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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Can somebody post latest SST map, latest TCHP map? Thanks.
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Bertha 2008 was not exactly a fish storm or a Dud, it seemed more agonizing for the folks on Bermuda and caused rip currents which can be very deadly.

http://en.wikipedia.org/wiki/Hurricane_Bertha_(2008)
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Quoting stormpetrol:
Its very HOT here in THE Caymans, we need some rain, but I sure don't want anything like Ivan 2004 or Paloma last year to bring it.

the same thing i'm talking about we neeeeed it
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Quoting hurricane2009:


Only reason May can be considered wet this year is due to a near record-breaking flooding event. The rest of May was bone dry. So I am not sure if this May can be used to compare to past ones.
It wasn't bone dry for us. Our rainy season started in mid-may rather than late may / early june, and we've had longer lasting events than usual. We had perhaps 3 days since about 15 May w/ no rain.

SFL seems to have had a similar pattern, from conversation here. R u in SFL, or up the coast more?
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hottest day of 2009 so far for me...and most likely of all of 2009..heat index up to near 100
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Quoting plywoodstatenative:
don't remind me of 04, the residents of North Florida do not want to see a repeat of that year.


I know. I have relatives that swore to move because they were so tired of the hurricanes hitting that year!
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Quoting plywoodstatenative:
Petrol,

I will be glad to give you the weather we have been having down here in South Florida the past few days. Gladly.

Don't want no severe storms, just some nice steady all day rain, but I understand where you're coming from.
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don't remind me of 04, the residents of North Florida do not want to see a repeat of that year.
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Petrol,

I will be glad to give you the weather we have been having down here in South Florida the past few days. Gladly.
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Now that the blog is slow due to inactivity, it's nice to be able to get in a word edgewise. LOL

Hi Chicklit, Good Memory! :)
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Its very HOT here in THE Caymans, we need some rain, but I sure don't want anything like Ivan 2004 or Paloma last year to bring it.
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Nice Graphic WPBHurrican05! Big Bertha = Fish Storm.
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I recall in 2004 my gardenias were brown crisps. It was very hot and the season started late...
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Thanks Weatherstudent.

I think that we will see storms this year, in spite of El Nino conditions...
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Bertha was a big dud.
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Quoting wxhatt:


What year was Bertha, and where did it hit?


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I'm not sure what the conditions were preluding the 2004 season. I have seen years without optimal conditions for hurricane formation, in which there were upticks in activity.
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From Wikipedia:
"The 2004 Atlantic hurricane season...was well above average in activity, although a weak El Niño with fifteen named storms and one of the highest Accumulated Cyclone Energy totals ever observed."

The 2004 season started late after a real hot, dry spell too, didn't it?
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Quoting CybrTeddy:


Not saying im bored and I think its been slow for June (We've already seen our first system lol) But I think this is starting to set up like Bertha. If we see more models jump in later on then I think Bertha part 2 is possible.


What year was Bertha, and where did it hit?
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Quoting hurricane2009:


Just because records can be broken doesnt mean they will be. Its a quiet time in the tropics and that is normal. Enjoy it while you can.


Not saying im bored and I think its been slow for June (We've already seen our first system lol) But I think this is starting to set up like Bertha. If we see more models jump in later on then I think Bertha part 2 is possible.
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954. HadesGodWyvern (Mod)
India Meteorological Department

Tropical Cyclone Outlook (0600z 24JUN)
========================================
The well marked low pressure area (ARB01-2009) over Saurashtra & Kutch and surrounding neighbourhood persists.

Convective clouds are seen over parts of northeast, east central and southeast Arabian Sea, central and southeast Bay of Bengal and Andaman Sea

MONSOON WATCH
===============

The southwest monsoon has further advanced into entire central Arabian sea, some parts of north Arabian sea, south Gujarat state, remaining parts of north Konkan and some more parts of Madhya Maharahtra. The northern limit of monsoon passes through 23.0N 60.0E and 23.0N 65.0E, Bhuj, Baroda, Nasik, Sholapur, Hyderabad, Kalingapatnam, Paradip, Balasore, Bankura and Gangtok.


