Isaac makes its final approach towards Louisiana

By: Dr. Jeff Masters , 3:29 PM GMT on August 28, 2012

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The winds and water are rising all along the coast from Louisiana to the Florida Panhandle as Tropical Storm Isaac makes its final approach. Two hurricane hunter aircraft in the storm are measuring a steadily lowering pressure and increasing winds aloft, but hurricane-force winds have not yet been observed at the surface. The 8:30 am center fix found a pressure of 976 mb, which is very low for a tropical storm. Top surface winds measured with the SFMR instrument were 70 mph, but the plane measured 102 mph at an altitude of 5,000 feet. It's more typical to see surface winds of 85 mph with a storm with these characteristics. Infrared and visible satellite loops and hurricane hunter reports from this morning have shown that Isaac has developed a 25-mile diameter eye, though the eyewall has not yet formed a full circle around the eye. Heavy thunderstorm activity is lacking on the north side, where light wind shear of 5 -10 knots is still pumping some dry air into the circulation.


Figure 1. Morning satellite image of Isaac. Note how dry air has wrapped into the west side of the storm, causing a lack of heavy thunderstorm activity.

Isaac's rains
One of the most remarkable features of Isaac has been the huge spiral band that parked itself along most of the east coast of Florida and remained there for an entire day, despite the fact the center of the storm moved 400 miles away. This rain band was amplified by a weak trough of low pressure along the East Coast, which pulled away from the coast Monday night, taking the band of heavy rain out to sea (except for a few lingering showers near West Palm Beach.) Isaac's heaviest rains fell along a swath from the east coast of Florida near West Palm Beach to the center of the state, just south of Orlando. The 2-day rainfall total of 9.03" at West Palm Beach brought their monthly rainfall total to 22.28", a new August record (old record: 20.12" in 1995.) Vero Beach's 6.48" of rain was a record for any August day. A possible tornado touched down there, damaging 20 mobile homes. In the Keys, rainfall totals as high as 7.94" (at Upper Matecumbe Key) were measured. Heavy rains from Isaac are lingering over Cuba but have ended in Haiti and the Dominican Republic; flash floods in Haiti from Isaac's torrential rains killed at least 24, and two died in the Dominican Republic. The big concern in Haiti is the heavy damage that was done to crops, and the likelihood that the storm's rains will worsen the cholera epidemic that has killed over 7,000 Haitians.


Figure 2. Radar-estimated rainfall from Miami, Florida radar shows that Isaac has dumped a wide swath of 8+ inches of rain (orange colors) across the state. Rainfall amounts in excess of 20" may have fallen just west of West Palm Beach, though the highest amount reported by a rain gauge was 13.10" at Greenacres in Palm Beach County.

Latest model runs for Isaac
The latest set of 0Z and 06Z (8 pm and 2 am EDT) model runs are fairly unified taking Isaac ashore near Southeast Louisiana late Tuesday night or early Wednesday morning, but continue to show some differences in what happens after that. Isaac may scoot nearly west-northwest just inland along the coast into Texas, as predicted by the ECMWF model, or head straight inland to the northwest and into Arkansas, as predicted by the GFS model. The latest 8-day precipitation forecast from the GFS model calls for 10 - 20 inches of rain over much of Louisiana. It appears likely that Arkansas will see some heavy rains of up to five inches, which would help put a dent in the exceptional drought conditions there.

Intensity forecast for Isaac
Low wind shear of 10 knots or less is likely until landfall, along with very warm ocean temperatures. An analysis of upper level winds from the University of Wisconsin CIMSS shows that Isaac's upper-level outflow is the strongest we've seen, with a solid outflow channel to the south. These conditions favor continued strengthening of Isaac until landfall. However, we've observed in the past many instances of hurricanes suddenly weakening in the final 12 hours before making landfall along the Central Gulf Coast. Katrina, Gustav, Dennis, Ivan, and Rita all did so. A July 2012 paper in the Bulletin of the American Meteorological Society by Rosenfeld et al. titled, AEROSOL EFFECTS ON MICROSTRUCTURE AND INTENSITY OF TROPICAL CYCLONES, theorizes that this may happen because of the impact of small particles that get pulled into the outer circulation of hurricanes, seeding the clouds. These small particles, primarily from air pollution, serve as the seed around which water condenses, increasing the rain in the outer spiral bands. The increase in rain and heat energy at the periphery of the storm comes at the expense of the eyewall and inner core, where the winds tend to weaken. A detailed modeling study by Khain et al. (2010) of Hurricane Katrina in the final day before landfall was able to reproduce the storm's weakening only when this air pollution effect was included. This impact of small particles on hurricanes is not included in any operational hurricane model.


