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DATA_SOURCES.md

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Data sources and limitations

  • Current PCB flag: Visit Panama City Beach, “Current Beach Conditions,” which states conditions are provided by Beach & Surf Patrol. The collector records polling time; it may not equal official issuance time.
  • Flag definitions: City of Panama City Beach beach-flag page.
  • Primary historical flag archive: User-supplied ALERTBAY/PCBFLAGS text-message export, parsed into structured records. These original records are preserved and always take precedence over any recovered secondary record for the same date.
  • Recovered historical flag tier: National Weather Service Tallahassee Surf Zone Forecast (SRFTAE) products retrieved from the Iowa Environmental Mesonet NWS text-product archive. Many SRFTAE products explicitly state that the listed area beach flags are based on communication with area beach officials and include a Bay flag entry. Know the Gulf promotes an NWS Bay flag only when that calendar date is absent from both the immutable ALERTBAY/PCBFLAGS archive and the automatic observation log. Every recovered observation retains its source product ID, URL, and record_tier=recovered provenance.
  • Recovery validation: Across 613 calendar dates where the NWS Bay-flag record overlaps the primary PCBFLAGS/automatic record, the recovered source agrees with the primary latest daily flag on 98.37% of days, with the peak daily flag on 98.69%, and with at least one reported flag on 99.51%. This strong overlap agreement supports its use as secondary historical evidence, but it does not make the recovered tier equivalent to original PCBFLAGS messages.
  • Purple overlays: Explicit Purple reports found in recovered NWS products are retained. A recovered NWS product that does not mention Purple is treated as Purple-unknown rather than proof that no Purple flag was posted, because historical Purple-overlay reporting is not demonstrably complete. Purple percentages therefore use only records with reliable Purple reporting.
  • Supplemental NWS surf-zone history: The SRFTAE archive also supplies historical rip-current risk, surf height, UV category, water temperature, winds, and related beach-zone forecast context. These fields are retained separately from the primary flag evidence for research and cross-checking.
  • Measured local coastal observations: NOAA/NOS station PCBF1 / 8729210 at Panama City Beach is retrieved through the National Data Buoy Center historical standard-meteorological archive. Know the Gulf derives daily observed wind, gust, air temperature, water temperature, and pressure fields from these measurements. Historical annual NDBC files are quality-controlled; recent realtime2 observations have only undergone NDBC gross-error checks until they enter the archive.
  • Measured offshore observations: NDBC station 42039 is used as the regional offshore measured-wave reference. Know the Gulf derives daily observed significant wave height, dominant/average wave period, wind, gust, pressure, and water-temperature context. This buoy is offshore and is not a direct measurement of breaker height at a Panama City Beach swimmer location.
  • Raw NOAA/NDBC policy: Know the Gulf does not republish the full timestamp-level NOAA/NDBC archive. The enrichment job processes raw source observations in memory, publishes compact daily derived features and station/source metadata, and leaves the raw measurements with NOAA/NDBC as the authoritative upstream record. This avoids duplicating hundreds of megabytes of federal source data while keeping every derived field reproducible.
  • Tropical-cyclone history: NOAA National Hurricane Center Atlantic HURDAT2 best-track data are parsed into storm-event, nearby-track-point, and daily proximity tables. Distances are great-circle distances from six-hourly best-track positions to the Know the Gulf Panama City Beach reference point. HURDAT2 is retrospective best-track history, not a forecast; these variables are therefore retained for retrospective association research and are not automatically used as operational prediction features.
  • Pre-2017 official-page hunt: Know the Gulf periodically checks archived copies of official Visit Panama City Beach current-condition pages for candidate pre-2017 flag evidence. Internet Archive captures are discovery evidence only. Candidate rows are never merged into the historical flag master without independent audit and corroboration.
  • West End PCB historical mirror: Know the Gulf also indexes explicitly dated historical flag-status posts from the independent local West End PCB site. This source has records reaching into 2010 and says its flag updates are posted when Beach & Surf Patrol sends a status text, but it is not an official government archive. Its records are therefore retained as a community_mirror_candidate research tier and are audited against later dates already covered by primary/NWS evidence. They never overwrite or automatically extend the master flag history.
  • Additional pre-2017 targets: retained City of Panama City Beach / Beach & Surf Patrol operational logs, Bay County emergency-management or beach-safety records, legacy ALERTBAY/888777 message exports, archived official condition widgets, and contemporaneous local reporting used only as corroboration.
  • Weather: Open-Meteo ERA5 for finalized model training. Live/current UI may use Open-Meteo forecast/current fields. Reanalysis is not the same as an on-beach instrument.
  • Marine: Open-Meteo ERA5-Ocean for finalized historical wave/swell features. It is relatively coarse and represents regional conditions, not exact breaker height at a specific swimmer location.
  • Tides: NOAA CO-OPS subordinate station 8729136, New Entrance Channel, St. Andrew Bay. Tide predictions are referenced to MLLW.
  • Research model: Time-aware logistic regression for red-or-worse association/prediction research. Measured NDBC and HURDAT2 context are preserved in the research table, but HURDAT2 best-track fields are excluded from the operational feature set because they are retrospective. The model is exploratory, is not an official rip-current forecast, and is never a swimming clearance.

Provenance note after the 2026 brand migration

Historical rows may retain Safe2Swim or Safe2Swim PCB source labels when that was the collector identity at the time of observation. Those labels are intentionally preserved as historical provenance. New public-facing documentation, site metadata, and future collector labels use Know the Gulf.