Johnston Channel, off Halftide Rock tidal current predictions

Now

Flood 0.8 ktToward S (179°)

Next slack

2:30 AMAKDT

Next max flood

1.6 kt12:51 PM

Next max ebb

1.3 kt6:42 AM

Knots along the channel: above the line the flood, running in toward S (179°); below it the ebb, running out toward NNW (337°). Times are Alaska Daylight Time. Today: flood 0.9 kt 12:22 AM, slack 2:30 AM, ebb 1.3 kt 6:42 AM, slack 10:39 AM, flood 1.6 kt 12:51 PM, slack 3:51 PM, ebb 1.2 kt 7:54 PM, slack 11:46 PM.

• Small Craft Advisory Small Craft Advisory issued October 1 at 8:22PM AKDT until October 3 at 5:00AM AKDT by NWS Anchorage AKUntil Sat 5:00 AM
  Full text

  Coastal Waters Forecast for Southwest Alaska+Bristol Bay+The Alaska Peninsula Waters and the Aleutian Islands up to 100 nm out. Wind forecasts reflect the predominant speed and direction expected. Sea forecasts represent an average of the highest one-third of the combined wind wave and swell height. .TONIGHT...NE wind 30 kt. Seas 7 ft. .FRI...NE wind 30 kt. Seas 6 ft. .FRI NIGHT...NE wind 30 kt. Seas 6 ft. .SAT...SE wind 15 kt. Seas 4 ft. .SAT NIGHT...SE wind 20 kt. Seas 2 ft. .SUN...S wind 25 kt. Seas 10 ft. .MON THROUGH TUE...NW wind 25 kt. Seas 9 ft.

• Small Craft Advisory Small Craft Advisory issued October 1 at 2:57PM AKDT until October 3 at 5:00AM AKDT by NWS Anchorage AKUntil Sat 5:00 AM
  Full text

  Coastal Waters Forecast for Southwest Alaska+Bristol Bay+The Alaska Peninsula Waters and the Aleutian Islands up to 100 nm out. Wind forecasts reflect the predominant speed and direction expected. Sea forecasts represent an average of the highest one-third of the combined wind wave and swell height. .TONIGHT...NE wind 30 kt. Seas 7 ft. .FRI...NE wind 30 kt. Seas 8 ft. .FRI NIGHT...NE wind 30 kt. Seas 6 ft. .SAT...SE wind 15 kt. Seas 4 ft. .SAT NIGHT...SE wind 20 kt. Seas 2 ft. .SUN...S wind 25 kt. Seas 10 ft. .MON THROUGH TUE...NW wind 25 kt. Seas 9 ft.

• Small Craft Advisory Small Craft Advisory issued October 1 at 3:43AM AKDT until October 2 at 5:00PM AKDT by NWS Anchorage AKUntil 5:00 PM
  Full text

  Coastal Waters Forecast for Southwest Alaska+Bristol Bay+The Alaska Peninsula Waters and the Aleutian Islands up to 100 nm out. Wind forecasts reflect the predominant speed and direction expected. Sea forecasts represent an average of the highest one-third of the combined wind wave and swell height. .TODAY...E wind 25 kt. Seas 6 ft. .TONIGHT...NE wind 30 kt. Seas 7 ft. .FRI...NE wind 30 kt. Seas 8 ft. .FRI NIGHT...NE wind 30 kt. Seas 7 ft. .SAT...SE wind 20 kt. Seas 6 ft. .SUN...SW wind 25 kt. Seas 10 ft. .MON...W wind 25 kt. Seas 10 ft.

• Small Craft Advisory Small Craft Advisory issued September 30 at 3:09PM AKDT until October 2 at 5:00AM AKDT by NWS Anchorage AKUntil 5:00 AM
  Full text

  Coastal Waters Forecast for Southwest Alaska+Bristol Bay+The Alaska Peninsula Waters and the Aleutian Islands up to 100 nm out. Wind forecasts reflect the predominant speed and direction expected. Sea forecasts represent an average of the highest one-third of the combined wind wave and swell height. .TONIGHT...Variable wind 10 kt. Seas 3 ft. .THU...E wind 20 kt. Seas 5 ft. .THU NIGHT...NE wind 30 kt. Seas 7 ft. .FRI AND FRI NIGHT...NE wind 30 kt. Seas 9 ft. .SAT...S wind 25 kt. Seas 7 ft. .SUN...SW wind 25 kt. Seas 11 ft. .MON...W wind 25 kt. Seas 11 ft.

The flood is the tidal current running in from the sea, the ebb the current running back out. Slack water is the short turn between them, when the current is weakest: the time to cross a strong channel, anchor, or dive. Slack in a channel is not the time of high or low tide; it can come hours after.

Speeds are knots along the channel's main axis, and directions are degrees true toward which the water flows, as NOAA prints its tables. A current against the wind stands the waves up steep and close together.

Predictions are astronomical: the moon and the sun, not the weather. Strong wind, river flow after heavy rain and storm surge all change the real current. This is a subordinate station: NOAA predicts it from a nearby harmonic station by fixed corrections to the times and speeds of its slack waters and maxima, so the curve between them is less exact.

• Hague Channel, east of Doe PointSubordinate current station4.7 mi
• Harbor PointSubordinate current station9.1 mi
• Entrance Point, 3 miles west ofSubordinate current station13 mi
• Entrance PointSubordinate current station13 mi

• Tide times at Port Moller 13 mi
• Tide times at Albatross Anchorage, Balboa Bay 18 mi
• Forecast for Sand Point, AK
• Open the live map with tidal currents
• All tidal current stations in Alaska

Tidal current predictions from NOAA’s Center for Operational Oceanographic Products and Services (CO-OPS), station PCT5766, bin 1: original at NOAA. Marine alerts from the National Weather Service.