Figure 3. Tide gauge data from Shell Beach, located in Lake Borgne just east of New Orleans. The green line shows the storm surge. The red line is the storm tide, the height of the water above Mean Sea Level (MSL.)

Storm surge observations from Isaac
Isaac's storm surge has peaked along the west coast of Florida. As I explain in our Storm Surge Tutorial, we are most interested in the storm tide--the height above Mean Sea Level (MSL) of the tide plus the storm surge. The storm tide is the number given in NHC advisories for how much above ground level the ocean will be at the coast. The storm surge is the extra elevation of the water due to wind blowing on the water, and does not include the action of waves on top of the water, nor the tide. Tide gauges are specially constructed so that transient waves do not impact water level measurements. At Cedar Key on the West Florida coast north of Tampa, a storm surge of 3' and storm tide of 3.8' were observed early this morning. These were the highest water levels measured at any tide gauge along the Florida west coast. Higher storm surges are occurring in the Florida Panhandle. As of 9 am EDT, here were the storm surge/storm tide measurements along the Florida Panhandle:

Apalachicola, FL: 3.5' storm surge, 4' storm tide
Panama City, FL: 2.3' storm surge, 3.3' storm tide
Pensacola, FL: 1.5' storm surge, 2.5' storm tide

A storm surge of 3.5 feet was recorded at 10 am EDT at Shell Beach on the east side of New Orleans in Lake Borgne. This site will have one of the highest surge values during Isaac; a storm surge of 9.5' was measured at Shell Beach during Hurricane Gustav in 2008.


Figure 4. Category 2 Hurricane Gustav of 2008 followed a very similar path to Isaac, and brought a storm tide (the combined effect of the storm surge and tidal levels) of up to 14.5' above ground level to the east side of New Orleans. Isaac's surge may be similar, though probably a little less, than Gustav's.


Figure 5. Track of Hurricane Gustav of 2008, which followed a path very similar to that of Isaac's predicted path.

Isaac: similar to Category 2 Hurricane Gustav of 2008 in destructive power?
Isaac is a huge and slow-moving storm, with tropical storm-force winds that extend out 205 miles from the center. Isaac has cut its forward speed down from 14 mph yesterday to 10 mph today, and a large swath of the coast will be subject to high winds and a large storm surge for an usually long period of time for a hurricane--up to 24 hours. Long duration winds are much more damaging than short duration winds, and a long duration storm surge event allows damage to occur during multiple high tide cycles. The long duration storm event will also allow very high rainfall totals, resulting in greater fresh-water flooding problems than usual. As a result, I expect Isaac's to cause more damage than the typical Category 1 hurricane. The 9:30 am EDT Integrated Kinetic Energy analysis from NOAA's Hurricane Research Division put the destructive potential of Isaac's winds near 2.3 on a scale of 0 to 6, but the destructive potential of Isaacs's storm surge was 4.1 on a scale of 0 to 6. For comparison, the storm surge destructive potential of Category 2 Hurricane Gustav of 2008 was rated at 4.2 on a scale of 0 to 6, and the wind destructive potential was 1.1--which is lower than Isaac's, even though Isaac was just a tropical storm at 9:30 am EDT. Gustav brought a storm tide (the combined height of the storm surge and high tide) of 14.5' to the east side of New Orleans, and 11' to Waveland, Mississippi. However, the destructive potential of Isaac's surge may be overrated by this analysis. Wave heights this morning from buoy and ships in Isaac have mostly been below 15', which is quite unimpressive. One ship report to the SE of the storm had a 19' wave height (thanks to meteorologist Steve Gregory for pointing this out.) With only another 12 - 18 hours over water, Isaac likely won't have time for its slowing increasing winds to build up a storm surge that will reach as high as 14', like Gustav did. The official NHC forecast of maximum storm surge height of 12' looks like a good one. The highest rainfall total observed in Gustav was 21" at Larto Lake, Louisiana, and I expect we'll exceed that for Isaac, since the storm is moving more slowly. Gustav spawned 41 tornadoes--21 in Mississippi, 11 in Louisiana, 6 in Florida, 2 in Arkansas, and 1 in Alabama. The strongest tornado was an EF2 in Evangeline Parish, Louisiana. Isaac will likely produce 10+ tornadoes. The total damage from Gustav in the U.S. was $4.5 billion (2012 dollars.) I expect Isaac's damage total will be in the $500 million - $4 billion range.

