Data And Editorial Methodology

TideAhead is a U.S. coastal planning aid. It combines tide predictions, current weather observations, hourly forecasts, limited marine-grid guidance, water temperature where a qualified nearby sensor reports it, sun and moon information, official-agency links, and transparent activity analysis. It is not a navigation product, emergency service, closure database, or substitute for local conditions.

The primary audience is a person deciding when and where to make a coastal visit. Design choices prioritize fast comparison and visible uncertainty: local time, datum, provider status, observation age, place-to-station distance, and unavailable fields appear near the values they qualify.

• Places: the 2025 U.S. Census Gazetteer for states, D.C., and Puerto Rico, supplemented by USGS GNIS populated places for supported Island Areas excluded from the national Census file.
• Stations and tides: NOAA Center for Operational Oceanographic Products and Services metadata and prediction APIs.
• Weather and marine: National Weather Service point, observation, hourly, and coastal forecast-grid products.
• Water temperature: fresh, quality-checked NOAA CO-OPS observations from the nearest reporting sensor within 30 miles.
• Astronomy: U.S. Naval Observatory Astronomical Applications API for the selected official coordinate and timezone.
• Rules and safety: jurisdiction-specific state or territorial resource agencies, NOAA Fisheries federal resources, and NWS rip-current safety guidance.

Map tiles are OpenStreetMap-derived community cartography served through an open map style, not a federal data layer. NOAA supplies station marker coordinates; Census or GNIS supplies place markers.

A place search first identifies an official Census or GNIS populated place. Candidate NOAA tide stations are prefiltered by a conservative latitude-longitude window and then ranked with the Haversine great- circle formula. The calculation uses an Earth radius of 3,958.8 miles, handles the longitude seam, and reports distance rounded to one decimal mile.

TideAhead creates a place forecast only when the nearest NOAA tide-prediction station is within 30 miles. Weather and astronomy use the official place coordinate. Tides remain the prediction for the named NOAA station, whose ID and distance are disclosed. No tide is spatially interpolated at the city coordinate, and proximity does not establish public access or identical hydrodynamics.

Provider responses are schema-validated before entering a page snapshot. Requests use finite timeouts, and data layers fail independently: a marine-grid failure does not erase a valid tide prediction, while a successful weather request cannot fill an unrelated missing tide field.

NWS weather observations older than three hours are withheld. NOAA water-temperature observations older than three hours, future-dated readings, readings with nonzero quality flags, and sensors beyond 30 miles are rejected. Provider issue or fetch times appear in the Sources And Confidence section so a visitor can judge recency.

NOAA reference stations use official six-minute MLLW predictions. TideAhead may compact that series for display while retaining official extrema and local-time labels. A current predicted height is estimated from the available continuous series; it is not described as an observed water level.

NOAA subordinate stations generally publish official high and low events rather than the same six-minute series. TideAhead can draw a dashed half-cosine estimate between adjacent official extrema. Every estimated point remains bounded by the two events. No segment is drawn outside them, and the page labels the curve as a derived interpolation rather than an official NOAA curve.

“Observed” identifies a current official sensor field. “Model” identifies official forecast or grid guidance. “Derived” identifies a TideAhead calculation whose inputs and boundaries are disclosed. “Unavailable” means no qualifying current value reached the page. A mixed display preserves field-level provenance instead of assigning one broad label to values with different sources.

TideAhead does not ship production fallback conditions or use sample values when an official provider fails. Tests use controlled mock responses to check validation behavior, but those fixtures are not reachable from the production data path.

Fishing, crabbing, and surfing scores are TideAhead-created planning indices. They combine only specified available official inputs and display the factors that raised, lowered, or limited the result. The scores do not estimate catch, confirm species presence, verify beach access, decide whether a season is open, or certify that conditions are safe.

Official state or territorial rules, federal-water resources, and NWS safety guidance remain separate links because they are decision gates, not numeric score ingredients. When required environmental inputs are missing, the affected analysis is withheld or explicitly limited.

TideAhead search and maps keep the full official NOAA tide-prediction catalog available. Coastal-place pages also remain available when they pass the 30-mile station rule. Availability inside the application does not mean every utility URL belongs in a public search-engine index.

The sitemap submits national and jurisdiction hubs, hand-edited educational pages, and NOAA reference-station forecast pages. Sparse subordinate-station pages, automatically matched coastal-place pages, and the commercial partnership page are marked for search engines not to index while still allowing links to be followed. This keeps the application useful without asking search engines to treat closely related utility pages as independent editorial destinations.

Review the source agencies directly: the NOAA CO-OPS Data API, NWS API documentation, and U.S. Naval Observatory API. The TideAhead About page summarizes the service's purpose and independence.

Send factual corrections, provider changes, source-quality concerns, or accessibility problems to admin@tideahead.com. Include the affected URL, station ID if relevant, the value or label in question, and a supporting official source when available.