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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173.
Even the higher flight level winds with the 10% reduction aren't very impressive. Definatly not a hurricane right now.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Conditions are there almost daily in Florida during the summer.
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Vortex Message - Andres. USAF HH's

Product: Air Force Vortex Message (URPN12 KNHC)
Transmitted: 23rd day of the month at 18:12Z
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: 06
A. Time of Center Fix: 23rd day of the month at 17:44:30Z
B. Center Fix Coordinates: 18°20'N 104°48'W (18.3333N 104.8W) (View map)
B. Center Fix Location:
C. Minimum Height at Standard Level: 2,982m (9,783ft) at 700mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 63kts (~ 72.5mph)
E. Location of the Estimated Maximum Surface Wind: 12 nautical miles (14 statute miles) to the SE (124°) of center fix
F. Maximum Flight Level Wind Inbound: From 228° at 49kts (From the SW at ~ 56.4mph)
G. Location of Maximum Flight Level Wind Inbound: 20 nautical miles (23 statute miles) to the SE (127°) of center fix
H. Minimum Sea Level Pressure: 988mb (29.18 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 7°C (45°F) at a pressure alt. of 3,050m (10,007ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 15°C (59°F) at a pressure alt. of 3,047m (9,997ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 6°C (43°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 Level: 700mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 2 nautical miles
Remarks Section - Remarks That Were Decoded...
Maximum Flight Level Wind: 62kts (~ 71.3mph) in the northwest quadrant at 17:50:00Z
Maximum Flight Level Wind Outbound: 62kts (~ 71.3mph) in the northwest quadrant at 17:50:00Z
Sea Level Pressure Extrapolation From: 700mb
Remarks Section - Additional Remarks...
SURFACE CENTER NOT VISIBLE DUE TO UNDERCAST
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the readings remind me of Omar last year and appearance too, how Omar went from Cat 4 to TS in a few hours, got the crap sheared out of it.
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Quoting CaneWarning:
Well now our severe t-storm watch has been extended until 9 PM. Now, I do agree with the need for a watch. The one that expired at 3 PM was silly.


conditions were there things just did not materialize, better be safe then wait for it to happen.
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Quoting Levi32:
Recon finding pressures of 985mb in the center with more 60kt winds on the ESE side.

I think we underestimated Andres' intensity yesterday. These kind of readings are typical of a rapidly weakening Cat 2+ hurricane that just got stripped of convection but still has a vigorous low-level center. I highly doubt this is the lowest pressure or the highest winds that Andre had.


I agree.
Member Since: August 2, 2007 Posts: 19 Comments: 19234


going... going ...
Member Since: July 15, 2006 Posts: 178 Comments: 56059
HH's in Andres..

18.367N 105.000W - 985.3 mb
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Recon finding pressures of 985mb in the center with more 60kt winds on the ESE side.

I think we underestimated Andres' intensity yesterday. These kind of readings are typical of a rapidly weakening Cat 2+ hurricane that just got stripped of convection but still has a vigorous low-level center. I highly doubt this is the lowest pressure or the highest winds that Andre had.
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Quoting extreme236:


Andres doesn't look too good...convective activity weakening as well.


Andres has had it. He's done, you won't see him coming back from this.
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Quoting Levi32:
SFMR picking up hurricane-force winds at the surface but 45kt flight-level winds as the recon passes into the center again from the WNW. Rather strange readings coming out of Andres.

Recon Data


Andres doesn't look too good...convective activity weakening as well.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
These numbers coming from the recon today make me think Andres was a solid Cat 1 hurricane yesterday before this weakening started.
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154. ossqss

Yep. Watching it and hoping to be able to get out of here before it hits.

Crazy temp swing. 98 yesterday. Got down to 74 this morning after the storms. Back up to 90 now. Will drop again after these new storms go through.

Don't mind it cooling off by any means, though. :)
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159. WAHA
I will be gone for now.
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Well now our severe t-storm watch has been extended until 9 PM. Now, I do agree with the need for a watch. The one that expired at 3 PM was silly.
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SFMR picking up hurricane-force winds at the surface but 45kt flight-level winds as the recon passes into the center again from the WNW. Rather strange readings coming out of Andres.

Recon Data
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156. HadesGodWyvern (Mod)
Subject: Category One Typhoon Overland The Philippines

At 18:00 PM UTC, Tropical Storm Nangka (994 hPa) located at 12.5N 123.1E has 10 minute sustained winds of 40 knots with gusts of 60 knots. The storm is reported as moving west-northwest at 9 knots.