Invest 97L in the Middle Atlantic
A tropical wave (Invest 97L) is located in the Middle Atlantic, about 1250 miles west-northwest of the Cape Verde Islands. The storm has a modest amount of spin and heavy thunderstorms, and is under moderate wind shear. In their 8 am EDT Tropical Weather Outlook, NHC gave 97L a 40% chance of developing by Thursday morning. None of the reliable models foresee that 97L will be a threat to any land areas.

Another tropical wave that moved off the coast of Africa on Sunday is located just southwest of the Cape Verde Islands, and is moving west at 15 mph. Several models develop the disturbance into a tropical depression late this week, and NHC is giving the disturbance a 10% chance of becoming a tropical depression by Thursday morning. The disturbance could begin to affect the Northern Lesser Antilles as early as Saturday night, though our two best models, the GFS and ECMWF, predict the center of the disturbance will pass a few hundred miles north of the islands. The disturbance could be a long-range threat to Bermuda.

Jeff Masters

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South Carolina coast.
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624. markw
Quoting dziban303:


Yes, please keep up with the radar images of Palm Beach every ten minutes. It's far more riveting than what's going on with this silly hurricane business in Louisiana.


As a resident in the path of Isaac....that was just a dumb statement to make.
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He's getting close to shore.

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Quoting dartboardmodel:
Wow! Charleston S.C is flooding big time! It's all over the local news here. People getting rescued, Market Steet in downtown is flooding, interstates are flooding. That stinking hurricane kicked up this huge feeder band waaaay east of the storm. It's pretty bad over here and the rain keeps developing!


That's the Isaac-band blob that disconnected from him and was over FL yesterday, more or less. Jacob or Esau, I guess, ha.

Good luck to you and to everybody dealing with it. It flooded the hell out of a whole lot of SE FL pretty quickly, they were lucky to have it finally move offshore when it did. Hope everybody in its rains manages ok, it's likely to be sucking up a lot of wet and throwing it at y'all for a while.
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NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1235 PM CDT TUE AUG 28 2012

ISAAC STILL PROGGED BY TPC TO MAKE LANDFALL OVER SE LOUISIANA. THE
12Z NAM IS TRENDING FURTHER WEST WITH ISAAC AND IT IS LOOKING MORE
AND MORE LIKE THE 00Z ECMWF. THERE COULD BE SOME SIGNIFICANT
CHANGES IN THE FORECAST PACKAGE THIS AFTN IF THE 12Z GFS SUPPORTS
THE THE 12Z NAM. THE NAM IS ADVERTISING THAT THE INFLOW FOR ISAAC
WILL COME THROUGH EAST/SOUTHEAST TEXAS ON THURSDAY NIGHT AND
FRIDAY. THIS BAND OF HIGHER MOISTURE COULD CAUSE SIGNIFICANTLY
HIGHER RAIN CHANCES THAN IS CURRENTLY PROJECTED. THE CURRENT TPC
TRACK WOULD KEEP THE HEAVY RAIN AXIS EAST OF SOUTHEAST TEXAS. 43

Well, I was wrong. Looks like we will get some rain after all.
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Well all toodle's and giggles aside...,

The Rainbow Loop shows the first "Impactor" fetch cluster feeder to come around in the next Hours.

Be ready..rush all PREPS to Completion as the time is now fast closing for everyone to Hunker Down and have the flashlights, NOAA Radio at the ready..pets inside.

The Situation will deteriorate fast soon.



Member Since: July 3, 2005 Posts: 428 Comments: 129833
Getting some good gusts here in Mandeville. Very strange....heavy gusts, low clouds, then sunshine. All mixed together. No rain yet.
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WATER WATER and more WATER ... that is the BIG story of the day!
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raining crazy hard on the new orleans webcam im watching
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The latest satellite frames of Isaac seem to show a very rapidly consolidating storm. He's already got the pressure, now here comes his last ace.
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Quoting Patrap:


No way, I might get a nose Bleed or Asphyxia, or a Buzz.

What are you adding to your Fresca?
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I need to go check and see if anything worth filming is happening yet.

