Unanswered questions concerning Hurricane Isaac

By: Dr. Jeff Masters , 4:35 PM GMT on August 31, 2012

The top winds of Tropical Depression Isaac have fallen to 25 mph, but the storm continues to be a potent rain-maker as it heads north-northwest at 11 mph into Missouri. Isaac has spawned up to 20 suspected tornadoes, brought storm surges as high as 13.6' to the coast (in Lake Borgne, LA), and dumped 20" of rain at one station in New Orleans. The 13.27" of rain that fell at Hattiesburg, MS broke the record for wettest August in the city's history (previous record: 13.03" in 1987.) Major flooding is occurring on seven rivers in Louisiana and Mississippi. Isaac is being blamed for at least four deaths in the U.S., 24 in Haiti, and five in the Dominican Republic.

A few notable rainfall totals from Isaac, through 11 am EDT on Friday:

20.08" New Orleans, LA
15.02" Marion, MS
13.99" Pascagoula, MS
13.27" Hattiesburg, MS
10.85" Gulfport, MS
10.39" Slidell, LA
10.17" Biloxi, MS
9.85" Mobile, AL
7.38" Pine Bluff, AR
5.95" Baton Rouge, LA

A major reason for Isaac's heavy rainfall totals has been its very slow motion. This slow speed was due to the fact Isaac has been bumping into a ridge of high pressure that is unusually strong, due to the intense drought over the center of the U.S.; strong drought-amplified high pressure areas are very resistant to allowing any low pressure areas to intrude into their domain. The high pressure area was strong enough this week to allow several all-time records for heat this late in the year to be set:

112° on August 29 at Winner, SD
108° on August 29 at Valentine, NE
107° on August 29 at Corpus Christi, TX
97° on August 29 at Denver, CO (2nd highest so late in the year)


Figure 1. Nighttime view of Hurricane Isaac taken at 1:57 am CDT August 29, 2012, by the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi-NPP satellite. The VIIRS day-night band detects light in a range of wavelengths from green to near-infrared, and uses light intensification to enable the detection of dim signals. In this case, the clouds of Isaac were lit by moonlight. Image credit: NASA.

Isaac's beneficial rains falling in drought-stricken regions
Hurricanes get a lot of attention because of the billions in damage they cost, and the lives they disrupt. AIR Worldwide estimated today that insured damage from Isaac would cost up to $2 billion. This does not include damage to infrastructure or uninsured damage, so the final price tag of Isaac's rampage will be more like $3 - $5 billion. However, Isaac is now dumping beneficial rains over Arkansas, Missouri, Illinois, Indiana, Ohio, and Kentucky--regions stricken by the worst drought since the 1950s or 1930s, depending upon the exact location. These regions need 9 - 18 inches of rain to pull them out of drought. Isaac's 3 - 6 inches of rain will not end the drought, but will put a pretty good dent in it. I expect that 3 - 6 inches of rain for a wide swath of prime agricultural land in extreme drought is probably worth at least $5 billion, when you consider that a recent estimate by a Purdue economist put the cost of the great drought of 2012 at more than $77 billion. Only Hurricane Katrina ($146 billion) and the drought of 1988 ($78 billion) have been more expensive disasters, according to NOAA's National Climatic Data Center. Unfortunately, Isaac's arrival is poorly timed, as the storm is arriving during harvest season. The strong winds associated with the storm will flatten many crops, making it more difficult to harvest them, and Isaac's winds may cost farmers several hundred million dollars due to unharvestable crops. Still, the rains from Isaac will be highly beneficial for the success of the upcoming winter wheat season, and for next year's growing season.


Figure 2. Predicted precipitation for the five-day period ending on Tuesday evening shows that Isaac is expected to bring a large region of 3 - 6 inches of rain (red, orange, and brown colors) to Arkansas, Missouri, Illinois, Indiana, Ohio, and Kentucky. Image credit: NOAA/HPC.


Figure 3. The great drought of 2012 has brought so little rain to the Midwest that some areas require over 15" of rain (dark purple colors) to end the drought. Image credit: NOAA/CPC.