Conditions are favourable for further advance of southwest monsoon over remaining parts of Gujarat state during next 48 hours

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Quoting Chicklit:

Hi Cayman.
We don't want a Felix or Ike, but there's a little spin at about 10/50 that, if it makes it through shear, could become a rainmaker.
Not sure if it will get that far west tho even if it does survive!

thank you
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Well we've seen records broken from previous seaons that were made the season before.
2008's Gustav beat out 2007's Humberto in terms of RI.
We'll have to watch the GFS, but it's reminding me more and more of Bertha.
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All I've got to say is, it's hot here in South MS. A little rain would be nice. I noticed the high that was over us moved out and was replaced by two lows. Not sure what's going on there but I welcome the rain. These 98+ days with 100+ heat index is getting old real quick and we're still in June. Just imagine what July and August are going to be like. The GOM is virtually boiling out there. Water temp is in the mid to upper 80s, which is crazy for this time of year. If anything does form or get in the GOM, I think it's going to explode.
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Quoting wunderkidcayman:
I am not asking for a hurricane or at the most a weak cat 1

Hi Cayman.
We don't want a Felix or Ike, but there's a little spin at about 10/50 that, if it makes it through shear, could become a rainmaker.
Not sure if it will get that far west tho even if it does survive!
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Quoting sporteguy03:
Bertha also had support from every single model as its formation became close and if I remember correctly the NHC mentioned it in the TWO before it even came off the African Coast


That is correct.
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Click image for link.
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946. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #18
TROPICAL STORM NANGKA (T0904)
6:00 AM JST June 25 2009
===================================

Subject: Category One Typhoon In The South China Sea

At 21:00 PM UTC, Tropical Storm Nangka (996 hPa) located at 14.5N 119.5E has 10 minute sustained winds of 40 knots with gusts of 60 knots. The storm is reported as moving west-northwest at 10 knots.

Gale-Force Winds
================
150 NM from the center in southern quadrant
120 NM from the center in northern quadrant

Dvorak Intensity:

Forecast and Intensity
=====================
24 HRS: 18.5N 118.2E - 45 knots (Tropical Storm/CAT 1)
45 HRS: 21.8N 117.5E - 45 knots (Tropical Storm/CAT 1)
69 HRS: 24.8N 119.4E - 40 knots (Tropical Storm/CAT 1)
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945. HadesGodWyvern (Mod)
Philippines Atmospherical Geophysical Astronomical Services and Administration

Tropical Depression "FERIA" has slowed down as it changes its course to the west northwest direction.

Tropical Cyclone Bulletin #9
===========================
At 5:00 AM PhST, Tropical Depression Feria (Nangka) located at 14.4°N 119.2°E or 105 kms west southwest of Subic, Zambales 10 minutes sustained winds of 55 km/h (30 knots).

Signal Warnings
===============

Signal Warning #1 (30-60 kph winds)

Luzon Region
-----------
1.Northern Mindoro
2.Lubang Is.
3.Batangas
4.Cavite
5.Bataan
6.Zambales
7.Metro Manila

Visayas Region
-------------
1.None

Mindanao Region
----------------
1.None

Additional Information
========================
Residents living in low-lying and mountainous areas are alerted against possible flashfloods and landslides.

Tropical Depression "FERIA" may reintensify into a storm over the South China Sea.

The public and the disaster coordinating councils concerned are advised to take appropriate actions and watch for the next bulletin to be issued at 11 a.m. today.
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For 1976 I count 8 storms, 6 of them hurricanes, which mostly stayed out to sea. (2 STSs were later added.)

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Evening all. quick check in here. NAS weather has continued wet, though shifted more to nighttime showers than afternoon ones. Mosquitos are loving it LOL.

Interesting that 1976 was last wet may for FL. IIRC, that was a rainy June and August also, but not stormy. And the record suggests lots of relatively low-profile events.