I got some video that I hope will be decent enough to watch earlier from clouds of different levels moving in. I swear there were at least 4 layers of clouds moving in different directions, counting the outflow way up in the air.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Quoting swlacanemom:
When do they update the models again?


Models start becoming irrelevant at this point and it becomes more a game of nowcasting rather than forecasting.
It's almost making landfall on the tip of Mississippi River delta right now.
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Member Since: Posts: Comments:
Quoting Patrap:


Actually..was just plain ol coincidence.

No Mescal was returned too.

: (
Hello Pat, welcome back. Could you tell me what the lattitude and longitude of New Orleans is? TIA
Member Since: June 13, 2009 Posts: 0 Comments: 6912
Quoting Patrap:


No way, I might get a nose Bleed or Asphyxia, or a Buzz.


LOL heartily
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Quoting SFLWeatherman:
This is not good not good at all


Yes, please keep up with the radar images of Palm Beach every ten minutes. It's far more riveting than what's going on with this silly hurricane business in Louisiana.
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Quoting CaneHunter031472:
Oh and by the way it's moving to the northside of the official track. Check the radar radar never lies.

Actually radar can be misleading. It samples a higher and higher level away from the radar site. What you see on radar might be a mid level circulation. Then again what you see might be rain falling from a higher altitude. In the latter case you might see a mid level feature superimposed on a low level feature.

When I looked at the RGB image it looked like there were some alignment issues with Isaac's eye that do not show up on radar. Might be tilted from SE to NW. I'm not sure where the center really is.


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When do they update the models again?
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Member Since: July 3, 2005 Posts: 428 Comments: 129833
wwltv.com has a live cam at the lake.
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Quoting Charmeck:


I watched these bands off of the far NE of Isaac the past few days dump copious amts of rain on the East coast of Florida - then Georgia and the Carolinas. Some of us have questioned what exactly is occurring but noone seems to have a really good answer. The focus has all been on the GOM (and I'm not saying that's not important for those in the path of this storm) but there IS something else going on with this storm and when it is all over maybe someone will be able to address this mess that has moved up the SE coast and is still a threat to the coastal areas.


I dont know..Dr. Masters thought it went out to sea..LOL, so maybe thats why people arent talking about it..
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Quoting blsealevel:
Wow just about all of these have this moving more wnw in a day or so or just before land fall

Link



Yes, it was originally supposed to do a rare left-hook landfall on the GFS and hit NOLA from the east, but it ended up coming in at a lower angle, and may still do the left hook later on in the track.

Notice in the steering layer, the left handed ridge over Texas and the plains states is oriented so that it really wants to push the storm south and west, this is probably what has been slowing down Isaac, as the storm is so big it literally cannot fit through the weakness created by the troughs, and is jammed between the two ridges.


Member Since: January 25, 2012 Posts: 33 Comments: 1520
SUMMARY OF 100 PM CDT...1800 UTC...INFORMATION
----------------------------------------------
LOCATION...28.4N 88.7W
ABOUT 55 MI...85 KM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 135 MI...220 KM SE OF NEW ORLEANS LOUISIANA
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...975 MB...28.79 INCHES
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Finally - an update from Mars -should be close to center - about 983mb

Link
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Whew! We just had a branch rattling gust here! Isaac's a big boy!



Fair
86°F
30°C

Humidity62%
Wind SpeedN 9 G 16 mph
Barometer29.83 in
Dewpoint72°F (22°C)
Visibility10.00 mi
Heat Index92°F (33°C)
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Observation station at Pilot Station in SW Pass
Winds to near Hurricane Force in Gusts

