Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather
By: Dr. Jeff Masters , 04:22 PM GMT on Νοέμβριος 13, 2009
Record storm surges have caused major flooding along the North Carolina, Virginia, Maryland, and Delaware coasts over the past 24 hours, thanks to the powerful winds of a slow-moving Nor'easter energized by the remains of Hurricane Ida. Norfolk, Virginia, suffered its highest storm surge on record last night, when a surge of 5.96 feet hit the Sewells Point tide station. The previous record was 5.62' during Hurricane Isabel of 2003, with the Chesapeake-Atlantic Hurricane of 1933 close behind at 5.61'. Last night's peak surge did not hit at high tide, and the storm tide--the combination of surge plus the tide--peaked at 7.74' above Mean Lower Low Water (MLLW), slightly below the 7.89' storm tide of Hurricane Isabel.
Figure 1. Rain gauge-measured precipitation from Ida-extratropical for the 24 hours ending at 7 am EST this morning. The storm dumped copious amounts of rain over a wide swath of coast. Image credit: NWS Advanced Hydrologic Prediction Service.
The highest storm surges at Sewell's Point tide gauge in Norfolk, Virginia since 1927:
5.96' Nov 2009 Ida-extratropical
5.62' Sep 2003 Hurricane Isabel
5.61' Aug 1933 Chesapeake-Atlantic Hurricane
4.73' Sep 1933 Hurricane 13, Cat 1)
4.66' Mar 1962 Ash Wednesday Nor'easter
4.05' Sep 1936 (Hurricane 13, Cat 2)
Top storm tides in Norfolk history:
1933 hurricane (Aug 23rd 1933)..............8.9 feet MLLW
April 11th 1956 Nor'easter..................8.0 feet MLLW
Hurricane Isabel (Sep 18th 2003)............7.9 feet MLLW
Ida-extratropical (Nov 12th 2009)...........7.8 feet MLLW
Ash Wednesday storm (Mar 7th 1962)..........7.8 feet MLLW
Serious coastal flooding is occurring from northern North Carolina to the Delaware/New Jersey border, with record high storm surges recorded at many locations. The storm surge at Lewes Point, Delaware at 9:48 pm EST last night reached 4.63 feet, beating the record high of 4.17' set during the January 4, 1992 Nor'easter. Tide records go back to 1919 at Lewes Point. The highest surge at any of the NOAA-maintained tide gauges from Ida-extratropical was 6.74' at 9:24 pm EST at Money Point, Virginia, located on an inlet about five miles south of downtown Norfolk.
Ida-extratropical also brought hurricane-force wind gusts to the Virginia coast yesterday, with a gust of 75 mph recorded at the Oceana NAS. The Norfolk airport recorded sustained winds of 52 mph, gusting to 70 mph, at the height of the Nor'easter last night. Heavy rains of 6 - 11 inches since Tuesday have created flooding on most of the the rivers along the entire North Carolina, Virginia, and Maryland coasts. Ida-extratropical is slowly weakening and pulling away to the northeast, and the rains have ended along most of the coast, though. Virginia has now seen its highest storm surges, but this afternoon's high tide cycle is likely to bring another round of record or near-record storm tides to the coasts of Maryland, Delaware, and extreme southern New Jersey. This afternoon's high tide is forecast to bring a storm tide of 7.6' to Atlantic City, NJ, which would be the 10th highest tide there since 1911, but well short of the record 8.98' storm tide during the December, 1992 Nor'easter. By Saturday, Ida-extratropical will be on its way out to sea, and the storm surges and rains will finally abate.
Figure 2. Predicted storm tide (height above Mean Lower Low Water (MLLW, the lowest tide measured in a full 19-year natural tidal cycle, black line) for Lewes, Delaware (at the mouth of Delaware Bay), as predicted by the GFS model. A storm tide of 8.0 feet is forecast this afternoon during the high tide. For a full description of this plot, see the NOAA Extratropical Surge web site.
