U.S. vulnerability to sea level rise
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
Reader Comments
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MESOSCALE DISCUSSION 1285
NWS STORM PREDICTION CENTER NORMAN OK
1021 AM CDT TUE JUN 23 2009
AREAS AFFECTED...WRN FLORIDA
CONCERNING...SEVERE THUNDERSTORM WATCH 495...
VALID 231521Z - 231715Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 495
CONTINUES.
SKIES ARE CLEARING RAPIDLY BEHIND THE MORNING CONVECTION...WITH A
DISTINCT OUTFLOW BOUNDARY ACROSS WRN FL. A VERY MOIST AND UNSTABLE
AIR MASS REMAINS ALONG AND W OF THIS OUTFLOW...AND EVEN THE OUTFLOW
ITSELF IS EXPECTED TO DESTABILIZE FURTHER. THE 12Z TBW SOUNDING
SHOWS OVER 4000 J/KG MLCAPE WHEN MODIFIED FOR CURRENT CONDITIONS.
GPS WATER VAPOR OBSERVATIONS CONTINUE TO SHOW PRECIPITABLE WATER
VALUES OVER 2.00 INCHES. IN ADDITION...WATER VAPOR IMAGERY SHOWS A
RELATIVE MOIST PLUME EXTENDING SEWD OUT OF SRN AL/GA INTO FL.
THUS...WITH CONTINUED DAYTIME HEATING...VIGOROUS UPDRAFTS ARE
EXPECTED TO FORM ALONG THE OUTFLOW BOUNDARY/SEA BREEZE...WITH STORMS
MOVING IN A SWD DIRECTION. WHILE DAMAGING WIND GUSTS WILL BE THE
PRIMARY THREAT...THERE IS SOME THREAT OF A BRIEF TORNADO ALONG THE
OUTFLOW BOUNDARY WHERE ENHANCED LOW LEVEL VORTICITY MAY EXIST.
..JEWELL.. 06/23/2009
Tropical Tidbit for Tuesday June 23 with Video
That ain't no hurricane.
Tropical Cyclone Intensity Algorithm
----- Current Analysis -----
Date : 23 JUN 2009 Time : 151500 UTC
Lat : 18:01:21 N Lon : 104:26:00 W
CI# /Pressure/ Vmax
4.1 / 987.3mb/ 67.4kt
Final T# Adj T# Raw T#
(3hr avg)
3.6 3.5 3.3
Latitude bias adjustment to MSLP : +1.9mb
Center Temp : -68.4C Cloud Region Temp : -57.1C
Scene Type : UNIFORM CDO CLOUD REGION
Positioning Method : FORECAST INTERPOLATION
Ocean Basin : EAST PACIFIC
Dvorak CI > MSLP Conversion Used : ATLANTIC
Tno/CI Rules : Constraint Limits : 0.7T/6hr
Weakening Flag : ON
Rapid Dissipation Flag : OFF
****************************************************
TROPICAL STORM ANDRES 12:00UTC 23June2009
UW-CIMSS Experimental Vertical Shear and TC Intensity Trend Estimates
Current Conditions (from TPC) :
Latitude : 17:47:12 N
Longitude : 103:48:06 W
Intensity (MSLP) : 990.5 hPa
Max Pot Int (MPI,from Emanuel) : 897.1 hPa
MPI differential (MSLP-MPI) : 93.4 hPa
CIMSS Vertical Shear Magnitude : 8.7 m/s
Direction : 46.1 deg
Outlook for TC Intensification Based on Current
Env. Shear Values and MPI Differential
Forecast Interval : 6hr 12hr 18hr 24hr
F F F F
Legend : VF-Very Favorable F-Favorable N-Neutral
U-Unfavorable VU-Very Unfavorable
-- Mean Intensity Trend (negative indicates TC deepening) --
6hr 12hr 18hr 24hr
VF <-3.0mb/ 6hr <-6.0mb/12hr <-9.0mb/18hr <-12.0mb/24hr
F -3.0 - -1.0 -6.0 - -2.0 -9.0 - -3.0 -12.0 - -4.0
N -1.0 - +1.0 -2.0 - +2.0 -3.0 - +3.0 -4.0 - +4.0
U +1.0 - +3.0 +2.0 - +6.0 +3.0 - +9.0 +4.0 -+12.0
VU >+3.0 >+6.0 >+9.0 >+12.0
I agree. It definitely looks a lot weaker than last night.
she's losing it big time at the moment lets see what the hunters find
Looks like it's getting eaten up by something...cooler waters? Shear?
A disorganized, nasty, annoying little thing that doesn't have enough time to amount to anything in the world lol. I do like the fact that I picked this area 2 weeks ago as having a strong chance of having a tropical disturbance around this time though lol.
I would have to say the main contributing factor is lack of poleward outflow. The upper low over central Mexico and the sub-tropical high in the NW Gulf of Mexico is blocking all outflow to the north. Andres is now limited to equatorial outflow channel. Dry stable air over cool SSTs to the NW is also getting injected into the system. Proximity to land as H2009 mentioned is probably also playing a role.
"Manzanillo Airport, MX (Airport)
Updated: 28 min 46 sec ago
Rain
77 °F
Rain
Humidity: 89%
Dew Point: 73 °F
Wind: 23 mph from the ESE
Pressure: 29.71 in (Rising)
Visibility: 2.0 miles
UV: 2 out of 16
Clouds:
Mostly Cloudy 1000 ft
Overcast 8000 ft
(Above Ground Level)
Elevation: 26 ft"
Picture they showed in the paper. (Warning...PDF file)
Link
It's on it's way to being finished...
Andres Update
Keep an eye on the SE GOM in a few days....
I can't tell you whether it will snow on Christmas Day in 2050. But I can tell you that it'll be colder on Christmas Day, 2050 than it was on July 4th, 2050.
Specifics are not predictable out beyond a week or two. Trends are.
Hurricane Hunter
Well at least the TUTT will have pulled out of the eastern Atlantic by that time. That wave will have much more breathing room than any of its predecessors.
Thanks =)
200 mb winds not equal wind shear
Pretty dead over there also... mind you to the east of this picture.. there is a big one brewing.
thanks
i did not know that
Where did you find that wind shear map?
Africa is free of clouds
WU model page
IRIS Seismic Monitor
Viewing: 1 - 51
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