Link
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Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 28th day of the month at 17:33Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 306)
Storm Number & Year: 09L in 2012
Storm Name: Isaac (flight in the North Atlantic basin)
Mission Number: 31
Observation Number: 19
A. Time of Center Fix: 28th day of the month at 16:48:50Z
B. Center Fix Coordinates: 28°22'N 88°36'W (28.3667N 88.6W)
B. Center Fix Location: 142 miles (228 km) to the SE (142°) from New Orleans, LA, USA.
C. Minimum Height at Standard Level: 1,222m (4,009ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 66kts (~ 76.0mph)
E. Location of the Estimated Maximum Surface Wind: 44 nautical miles (51 statute miles) to the NE (55°) of center fix
F. Maximum Flight Level Wind Inbound: From 145° at 89kts (From the SE at ~ 102.4mph)
G. Location of Maximum Flight Level Wind Inbound: 53 nautical miles (61 statute miles) to the NE (54°) of center fix
H. Minimum Sea Level Pressure: 975mb (28.79 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 17°C (63°F) at a pressure alt. of 1,443m (4,734ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 23°C (73°F) at a pressure alt. of 1,524m (5,000ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 20°C (68°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character (Undecoded): SPIRAL BAND
M. Eye Shape: Elliptical (oval shaped)
M. Orientation of Major Axis in Elliptical Eye: 110° to 290° (ESE to WNW)
M. Length of Major Axis in Elliptical Eye: 70 nautical miles (81 statute miles)
M. Length of Minor Axis in Elliptical Eye: 60 nautical miles (69 statute miles)
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind: 94kts (~ 108.2mph) in the east quadrant at 15:50:30Z
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BULLETIN
HURRICANE ISAAC INTERMEDIATE ADVISORY NUMBER 30A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
100 PM CDT TUE AUG 28 2012

...HURRICANE ISAAC MOVING NORTHWESTWARD TOWARD THE MOUTH OF THE
MISSISSIPPI RIVER...FLOODING FROM STORM SURGE AND RAINFALL
EXPECTED...


SUMMARY OF 100 PM CDT...1800 UTC...INFORMATION
----------------------------------------------
LOCATION...28.4N 88.7W
ABOUT 55 MI...85 KM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 135 MI...220 KM SE OF NEW ORLEANS LOUISIANA
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...975 MB...28.79 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A HURRICANE WARNING IS IN EFFECT FOR...
* EAST OF MORGAN CITY LOUISIANA TO THE MISSISSIPPI-ALABAMA BORDER...
INCLUDING METROPOLITAN NEW ORLEANS...LAKE PONTCHARTRAIN...AND LAKE
MAUREPAS

A HURRICANE WATCH IS IN EFFECT FOR...
* INTRACOASTAL CITY TO MORGAN CITY LOUISIANA

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* THE MISSISSIPPI-ALABAMA BORDER TO DESTIN FLORIDA
* MORGAN CITY TO CAMERON LOUISIANA

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* EAST OF HIGH ISLAND TEXAS TO JUST WEST OF CAMERON LOUISIANA

A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED
SOMEWHERE WITHIN THE WARNING AREA. PREPARATIONS TO PROTECT LIFE AND
PROPERTY SHOULD BE RUSHED TO COMPLETION.

A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE
WITHIN THE WATCH AREA.

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE FORECAST
OFFICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 100 PM CDT...1800 UTC...THE CENTER OF HURRICANE ISAAC WAS LOCATED
BY AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT NEAR LATITUDE
28.4 NORTH...LONGITUDE 88.7 WEST. ISAAC IS MOVING TOWARD THE
NORTHWEST NEAR 10 MPH...17 KM/H. A NORTHWESTWARD MOTION AT A
SLIGHTLY SLOWER SPEED IS EXPECTED OVER THE NEXT DAY OR TWO. ON THE
FORECAST TRACK...THE CENTER OF HURRICANE ISAAC SHOULD REACH THE
COASTLINE OF SOUTHEASTERN LOUISIANA AS EARLY AS THIS EVENING.

MAXIMUM SUSTAINED WINDS ARE NEAR 75 MPH...120 KM/H...WITH HIGHER
GUSTS. ISAAC IS A CATEGORY ONE HURRICANE ON THE SAFFIR-SIMPSON
HURRICANE WIND SCALE. SOME ADDITIONAL STRENGTHENING IS FORECAST
UNTIL ISAAC MAKES LANDFALL. GRADUAL WEAKENING IS EXPECTED AFTER
LANDFALL OCCURS.

HURRICANE-FORCE WINDS EXTEND OUTWARD UP TO 60 MILES...95 KM...
NORTHEAST AND EAST OF THE CENTER. TROPICAL-STORM-FORCE WINDS EXTEND
OUTWARD UP TO 185 MILES...295 KM FROM THE CENTER.
TROPICAL-STORM-FORCE WINDS ARE OCCURRING AT THE MOUTH OF THE
MISSISSIPPI RIVER...WHERE A NOAA OBSERVING SITE AT SOUTHWEST PASS
LOUISIANA RECENTLY MEASURED SUSTAINED WINDS OF 60 MPH...93
KM/H...AND A GUST TO 76 MPH...122 KM/H...AT AN ELEVATION OF 80
FEET.

