New Moon – High Tides

There’s been a lot of talk of wind gusts and rainfall totals as we watch Chris make its way toward Newfoundland’s Avalon Peninsula. This storm is going to produce a fair amount of both but Chris is also a marine storm and is having a powerful impact offshore.

Gale warnings are in place just off Nova Scotia’s Eastern Shore up to Forchu, then over to the south and southwest shorelines of Newfoundland. Storm warnings have been issued for Thursday afternoon for the east coast — Cape St. Francis and south. There, the south wind around the storm will be as high as 55 knots or just over 100 km/h.

Then there’s the issue of storm surge. That term comes up quite frequently during hurricane season, but it’s not well understood. What exactly is a storm surge? storm surge is a coastal flood of rising water commonly associated with an area of low pressure, but low pressure is not the only consideration when issuing a storm surge warning: wind direction and the phase of the moon are also considered.

Right now, the phase of the moon is of particular concern. This month’s new moon is Thursday. When the moon is full or new, the gravitational pull of the moon and sun are combined. At these times, the high tides are very high and the low tides are very low. This is known as a spring high tide and it’s happening now.

When the storm surge of a hurricane comes in at high tide the affect is worse, as the height of the high tide is added to the storm surge to produce a storm tide.

That storm tide, combined with brisk south winds, will bring particularly high tides and higher than normal water levels along Newfoundland’s east coast Cape St. Francis and south late Thursday. This has the potential to create localized flooding.

High wind and stormy sea conditions will subside Friday afternoon.