Unanswered questions about Hurricane Isaac

1. Did the passage of Hurricane Isaac stir up oil from the Deepwater Horizon oil spill? Isaac was the first hurricane to pass over the site of the 2010 Deepwater Horizon oil spill. We know that large hurricanes are capable of creating currents in deep water at the bottom of the Gulf of Mexico; Hurricane Ivan caused upwelling currents of 0.5 cm/s at a depth of about 500 meters. In an August 28 article in the Huffington Post, Nick Shay, professor of meteorology and physical oceanography at the University of Miami, said: "Winds will push water away from the center of a storm, which causes an upwelling as the ocean tries to adjust. It brings whatever is near the bottom up higher in the water column and currents can then push it towards the coast." Up to 1 million barrels of oil from the spill are estimated to still be present in the deep water sediment, on beaches, and in the marshes of Louisiana, and it is possible some of this oil will wash up on the Gulf Coast in coming months. The storm surge of Isaac also likely flushed out oil lodged in the coastal marshes of Louisiana, but it is unknown how much of a concern this might be.

2. What's the deal with these super-sized Category 1 and 2 hurricanes that have been hitting the U.S.? The past three landfalling hurricanes in the U.S.--Isaac (2012), Irene (2011), and Ike (2008)--have all been exceptionally large, among the top ten on record for horizontal extent of tropical storm-force winds. Each of these storms had an unusually low pressure characteristic of a storm one full Saffir-Simpson category stronger. Is this the new normal for U.S. hurricanes?

3. Did the new $14.5 billion upgrade to the New Orleans levee system cause worse flooding elsewhere? Whenever a new levee or flood control structure is created, you make someone else's flood problem worse, since the water has to go somewhere. Where did the water was stopped by the new $1.1 billion, 1.8 mile-long Lake Borgne flood barrier on the east side of New Orleans go? Did it flow south and contribute to the overtopping of the levees near Braithwaite? Or did it go north and contribute to the 36 hours of storm surge in excess of 5' observed along the Mississippi coast at Waveland? I posed this question to NHC's storm surge expert Jaime Rhome, and he said it was impossible to know without doing detailed storm surge modeling studies.

4. Can only hurricanes beginning with the letter "I" hit the U.S. now? Isaac (2012), Irene (2011), and Ike (2008) are the last three hurricanes to hit the U.S. It turns out that hurricanes that begin with the letter "I" and "C" have more names on the list of retired hurricanes than any other letter (nine each.) I'm thinking Isaac will get its name retired, letting storms beginning with "I" take over sole possession of first place on the retired storms list.

Hurricane Kirk in the Central Atlantic
Hurricane Kirk intensified into a 105 mph Category 2 hurricane this morning, becoming the 2nd strongest hurricane of the 2012 Atlantic hurricane season. Hurricane Gordon was the only stronger storm; Gordon hit sustained winds of 110 mph just before reaching the Azores Islands on August 18. Kirk has probably peaked in intensity, and is about to move over colder waters and gradually decay. Kirk is not a threat to any land areas.


Figure 4. Morning satellite image of Tropical Storm Leslie.

Tropical Storm Leslie a long-range threat to Bermuda, Canada, and the U.S. East Coast
Tropical Storm Leslie formed on Thursday in the Central Atlantic. Leslie's formation date of August 30 puts 2012 in 2nd place for earliest formation date of the season's 12th tropical storm. Only 1995 had an earlier formation date of the season's 12th storm. With records dating back to 1851, this year is only the second time 8 total storms have formed in August. The other year was 2004, when the first storm of the season formed on August 1 (Alex), and the 8th storm (Hermine) formed on August 29th. Satellite loops show that Leslie has a modest amount of heavy thunderstorm activity, and respectable low-level spiral bands and upper-level outflow. Conditions appear ripe to allow Leslie to intensify into a Category 2 hurricane by Sunday. Fortunately, Hurricane Kirk is weakening the ridge of high pressure to the north of Leslie, and Leslie is expected to turn to the northwest and miss the Lesser Antilles Islands. However, steering currents for Leslie are expected to collapse early next week, as Leslie gets stuck between two upper level lows. The storm will then slowly meander over the open ocean for many days, potentially threatening Bermuda. Leslie will stay stuck until a strong trough of low pressure approaches the U.S. East Coast around September 8. This trough should be strong enough to pull Leslie to the north and then northeast by September 9. At that time, Leslie may be close enough to the coast that the storm will make landfall in New England, Canada, or the Mid-Atlantic states. Leslie could also miss land entirely; this all depends upon the timing and strength of the September 8 trough of low pressure. Regardless, Leslie is expected to bring an extended period of high waves to the U.S. coast. According to NOAA's Wavewatch III model, large swells from Leslie will reach Bermuda by Monday, and arrive along the U.S. East Coast on Tuesday. These waves will be capable of creating dangerous rip currents and beach erosion.

