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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Quoting jeffs713:


It doesn't have far to go from much colder waters. With how it looks right now (exposed LLC, entraining dry air, no poleward outflow), it will take 24-48 hours to get its act together. By that time, it will be in colder waters that can't support a TC anyway.


You make some good observations...but the one I don't agree with is the 24-48 hour time frame. A disturbance/wave that is getting its act together takes a great deal of time to get going (24-48 or more hours), but a pre-existing tight circulation like this can get going again in a matter of hours if shear were to relax.

I'm not forecasting some massive restrengthening into a major hurricane or anything...but status quo near hurricane strength is certainly possible for at least as long as its over warm water.
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Quoting southtexredneck:
Has anyone got any idea when the "Hell High" is going to move east or dissipate! In San Antonio, TX it's so dry the weeds are even crunchy!


That "doom High" you're experiencing is moving slowly to the northwest...staying in Texas the entire time.

You've still got a while before it moves out, so make sure you pay the ice man when he comes to your door with the next load! :)
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EP, 02, 2009062318, , BEST, 0, 184N, 1048W, 65, 988, HU,
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Quoting KEEPEROFTHEGATE:
i would wait till after sunset before ripping the storm see how it fairs after that it could just as easily fire back up even if at the moment it appears done it may not be the case


This isn't like a diurnal cycle though. This is environmental effect thanks to wind shear and drier air.
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Quoting nrtiwlnvragn:
ANDRES, EP, E, , , , , 02, 2009, HU, O, 2009062018, 9999999999, , , , , , WARNING, 2, EP022009


Hurricane at 5 pm.
iam expecting them to call it as well but it has been a cane since midnight last night imo
Member Since: July 15, 2006 Posts: 169 Comments: 53296
Probably just covering by the NHC on their part...it was likely a hurricane yesterday and they missed it.
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Yeah Andres to be a hurricane...65 kts, 988mb pressure.
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i would wait till after sunset before ripping the storm see how it fairs after that it could just as easily fire back up even if at the moment it appears done it may not be the case
Member Since: July 15, 2006 Posts: 169 Comments: 53296
Has anyone got any idea when the "Hell High" is going to move east or dissipate! In San Antonio, TX it's so dry the weeds are even crunchy!
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Quoting homelesswanderer:
Good Afternoon Everyone. The 12z ECMWF seems to show something trying to develope in the mid Atlantic. Then it dissapates and something new pops up in the S Caribbean. Maybe what the GFS is seeing?


Well the European is seeing a possible disturbance in the Caribbean 5 days after the GFS, so it's unlikely that they are seeing the same thing. The mid-Atlantic low on the European looks cold-core to me.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
ANDRES, EP, E, , , , , 02, 2009, HU, O, 2009062018, 9999999999, , , , , , WARNING, 2, EP022009


Hurricane at 5 pm.
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Quoting Levi32:
These numbers coming from the recon today make me think Andres was a solid Cat 1 hurricane yesterday before this weakening started.


Agree, I think Andres reach Hurricane strength for a couple of hours maybe 6 to 8 hrs last night.
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Quoting 2010hurricane:
I saw the ENSO SST values and the 3.4 region are +0.7. +0.5 is supposed to mean a very weak El Nino

We don't have it sustained for 3 months at more than +0.5
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Link

oops. Theres the link. Sorry still asleep. :)
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The ridge that is shearing Andres will also help steer it further west than some of the hi-res models indicated.

This morning's hi-res hurricane models all have to be thrown out as they moved him over land...

At any rate...it will be interesting to see what the NHC says in its forecast discussion here at 5pm EST.
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Quoting OSUWXGUY:


Lot of people proclaiming the end to Andres... But the storm is actually pulling farther away from the coastline!

Admittedly it has been sheared today with some strong upper level easterlies flowing clockwise around the ridge that is retrograding west from the Gulf Coast back over Texas...but it still has a while over warm SSTs...so I'm not willing to completely write him off... The circulation/pressure readings from the reconnaisance indicated that the system is still strong.


Well it will take time to weaken, but the winds aren't impressive and neither is the satelite presentation. Clearly, wind shear has taken its toll.
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Quoting OSUWXGUY:


Lot of people proclaiming the end to Andres... But the storm is actually pulling farther away from the coastline!

Admittedly it has been sheared today with some strong upper level easterlies flowing clockwise around the ridge that is retrograding west from the Gulf Coast back over Texas...but it still has a while over warm SSTs...so I'm not willing to completely write him off... The circulation/pressure readings from the reconnaisance indicated that the system is still strong.


