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AK · NOAA 9450460 · 55° 20′ N · 131° 38′ W
Tides at Ketchikan
A mixed, mainly semidiurnal tide (form factor 0.33), spring this week. Predicted from the station's 32 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, 12:35 PM | High | 17.5 ft |
| Sun, Oct 25, 6:58 PM | Low | -2.0 ft |
| Mon, Oct 26, 1:15 AM | High | 15.9 ft |
| Mon, Oct 26, 6:58 AM | Low | 1.4 ft |
| Mon, Oct 26, 1:09 PM | High | 18.2 ft |
| Mon, Oct 26, 7:37 PM | Low | -2.8 ft |
| Tue, Oct 27, 1:58 AM | High | 16.0 ft |
| Tue, Oct 27, 7:36 AM | Low | 1.9 ft |
| Tue, Oct 27, 1:46 PM | High | 18.5 ft |
| Tue, Oct 27, 8:19 PM | Low | -3.1 ft |
| Wed, Oct 28, 2:42 AM | High | 15.7 ft |
| Wed, Oct 28, 8:16 AM | Low | 2.5 ft |
| Wed, Oct 28, 2:26 PM | High | 18.3 ft |
| Wed, Oct 28, 9:03 PM | Low | -2.7 ft |
| Thu, Oct 29, 3:30 AM | High | 15.0 ft |
| Thu, Oct 29, 8:59 AM | Low | 3.4 ft |
| Thu, Oct 29, 3:10 PM | High | 17.6 ft |
| Thu, Oct 29, 9:52 PM | Low | -1.9 ft |
| Fri, Oct 30, 4:23 AM | High | 14.2 ft |
| Fri, Oct 30, 9:49 AM | Low | 4.4 ft |
| Fri, Oct 30, 4:00 PM | High | 16.5 ft |
| Fri, Oct 30, 10:48 PM | Low | -0.7 ft |
| Sat, Oct 31, 5:24 AM | High | 13.3 ft |
| Sat, Oct 31, 10:49 AM | Low | 5.3 ft |
| Sat, Oct 31, 5:01 PM | High | 15.1 ft |
| Sat, Oct 31, 11:53 PM | Low | 0.5 ft |
| Sun, Nov 1, 5:36 AM | High | 12.8 ft |
| Sun, Nov 1, 11:09 AM | Low | 5.9 ft |
The constants that make it
| Constituent | Amplitude | Phase |
|---|---|---|
| M2 | 6.1 ft | 270.0° |
| S2 | 2.1 ft | 301.7° |
| K1 | 1.7 ft | 261.0° |
| N2 | 1.2 ft | 246.4° |
| O1 | 1.0 ft | 245.1° |
| K2 | 0.6 ft | 294.4° |
| P1 | 0.5 ft | 258.2° |
| SA | 0.4 ft | 262.6° |
The eight largest of 32. Source: NOAA CO-OPS harmonic constituents for 9450460, public domain.
The year as a print
The last two days, measured
At Sun, Oct 25 12:24 the gauge read 17.3 ft, 0.2 ft below the computed curve: wind and pressure, not the moon. The widest gap of the two days was 0.7 ft, at Sat, Oct 24 22:36.
- 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 01:00 | 14.84 ft | 15.28 ft | 15.22 ft |
| Sun, Oct 25 02:00 | 13.17 ft | 13.46 ft | 13.41 ft |
| Sun, Oct 25 03:00 | 10.01 ft | 10.21 ft | 10.17 ft |
| Sun, Oct 25 04:00 | 6.25 ft | 6.42 ft | 6.39 ft |
| Sun, Oct 25 05:00 | 2.92 ft | 3.17 ft | 3.15 ft |
| Sun, Oct 25 06:00 | 1.08 ft | 1.41 ft | 1.41 ft |
| Sun, Oct 25 07:00 | 1.28 ft | 1.67 ft | 1.69 ft |
| Sun, Oct 25 08:00 | 3.53 ft | 3.88 ft | 3.91 ft |
| Sun, Oct 25 09:00 | 7.15 ft | 7.45 ft | 7.50 ft |
| Sun, Oct 25 10:00 | 11.23 ft | 11.51 ft | 11.56 ft |
| Sun, Oct 25 11:00 | 14.80 ft | 15.04 ft | 15.09 ft |
| Sun, Oct 25 12:00 | 17.00 ft | 17.18 ft | 17.24 ft |
Measured heights from NOAA CO-OPS station 9450460, preliminary, above mean lower low water. The print carries the computed curve only: one year, no weather.