Gale-Force Winds
================
150 NM from the center

Dvorak Intensity: T3.0

Forecast and Intensity
=====================
24 HRS: 15.0N 120.2E - 40 knots (Tropical Storm/CAT 1)
48 HRS: 18.0N 119.5E - 45 knots (Tropical Storm/CAT 1)
72 HRS: 20.9N 119.1E - 45 knots (Tropical Storm/CAT 1)
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SE FL, some boomers coming just in time for rush hour. Should at least cool it off a bit.

Member Since: June 12, 2005 Posts: 6 Comments: 8188
153. WAHA
Quoting fire635:


Is that front still sliding southward? If so, there might be a chance for some of the convection to head this way. No?

It is still sliding southward, and I do see a tiny bit of convection just southeast of Florida. But it is weakening rapidly, and will probably not see development there.
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Andres Update
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Quoting IKE:
Andres is falling apart......
yep and in about 3 or 4 hrs the winds should drop may get a brief refire after sunset but at the moment its looking rather ragged to say the least i know that they can rebound as fast as they fall apart so its a wait watch and see for the time being
Member Since: July 15, 2006 Posts: 178 Comments: 56059
please stop pushing your global warming beliefs. it's scientfic FACT that the earth has been COOLING for 10 years.

http://www.globalresearch.ca/index.php?context=va&aid=10783

the earth goes through ~30 year cycles and we are in the 10th year of a 30 year cooling cycle.
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Quoting Levi32:


Those flight-level winds don't quite support a 60kt system. Maybe 50 or 55kts. It has an amazing core temperature difference of 8C for a system with no central convection.

{edit} - I didn't notice the 63kt surface reading at "D." Apparently the difference in winds with height is not significant in this case due to weakening.


Not sure where they got the 63kt surface. I did not see any SFMR readings that high, but it could be an "unreported" SFMR reading since they only transmit a peak average 10 second SFMR reading every 30 seconds.
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TROPICAL STORM 02E 18:00UTC 23June2009
UW-CIMSS Experimental Vertical Shear and TC Intensity Trend Estimates

Current Conditions (from TPC) :
Latitude : 18:17:30 N
Longitude : 104:48:08 W
Intensity (MSLP) : 990.5 hPa

Max Pot Int (MPI,from Emanuel) : 914.0 hPa
MPI differential (MSLP-MPI) : 76.5 hPa

CIMSS Vertical Shear Magnitude : 7.5 m/s
Direction : 19.3 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

Member Since: July 15, 2006 Posts: 178 Comments: 56059
Quoting CaneWarning:


I agree. I was questioning the severe weather threat for Tampa all day long.


Is that front still sliding southward? If so, there might be a chance for some of the convection to head this way. No?
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146. IKE
Andres is falling apart......
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 23 JUN 2009 Time : 171500 UTC
Lat : 18:14:15 N Lon : 104:42:00 W


CI# /Pressure/ Vmax
3.8 / 991.6mb/ 61.0kt


Final T# Adj T# Raw T#
(3hr avg)
3.3 3.1 2.7

Latitude bias adjustment to MSLP : +1.8mb

Center Temp : -23.7C Cloud Region Temp : -39.9C

Scene Type : CURVED BAND with 0.42 ARC in LT GRAY
Maximum CURVED BAND with 0.48 ARC in LT GRAY
at Lat: 18:13:47 N Lon: 104:54:00 W

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 : FLAG

Member Since: July 15, 2006 Posts: 178 Comments: 56059

weakening flag on
Member Since: July 15, 2006 Posts: 178 Comments: 56059
Thats an intense band of storms coming into the tri-county area!
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142. Skyepony (Mod)
nrtiwlnvragn ~ Thanks I was suprised to find it under the Altlantic earlier. Perhaps since they happened to be flying over a NOAA invest with the SFMR on..

They're at the upper level of their planned altitude in Andres. Maybe this is the last hurra, it's clearly becoming exposed. Those higher winds up high tend to fall to the surface in the weakening before it really lets up.
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141. WAHA
Quoting Levi32:


Lol I'm just playing around. Yes all the convection is now south of the center which is now exposed completely.

Sorry I take a ton of things seriously.
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Quoting nrtiwlnvragn:
000
URPN12 KNHC 231812
VORTEX DATA MESSAGE EP022009
A. 23/17:44:30Z
B. 18 deg 20 min N
104 deg 48 min W
C. 700 mb 2982 m
D. 63 kt
E. 124 deg 12 nm
F. 228 deg 49 kt
G. 127 deg 20 nm
H. EXTRAP 988 mb
I. 7 C / 3050 m
J. 15 C / 3047 m
K. 6 C / NA

L. NA
M. NA
N. 12345 / 7
O. 0.02 / 2 nm
P. AF306 0102E ANDRES OB 06
MAX FL WIND 62 KT NW QUAD 17:50:00Z
MAX OUTBOUND FL WIND 62 KT NW QUAD 17:50:00Z

SLP EXTRAP FROM 700 MB
SURFACE CENTER NOT VISIBLE DUE TO UNDERCAST
;


Those flight-level winds don't quite support a 60kt system. Maybe 50 or 55kts. It has an amazing core temperature difference of 8C for a system with no central convection.