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Bertha also had support from every single model as its formation became close and if I remember correctly the NHC mentioned it in the TWO before it even came off the African Coast
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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
407 PM CDT WED JUN 24 2009

THE MID/UPPER RIDGE IS FORECAST TO REMAIN QUASI-STATIONARY THROUGH
FRIDAY...BEFORE STARTING TO FLATTEN OUT AND STRETCH EAST OVER US ON
SATURDAY AS A MID/UPPER TROF ROUNDS THE RIDGE THROUGH THE
NORTHERN/CENTRAL PLAINS. MEANWHILE...AT THE SURFACE THE BERMUDA HIGH
WILL BECOME DOMINANT OVER THE GULF...WITH A PERSISTENT
SOUTH/SOUTHWESTERLY FLOW PREVAILING AT THE SURFACE.
THIS SHOULD
START TO MODERATE TEMPERATURES NEAR THE COAST...WHILE INTERIOR
LOCATIONS CONTINUE TO BAKE. THE TROF IS FORECAST TO CLOSE OFF AND
STALL OVER THE GREAT LAKES...WITH THE RIDGE RETROGRADING TO THE
SOUTHWEST CONUS...RESULTING IN NORTHWEST FLOW OVERHEAD.
THE GFS
AND ECMWF SHOW A FRONT SAGGING TO THE COAST BY THE EARLY TO MID
PART OF NEXT WEEK...AND WITH THE LOW LEVEL INFLUX OF MOISTURE...WE
MAY FINALLY SEE MORE THAN JUST ISOLATED CONVECTION.

I need pictures. Lol. Does this mean we're going to have a SSW winds or NW winds/flow whatever? And I really don't like anything about the Bermuda High setting up in the gulf to where we have south or southwest flow around it. Thats when we get in trouble when anything forms. I'm hoping its not going to park there for the rest of the season. But maybe this front will move it? Oh well I don't think a cold front will help with the temps here anyway. We'll just continue to bake. Actually broil would be a better word. :)
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1 week from now, and the GFS shows the emergence of the easternmost wave over the Atlantic.

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Quoting Acemmett90:

8- 10 days isnt soon so i agree with you on this


I don't see anything forming over the next two weeks. At best conditions will become marginally favorable next week in the Caribbean. There does no appear to be any significant upcoming disturbance to instigate cyclogenesis.
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One thing that it interesting, is that over the past years, especially with DM's blog is that we are accustom to having our first named storm by June 15. I guess we got a little spoiled. lol lol, The latest start since 2004.

Arlene
Alberto
Andrea & Barry
Arthur
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hurricane2009,

very true but I want to the classic characteristics I saw with Dean and Bertha. One thing I've notice, our model support lies with the stronger wave over t Eastern Africa.
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Nothing is going to form anytime soon. From the Gulf of Mexico to the Atlantic a ridge-trough-ridge-trough pattern is evident with the upper level troughing dominating the synoptic scale.
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Quoting wunderkidcayman:
weather456 do you think us in cayman would get something
soon around the 1-15


Cannot say, it would be irresponsible to do so. Forecasts are only good 1 week out, if that much. I can tell you that the tropical wave currently in the Eastern Caribbean, may seek enhance moisture in your vicinity later this week.
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Here's the wave that spawned Bertha: This is what I'm looking for:

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THE TROPICAL 30-60 DAY OSCILLATION - SOMETIMES CALLED MADDEN JULIAN OSCILLATION (MJO) - AFFECTS CLIMATE VARIABILITY WITHIN SEASONS. 4) THE NORTH ATLANTIC OSCILLATION (NAO) AND THE PACIFIC NORTH AMERICAN (PNA) PATTERNS - WHICH AFFECT THE TEMPERATURE ANOMALY PATTERN ESPECIALLY DURING THE COLD SEASONS. THESE PHENOMENA ARE CURRENTLY KNOWN TO BE PREDICTABLE ONLY OVER A WEEK OR SO.
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weather456 do you think us in cayman would get something
soon around the 1-15
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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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