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VI · NOAA 9751639 · 18° 20′ N · 64° 56′ W
Tides at Charlotte Amalie
A mixed, mainly diurnal tide (form factor 2.80), spring this week. Predicted from the station's 29 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, 6:14 PM | High | 0.6 ft |
| Mon, Oct 26, 1:08 AM | Low | 0.2 ft |
| Mon, Oct 26, 9:26 AM | High | 1.1 ft |
| Tue, Oct 27, 1:31 AM | Low | 0.1 ft |
| Tue, Oct 27, 10:17 AM | High | 1.2 ft |
| Wed, Oct 28, 2:00 AM | Low | 0.0 ft |
| Wed, Oct 28, 11:14 AM | High | 1.2 ft |
| Thu, Oct 29, 2:39 AM | Low | -0.0 ft |
| Thu, Oct 29, 12:21 PM | High | 1.2 ft |
| Fri, Oct 30, 3:31 AM | Low | -0.0 ft |
| Fri, Oct 30, 1:33 PM | High | 1.1 ft |
| Sat, Oct 31, 4:39 AM | Low | 0.0 ft |
| Sat, Oct 31, 2:37 PM | High | 1.1 ft |
| Sun, Nov 1, 5:55 AM | Low | 0.1 ft |
| Sun, Nov 1, 3:27 PM | High | 1.1 ft |
The constants that make it
| Constituent | Amplitude | Phase |
|---|---|---|
| K1 | 0.3 ft | 229.5° |
| SA | 0.2 ft | 181.2° |
| O1 | 0.2 ft | 221.6° |
| M2 | 0.1 ft | 23.1° |
| P1 | 0.1 ft | 231.2° |
| SSA | 0.1 ft | 46.0° |
| MF | 0.0 ft | 358.7° |
| Q1 | 0.0 ft | 208.8° |
The eight largest of 29. Source: NOAA CO-OPS harmonic constituents for 9751639, public domain.
The year as a print
The last two days, measured
At Sun, Oct 25 16:24 the gauge read 1.1 ft, 0.5 ft above the computed curve: wind and pressure, not the moon. The widest gap of the two days was 0.7 ft, at Fri, Oct 23 19:12.
- 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 05:00 | 1.25 ft | 0.70 ft | 0.69 ft |
| Sun, Oct 25 06:00 | 1.39 ft | 0.84 ft | 0.84 ft |
| Sun, Oct 25 07:00 | 1.65 ft | 0.96 ft | 0.96 ft |
| Sun, Oct 25 08:00 | 1.65 ft | 1.03 ft | 1.03 ft |
| Sun, Oct 25 09:00 | 1.69 ft | 1.04 ft | 1.04 ft |
| Sun, Oct 25 10:00 | 1.55 ft | 0.99 ft | 1.00 ft |
| Sun, Oct 25 11:00 | 1.51 ft | 0.90 ft | 0.91 ft |
| Sun, Oct 25 12:00 | 1.35 ft | 0.80 ft | 0.81 ft |
| Sun, Oct 25 13:00 | 1.22 ft | 0.70 ft | 0.72 ft |
| Sun, Oct 25 14:00 | 1.12 ft | 0.63 ft | 0.64 ft |
| Sun, Oct 25 15:00 | 1.04 ft | 0.58 ft | 0.59 ft |
| Sun, Oct 25 16:00 | 1.09 ft | 0.56 ft | 0.57 ft |
Measured heights from NOAA CO-OPS station 9751639, preliminary, above mean lower low water. The print carries the computed curve only: one year, no weather.