It doesn't have far to go from much colder waters. With how it looks right now (exposed LLC, entraining dry air, no poleward outflow), it will take 24-48 hours to get its act together. By that time, it will be in colder waters that can't support a TC anyway.
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Quoting OSUWXGUY:


Lot of people proclaiming the end to Andres... But the storm is actually pulling farther away from the coastline!

Admittedly it has been sheared today with some strong upper level easterlies flowing clockwise around the ridge that is retrograding west from the Gulf Coast back over Texas...but it still has a while over warm SSTs...so I'm not willing to completely write him off... The circulation/pressure readings from the reconnaisance indicated that the system is still strong.


Hey may attempt to form more convection later on but I doubt he'll actually strengthen. The recon readings today suggest that he was a solid hurricane yesterday. You just don't go from -80 cloud tops with a CDO and partial eyewall to a naked low-level vortex with no change in intensity. Andres had to have been stronger yesterday than the current readings.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
I saw the ENSO SST values and the 3.4 region is at 0.7. 0.5 is supposed to mean a very weak El Nino
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Good Afternoon Everyone. The 12z ECMWF seems to show something trying to develope in the mid Atlantic. Then it dissapates and something new pops up in the S Caribbean. Maybe what the GFS is seeing?
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Quoting CycloneOz:


That's why I always take time to be sure before I pull the trigger on the R.I.P.

It's a solemn yet xtremely pleasurable moment for me.

BTW: I never pulled the R.I.P. trigger on Hurricane Ivan in 2004. And sure enough, the dang thing came back for 2nds! What a loop!


I remember that....I kept watching it and tracking the low center....that was the most awesome hurricane loop I've ever seen.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
Quoting jeffs713:

At least this one has pretty much zero chance of coming back from the dead and being a zombie. Too many storms in recent history find ways to revive themselves.


Lot of people proclaiming the end to Andres... But the storm is actually pulling farther away from the coastline!

Admittedly it has been sheared today with some strong upper level easterlies flowing clockwise around the ridge that is retrograding west from the Gulf Coast back over Texas...but it still has a while over warm SSTs...so I'm not willing to completely write him off... The circulation/pressure readings from the reconnaisance indicated that the system is still strong.
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Quoting jeffs713:

At least this one has pretty much zero chance of coming back from the dead and being a zombie. Too many storms in recent history find ways to revive themselves.


That's why I always take time to be sure before I pull the trigger on the R.I.P.

It's a solemn yet xtremely pleasurable moment for me.

BTW: I never pulled the R.I.P. trigger on Hurricane Ivan in 2004. And sure enough, the dang thing came back for 2nds! What a loop!
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Quoting KEEPEROFTHEGATE:
thats a bad habit 09 i call em all she's


Me too...I consider them all female in nature...even with a guy's name.
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Quoting CycloneOz:
My favorite blog activity:

R.I.P..ing a TC! :)

At least this one has pretty much zero chance of coming back from the dead and being a zombie. Too many storms in recent history find ways to revive themselves.
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Very Nice MODIS Shot of Andres... Click Image to enlarge..(193kb)

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My favorite blog activity:

R.I.P..ing a TC! :)
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Member Since: July 15, 2006 Posts: 169 Comments: 53296
They're popping up all over the place!
Member Since: July 8, 2005 Posts: 259 Comments: 23568
WOW! Huge storm here in South Fl. I'm glad I'm safe in my house right now. Can't imagine what it's like for someone driving in that weather.
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Quoting KEEPEROFTHEGATE:
thats a bad habit 09 i call em all she's


Just like Planes, Ships, and Space Shuttles.
Member Since: July 8, 2005 Posts: 259 Comments: 23568
Dropsonde and SFMR readings hovering around 74 mph it's really up to the NHC to decide to updrage it or not... With current visible presentaion I would bet that they wouldn't.
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Product: Air Force Vortex Message (URPN12 KNHC)
Transmitted: 23rd day of the month at 19:37Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 306)
Storm Number & Year: 02E in 2009
Storm Name: Andres (in the Northeast Pacific basin)
Mission Number: 1
Observation Number: 09
A. Time of Center Fix: 23rd day of the month at 19:01:00Z
B. Center Fix Coordinates: 18°23'N 104°59'W (18.3833N 104.9833W) (View map)
B. Center Fix Location:
C. Minimum Height at Standard Level: 2,988m (9,803ft) at 700mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 67kts (~ 77.1mph)
E. Location of the Estimated Maximum Surface Wind: 10 nautical miles (12 statute miles) to the WSW (255°) of center fix
F. Maximum Flight Level Wind Inbound: From 21° at 62kts (From the NNE at ~ 71.3mph)
G. Location of Maximum Flight Level Wind Inbound: 23 nautical miles (26 statute miles) to the W (275°) of center fix
H. Minimum Sea Level Pressure: 988mb (29.18 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 8°C (46°F) at a pressure alt. of 3,043m (9,984ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 15°C (59°F) at a pressure alt. of 3,051m (10,010ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 4°C (39°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Levels (sfc and flt lvl centers are within 5nm of each other): Surface and 700mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind: 62kts (~ 71.3mph) in the west quadrant at 18:53:50Z