{edit} - I didn't notice the 63kt surface reading at "D." Apparently the difference in winds with height is not significant in this case due to weakening.
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Statement as of 2:20 PM EDT on June 23, 2009

The National Weather Service in Miami has issued a

* Severe Thunderstorm Warning for...
western Palm Beach County in South Florida.

* Until 315 PM EDT

* at 218 PM EDT... National Weather Service Doppler radar indicated a
line of severe thunderstorms capable of producing nickel size
hail... and damaging winds in excess of 60 mph. These storms were
located along a line extending from 15 miles north of Canal Point
to 41 miles west of South Bay... and moving southeast at 30 mph.

* The line of storms will affect...
Canal Point...
Belle Glade...
Okeelanta...
lion country safari...
and surrounding communities.
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Quoting WAHA:

I don't see a regular shape. It is shaped like an oval with the center far off to one side.

You like arguing with me, don't you? You said it was struggling, too.


Lol I'm just playing around. Yes all the convection is now south of the center which is now exposed completely.
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000
URPN12 KNHC 231812
VORTEX DATA MESSAGE EP022009
A. 23/17:44:30Z
B. 18 deg 20 min N
104 deg 48 min W
C. 700 mb 2982 m
D. 63 kt
E. 124 deg 12 nm
F. 228 deg 49 kt
G. 127 deg 20 nm
H. EXTRAP 988 mb
I. 7 C / 3050 m
J. 15 C / 3047 m
K. 6 C / NA
L. NA
M. NA
N. 12345 / 7
O. 0.02 / 2 nm
P. AF306 0102E ANDRES OB 06
MAX FL WIND 62 KT NW QUAD 17:50:00Z
MAX OUTBOUND FL WIND 62 KT NW QUAD 17:50:00Z
SLP EXTRAP FROM 700 MB
SURFACE CENTER NOT VISIBLE DUE TO UNDERCAST
;
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136. 0741
we got strong storm here in miami doing morning noaa radio came on few time during morning most were marine warring
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135. WAHA
Quoting Levi32:


Oh really what was your first clue....?

lol

I don't see a regular shape. It is shaped like an oval with the center far off to one side.

You like arguing with me, don't you? You said it was struggling, too.
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134. HadesGodWyvern (Mod)
India Meteorological Department
Tropical Cyclone Warning Number SIX
DEPRESSION ARB01-2009
20:30 PM IST June 23 2009
==================================

Subject: Depression crossed near Diu of south Gujarat coast.

At 15:00 PM UTC, Depression ARB01-2009 over east central Arabian Sea moved further northwestwards and crossed the coast near Diu of south Gujarat coast between 1300 to 1500 PM UTC (1830-2030 IST).

The system is likely to move in a north-northwesterly direction and weaken gradually
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133. HadesGodWyvern (Mod)
ya cyclone has done that a lot over the Philippine, but it still amazes me. =)
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Quoting WAHA:

Well, that's annoying. By the way, Andres looks like it's struggling.


Oh really what was your first clue....?

lol
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131. WAHA
Quoting Levi32:


They usually put satellite floaters on it when something is mentioned in the NHC tropical outlook but that doesn't make it an official invest.

Well, that's annoying. By the way, Andres looks like it's struggling.
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Can't believe I wasn't putting this up before...

Cuyutlan Radar

You can see the rain bands right on the east side of the COC that would have been the eyewall had the CDO stayed intact. No rain over land anymore.
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Quoting FLWeatherFreak91:
I am not sure, but I think the severe weather threat has passed for most of west central Florida. All of is is staying inland and to the south... I'm hoping we will at least get some rain in the Tampa Bay area to kill the heat. It's near 100 in a few spots.


I agree. I was questioning the severe weather threat for Tampa all day long.
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Quoting WAHA:

I agree with you but Noaa still calls it INVEST. Why do they do that?


They usually put satellite floaters on it when something is mentioned in the NHC tropical outlook but that doesn't make it an official invest.
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127. IKE
Quoting Levi32:
Dvorak agrees with weakening based on satellite presentation:





Heaviest convection is all offshore...raining on the fishie's.
Member Since: June 9, 2005 Posts: 23 Comments: 37860

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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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