U.S. vulnerability to sea level rise

By: Dr. Jeff Masters , 4:04 PM GMT on June 23, 2009

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In the last century, sea level rose 5 - 6 inches (13 - 15 cm) more than the global average of 7 inches (18 cm) along the U.S. Mid-Atlantic and Gulf Coasts, because coastal lands there are sinking. Over 50% of the U.S. coastline is vulnerable or highly vulnerable to sea level rise, according to the Coastal Vulnerability Index (CVI) developed by the United States Geological Survey (USGS). In the U.S., relative sea level rise (the combined effects of global sea level rise plus the fact the land is sinking) is highest along the Mississippi River Delta in Louisiana, where relative sea level rises of 3.2 ft (.98 meters) have been observed during the 20th century. This is one of the highest relative sea level rises in the world. According to the NOAA Tides and Currents sea level rise interactive tool, the U.S. tide gauges that have shown the highest rates of sea level rise over the past century are at Grand Island, LA (1.8 ft rise since 1947), Galveston, TX (1.1 ft since 1957), and Chesapeake Bay, VA (0.6 feet since 1975). Alaska and some areas along the Pacific Northwest coast are at low risk of sea level rise, because the relative sea level is actually falling at present. Land in these regions is rising as it recovers from removal of the weight of the great ice sheets that covered much of North America during the last Ice Age. For example, relative sea level at Kodiak Island, Alaska has fallen by 1.1 feet since 1975, despite the fact global sea level has been increasing.


Figure 1. Twentieth century annual relative sea-level rise rates in mm/year along the U.S. coast. The higher rates for Louisiana (9.85 millimeters [mm] per year, about 3.3 ft/century) and the mid-Atlantic region (1.75 to 4.42 mm per year, 0.6 - 1.4 ft/century) are due to land subsidence. Sea level is stable or dropping relative to the land in the Pacific Northwest, as indicated by the negative values, where the land is tectonically active or rebounding upward in response to the melting of ice sheets since the last Ice Age. Image credit: Coastal Sensitivity to Sea-Level Rise: A Focus on the Mid-Atlantic Region (data from Zervas, 2001).

U.S. Coastal Vulnerability
The Coastal Vulnerability Index (CVI) takes into account six factors:

1) The geology of the coast. Barrier islands, river deltas, and marshes are the most vulnerable to erosion and sea level rise, while steep, rocky cliff shores are the least. Sheltered bays like Galveston Bay and Tampa Bay are less vulnerable than the exposed coasts. (Note, however, that hurricane storm surges are typically higher in sheltered bays, at least for slow-moving storms).

2) How steep the land near the coast is. Gently sloping lands are the most vulnerable. In the Gulf Coast region, the slope variable has the highest risk ranking along the Louisiana coast, the Texas coast north of Corpus Christi, and the southwest Florida coast.

3) The local rate of sea level rise. The sea level is rising faster along the western Gulf of Mexico than the eastern Gulf. The highest rates of sea-level rise in the Gulf of Mexico (and in the United States) are in the Mississippi delta region (10 mm/yr, or 1 inch/2.5 years).

4) The amount of shoreline erosion going on. Most of the U.S. coast is moderately or severely eroding, and very few areas are gaining (Figure 2).

5) The mean tidal range. Shores that have a large difference between low and high tide are less likely to get a significant storm tide--the height above mean sea level of the sum of the storm surge plus the tide. For example, in a region like Maine, which has a 12 ft range between low and high tide, a storm having a 9 ft storm surge will have a storm tide below local high tide for a quarter of a tidal cycle. Shores with a very narrow tidal range (e.g., the 2 ft tidal range common along the Texas and Louisiana Gulf Coast) will get a storm tide of 8 - 10 feet with the 9 ft storm surge in the above example. Shorelines with a narrow tidal range always get high storm tides regardless of when the storm surge hits.

6) How high the waves at shore are. Obviously, shores that experience higher wave heights are at greater risk. In the Gulf of Mexico, wave energy is highest along sections of the Texas coast and on the southern tip of the Mississippi delta.

