Atlantic Nor'easter to Bring Rough Surf, Beach Erosion

By Alex Sosnowski, Expert Senior Meteorologist

November 15,2012; 9:20PM,EST

Provided a nor'easter fails to move northward along the Eastern Seaboard, there will still be impact due to seas and winds along the southern Atlantic coast.
The latest indications are that a slowly brewing storm in the western Atlantic will stay away from the mid-Atlantic and New England during the week of Thanksgiving.
With the more eastern track becoming more likely for this particular storm, a zone of sunshine will stretch from the interior South to the New England coast this weekend and perhaps right through Thanksgiving Day.

However, the slow-moving nature of the storm will bring some spoils to coastal areas from North Carolina to the Atlantic side of Florida.

This could just be the start of an extended period of unsettled surf along the southern Atlantic Seaboard.

The circulation around the storm will create north to northeasterly winds in the region for days.
Where the component of the wind and movement of water is onshore, the potential for coastal flooding at times of tide and beach erosion will be greatest.
Water levels are likely to run up to a couple of feet above normal tides. This risk area runs from the southern part of the Delmarva Peninsula and southeastern Virginia to part of the Florida east coast.
Significant beach erosion and coastal flooding along the New Jersey, Long Island and New England coasts are not expected.
However, beach interests in or heading to the South for Thanksgiving vacation may have some issues.
While waters are becoming chilly off the coast of North Carolina for bathers, the waves along the Florida east coast may be rough and dangerous with the risk of strong and frequent rip currents.
Surf temperatures range from the 50s along much of North Carolina to the mid- to upper 70s in Florida waters.
Gulf of Mexico waters will not be affected by the storm.
Offshore boating and shipping interests should expect building seas into the first part of next week from Georges Bank to the Bahama Bank and part of the Florida Straits.
Seas east of the barrier islands could build to 20 to 25 feet over a broad area. Most seas in this area were between 8 and 12 feet as of Thursday afternoon, Nov. 15, 2012.
Spring Tides
The new moon and weak onshore flow was producing spring tides and minor coastal flooding issues in part of the southern Atlantic Seaboard ahead of the storm.
Spring tides occur when the sun, Earth and the moon are lined up and the gravitational pull on the oceans is greatest. During the new moon, the moon is between the Earth and the sun. During the full moon, the Earth is between the moon and the sun.

Areas from northern Florida to eastern North Carolina have experienced minor coastal flooding during the high tide cycles. From a couple of inches to a foot of water has entered some areas.
The effect of the moon will be diminished moving into next week with the first quarter phase on Nov. 20. However, as the spring tides diminish, the effect from the offshore storm will increase into midweek.
Spring tide effect is delayed and can be greatest from one to two days past the new and full moon. The reason is complex but is essentially due to friction and shape of land masses, the sea floor, rotation of the Earth and the water itself slowing the reaction of the tide from the maximum gravitational pull.