Spectacle I. and Thompson I., between tidal current predictions

Now

Ebb 0.2 ktToward SE (127°)

Next slack

4:07 PMEDT

Next max flood

0.3 kt4:25 PM

Next max ebb

0.4 kt11:57 AM

Knots along the channel: above the line the flood, running in toward NW (306°); below it the ebb, running out toward SE (127°). Times are Eastern Daylight Time. Today: slack 3:43 AM, flood 0.3 kt 4:11 AM, slack 8:51 AM, ebb 0.4 kt 11:57 AM, slack 4:07 PM, flood 0.3 kt 4:25 PM, slack 9:00 PM.

• Storm Warning Storm Warning issued September 26 at 1:58AM EDT until September 26 at 8:00PM EDT by NWS Boston/Norton MAUntil 8:00 PM
  Full text

  * WHAT...Northeast winds 20 to 25 kt with gusts up to 50 kt and waves 2 to 4 feet. * WHERE...In Massachusetts coastal waters, Boston Harbor. In Rhode Island coastal waters, Narragansett Bay. * WHEN...Until 8 PM EDT this evening. * IMPACTS...Storm force winds and hazardous waves will capsize or damage vessels and reduce visibility.

  Mariners should remain in port, alter course, and/or secure the vessel for severe conditions.

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.

• Spectacle Island, 0.2 nmi south ofSubordinate current station0.5 mi
• Thompson Island, 0.7 nmi NNE ofSubordinate current station0.9 mi
• Spectacle I. and Long I., betweenSubordinate current station1.0 mi
• Spectacle Island, 0.4nm north ofHarmonic current station1.0 mi
• Boston Channel Light No.5Harmonic current station1.1 mi
• City Point, 0.8 nmi SSE ofSubordinate current station1.1 mi
• Moon Head, 0.4 nmi east ofSubordinate current station1.2 mi
• Deer Island Light, 1.0 nmi WSW ofSubordinate current station1.3 mi

• Tide times at Moon Head 0.9 mi
• Tide times at Deer Island (south end) 2.5 mi
• Tide times at Neponset, Neponset River 3.5 mi
• Forecast for South Boston, MA
• Open the live map with tidal currents
• All tidal current stations in Massachusetts

Tidal current predictions from NOAA’s Center for Operational Oceanographic Products and Services (CO-OPS), station ACT1176, bin 1: original at NOAA. Marine alerts from the National Weather Service.