Figure 2. Shoreline change around the United States based on surveys over the past century. All 30 coastal states are experiencing overall erosion due to natural processes (e.g., storms, sea-level rise) and human activity. If the shoreline is uncolored, no data was available. Image credit: USGS, 1985, and taken from Coastal Sensitivity to Sea-Level Rise: A Focus on the Mid-Atlantic Region).

The Coastal Vulnerability Index (CVI) web page gives detailed maps of each section of the U.S. coast, along with specific reasons why each portion of the coast was assigned the ranking it got. A brief summary:

The Gulf Coast
The Gulf Coast has 55% of its length in the "very high" or "high" vulnerability range. Fully 41% of the coast falls in the "very high" range, far more than the 28% in that category along the Pacific coast and 23% along the Atlantic coast. The region around New Orleans is the most vulnerable region of the entire U.S. coast. The Florida Panhandle, as well as the West Florida coast, are at low to moderate risk because the land is not sinking much, wave heights are lower, and the slope of the land is relatively steep near the coast. The Texas coast is considered to be at a high to very high risk because of the relatively high mean wave height, sinking land, and shallow coastal slope.

The East Coast
The East Coast has 50% of its length in the "very high" or "high" vulnerability range. The highest vulnerability areas are typically high-energy coastlines where the regional coastal slope is low and where the major landform type is a barrier island. A significant exception to this is found in the lower Chesapeake Bay. Here, the low coastal slope, vulnerable landform type (salt marsh) and high rate of relative sea-level rise combine for a high CVI value. The coastline of northern New England, particularly Maine, shows a relatively low vulnerability to future sea-level rise. This is primarily due to the steep coastal slopes and rocky shoreline characteristic of the region, as well as the large tidal range.

The Pacific Coast
The Pacific Coast has 50% of its length in the "very high" or "high" vulnerability range. Areas of very high vulnerability include the San Francisco - Monterey Bay coast and in southern California from San Luis Obispo to San Diego, where the coast is most highly populated. The highest vulnerability areas are typically lower-lying beach areas. The low risk, least vulnerable areas generally occur at rocky headlands along cliffed coasts where the coastal slope is steep, relative sea-level is falling, tide range is large, and wave energy is lower. Examples of these areas are the northern coast of Washington, Monterey, and Cape Mendocino, California.


Figure 3. The Coast Vulnerability Index (CVI) for the U.S.

References
Coastal Sensitivity to Sea-Level Rise: A Focus on the Mid-Atlantic Region.

National Assessment of Coastal Vulnerability to Sea-Level Rise: Preliminary Results for the U.S. Gulf of Mexico Coast (USGS, 2000).

Jeff Masters

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In Florida, having weather that isn't anomalous would be an anomaly. ;)
Member Since: Posts: Comments:
Quoting Ossqss:
Howdy, I was doing some research on weather anomalies and found this graphic. Is it for real? It kinda caught my eye :)



Some say that the 1997 El Nino was stronger than the 1982-1983 event, which unfortunately, I don't have anomalies for.

That being said, the 1982-1983 event was quite strong, evidenced by the fact that the Atlantic was terribly inactive in both years (6 storms the first year, 4 the next). For the 1997 El Nino to surpass that is quite remarkable indeed.
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Quoting OnTheFlats:
I agree with both of you. The last two days in my area have been some of the weirdest June days in my life. I was thinking about it and if you really put it together it's like we just had a cool front pass through? I know it sounds crazy but yesterday was 94 deg at this time on the approach/backside of the front, which was pretty much stationary, and then last nights line of thunderstorms dropped the temp 20 deg or so and right now 24 hours later it's 75 deg. I just walked the dog and it's beautiful out. What do you guys think?


drier air behind the front.
Member Since: July 7, 2005 Posts: 0 Comments: 5307
BTW, if you live in Boca or Deerfield by me, we're about to get pounded. I can see massive lightning flashes already out my window looking north toward the coast of Boca. Loud grumbles getting more frequent!!!
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Quoting clwstmchasr:
Florida gets severe weather all the time in the summer months, this is common from May - August this happens, this is actually the return to the normal pattern that we had in the 90s of afternoon storms, after about 1998 we saw less and less of these severe storms. So really these storms are normal if you really think about it and the last 10 years of not having them was the irregular part.



