Massive Hurricane Sandy building a huge and destructive storm surge

[phantom power]

Massive and dangerous Hurricane Sandy has grown to record size as it barrels northeastwards along the North Carolina coast at 10 mph. At 8 am EDT, Sandy's tropical storm-force winds extended northeastwards 520 miles from the center, and twelve-foot high seas covered a diameter of ocean 1,030 miles across. Since records of storm size began in 1988, only one tropical storm or hurricane has been larger--Tropical Storm Olga of 2001, which had a 690 mile radius of tropical storm-force winds when it was near Bermuda (note: I earlier reported this was a subtropical storm, as per the original NHC advisory, but it was later re-analyzed as a tropical storm.) Sandy has put an colossal volume of ocean water in motion with its widespread and powerful winds, and the hurricane's massive storm surge is already impacting the coast. A 2' storm surge has been recorded at numerous locations this morning from Virginia to Connecticut, including a 3' surge at Virginia's Chesapeake Bay Bridge Tunnel and Sewells Point at 9 am EDT. Huge, 10 - 15 foot-high battering waves on top of the storm surge have washed over Highway 12 connecting North Carolina's Outer Banks to the mainland at South Nags Head this morning. The highway is now impassable, and has been closed. The coast guard station on Cape Hatteras, NC, recorded sustained winds of 50 mph, gusting to 61 mph, at 5:53 am EDT this morning. In Delaware, the coastal highway Route 1 between Dewey Beach and Bethany Beach has been closed due to high water. Even though Sandy is a minimal Category 1 hurricane, its storm surge is extremely dangerous, and if you are in a low-lying area that is asked to evacuate, I strongly recommend that you leave.

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Sandy's storm surge a huge threat
Last night's 9:30 pm EDT H*Wind analysis from NOAA's Hurricane Research Division put the destructive potential of Sandy's winds at a modest 2.6 on a scale of 0 to 6. However, the destructive potential of the storm surge was exceptionally high: 5.7 on a scale of 0 to 6. This is a higher destructive potential than any hurricane observed between 1969 - 2005, including Category 5 storms like Katrina, Rita, Wilma, Camille, and Andrew. The previous highest destructive potential for storm surge was 5.6 on a scale of 0 to 6, set during Hurricane Isabel of 2003. Sandy is now forecast to bring a near-record storm surge of 6 - 11 feet to Northern New Jersey and Long Island Sound, including the New York City Harbor. While Sandy's storm surge will be nowhere near as destructive as Katrina's, the storm surge does have the potential to cause many billions of dollars in damage if it hits near high tide at 9 pm EDT on Monday. The full moon is on Monday, which means astronomical high tide will be about 5% higher than the average high tide for the month. This will add another 2 - 3" to water levels. Fortunately, Sandy is now predicted to make a fairly rapid approach to the coast, meaning that the peak storm surge will not affect the coast for multiple high tide cycles. Sandy's storm surge will be capable of overtopping the flood walls in Manhattan, which are only five feet above mean sea level. On August 28, 2011, Tropical Storm Irene brought a storm surge of 4.13' to Battery Park on the south side of Manhattan. The waters poured over the flood walls into Lower Manhattan, but came 8 - 12" shy of being able to flood the New York City subway system. According to the latest storm surge forecast for NYC from NHC, Sandy's storm surge is expected to be several feet higher than Irene's. If the peak surge arrives near Monday evening's high tide at 9 pm EDT, a portion of New York City's subway system could flood, resulting in billions of dollars in damage. I give a 50% chance that Sandy's storm surge will end up flooding a portion of the New York City subway system.

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2278

[factsarenotfair]

1. Outer Banks - Kill Devil Hills, NC webcam

http://www.visitob.com/webcams/sea-ranch-kill-devil-hills/

[RobertEarl]

2. Well they were wrong

There was a surge of closer to 14 feet. Which in the map above would have been dark green. It shows only blue representing less than a 12 foot surge.

Looks like they just were afraid they get called hyperbolic? Just think of the people who could have been saved tons of misery had officials been convinced of what Sandy was really quite capable of doing.

[GliderGuider]

3. No, the maximum storm surge was about 9 feet.

The surge happened at high tide, so that added over 4 feet.

I captured this graph last night at 8:00 pm. It's an automated reading from the tidal gauge at the Battery in lower Manhattan:

In this graph the blue line is the predicted tide, the green line is the surge, and the red line is tide+surge.

The red line went a little higher after I captured the graph, to a maximum of about 13.87 feet. The maximum tide height at that time was 4.71 feet, so the actual storm surge was 9.16 feet.

[RobertEarl]

4. Well they were right

They are an amazing bunch, are they not?

[RobertEarl]

5. One thing that wasn't mentioned

Waves on top of the surge. How high were the waves? 2 feet? 4?

Tide gauges are set inside of poles so that waves don't effect the readings, just the level of the body of water heights.

Were not the waves part of the storm?