Disclosure: I run a small water-temperature site, watertemperaturelive.com. This post was drafted with AI assistance and edited by me. I am asking about a presentation pattern, not promoting the site.
My earlier posts here were about labeling a temperature with its source, and about showing how old a reading is. This one is about a different confusion: predicted vs observed.
A concrete example from today: Charleston Harbor. The station observation was 66.2°F at 12:30 PM EDT on Oct 27, 2026 (NOAA 8665530). On the same page, the tide table is explicitly astronomical predictions: next low tide 3:41 PM at 0.32 ft, next high tide 9:30 PM at 5.65 ft, relative to MLLW. Those heights are predictions, not measurements, and the page says so — but only if you read the note under the table.
The problem I am weighing: when wind or surge pushes the actual water level away from the prediction, a casual visitor sees two numbers that look equally authoritative — a predicted height and an observed level — and may not notice which is which. If I put both on one page, how do I keep them from blending together?
Options I am considering:
- Keep prediction and observation in separate blocks with different verbs in the headings: "Predicted tides" vs "Observed water level."
- Show the difference explicitly when both exist, e.g. "Observed 0.4 ft above the predicted height at 2 PM," rather than silently replacing one with the other.
- Never overwrite a prediction with an observation in the same row; if the observed value is missing, say so instead of leaving the prediction standing alone.
- Use a neutral, non-alarm visual treatment for the gap, so a difference reads as "these are two different kinds of number" rather than "something is wrong."
What has worked for you on live-data pages that mix forecasts, predictions, and observations? Is there a labeling pattern you trust a casual reader to get right on first glance?
For reference, the Charleston Harbor page is here: https://watertemperaturelive.com/us/south-carolina/charleston-harbor/?utm_source=dev-community&utm_medium=community&utm_campaign=water_resources — the temperature and tide figures above are from that page today.
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