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thats a bad habit 09 i call em all she's
Member Since: July 15, 2006 Posts: 169 Comments: 53296
Quoting hurricane2009:
Andres still looks better than the area in the BOC though lmao
lol
maybe they will do a fly by on the way home to have a laugh too if she fails to refire after sunset this will be the only flight into andres imo tomorrows plan will be scrapped i reckon
Member Since: July 15, 2006 Posts: 169 Comments: 53296
Quoting hurricane2009:


I bet that person wasnt a fish


nope but he was a fisherman
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Hummm, plane crash item. If the signal they found is not from a black box, what else would be in the middle of the ocean pinging?

france-denies-black-box-detected
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Anyone have any models showing the movement of the "cold" front in central FL? If it could move just a little more south we might see some storms popping off in western Pasco County intstead of the training Im seeing over eastern Pasco and Polk County
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Dropsonde 65kt

Significant Wind Levels...
Level Wind Direction Wind Speed
1000mb (Surface) 145° (from the SE) 65 knots (75 mph)
991mb 150° (from the SSE) 62 knots (71 mph)
984mb 155° (from the SSE) 73 knots (84 mph)
976mb 165° (from the SSE) 74 knots (85 mph)
970mb 165° (from the SSE) 86 knots (99 mph)
964mb 160° (from the SSE) 81 knots (93 mph)
948mb 165° (from the SSE) 81 knots (93 mph)
942mb 160° (from the SSE) 84 knots (97 mph)
925mb 165° (from the SSE) 78 knots (90 mph)
920mb 180° (from the S) 85 knots (98 mph)
900mb 175° (from the S) 71 knots (82 mph)
882mb 175° (from the S) 72 knots (83 mph)
874mb 175° (from the S) 68 knots (78 mph)
850mb 180° (from the S) 67 knots (77 mph)
781mb 165° (from the SSE) 53 knots (61 mph)
697mb 170° (from the S) 53 knots (61 mph)
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Link

Andres takes 1st life...Tropical Storm Andres flooded homes and knocked down trees along Mexico's Pacific coast
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Quoting hurricane2009:
Andres still looks better than the area in the BOC though lmao


LOL

Hey he's still got an eye lol:

Member Since: November 24, 2005 Posts: 635 Comments: 26547
Double post**
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Quoting StSimonsIslandGAGuy:
Regarding Omar, is that the fastest that a storm over warm water has gone from a Cat 4 to a tropical storm? I know we've seen Cat 4s get torn apart faster in the mountains of Hispaniola and other storms fall apart very quickly when they race north of the Gulf Stream. But I can not remember a Cat 4 falling to tropical storm strength that quickly over warm water before, ever.


I remember tracking Hurricane Lili in 2002 that went from a Cat 4 to a Cat 1 in under 12 hours before making landfall in central Louisiana. That was primarily due to the SST wake left by Hurricane Isidore a week before.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
Quoting extreme236:
173.
Even the higher flight level winds with the 10% reduction aren't very impressive. Definatly not a hurricane right now.


I agree you, you can't accurately measure SFC winds at 700 mb without a dropsonde. But you can extrapolate SFC pressure accurately. That's what is semi-surprising me about Andres with its poor visible presentation.
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Quoting weathermanwannabe:
Hear the thunder & see the clouds!..About to get a few pop-up showers south of Tallahassee after about 7 days of blistering heat & no rain...Will it help?........Proabably not; temps are 98F outside right now...Once the rain hits the streets and parking lots, I expect some steam to rise (a natural sauna).


Gotta love Florida!
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Hear the thunder & see the clouds!..About to get a few pop-up showers south of Tallahassee after about 7 days of blistering heat & no rain...Will it help?........Proabably not; temps are 98F outside right now...Once the rain hits the streets and parking lots, I expect some steam to rise (a natural sauna).
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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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