Portlight disaster relief charity responds to Isaac
The Portlight.org disaster relief charity, founded and staffed by members of the wunderground community, are in Mississippi, helping out with Isaac relief efforts. You can check out their progress or donate to Portlight's disaster relief fund at the portlight.org website.

I'm planning on taking Saturday off, but will have a new post for you on Sunday. Have a great holiday weekend, everyone!

Jeff Masters

Hurricane Isaac Louisiana (apphotos)
People play in the storm surge from Hurricane Isaac, on Lakeshore Drive along Lake Pontchartrain, as the storm nears land, in New Orleans, Tuesday, Aug. 28, 2012. (AP Photo/Gerald Herbert)
Hurricane Isaac Louisiana
Portlight volunteers at Biloxi shelter (Portlight)
Portlight volunteers at Biloxi shelter
Hurricane Isaac Louisiana (apphotos)
Research students from the the University of Alabama measure wind speeds as Hurricane Isaac makes landfall, Wednesday, Aug. 29, 2012, in New Orleans, La. Isaac was packing 80 mph winds, making it a Category 1 hurricane. It came ashore early Tuesday near the mouth of the Mississippi River, driving a wall of water nearly 11 feet high inland and soaking a neck of land that stretches into the Gulf. The storm stalled for several hours before resuming a slow trek inland, and forecasters said that was
Hurricane Isaac Louisiana
TS Isaac (Raine911)
Between the rain bands
TS Isaac

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1872. sar2401
Quoting Grothar:
If anybody from the Weather Channel is watching, can you tell us why you have a map of Los Angeles next to a warning for the possible dam failure in Louisiana?


I know LA is the abbreviation for Los Angeles and Louisiana, but it could be confusing.


Link


Arf! LA, L.A., kinda the same thing except for that mileage difference. :) I guess TWC computers on recognize one LA, and it ain't down by the Gulf.
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TWC has a reporter in a pile of dead corn LLOLL
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1870. Grothar
If anybody from the Weather Channel is watching, can you tell us why you have a map of Los Angeles next to a warning for the possible dam failure in Louisiana?


I know LA is the abbreviation for Los Angeles and Louisiana, but it could be confusing.


Link
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Well one thing is for certain... Leslie will go somewhere, eventually. How's that for sticking my neck out to make a bold prediction :)
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1868. breald
Quoting sar2401:


No, the lower level center of circulation appeared to have made a jog to the west, while the main storm continues NNW. Leslies is a weakening tropical cyclone trying fight off high wind shear and dry air. Her only escape route is due north, so the wind shear will affect her in terms of short term jogs. They are not a trend. Leslie's survival, at this point, is by no means certain.


oh...I get it...thanks
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1867. sar2401
Quoting LostTomorrows:
Leslie looks immensely better now than she did just a handful of hours ago, you go girl.


It's now 7 hours later and Leslie looks much worse. The wind shear is really tearing her up. I guess the increase in convection closer to her center is what caused the NHC to bump up her intial wind speed, but her overall structure looks terrible.
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1866. sar2401
Quoting breald:


Well, she is certainly turning more westward than the last time I looked..Look at the NOAA updates. Any who, I am no expert in determining what she is doing, so I am be completely off.


No, the lower level center of circulation appeared to have made a jog to the west, while the main storm continues NNW. Leslies is a weakening tropical cyclone trying fight off high wind shear and dry air. Her only escape route is due north, so the wind shear will affect her in terms of short term jogs. They are not a trend. Leslie's survival, at this point, is by no means certain.
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1865. sar2401
Quoting LargoFl:
This is a tragedy, ongoing, dam after dam failing, those poor people....................BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE NEW ORLEANS LA
251 AM CDT SUN SEP 2 2012

THE NATIONAL WEATHER SERVICE IN NEW ORLEANS HAS EXTENDED THE

* FLASH FLOOD WARNING FOR...
CENTRAL ST. TAMMANY PARISH IN SOUTHEAST LOUISIANA...

