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Guam · NOAA 1630000 · 13° 27′ N · 144° 39′ E
Tides at Apra Harbor, Guam
A mixed, mainly semidiurnal tide (form factor 1.01), spring this week. Predicted from the station's 33 harmonic constants; heights above mean lower low water, times in station time. Weather is not in these numbers.
This week
| When | Water | Height |
|---|---|---|
| Mon, Oct 26, 7:47 AM | High | 2.4 ft |
| Mon, Oct 26, 1:25 PM | Low | 1.0 ft |
| Mon, Oct 26, 6:55 PM | High | 2.4 ft |
| Tue, Oct 27, 1:47 AM | Low | -0.4 ft |
| Tue, Oct 27, 8:38 AM | High | 2.4 ft |
| Tue, Oct 27, 2:10 PM | Low | 1.2 ft |
| Tue, Oct 27, 7:25 PM | High | 2.4 ft |
| Wed, Oct 28, 2:29 AM | Low | -0.6 ft |
| Wed, Oct 28, 9:32 AM | High | 2.4 ft |
| Wed, Oct 28, 2:58 PM | Low | 1.4 ft |
| Wed, Oct 28, 7:57 PM | High | 2.4 ft |
| Thu, Oct 29, 3:14 AM | Low | -0.7 ft |
| Thu, Oct 29, 10:32 AM | High | 2.4 ft |
| Thu, Oct 29, 3:50 PM | Low | 1.5 ft |
| Thu, Oct 29, 8:35 PM | High | 2.3 ft |
| Fri, Oct 30, 4:05 AM | Low | -0.7 ft |
| Fri, Oct 30, 11:39 AM | High | 2.3 ft |
| Fri, Oct 30, 4:49 PM | Low | 1.6 ft |
| Fri, Oct 30, 9:18 PM | High | 2.2 ft |
| Sat, Oct 31, 5:02 AM | Low | -0.6 ft |
| Sat, Oct 31, 12:55 PM | High | 2.2 ft |
| Sat, Oct 31, 6:03 PM | Low | 1.7 ft |
| Sat, Oct 31, 10:11 PM | High | 2.1 ft |
| Sun, Nov 1, 6:05 AM | Low | -0.5 ft |
| Sun, Nov 1, 2:08 PM | High | 2.2 ft |
| Sun, Nov 1, 7:30 PM | Low | 1.6 ft |
| Sun, Nov 1, 11:22 PM | High | 1.9 ft |
The constants that make it
| Constituent | Amplitude | Phase |
|---|---|---|
| M2 | 0.7 ft | 291.4° |
| K1 | 0.5 ft | 64.7° |
| O1 | 0.4 ft | 43.6° |
| SA | 0.2 ft | 103.6° |
| S2 | 0.2 ft | 306.7° |
| P1 | 0.2 ft | 66.4° |
| N2 | 0.2 ft | 276.5° |
| Q1 | 0.1 ft | 36.8° |
The eight largest of 33. Source: NOAA CO-OPS harmonic constituents for 1630000, public domain.
The year as a print
The last two days, measured
At Mon, Oct 26 06:24 the gauge read 1.9 ft, 0.2 ft below the computed curve: wind and pressure, not the moon. The widest gap of the two days was 0.5 ft, at Sun, Oct 25 22:12.
- 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 |
|---|---|---|---|
| Sun, Oct 25 19:00 | 2.07 ft | 2.32 ft | 2.35 ft |
| Sun, Oct 25 20:00 | 1.76 ft | 2.06 ft | 2.08 ft |
| Sun, Oct 25 21:00 | 1.22 ft | 1.58 ft | 1.60 ft |
| Sun, Oct 25 22:00 | 0.54 ft | 1.00 ft | 1.01 ft |
| Sun, Oct 25 23:00 | -0.02 ft | 0.46 ft | 0.46 ft |
| Mon, Oct 26 00:00 | -0.40 ft | 0.06 ft | 0.05 ft |
| Mon, Oct 26 01:00 | -0.56 ft | -0.11 ft | -0.12 ft |
| Mon, Oct 26 02:00 | -0.49 ft | -0.03 ft | -0.04 ft |
| Mon, Oct 26 03:00 | -0.07 ft | 0.30 ft | 0.28 ft |
| Mon, Oct 26 04:00 | 0.51 ft | 0.82 ft | 0.79 ft |
| Mon, Oct 26 05:00 | 1.18 ft | 1.42 ft | 1.39 ft |
| Mon, Oct 26 06:00 | 1.75 ft | 1.95 ft | 1.92 ft |
Measured heights from NOAA CO-OPS station 1630000, preliminary, above mean lower low water. The print carries the computed curve only: one year, no weather.