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WA · NOAA 9447130 · 47° 36′ N · 122° 20′ W
Tides at Seattle
A mixed, mainly semidiurnal tide (form factor 0.97), spring this week. Predicted from the station's 34 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, 11:30 AM | Low | 5.6 ft |
| Mon, Oct 26, 4:52 PM | High | 11.5 ft |
| Mon, Oct 26, 11:49 PM | Low | -2.1 ft |
| Tue, Oct 27, 6:50 AM | High | 11.8 ft |
| Tue, Oct 27, 12:16 PM | Low | 6.4 ft |
| Tue, Oct 27, 5:23 PM | High | 11.4 ft |
| Wed, Oct 28, 12:30 AM | Low | -2.8 ft |
| Wed, Oct 28, 7:42 AM | High | 12.1 ft |
| Wed, Oct 28, 1:05 PM | Low | 7.2 ft |
| Wed, Oct 28, 5:59 PM | High | 11.2 ft |
| Thu, Oct 29, 1:15 AM | Low | -3.0 ft |
| Thu, Oct 29, 8:38 AM | High | 12.1 ft |
| Thu, Oct 29, 1:59 PM | Low | 7.7 ft |
| Thu, Oct 29, 6:41 PM | High | 10.8 ft |
| Fri, Oct 30, 2:04 AM | Low | -2.7 ft |
| Fri, Oct 30, 9:39 AM | High | 11.9 ft |
| Fri, Oct 30, 3:04 PM | Low | 8.0 ft |
| Fri, Oct 30, 7:32 PM | High | 10.1 ft |
| Sat, Oct 31, 2:58 AM | Low | -1.9 ft |
| Sat, Oct 31, 10:45 AM | High | 11.7 ft |
| Sat, Oct 31, 4:26 PM | Low | 7.9 ft |
| Sat, Oct 31, 8:37 PM | High | 9.3 ft |
| Sun, Nov 1, 2:57 AM | Low | -0.9 ft |
| Sun, Nov 1, 10:53 AM | High | 11.6 ft |
| Sun, Nov 1, 5:05 PM | Low | 7.2 ft |
| Sun, Nov 1, 9:03 PM | High | 8.4 ft |
| Mon, Nov 2, 4:02 AM | Low | 0.2 ft |
The constants that make it
| Constituent | Amplitude | Phase |
|---|---|---|
| M2 | 3.5 ft | 10.8° |
| K1 | 2.7 ft | 276.8° |
| O1 | 1.5 ft | 254.6° |
| S2 | 0.9 ft | 36.8° |
| P1 | 0.8 ft | 276.2° |
| N2 | 0.7 ft | 341.1° |
| K2 | 0.3 ft | 37.7° |
| Q1 | 0.2 ft | 248.9° |
The eight largest of 34. Source: NOAA CO-OPS harmonic constituents for 9447130, public domain.
The year as a print
The last two days, measured
At Mon, Oct 26 10:42 the gauge read 6.6 ft, 0.6 ft above the computed curve: wind and pressure, not the moon. The widest gap of the two days was 1.1 ft, at Sun, Oct 25 19:00.
- 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 23:00 | -0.23 ft | -1.02 ft | -1.04 ft |
| Mon, Oct 26 00:00 | 0.27 ft | -0.55 ft | -0.60 ft |
| Mon, Oct 26 01:00 | 2.08 ft | 1.27 ft | 1.21 ft |
| Mon, Oct 26 02:00 | 4.51 ft | 3.92 ft | 3.85 ft |
| Mon, Oct 26 03:00 | 7.34 ft | 6.79 ft | 6.70 ft |
| Mon, Oct 26 04:00 | 9.74 ft | 9.26 ft | 9.17 ft |
| Mon, Oct 26 05:00 | 11.23 ft | 10.84 ft | 10.76 ft |
| Mon, Oct 26 06:00 | 11.69 ft | 11.36 ft | 11.28 ft |
| Mon, Oct 26 07:00 | 11.24 ft | 10.92 ft | 10.86 ft |
| Mon, Oct 26 08:00 | 10.32 ft | 9.76 ft | 9.72 ft |
| Mon, Oct 26 09:00 | 8.95 ft | 8.21 ft | 8.19 ft |
| Mon, Oct 26 10:00 | 7.36 ft | 6.69 ft | 6.69 ft |
Measured heights from NOAA CO-OPS station 9447130, preliminary, above mean lower low water. The print carries the computed curve only: one year, no weather.