Why is the sea water so cold in the northern Outer Banks? | Time


Thursday could end up being the hottest day of the week, as afternoon temperatures spend a few hours in the mid-90s. Warmer air several thousand feet above sea level will also make training more difficult. thunderstorms in the atmosphere, so the risk of a refreshing shower or thunderstorm decreases a bit compared to the last few days.

Friday will also hit the 90s, but unlike Thursday, there is a very good chance that all of Richmond Metro will get one or two showers and thunderstorms in the afternoon or evening.

Reaching 90 degrees on Friday would make Richmond 13 straight days to reach 90 degrees or higher. This streak has occurred 20 other times in Richmond weather records, but is far from the longest such streak, which was 27 days in 1995.

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A cool front crosses Richmond from the north on Friday and will be the center of these showers and thunderstorms. The front is expected to stall near the North Carolina state line on Saturday, allowing cooler, less humid air to seep south into metro Richmond on Saturday.

However, we may be close enough to see some remnant clouds and maybe a few showers on Saturday, so we’re not quite clear yet for outdoor activities. Sunday has a similar feel, with clouds, sunshine and temperatures in the 80s, although you might notice the humidity starting to pick up by then.

If you have been to the Outer Banks beaches to cool off recently, the ocean water may have been colder than expected.

Ocean temperatures at the beaches of Virginia and the Carolinas generally allow for pleasant swimming and wading in late July. But there is a thorny exception along the northern Outer Banks.

South of Cape Hatteras, the ocean current of the Gulf Stream keeps the water relatively warm, with a steady supply of tropical water from the southwest.

This current continues to move northeastward into the Atlantic, even though the North Carolina coast begins to turn slightly westerly as it moves north of the Cape Hatteras National Seashore. The result is relatively cooler water on the beaches north of Nags Head.

The past two mornings the water temperature at Duck Pier has been below 60°C. At the same time, Nags Head ocean temperatures were in the 70s and Oregon Inlet ocean temperatures were in the 80s.

Wind direction also plays a big role in the water temperature at this time of year north of Nags Head.

During extended periods of southerly and southwesterly winds, near-surface ocean water along the coast is blown offshore. But because the Earth is curved, the water is not pulled in the same direction as the wind; it is pulled at an angle of about 45 degrees to the right of the wind direction. This movement of water relative to the shoreline is known as the Ekman transport, named after the Swedish scientist who first described it in 1905.

To compensate for the fact that water near the surface is pushed away from the coast, deeper water moves upward from below. This water is much colder than surface water, so the water temperature near the coast drops considerably. Lighter or slightly onshore winds stop the process and raise the water temperature.

So when guessing the water temperature in the northern Outer Banks, pay attention to the winds. You can find real-time information on tides and water temperatures on the NOAA Tides and Currents page.


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