I agree that FL gets it share of severe storms but I would not call today a normal day in FL. The storms have been moving from NW to SE all day. This is not the norm. The norm is a SE trade wind bumping up against the West Coast seabreaze. This is what triggers that afternoon storms that at any time can get severe.
I agree with both of you. The last two days in my area have been some of the weirdest June days in my life. I was thinking about it and if you really put it together it's like we just had a cool front pass through? I know it sounds crazy but yesterday was 94 deg at this time on the approach/backside of the front, which was pretty much stationary, and then last nights line of thunderstorms dropped the temp 20 deg or so and right now 24 hours later it's 75 deg. I just walked the dog and it's beautiful out. What do you guys think?
Member Since: Posts: Comments:
Howdy, I was doing some research on weather anomalies and found this graphic. Is it for real? It kinda caught my eye :)

Member Since: June 12, 2005 Posts: 6 Comments: 8186
Blustery outside..looks like round 2 coming up for West Palm / Lake Worth.
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Lake Monroe, on the St. Johns River, near Sanford, Fl is 160 miles from the mouth of the river (Atlantic Ocean, Jacksonville, FL). It's base level is essentially sea level, so any rise in sea level takes away from the available capacity to absorb flooding rains. The spike from Fay (twice as high as 90L, shown below) put water within 6" of our home. In times of drought, the river actually flows backward as water in the headwater swamps evaporates, but the salt water doesn't make it this far up river. A 3 meter rise at the mouth would flood us here 30 miles as the crow flies form the ocean.
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Add a backdoor surface front and you add another element to the sea breeze effect, the build up of heat and pieces of energy riding around the ridge increase the severe weather effect.
Member Since: July 7, 2005 Posts: 0 Comments: 5307
South Florida's in for a rough ride tonight:
HAZARDOUS WEATHER OUTLOOK FOR SOUTH FLORIDA
NATIONAL WEATHER SERVICE MIAMI FL
850 PM EDT TUE JUN 23 2009

FLZ063-066>075-168-172>174-240715-GLADES-HENDRY-INLAND PALM BEACH-METRO PALM BEACH-COASTAL COLLIER-INLAND COLLIER-INLAND BROWARD-METRO BROWARD-INLAND MIAMI DADE-METRO MIAMI DADE-MAINLAND MONROE-COASTAL PALM BEACH-COASTAL BROWARD-COASTAL MIAMI DADE-FAR SOUTH MIAMI DADE-
850 PM EDT TUE JUN 23 2009

...SEVERE THUNDERSTORM WATCH FOR PARTS OF SOUTH FLORIDA UNTIL 11 PM EDT...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH FLORIDA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

THUNDERSTORMS: SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED THIS EVENING AND SOME THUNDERSTORMS MAY POSSIBLY BECOME SEVERE OVER THE WESTERN AND INTERIOR PORTIONS OF SOUTH FLORIDA, INCLUDING INLAND PALM BEACH AND INLAND BROWARD COUNTIES, WITH WIND GUSTS TO NEAR 60 MPH. HAIL TO NICKEL SIZE MAY ALSO BE POSSIBLE ALONG WITH FREQUENT LIGHTNING AND HEAVY RAINFALL.

TORNADOES: THE STRONGEST THUNDERSTORMS WILL ALSO BE CAPABLE OF PRODUCING A BRIEF TORNADO.

WIND: WIND GUSTS TO NEAR 60 MPH MAY BE POSSIBLE TODAY IN THE STRONGEST THUNDERSTORMS.

HAIL: HAIL TO NEAR NICKEL SIZE MAY BE POSSIBLE IN THE STRONGEST THUNDERSTORMS.

FLOODING: THUNDERSTORMS WILL BE CAPABLE OF PRODUCING VERY HEAVY RAINFALL THIS EVENING WHICH MAY PRODUCE PONDING OF WATER ON POORLY DRAINED ROADWAYS.

Goodnight Fellow Wunderbloggers and enjoy the quiet evening (except if you live in South Florida!)
Member Since: July 11, 2006 Posts: 14 Comments: 11328
Quoting IKE:
Two things.....

(1)this blog is dead.
(2)need at Atlantic invest....


