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Midway · NOAA 1619910 · 28° 13′ N · 177° 22′ W
Tides at Sand Island, Midway Islands
A mixed, mainly semidiurnal tide (form factor 0.93), toward spring this week. Predicted from the station's 28 harmonic constants; heights above mean lower low water, times in station time. Weather is not in these numbers.
This week
| When | Water | Height |
|---|---|---|
| Sun, Oct 25, 10:42 AM | Low | 0.6 ft |
| Sun, Oct 25, 3:31 PM | High | 1.0 ft |
| Sun, Oct 25, 9:44 PM | Low | 0.1 ft |
| Mon, Oct 26, 4:58 AM | High | 1.6 ft |
| Mon, Oct 26, 11:34 AM | Low | 0.6 ft |
| Mon, Oct 26, 4:04 PM | High | 1.0 ft |
| Mon, Oct 26, 10:24 PM | Low | -0.0 ft |
| Tue, Oct 27, 5:42 AM | High | 1.7 ft |
| Tue, Oct 27, 12:19 PM | Low | 0.7 ft |
| Tue, Oct 27, 4:39 PM | High | 1.0 ft |
| Tue, Oct 27, 11:08 PM | Low | -0.1 ft |
| Wed, Oct 28, 6:27 AM | High | 1.7 ft |
| Wed, Oct 28, 1:01 PM | Low | 0.7 ft |
| Wed, Oct 28, 5:19 PM | High | 1.0 ft |
| Wed, Oct 28, 11:55 PM | Low | -0.1 ft |
| Thu, Oct 29, 7:15 AM | High | 1.7 ft |
| Thu, Oct 29, 1:43 PM | Low | 0.7 ft |
| Thu, Oct 29, 6:05 PM | High | 1.0 ft |
| Fri, Oct 30, 12:45 AM | Low | -0.1 ft |
| Fri, Oct 30, 8:04 AM | High | 1.6 ft |
| Fri, Oct 30, 2:27 PM | Low | 0.7 ft |
| Fri, Oct 30, 6:59 PM | High | 1.0 ft |
| Sat, Oct 31, 1:38 AM | Low | -0.0 ft |
| Sat, Oct 31, 8:55 AM | High | 1.6 ft |
| Sat, Oct 31, 3:16 PM | Low | 0.6 ft |
| Sat, Oct 31, 8:03 PM | High | 1.0 ft |
| Sun, Nov 1, 2:34 AM | Low | 0.1 ft |
The constants that make it
| Constituent | Amplitude | Phase |
|---|---|---|
| M2 | 0.4 ft | 91.8° |
| K1 | 0.2 ft | 274.7° |
| O1 | 0.2 ft | 279.2° |
| SA | 0.2 ft | 232.6° |
| N2 | 0.1 ft | 54.9° |
| P1 | 0.1 ft | 274.0° |
| S2 | 0.1 ft | 165.5° |
| Q1 | 0.0 ft | 278.7° |
The eight largest of 28. Source: NOAA CO-OPS harmonic constituents for 1619910, public domain.
The year as a print
The last two days, measured
At Sun, Oct 25 09:24 the gauge read 1.0 ft, 0.3 ft above the computed curve: wind and pressure, not the moon. The widest gap of the two days was 0.4 ft, at Sun, Oct 25 09:12.
- Computed here, from the constants
- NOAA's own prediction
- Measured at the gauge, every six minutes
The last twelve hours as numbers
| Station time | Measured | Computed here | NOAA |
|---|---|---|---|
| Sat, Oct 24 22:00 | 0.41 ft | 0.24 ft | 0.23 ft |
| Sat, Oct 24 23:00 | 0.63 ft | 0.39 ft | 0.39 ft |
| Sun, Oct 25 00:00 | 0.86 ft | 0.63 ft | 0.62 ft |
| Sun, Oct 25 01:00 | 1.19 ft | 0.91 ft | 0.90 ft |
| Sun, Oct 25 02:00 | 1.43 ft | 1.16 ft | 1.16 ft |
| Sun, Oct 25 03:00 | 1.60 ft | 1.36 ft | 1.35 ft |
| Sun, Oct 25 04:00 | 1.74 ft | 1.44 ft | 1.44 ft |
| Sun, Oct 25 05:00 | 1.71 ft | 1.41 ft | 1.41 ft |
| Sun, Oct 25 06:00 | 1.52 ft | 1.28 ft | 1.28 ft |
| Sun, Oct 25 07:00 | 1.34 ft | 1.09 ft | 1.09 ft |
| Sun, Oct 25 08:00 | 1.17 ft | 0.90 ft | 0.90 ft |
| Sun, Oct 25 09:00 | 1.08 ft | 0.74 ft | 0.75 ft |
Measured heights from NOAA CO-OPS station 1619910, preliminary, above mean lower low water. The print carries the computed curve only: one year, no weather.