Predicted vs. measured tides
Newport Bay · UC Davis gauge
Today and the previous six days · Pacific time · feet & inches MLLW
Select Tide Charts to load recent tides.
Previous six days
Gauge sources & reading the charts
Measured levels are reported in meters NAVD88, converted to feet MLLW with NOAA’s historical +0.18 ft tie. The gauge is compared with Newport Bay Entrance predictions; harbor timing, calibration and benchmark differences may affect the comparison. Readings are provisional and the gauge’s tie has not been independently verified.
Daily tide charts use original readings paired with predictions at the same times, without interpolation. Today is partial. The model baseline and prepared historical trend weight qualifying hours equally; recent dates without prepared data use the original readings. Measured readings are five-minute averages.
Hover, tap or use arrow keys to inspect a chart. Hover values interpolate gaps up to 15 minutes; longer gaps stay open. Daily charts share one height scale. The server checks measured readings every five minutes and predicted tides daily. The daily mean forecast is regenerated each day, with further checks for newer model inputs. This page refreshes every six minutes while visible. If updates are delayed, saved data stays visible with its original timestamps.
The measured tide map link uses a community-reported location near Marcus Avenue and 32nd Street, not independently verified.
Ocean & tide data
Explore water levels, temperature, depth, and Pacific climate records.
Daily mean difference (previous 3 months + forecast)
Past 3 months · 6-day forecast · days 7–14 outlook · inches above predicted tide
Forecast loads with tide charts.
UC Davis reported tide levels
Compare UC Davis observed water levels with NOAA’s predicted tide. Choose a range or drag across the chart to zoom.
Loading saved observations…
Source & method
Both lines use hourly values in feet MLLW. UC Davis readings are averaged by hour; NOAA prediction samples are averaged by hour where available. UC Davis reports meters NAVD88; observations here use NOAA’s historical +0.18 ft tie to MLLW, which has not been independently resurveyed. NOAA’s predictions are for Newport Bay Entrance (station 9410580), a nearby but different location. UC Davis history begins April 1, 2025.
Sources: UC Davis Coastal Oceanography water levels · NOAA station 9410580
Forecast
Local weather and offshore wave forecasts provide context for future coastal conditions. Historical reforecast charts are labeled as retrospective research and are not inputs to the live tide forecast. Ensemble spread shows disagreement among wave-model members; it is not a tide-forecast error range.
Forecast context loads with this page.
Historical model research
Five years of retrospective wave-model output and regional tide-residual observations. These charts explore possible relationships; they do not measure Newport Bay or change the live forecast.
Changes in measured tide excess
How the extra water above predicted tide changes over days, weeks, and months. Positive values show an increase; negative values show a decrease.
Temperature & depth
Compare available locations and depths. Each chart identifies its source, dates, and whether values are observations, mapped measurements, or model output.
Pacific climate history
Long-term basin records provide context; they do not measure Newport Bay or attribute local flooding.
Coastal conditions
Forecast & sources
Past values: six-day replays and saved forecasts at their original lead. Future values: forecast through day 6; outlook for days 7–14.
Forecast formula & data
The tide is the clock. The ocean sets the starting height.
The Moon and Sun give tides their familiar rhythm. But a high tide can ride on a higher or lower background ocean. These charts track that extra water above NOAA’s predicted tide, averaged over a day. NOAA’s reference also includes fitted long-period seasonal effects; it does not isolate astronomy perfectly.
We start with the last complete day measured in Newport Bay. Then two ocean forecasts estimate how that background might change. They carry the effects of weather and the wider ocean; the model also adds an explicit air-pressure adjustment. Lower air pressure lets the water rise, while higher pressure pushes it down.
Measured starting point forecast change daily mean excess
The next six days are the primary forecast. Days 7–14 use the same calculation as a longer-range outlook. A daily mean describes the background beneath the tide; it does not predict an individual high-tide peak or wave run-up.
What goes into this forecast?
The contribution breakdown will appear when the shared forecast loads.
The first three rows are the formula’s direct forecast adjustments. Percentages compare their absolute changes, not each process’s causal importance or predictive skill. The other rows explain the physics inside the provider models, the tide reference, and research data. The measured starting level is excluded from this table; it still anchors the forecast.