Good evening Ike

This looks to be a slow starter of a season. Check back around the end of July IMO
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Quoting IKE:
Two things.....

(1)this blog is dead.
(2)need at Atlantic invest....


Are those those bad things Ike, lol ? :)
Member Since: July 7, 2005 Posts: 0 Comments: 5307
Andres Visible Loop

As we thought he's trying to revive the CDO. I don't see it lasting very long though. Cold SSTs are just to the west, and outflow to the north is still non-existent.
Member Since: November 24, 2005 Posts: 635 Comments: 26647
312. IKE
Two things.....

(1)this blog is dead.
(2)need at Atlantic invest....
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I think LSU and Texas may be about to get underway............maybe.
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Quoting hurricane2009:


Well Storm I think what plywood is saying is that the severe storms arent normal, actually they are, the lack of them that Florida didnt have the last 10 years wasnt normal.


Believe me, I understand. We have tied record highs here in Mobile for the past few days and I'm more than ready for a drenching downpour.
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TexasGulf

Nothing stopping anyone from tuning i to that signal. ;)
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Quoting plywoodstatenative:
2009 then explain the increased activity that we are seeing in South Florida along the lines of non tropical items. It seems we get pounded on alot more lately in the way of severe weather than I have seen in a while.

Why is the fact that a lot of the storms we are seeing now becoming severe in nature, even though the tropical season is persona nan grata right now?


You're lucky enough to have both double seabreeze and lots of tropical air.
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AOI #1

AOI #2

Member Since: October 1, 2007 Posts: 81 Comments: 26511
Before the recent switch to Digital TV, I've read there was a way to detect lightning flashes and tornados using your old Analog TV set.

Apparently, you could tune the set to Channel 13, darken the screen to almost black, then turn to Channel 2. Nearby lightning would cause quick lines across the screen and a tornado (supposedly) will produce a white or multi-colored snowy screen, like continuous static.

Its not a good detector and at best is unreliable. There is no way to tell the distance or strength of the lightning strike. I guess tornados spinning generates static electricity that registers on lower UHF frequencies.

Now... with the switch to Digital TV, I will just have to resort to tuning into a local broadcast that provides actual information about approaching storms. The only other option is to look at approaching weather & warnings on-line or (gasp) go outside and observe the conditions manually.

Digital TV is a conspiracy, I tell ya!

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Quoting KEEPEROFTHEGATE:
if ya start gettin canes up there levi iam moving to antarctica the last frontier on earth



Interesting you say that. It gained protection on this date many moons ago.

Antarctic_Treaty
Member Since: June 12, 2005 Posts: 6 Comments: 8186
2009 then explain the increased activity that we are seeing in South Florida along the lines of non tropical items. It seems we get pounded on alot more lately in the way of severe weather than I have seen in a while.

Why is the fact that a lot of the storms we are seeing now becoming severe in nature, even though the tropical season is persona nan grata right now?
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Big trough east of Florida backing in to Alabama and Mississippi tomorrow bringing some well deserved afternoon t-storms if we're lucky enough to get one. you can see it. the rest of the Atlantic basin is moot.



Link
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Please, let it rain!!
Member Since: May 11, 2008 Posts: 0 Comments: 153
hey there Surgeon
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The inactivity we are seeing, could that be the season regressing in a sense. Meaning after 05 we have seen the year start later and later, could this be a sign of the times?
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Hey Pat, IKE, Levi, 456, StormW and others,,,,
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TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT TUE JUN 23 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

1. AN AREA OF LOW PRESSURE IS LOCATED IN THE WESTERN GULF OF MEXICO
JUST EAST OF THE NORTHEASTERN COAST OF MEXICO. THE ASSOCIATED
SHOWER ACTIVITY REMAINS DISORGANIZED AT THIS TIME. THIS SYSTEM IS
EXPECTED TO MOVE INLAND INTO NORTHEASTERN MEXICO OR SOUTHERN TEXAS
DURING THE NEXT DAY OR SO WITHOUT SIGNIFICANT DEVELOPMENT. THERE
IS A LOW CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.
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HURRICANE ANDRES INTERMEDIATE ADVISORY NUMBER 9A
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP022009
500 PM PDT TUE JUN 23 2009

...CENTER OF ANDRES PASSING WEST OF MANZANILLO...

