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 Sea Level Trend
 Table in mm/yr

 Sea Level Trend
 Table in feet/century

 Main Page Extreme Water Levels

Extreme Water Levels
8658120 Wilmington, North Carolina

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8658120.png

At this location, the tidal range has increased significantly over the period of record.

The monthly extreme high water levels include a Mean High Water (MHW) trend of 3.94 millimeters/year
with a 95% confidence interval of +/- 0.35 millimeters/year based on monthly MHW data
from 1935 to 2011 which is equivalent to a change of 1.29 feet in 100 years.

The monthly extreme low water levels include a Mean Low Water (MLW) trend of -0.91 millimeters/year
with a 95% confidence interval of +/- 0.45 millimeters/year based on monthly MLW data
from 1935 to 2011 which is equivalent to a change of -0.30 feet in 100 years.

The plots show the monthly highest and lowest water levels with the 1%, 10%, 50%, and 99% annual exceedance probability levels in red, orange, green, and blue. The plotted values are in meters relative to the National Tidal Datum Epoch (1983-2001) Mean Higher High Water (MHHW) or Mean Lower Low Water (MLLW) datums established by CO-OPS (1 foot = 0.3 meters). On average, the 1% level (red) will be exceeded in only one year per century, the 10% level (orange) will be exceeded in ten years per century, and the 50% level (green) will be exceeded in fifty years per century. The 99% level (blue) will be exceeded in all but one year per century, although it could be exceeded more than once in other years.

8658120.png
Exceedance
probability curves
versus return period
8658120.png
Seasonal variation
of exceedance
probability levels
8658120.png
Tidal datums and
exceedance probability levels
relative to mean sea level


Highest and lowest extremes which exceeded the 10% annual exceedance probability levels
Highest Extremes 8/1/1944 10/15/1954 8/17/1955 1/1/1987 3/13/1993 9/6/1996 10/8/1996 9/16/1999
Lowest Extremes 2/3/1940 2/6/1977 12/25/1980 2/12/1981 3/17/1981 4/7/1982 2/19/2007 1/25/2008 1/12/2009 1/3/2011


NOAA's Continental US Daily Weather Maps: 1871-2002 September 2002-Present

Frequently Asked Questions:

What is Sea Level?
Why does Sea Level change over time?
What does Sea Level have to do with Climate?
What is Exceedance Probability Statistics?

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