* UNTIL 900 AM CDT

* AT 246 AM CDT...ST TAMMANY PARISH OFFICE OF EMERGENCY MANAGEMENT
AND THE CORPS OF ENGINEERS CONTINUE TO REVIEW THE STRUCTURAL
INTEGRITY OF THE PEARL RIVER DIVERSION CANAL LOCK AND DAM NUMBER TWO
THAT IS EXPECTED TO FAIL. HEAVY SCOUR HAS TAKEN PLACE ALONGSIDE THE
RELIEF SILL. THE BOGUE CHITTO RIVER STAGE READING AT BUSH WAS 19.75
FEET AT 215 AM CDT.

THIS IS A FLASH FLOOD WARNING IS FOR ALL RESIDENTS AND INTEREST
DOWNSTREAM OF PEARL RIVER LOCK AND DAM #2 NEAR BUSH DOWNSTREAM TO
HIGHWAY 36 AT HICKORY FOR AREAS EAST OF HIGHWAY 41.

THE FOLLOWING ARE SOME MORE DETAILS REGARDING THE FLASH FLOOD
WARNING FOR THE PEARL RIVER DIVERSION CANAL.

IF AND WHEN THE STRUCTURE FAILS...THE ESTIMATED INITIAL FLOOD WAVE
IS EXPECTED TO BE AROUND 11 FEET.

THE CAMPGROUND ONE-HALF MILE DOWNSTREAM OF THE LOCK STRUCTURE IS
ESTIMATED TO GET ABOUT 10 FEET OF FLOOD WAVE. THIS CAMPGROUND AND
NEARBY RESIDENTS HAVE BEEN EVACUATED.

TRAVEL TIME OF THE FLOOD WAVE TO LOCK AND DAM NUMBER ONE...11 MILES
DOWNSTREAM...IS ESTIMATED TO BE ONE HOUR WITH A FLOOD WAVE ESTIMATED
TO BE 5.5 FEET. THIS STRUCTURE WILL OFFER SOME RESISTANCE TO FURTHER
TRAVEL DOWNSTREAM.

IF THE WAVE SHOULD CONTINUE BEYOND LOCK AND DAM NUMBER ONE...
AT INTERSTATE 59 AT THE PEARL RIVER...18 MILES DOWNSTREAM...A FLOOD
WAVE OF AN ADDITIONAL 2.5 FEET OF WATER LEVEL WOULD REACH THAT POINT
BETWEEN 2 AND 4 HOURS OF PASSING LOCK AND DAM NUMBER ONE.

THESE HEIGHTS AND TIMES ARE ESTIMATES AS COORDINATED WITH THE LOWER
MISSISSIPPI RIVER FORECAST CENTER. AT THIS TIME...THE STRUCTURE IS
STILL INTACT AND RELIEF VALVES HAVE BEEN OPENED TO LESSEN SOME
PRESSURE ON THE STRUCTURE.

PERSONS AND INTERESTS IN THIS WARNED AREA SHOULD NOT RETURN UNTIL
THE LOCAL OFFICIALS GIVE THE ALL CLEAR. THIS REMAINS A DANGEROUS
SITUATION WITHIN A LIMITED AREA NEAR AND DOWNSTREAM OF THE PEARL
RIVER DIVERSION CANAL BELOW LOCK AND DAM NUMBER TWO.


Largo, no dam has yet failed. The structures have been compromised by the water levels and wave action, causing upstream scouring to weaken the toes and crest structures. These events happen and are planned for when the dams are built. Controlled water releases and backfilling seem to be working so far, so let's hope that continues.
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1864. Hangten
Where is Grothar. I have not seen him. He gives good entries of these with always some humor. He has thus far been good with this one.
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I updated the discussion Modifying the Saffir Simpson Scale

Here is the proposed new scale...

category - wind speed threshold

tropical storm - 35 kts
strong tropical storm - 50 kts
cat 1 hurricane - 65 kts
cat 2 hurricane - 80 kts
cat 3 hurricane - 95 kts
cat 4 hurricane - 110 kts
cat 5 hurricane - 130 kts
cat 6 hurricane - 150 kts

The scale would also include mandatory "bump-ups" for high flight level winds, large area/kinetic energy, explosive deepening of the storm, and possibly other factors.