Figure 3. Tide gauge trace from the Sewell's Point gauge in Norfolk, VA, shows a storm surge of nearly 6 feet (green line) hit at 8:30 pm EST, with a maximum storm tide of 7.8 feet above MLLW occurring at high tide. Image credit: NOAA Tides and Currents.
Storm surges and sea level rise
The storm surge flooding in the Norfolk area was exacerbated by the fact that sea level has risen and the land has subsided significantly over the past century. Over the past 60 years, absolute sea level along the coast of Virginia has risen by about 2.6 mm/year. However, the relative sea level has risen by 4.44 mm/year since 1927 (Figure 4), meaning that the land has sunk by about 1.84 mm/year. The net result is that the ocean is now about 1.16 feet higher at Norfolk than it was in 1927. The Norfolk tide gauge shows the highest rate of relative sea level rise of any gauge on the U.S. East Coast (though relative sea level rise is much higher along the Gulf Coast, with rises near 3 feet/century at New Orleans). Thus, today's 5+ foot storm surge brought water more than a foot higher in Norfolk than the 5+ foot storm surge of the 1933 hurricane. Storm surge damages will steadily increase along the entire coast this century as sea level rise accelerates and coastal development continues. It is urgent that government take action in coming years to limit development in vulnerable coastal regions. The ocean is going flood our sand castles that we are building in harm's way, at an ever increasing rate.
Figure 4. Monthly mean sea level at the Sewells Point, VA tide gauge in Norfolk, without the regular seasonal fluctuations due to coastal ocean temperatures, salinities, winds, atmospheric pressures, and ocean currents. The long-term linear trend is also shown, including its 95% confidence interval. Relative sea level has increased by 1.16 feet since 1927, the highest rate of rise on the U.S. East Coast. Image credit: NOAA Tides and Currents.
Portlight responding to the flooding in Virginia
Portlight.org is deploying up to 3 self-sufficient mobile kitchens capable of feeding over 2000 people a day to the Virginia coast. They will be providing meals for first responders, volunteers, and, of course, affected residents. Donations are welcome--visit the portlight blog to learn more and make a PayPal donation. Thanks!
Take action: sign the QuikSCAT letter
The QuikSCAT satellite, launched in 1999, provides crucial measurements of surface wind speed and direction over Earth's oceans twice per day. Forecasters world-wide have come to rely on data from QuikSCAT to issue timely warnings and make accurate forecasts of tropical and extratropical storms, wave heights, sea ice, aviation weather, iceberg movement, coral bleaching events, and El Niño. QuikSCAT's antenna is expected to fail within the next six months, according to engineers at NASA/JPL, and QuikSCAT data has already been removed from our global weather forecast models, due to concerns about data reliability.
There exists a narrow window of opportunity in the next few days to get the wheels in motion to launch a QuikSCAT replacement instrument on a Japanese satellite in 2015. The funding for this must start within the next budget cycle, and there is currently no funding in place for a replacement QuikSCAT. If we miss this this opportunity, it may be ten years or more before a QuikSCAT replacement can be launched. To this end, I urge all of you to sign the QuikSCAT funding letter being presented to John Holdren, Director of the White House Office of Science and Technology Policy.
The letter is at: http://coaps.fsu.edu/scatterometry/statement/.
If you agree with the letter, please sign it (via the web site) as soon as possible: there is a very small window of opportunity to influence the next budget cycle, with this window closing within a few days.
Note that to validate your signature you must type the validation code in the bottom box. This code is the word that appears after 'code =', then click on the sign button.
For more information on QuikSCAT, see my post, The case for a new QuikSCAT satellite.
Figure 5. NASA's QuikSCAT satellite, launched in 1999. Image credit: NASA.
Expect a new blog until Monday, when I'll discuss the outlook for the remainder of hurricane season. It is finally over?
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