A HURRICANE WARNING REMAINS IN EFFECT FOR THE SOUTHWESTERN COAST OF
MEXICO FROM PUNTO SAN TELMO TO CABO CORRIENTES.

INTERESTS ELSEWHERE ALONG THE WESTERN COAST OF MEXICO AND THE
SOUTHERN BAJA PENINSULA SHOULD MONITOR THE PROGRESS OF ANDRES.

AT 500 PM PDT...0000 UTC...THE CENTER OF HURRICANE ANDRES WAS
LOCATED NEAR LATITUDE 19.0 NORTH...LONGITUDE 105.6 WEST OR ABOUT
70 MILES...110 KM...WEST OF MANZANILLO MEXICO AND ABOUT 95 MILES...
155 KM...SOUTH OF CABO CORRIENTES MEXICO.

ANDRES IS MOVING TOWARD THE NORTHWEST NEAR 13 MPH...20 KM/HR. THIS
MOTION IS EXPECTED TO CONTINUE DURING THE NEXT DAY OR SO...FOLLOWED
BY A TURN TOWARD THE WEST-NORTHWEST WITH A GRADUAL DECREASE IN
FORWARD SPEED. ON THE FORECAST TRACK...ANDRES WILL CONTINUE
PASSING VERY CLOSE TO...OR OVER...THE COAST OF SOUTHWESTERN MEXICO
TONIGHT.

MAXIMUM SUSTAINED WINDS ARE ESTIMATED TO BE NEAR 75 MPH...
120 KM/HR...WITH HIGHER GUSTS. ANDRES IS A CATEGORY ONE HURRICANE
ON THE SAFFIR-SIMPSON SCALE. WEAKENING IS FORECAST DURING THE NEXT
DAY OR TWO.
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Rain delay....LSU up 1.

Omaha Radar
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288. SLU
It's been very disappointing to see the way the GFS is behaving this year. What has become of the Cape Verde project they had in 2006 to feed the models with proper atmospheric data? .. Anyone knows?
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who left the faucets wide open down here in south florida? Its nasty, damage reports from this afternoon storms range from billboards down to tree damage. Nothing major that I saw on my way home though.
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As I said, Don't ignore the GFS.
Doing the EXACT thing it did last year with Bertha and in the same time Period.
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Quoting Levi32:


Hey my home basin IS the Pacific hehe =)

My primary focus will also be the Atlantic but if there's a storm threatening land in the Pacific I intend to give it attention. The majority of east Pacific systems never affect land which makes it an easy basin to ignore.
if ya start gettin canes up there levi iam moving to antarctica the last frontier on earth

Member Since: July 15, 2006 Posts: 171 Comments: 53841
283. JRRP
plop!!!!

as i said earlier
the gfs have had problems in this season
Member Since: August 16, 2007 Posts: 0 Comments: 5822
282. HadesGodWyvern (Mod)
Investigators are looking into whether a fiery train derailment in Rockford over the weekend caused a fish kill on the Rock River in northwestern Illinois.

Sgt. Carl Lewis of the Illinois Department of Natural Resources says the agency is trying to determine if run-off from the derailment got into the Kishaukee River, which flows into the Rock River. The state is advising the public not to eat the fish.

---
note the dead fish may reach the Mississippi river near the Quad Cities.

No more summer fishing here due to the chemical being in the water T_T
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Causeway Webcam

Member Since: July 3, 2005 Posts: 424 Comments: 128339
280. IKE
Quoting Patrap:
So hot here the 25 mile Causeway Across the Lake shows up on the Radar.

As do the twin Spans in the east.



Hey, I see the vehicles crossing it.
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So hot here the 25 mile Causeway Across the Lake shows up on the Radar.

As do the twin Spans in the east.

Member Since: July 3, 2005 Posts: 424 Comments: 128339
GFS still develops the tropical wave forecast to exit off Africa in 48-72 hours.

132-hour GFS:

Member Since: November 24, 2005 Posts: 635 Comments: 26647
277. IKE
Even though the image I just posted doesn't show a low with that moisture in the GOM, note how the latest GFS shows Andres at 6 hours.....where is it? LOL.....

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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