| Input or process | Role in the forecast | Contribution and evidence |
|---|---|---|
| ECMWF IFS ocean height | Half the forecast ocean-height change at the offshore 33.5°N, 118°W grid point. | Awaiting forecast |
| IFS air pressure | Half the pressure-driven water-level adjustment from the same forecast. Falling pressure raises this term. | Awaiting forecast |
| NOAA CFSv2 ocean height | Half the archived ocean-height change at 33°N, 118°W. No extra CFS pressure correction is added; the archived pressure treatment remains a limitation. | Awaiting forecast |
| NOAA tide prediction | Newport Bay Entrance, station 9410580, provides the reference subtracted from the gauge. It is not another forecast-change term. | Reference Not apportioned |
| Wind and weather | Wind can push water toward or away from the coast and change circulation. IFS/CFS simulate this forcing. Our formula uses their ocean-height forecasts; it does not directly read local wind observations. | Coastal water movement Separate share unknown |
| Water temperature and salinity | IFS/CFS simulate temperature and salinity through the water column. Warming expands water; salinity also changes density. Our formula reads their predicted ocean height. The temperature profiles we collected remain research data, with no separate temperature term. | Expansion & density Separate share unknown |
| Currents and the wider ocean | Currents and traveling ocean disturbances redistribute water. The provider models simulate that movement; our formula uses their predicted ocean height. A separate current predictor is still being tested. | Water redistribution Separate share unknown |
| Gliders, moorings and coastal radar | These measurements support research into the changing ocean. They are not separate inputs to this forecast calculation. | Research only No separate formula term |
| Swell and wave height | Buoy height, period and direction measurements were studied, with too few usable six-day tests to establish a benefit. A separate test of archived directional wave forecasts did not improve accuracy. No explicit harbor wave-setup correction is used. | Research only No separate wave term; physical effect remains unresolved |
| Observed weather and rainfall | Local wind and temperature observations, plus the tested rainfall predictors, remain research data. They are not additional terms in this accepted formula. | Not a direct input Research observations |
How much does ocean guidance help? Across 92 six-day historical replays (Jul 24–Oct 23, 2026), removing the IFS ocean-height adjustment increased average error from 1.47″ to 1.74″—about 18%. That measures the value of the whole ocean-height term, including interacting temperature, salinity and circulation effects. It is not a temperature-only percentage, and these exploratory tests do not establish future accuracy.
The calculation and source coverage
R̂d = Rb + ½(ΔOIFS − k ΔPIFS) + ½ΔOCFS
All water-level terms are in inches. The pressure response uses k ≈ 0.392 inches per hPa. The 50/50 weights apply to the two forecast changes, not to the observed starting point. A large baseline can therefore account for most of the displayed level.
The gauge baseline averages readings within each qualifying hour, then weights hours equally. An hour needs nine readings; at least 90% of the day’s hours must qualify. Measured levels in meters NAVD88 are converted to feet MLLW using the historical +0.18 ft tie. Gauge calibration and benchmark continuity have not been independently verified.
IFS supplies hourly ocean height and mean-sea-level pressure. Changes within separate runs are joined on a shared day, with complete hourly coverage required. Historical replays use the baseline day’s 00 UTC run and issue day’s 12 UTC run, allowing a 12-hour publication delay because exact release timestamps are unavailable. Scheduled updates select a qualifying 00 or 12 UTC run.
CFS supplies six-hour ocean-height forecasts from the baseline day’s 00 UTC run. Values are interpolated between supplied times and averaged over each Pacific day, including daylight-saving changes. Recorded source publication timestamps must precede the issue cutoff. These offshore grids do not resolve the harbor or individual properties.
What the test establishes
The main chart shows six-day historical replays and saved forecasts at their original lead. The comparison chart covers April 2026 onward and compares six-day and 14-day replays by default; its selector also offers individual horizons. Each replay uses its own forecast origin. Refreshing never turns an older outlook into a new forecast.
The fixed equal blend had lower 14-day average error than IFS alone across this period, but October’s improvement was negligible. Its six-day October error increased from 1.12″ to 1.77″. Additional remote ocean-height, heat-content and pressure corrections did not earn a place in this version. This is the selected model after exploratory comparisons, not a pristine prospective validation. Overlapping test dates are not independent events.
This predicts total excess water, not an isolated Kelvin wave or its arrival date. Archived observations may have been revised; exact IFS publication times and current pressure conventions remain limitations. A daily average does not predict an individual high-tide peak, wave run-up or property flooding.
Data downloads
CSV files include the values behind each chart. Saved research records retain their original coverage dates; refreshing the page does not extend those archives.
Open Data to load the saved ocean records.
Bringing the shoreline into focus
Loading measured terrain and connected water paths for Newport Harbor.
Calculating water movement
Preparing the selected tide…
The map will update when the complete simulation passes its numerical checks.
Storm drainage
Open the network to inspect City records.
Tap an asset for its source, dates and recorded dimensions. Dashed pipes are other-agency or recorded abandoned assets.
Evidence only. Drainage is not included in the flood simulation. Closing levels have an unconfirmed datum and do not indicate live valve status.
Overview expands narrow wet paths. Zoom in and inspect for local depth.