dates here are bounded by local midnight in the configured timezone (Settings), not 00Z UTC — so an overnight event isn't split across two different "days" the way a strict UTC day would.

Confidence score: the percentage shown per-warning is a simple, unofficial heuristic (based on lead time and number of matching reports) meant to give a quick visual sense of how solid the verification is — it is not an NWS or IEM statistic.

Data is unofficial. Per IEM's own disclaimer, this data is intended for educational/situational-awareness use, not as an official verification record.

Switching offices: the office dropdown in the header lists every NWS Weather Forecast Office nationwide (sourced live from IEM's own WFO network table) — pick one and the app re-queries live NWS zone boundaries for that office and re-centers the map.

Date ranges: the Archive picker loads every matching warning and LSR for the whole range directly onto the map, table, and stats (using the same boundary-safe padding logic as single-day view), rather than just showing a summary.

Basemap: CartoDB Voyager. Zone boundaries: official NWS zone reference service (mapservices.weather.noaa.gov). Office list: IEM WFO network table. Radar: IEM's time-enabled NEXRAD composite reflectivity WMS, snapped to the nearest 5-minute composite (archive available back to Feb 16, 2011). Map library: Leaflet.

PDS / Emergency badges: shown when a Tornado or Flash Flood warning's product text contains "PARTICULARLY DANGEROUS SITUATION" or "TORNADO/FLASH FLOOD EMERGENCY" wording. This is a plain-text scan, not a structured IEM field, so it's skipped for very large date ranges to avoid hammering IEM with requests — it still works normally for a single day or a short range.

Keyboard shortcuts: ← / → previous/next day, j / k step through the warnings table, n jump to the next unverified warning, Esc close dialogs.

Sharing a view: the URL updates automatically with the current office and date (or range), so copying the address bar link takes someone straight to the same view.

PNG export: captures the queue, table, summary, stats, and warning-details panels, plus the warning polygons/zone lines/LSR markers on the map — but not the basemap street imagery itself, since CartoDB's tile server doesn't allow that imagery to be read back into an exported image. Use "Print" instead for a version with full basemap tiles included.

Year heatmap: the Trends modal's "1 Year" option shows a GitHub-style calendar grid colored by that day's CSI — click any cell to jump straight into that day.

Counties tab: a ranked breakdown of which counties/zones see the most warnings and their false-alarm rate for the current day or range.

Live mode: while viewing today, the app quietly re-polls IEM every few minutes and toasts new warnings as they're issued — a red "LIVE" badge next to the date shows it's active. It turns off automatically for any other day or a date range.

Forecaster coverage: the stats panel shows a count of distinct forecaster codes active in the window — intentionally an aggregate, not a per-person breakdown, since named scorecards aren't something this tool is meant to produce.

Accessibility: modals trap focus and return it on close, icon-only controls carry aria-labels, and Settings has a colorblind-safe palette toggle for the status colors. The layout also reflows to a single column below ~900px wide for phones and tablets.