About
longhorizon.blue gathers public observations and model forecasts of coastal water and shows each with its age, its source and its recent history, so that present conditions and the next two days can be read against recent experience. The first waterway is Long Island Sound. It is an early public version, curated locally by Long Horizon Observatory. All data are provisional and may be revised, and nothing here is for navigation.
The site is a demonstration. It joins classic marine datasets and forecasts in a few new views: a comfort index for the reader's boat, wind against tide on the wave model's cells, and HRRR's last forecast before each hour as a stand-in where a station is out. It is built in the open from open data, and its code is open source, so each method here can be adapted and rebuilt.
Limitations and use
The observations on this site are provisional and may contain errors, gaps and delays. Model values are forecasts, not measurements. The comfort index and the wind-against-tide layer are indicative products derived from those data; their thresholds are judgements, not standards. The site is a demonstration, provided for general information, as is and without warranty of any kind.
It is not a navigation aid and is not intended for navigation, safety-of-life, operational or legal decisions. Consult the National Weather Service marine forecasts and warnings and NOAA's official charts; the decision to go out, and how, rests with the vessel's operator. Use of the site is subject to the terms.
Where the data come from
- Buoys: LISICOS, Department of Marine Sciences, University of Connecticut: water temperature, salinity, dissolved oxygen and turbidity at depth, weather and waves, through the LISICOS ERDDAP server. While that server is unreachable, the newest readings are transcribed from the LISICOS station panels and marked as transcribed.
- Shore stations: NOAA CO-OPS at Kings Point, Bridgeport, New Haven and New London (water temperature, water level, tide predictions and weather), and USGS tidal gauges.
- Coastal airports: NWS ASOS weather at Sikorsky (Stratford, KBDR) and Tweed (New Haven, KHVN), through the Iowa Environmental Mesonet: wind, gusts, air temperature and pressure.
- Rivers: USGS stream gauges: flow and river turbidity.
- Forecasts and models: NOAA's High-Resolution Rapid Refresh (HRRR) for wind, air and pressure; the NWS Nearshore Wave Prediction System (NWPS) for waves; NECOFS (FVCOM, UMass Dartmouth) for currents; NOAA CO-OPS tidal current predictions.
- Satellite: the MUR sea surface temperature analysis (NASA JPL) and VIIRS chlorophyll-a and water clarity, through NOAA NESDIS CoastWatch.
- Advisories: the National Weather Service marine alerts for the Sound's zones, each linked to its zone forecast.
The regional picture is on the NERACOOS Mariners' Dashboard. Models are fetched through forcingkit, our open-source forcing library. The papers and monitoring programs behind the page are on the references page.
How the page works
Each plot's (i), and each map layer's, explains what it shows, how it is computed and where it comes from. The same text is collected here, with references.
Conventions
Times are stored in UTC and labelled in New York time. Each value carries its age; a value that fails a quality check is flagged with the reason. Speeds, heights and temperatures follow the Units switch in the menu. Scales are fixed, so a colour means the same value from one day to the next, and the heaviest marks are kept for unusual days. The plots owe their form to Edward Tufte: data in line work, small multiples on shared axes, sparklines (his books).
More
References · Terms and use of AI · Forecast verification · Code (MIT license) · Motivation. Questions and corrections: hello@longhorizon.blue, or "Send us a suggestion" under Collect.