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ME · NOAA 8418150 · 43° 39′ N · 70° 15′ W
Tides at Portland
A semidiurnal tide (form factor 0.16), 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 |
|---|---|---|
| Sun, Oct 25, 5:01 PM | Low | -0.6 ft |
| Sun, Oct 25, 11:14 PM | High | 9.8 ft |
| Mon, Oct 26, 5:12 AM | Low | -0.0 ft |
| Mon, Oct 26, 11:25 AM | High | 10.8 ft |
| Mon, Oct 26, 5:45 PM | Low | -1.0 ft |
| Mon, Oct 26, 11:59 PM | High | 9.9 ft |
| Tue, Oct 27, 5:56 AM | Low | -0.1 ft |
| Tue, Oct 27, 12:08 PM | High | 11.1 ft |
| Tue, Oct 27, 6:32 PM | Low | -1.2 ft |
| Wed, Oct 28, 12:46 AM | High | 9.9 ft |
| Wed, Oct 28, 6:42 AM | Low | -0.1 ft |
| Wed, Oct 28, 12:54 PM | High | 11.2 ft |
| Wed, Oct 28, 7:20 PM | Low | -1.2 ft |
| Thu, Oct 29, 1:35 AM | High | 9.7 ft |
| Thu, Oct 29, 7:30 AM | Low | 0.1 ft |
| Thu, Oct 29, 1:43 PM | High | 11.1 ft |
| Thu, Oct 29, 8:12 PM | Low | -1.0 ft |
| Fri, Oct 30, 2:28 AM | High | 9.4 ft |
| Fri, Oct 30, 8:23 AM | Low | 0.4 ft |
| Fri, Oct 30, 2:37 PM | High | 10.8 ft |
| Fri, Oct 30, 9:09 PM | Low | -0.7 ft |
| Sat, Oct 31, 3:27 AM | High | 9.1 ft |
| Sat, Oct 31, 9:21 AM | Low | 0.7 ft |
| Sat, Oct 31, 3:38 PM | High | 10.4 ft |
| Sat, Oct 31, 10:11 PM | Low | -0.3 ft |
| Sun, Nov 1, 3:32 AM | High | 8.9 ft |
| Sun, Nov 1, 9:26 AM | Low | 1.0 ft |
The constants that make it
| Constituent | Amplitude | Phase |
|---|---|---|
| M2 | 4.5 ft | 102.2° |
| N2 | 1.0 ft | 70.5° |
| S2 | 0.7 ft | 139.1° |
| K1 | 0.5 ft | 201.4° |
| O1 | 0.4 ft | 182.0° |
| NU2 | 0.2 ft | 77.1° |
| L2 | 0.2 ft | 155.3° |
| K2 | 0.2 ft | 137.6° |
The eight largest of 34. Source: NOAA CO-OPS harmonic constituents for 8418150, public domain.
The year as a print
The last two days, measured
At Sun, Oct 25 16:24 the gauge read -0.1 ft, 0.2 ft above the computed curve: wind and pressure, not the moon. The widest gap of the two days was 1.2 ft, at Sat, Oct 24 02:36.
- 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 05:00 | 0.47 ft | 0.31 ft | 0.30 ft |
| Sun, Oct 25 06:00 | 1.56 ft | 1.47 ft | 1.46 ft |
| Sun, Oct 25 07:00 | 3.54 ft | 3.59 ft | 3.59 ft |
| Sun, Oct 25 08:00 | 6.16 ft | 6.22 ft | 6.23 ft |
| Sun, Oct 25 09:00 | 8.50 ft | 8.61 ft | 8.62 ft |
| Sun, Oct 25 10:00 | 9.87 ft | 10.07 ft | 10.08 ft |
| Sun, Oct 25 11:00 | 10.20 ft | 10.36 ft | 10.38 ft |
| Sun, Oct 25 12:00 | 9.49 ft | 9.45 ft | 9.47 ft |
| Sun, Oct 25 13:00 | 7.57 ft | 7.46 ft | 7.47 ft |
| Sun, Oct 25 14:00 | 4.87 ft | 4.77 ft | 4.79 ft |
| Sun, Oct 25 15:00 | 2.34 ft | 2.07 ft | 2.09 ft |
| Sun, Oct 25 16:00 | 0.37 ft | 0.11 ft | 0.13 ft |
Measured heights from NOAA CO-OPS station 8418150, preliminary, above mean lower low water. The print carries the computed curve only: one year, no weather.