THE LATEST MINIMUM CENTRAL PRESSURE REPORTED BY THE HURRICANE HUNTER
AIRCRAFT WAS 975 MB...28.79 INCHES.


HAZARDS AFFECTING LAND
----------------------
STORM SURGE...THE COMBINATION OF A STORM SURGE AND THE TIDE WILL
CAUSE NORMALLY DRY AREAS NEAR THE COAST TO BE FLOODED BY RISING
WATERS. THE WATER COULD REACH THE FOLLOWING DEPTHS ABOVE GROUND IF
THE PEAK SURGE OCCURS AT THE TIME OF HIGH TIDE...

* MISSISSIPPI AND SOUTHEASTERN LOUISIANA...6 TO 12 FT
* ALABAMA...4 TO 8 FT
* SOUTH-CENTRAL LOUISIANA...3 TO 6 FT
* FLORIDA PANHANDLE...3 TO 6 FT
* APALACHEE BAY...2 TO 4 FT
* REMAINDER OF FLORIDA WEST COAST...1 TO 3 FT

THE DEEPEST WATER WILL OCCUR ALONG THE IMMEDIATE COAST IN AREAS OF
ONSHORE WINDS. SURGE-RELATED FLOODING DEPENDS ON THE RELATIVE
TIMING OF THE SURGE AND THE TIDAL CYCLE...AND CAN VARY GREATLY OVER
SHORT DISTANCES. FOR INFORMATION SPECIFIC TO YOUR AREA...PLEASE
SEE PRODUCTS ISSUED BY YOUR LOCAL WEATHER SERVICE OFFICE. NEAR THE
COAST...THE SURGE WILL BE ACCOMPANIED BY LARGE AND DANGEROUS WAVES.

WIND...TROPICAL STORM CONDITIONS ARE ALREADY OCCURRING NEAR THE
MOUTH OF THE MISSISSIPPI RIVER...AND WILL REACH OTHER PORTIONS OF
THE COASTLINE WITHIN THE TROPICAL STORM AND HURRICANE WARNING AREAS
BY LATE THIS AFTERNOON. HURRICANE CONDITIONS ARE EXPECTED TO FIRST
REACH THE COAST THIS AFTERNOON.

RAINFALL...ISAAC IS EXPECTED TO PRODUCE TOTAL RAINFALL AMOUNTS OF
7 TO 14 INCHES...WITH POSSIBLE ISOLATED MAXIMUM AMOUNTS OF 20
INCHES...IN SOUTHEASTERN LOUISIANA...SOUTHERN MISSISSIPPI...
SOUTHERN ALABAMA...AND THE EXTREME WESTERN FLORIDA PANHANDLE.
THESE RAINS COULD RESULT IN SIGNIFICANT LOWLAND FLOODING.

TORNADOES...TORNADOES MAY OCCUR ALONG THE NORTHERN GULF COAST TODAY.

SURF...DANGEROUS SURF AND RIP CURRENT CONDITIONS WILL CONTINUE TO
AFFECT THE FLORIDA COASTLINE AND PORTIONS OF THE NORTHERN GULF COAST
FOR THE NEXT DAY OR SO.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...400 PM CD
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Last Observed Sample: 08/28/2012 12:30 (CDT)
Wind Speed: 50 knots Gusts: 67 knots Direction: 29° T
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Quoting Unfriendly:


You have to come home early? No bueno, muchacho. I'm sure the "fresca" down in Mehico was better than the water.


Actually..was just plain ol coincidence.

No Mescal was returned too.

: (
Member Since: July 3, 2005 Posts: 428 Comments: 129833
Quoting Elena85Vet:


Don't forget about coastal Mississippi.

They don't get the press.

You mean "the landmass between NOLA and Mobile"?
Member Since: July 12, 2008 Posts: 7 Comments: 383
Quoting blsealevel:


Agreed didnt this happen not to long ago with one these storms?


Alex, but it was like category 2/3 but with a category 4 pressure.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Sure looks like the center has wobbled southwest to about 28, 89.2.
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Quoting dartboardmodel:
Wow! Charleston S.C is flooding big time! It's all over the local news here. People getting rescued, Market Steet in downtown is flooding, interstates are flooding. That stinking hurricane kicked up this huge feeder band waaaay east of the storm. It's pretty bad over here and the rain keeps developing!


It looks like you've had some rainfall totals above 6 inches as that feeder band broke away and merged with the trough. There may be isolated totals higher.

