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December 21, 1999 — In the wake of numerous inquires regarding erroneous reports currently circulating about impending coastal flooding from unusually high tides, NOAA tides experts want to calm the waters.

From Dec. 22 to 23 there will be a condition known as a "spring tide," a normal upswing in the tide cycle that occurs twice a month. NOAA suspects that the looming passage into a new millennium has fueled speculation of massive tides and flooding. Over the past two weeks NOAA has received numerous calls from individuals and the news media concerned about the spring tides. NOAA's advice: Don't build an ark.

"There won't be any coastal flooding or record breaking tides over the next few days due to astronomical phenomena," said Tom Kendrick, senior oceanographer for tide and tidal current predictions with NOAA's National Ocean Service in Silver Spring, Md. "Every few years there are rumors like this, but the tides over the next couple of days are just part of the normal cycle," he said.

But NOAA does caution that low-lying coastal areas normally susceptible to flooding should not let their guard down. In addition to astronomical influences, primarily from the gravitational pull of the sun and moon, meteorological effects—the weather—also influence tides on a local and regional basis. Winds and storms can essentially "push" water into and out of bays, estuaries, and coastal areas, causing water levels to rise above or fall below the published predictions.

Kendrick also noted that during the upcoming spring tide, some areas of the country may see an above-average range for the tides; in other words, a greater than normal difference between high and low water. That would primarily be a concern to operators of boats and ships because of the danger of running aground at the low tide—but even these low tides aren't expected to set any records. "Most prudent mariners and recreational boaters are familiar with tides and check the predicted tides and weather before they get underway—and if they don't, they should," Kendrick said.

The effects and timing of the late December spring tides vary at different locations around the country. Examples of predicted high tides:

• In Anchorage, Alaska, the predicted maximum high for Dec. 22-23 is 33.0 ft. This is lower than spring tides there on Oct. 26, 33.4 ft.; and Nov. 24, 33.6 ft.
  
  
• In Astoria, Ore., the Dec. 22-23 high is expected to be 10.5 ft., slightly higher than the Nov. 23-24 high of 10.3 ft.
  
  
• In Atlantic City, N.J., the predicted high tide for Dec. 22-23 is 5.6 ft., exactly what was predicted on Oct. 26-27 and one-tenth of a foot lower than the November high in the area.

Official NOAA tide predictions, based on astronomical factors, are published in many coastal newspapers, usually near weather forecast information. Tide prediction and near real-time tide information from NOAA's nationwide system of tide gauges is available from NOAA via a Web site: http://www.CO-OPS.nos.noaa.gov