For example the hurricane threshold is 65 knots. My suggestion is that a storm's category (tropical storm, or strong tropical storm) automatically be "bumped up" to a hurricane if the flight level winds of 90 kts, or around 103mph, are detected.

Here is a draft of possible flight level wind triggers for each type of storm. The question is, do storms exhibiting these winds deserve to be "bumped up" to the next level? How do you all feel about this idea?

tropical storm - 70 kts
strong tropical storm - 90 kts
cat 1 hurricane - 110 - kts
cat 2 hurricane - 130 - kts
cat 3 hurricane - 150 - kts
cat 4 hurricane - 175 - kts
cat 5 hurricane - 200 kts
cat 6 hurricane
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1862. breald
Quoting clwstmchasr:


Who has her turning west towards the east coast?


Well, she is certainly turning more westward than the last time I looked..Look at the NOAA updates. Any who, I am no expert in determining what she is doing, so I am be completely off.
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ATCF says Leslie's winds are back down to 55 knots, and the pressure has risen three millibars:

AL, 12, 2012090212, , BEST, 0, 214N, 609W, 55, 997, TS, 50, NEQ, 90, 90, 0, 0, 1012, 225, 75, 0, 0, L, 0, , 0, 0, LESLIE, M,
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1860. sar2401
Quoting LargoFl:
Guess everything off africa recurves now..................


That would be a good thing, no?
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1859. sar2401
Quoting breald:
Morning Everyone. The last time I looked at Leslie she was turning north well away from any land. Now they have her turning west towards the east coast. Hopefully she will stay away from any land mass.


Who has her turning west towards the east coast? I haven't seen a reliable model that predicts such a thing. Her first task is to survive until Wednesday. If she does, then it will be time to look at the models and see what happens. Until then, it appears Bermuda is the area at risk.
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Link

Kinda choppy here from Leslie.
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1856. breald
Morning Everyone. The last time I looked at Leslie she was turning north well away from any land. Now they have her turning west towards the east coast. Hopefully she will stay away from any land mass.
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Here's my Daily Briefing video blog for Sunday Link
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Quoting GTcooliebai:
We have Invest 99L




It's so tiny and cute... 0.o
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1850-Largo--fingers crossed they continue to recurve!
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1851. LargoFl
Member Since: December 31, 1969 Posts: Comments:
1850. LargoFl
Guess everything off africa recurves now..................
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1849. LargoFl
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1848. flcanes
Quoting seer2012:
I have done some reading overnight and this morning on cold core cyclones.This convection developement to the SE of the llcoc appears to be one of the characteristics.Another one is that the storms are stronger at altitude than at the surface.I would like to find out more about this type of storm.It seems to fit what is happening this year.

intresting
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Quoting seer2012:
Yes, I have noticed similarties between the 2 storms also.
I have done some reading overnight and this morning on cold core cyclones.This convection developement to the SE of the llcoc appears to be one of the characteristics.Another one is that the storms are stronger at altitude than at the surface.I would like to find out more about this type of storm.It seems to fit what is happening this year.
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Quoting Gearsts:
Im talking about the LLC, it did a nice jog west and is funny that the NHC has it at 70mph is probably closer to 45 or 50 just like Isaac was when it enter the Northeast caribbean.
Yes, I have noticed similarties between the 2 storms also.
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1845. Gearsts
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1844. Gearsts
Quoting seer2012:
Once again it appears that the mlcoc is tracking west while the llcoc continues NW.
Im talking about the LLC, it did a nice jog west and is funny that the NHC has it at 70mph is probably closer to 45 or 50 just like Isaac was when it enter the Northeast caribbean.
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Quoting Gearsts:
Nice west jog there.
Once again it appears that the mlcoc is tracking west while the llcoc continues NW.
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1842. Gearsts
Nice west jog there.
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1841. LargoFl
.................................Good Morning folks..a great day for the beach today here around Tampa Bay..hot,sunny and dry..BBQ day for sure...have a great day and stay safe out there.
Member Since: December 31, 1969 Posts: Comments:
1840. LargoFl
Member Since: December 31, 1969 Posts: Comments:
1839. LargoFl