SC has more hills than Louisiana right?

Figure that's where your flash flooding is coming from.


Be prepared for more of this "down wind" from Isaac.

Since this storm is going to stall or move very slowly, it will be pumping HUGE amounts of moisture up into the next trough as well.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Quoting LAlurker:

Pat you need to walk up to Monkey Hill! Yea, I know that was manmade.


No way, I might get a nose Bleed or Asphyxia, or a Buzz.
Member Since: July 3, 2005 Posts: 428 Comments: 129833
Getting heavy rain dumped on us again here near Myrtle Beach. We are about to get badly flooded. I am kind of taken back that the forecasting for this wasn't better. It's been raining for weeks here, now this ! Hope the kids get out of school safely.
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D. Estimated (by SFMR or visually) Maximum Surface Wind: 66kts (~ 76.0mph)
H. Minimum Sea Level Pressure: 975mb (28.79 inHg
L. Eye Character (Undecoded): SPIRAL BAND
M. Eye Shape: Elliptical (oval shaped)
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8/27/12
Month to date precipitation 22.28 6.86
Year to date precipitation 61.09 39.63
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Quoting southfla:
Here is a generally accepted range of pressures for hurricane categories:

Cat Wind Speed    Pressure        Storm Surge
1    75-95 mph       > 980 mb          4-5 ft
2    96-110 mph     965-979 mb      6-8 ft
3    111-130 mph    945-964 mb     9-12 ft
4    131-155 mph    920-944 mb    13-18 ft
5    > 155 mph         &nbs p; 18 ft

I like how you put generally accepted like it carries more authority by consensus than my assertion that pressure relationships are only a statistical creation and not a metric of the SS Category Scale. :)
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Observation station at SW Pass Miss River

Link
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No change so far

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Quoting Patrap:


Not unless they Built a Superedome .

: )

Back in NOLA ...yesterday,late, late.


You have to come home early? No bueno, muchacho. I'm sure the "fresca" down in Mehico was better than the water.
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Quoting ScottLincoln:


Isn't that the "Land Mass Between New Orleans and Mobile" (tm)?


According to TWC that's what we are called now. Reason number 5,000 why TWC is on my s*** list.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting AtHomeInTX:


Nope. It's up to the NHC to change track. Guess we'll see if they do soon.


I would just hate to see NOLA on the east side(dirty side)
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Quoting southfla:
Here is a generally accepted range of pressures for hurricane categories:

Cat Wind Speed Pressure Storm Surge
1 75-95 mph > 980 mb 4-5 ft
2 96-110 mph 965-979 mb 6-8 ft
3 111-130 mph 945-964 mb 9-12 ft
4 131-155 mph 920-944 mb 13-18 ft
5 > 155 mph &nbs p; 18 ft

That means we have a pressure of a cat2 hurricane, storm surge of a cat2/3 hurricane, and winds of a cat1 hurricane. I'm out for a while, stay safe everyone.
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Isaac is Now a cat 1 hurricane . .... yall be safe if you are in the eye/cone of that storm!
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Quoting Patrap:


There is no Higher ground than here..at 20 Ft.


Audubon Ridge,Uptown NOLA

Weather Station - report

Uptown, New Orleans

Elevation
20 ft


Station Select
Now

Heavy Rain
Temperature
83.0 °F
Feels Like 91 °F

Pat you need to walk up to Monkey Hill! Yea, I know that was manmade.
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Quoting ncstorm:


Understandably there is a hurricane in the GOM but the Carolinas are having a time here..round two is next for those in eastern NC..we are under a flood watch and I think this round will upgrade it..



Quoting ncstorm:


Understandably there is a hurricane in the GOM but the Carolinas are having a time here..round two is next for those in eastern NC..we are under a flood watch and I think this round will upgrade it..





I watched these bands off of the far NE of Isaac the past few days dump copious amts of rain on the East coast of Florida - then Georgia and the Carolinas. Some of us have questioned what exactly is occurring but noone seems to have a really good answer. The focus has all been on the GOM (and I'm not saying that's not important for those in the path of this storm) but there IS something else going on with this storm and when it is all over maybe someone will be able to address this mess that has moved up the SE coast and is still a threat to the coastal areas.
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Quoting ScottLincoln:

Slidell area... about to head in to work.


Pearl River, but part of the time I live in NOLA in the channel. not today though.
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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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