Tropical Storm LESLIE Public Advisory

Home Public Adv Fcst Adv Discussion Wind Probs Graphics Archive

000
WTNT32 KNHC 020849
TCPAT2

BULLETIN
TROPICAL STORM LESLIE ADVISORY NUMBER 12
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122012
500 AM AST SUN SEP 02 2012

...LESLIE STRENGTHENS SLIGHTLY AS IT CONTINUES TO MOVE NORTHWESTWARD
AWAY FROM THE LEEWARD ISLANDS...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...20.8N 59.5W
ABOUT 295 MI...475 KM NNE OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...994 MB...29.35 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 500 AM AST...0900 UTC...THE CENTER OF TROPICAL STORM LESLIE WAS
LOCATED NEAR LATITUDE 20.8 NORTH...LONGITUDE 59.5 WEST. LESLIE IS
MOVING TOWARD THE NORTHWEST NEAR 15 MPH...24 KM/H...AND THIS
GENERAL MOTION IS FORECAST TO CONTINUE TODAY. A GRADUAL TURN TOWARD
THE NORTH-NORTHWEST AND NORTH...ALONG WITH A DECREASE IN FORWARD
SPEED...IS EXPECTED DURING THE NEXT COUPLE OF DAYS. ON THE FORECAST
TRACK...THE CENTER OF LESLIE WILL CONTINUE TO MOVE AWAY FROM THE
LEEWARD ISLANDS.

MAXIMUM SUSTAINED WINDS ARE NEAR 70 MPH...110 KM/H...WITH HIGHER
GUSTS. LESLIE IS CURRENTLY IN AN AREA OF UNFAVORABLE UPPER-LEVEL
WINDS...AND SOME FLUCTUATIONS IN STRENGTH WILL BE POSSIBLE DURING
THE NEXT 48 HOURS.

TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 175 MILES...280 KM
FROM THE CENTER. NOAA BUOY 41044...LOCATED NORTH OF THE CENTER...
HAS BEEN REPORTING 1-MINUTE MEAN WINDS OF 50 MPH...80 KM/HR...WITH
GUSTS TO NEAR 60 MPH...92 KM/HR...OVER THE PAST FEW HOURS.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 MB...29.35 INCHES.
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1838. LargoFl
Member Since: December 31, 1969 Posts: Comments:
1837. LargoFl
This is a tragedy, ongoing, dam after dam failing, those poor people....................BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE NEW ORLEANS LA
251 AM CDT SUN SEP 2 2012

THE NATIONAL WEATHER SERVICE IN NEW ORLEANS HAS EXTENDED THE

* FLASH FLOOD WARNING FOR...
CENTRAL ST. TAMMANY PARISH IN SOUTHEAST LOUISIANA...

* UNTIL 900 AM CDT

* AT 246 AM CDT...ST TAMMANY PARISH OFFICE OF EMERGENCY MANAGEMENT
AND THE CORPS OF ENGINEERS CONTINUE TO REVIEW THE STRUCTURAL
INTEGRITY OF THE PEARL RIVER DIVERSION CANAL LOCK AND DAM NUMBER TWO
THAT IS EXPECTED TO FAIL. HEAVY SCOUR HAS TAKEN PLACE ALONGSIDE THE
RELIEF SILL. THE BOGUE CHITTO RIVER STAGE READING AT BUSH WAS 19.75
FEET AT 215 AM CDT.

THIS IS A FLASH FLOOD WARNING IS FOR ALL RESIDENTS AND INTEREST
DOWNSTREAM OF PEARL RIVER LOCK AND DAM #2 NEAR BUSH DOWNSTREAM TO
HIGHWAY 36 AT HICKORY FOR AREAS EAST OF HIGHWAY 41.

THE FOLLOWING ARE SOME MORE DETAILS REGARDING THE FLASH FLOOD
WARNING FOR THE PEARL RIVER DIVERSION CANAL.

IF AND WHEN THE STRUCTURE FAILS...THE ESTIMATED INITIAL FLOOD WAVE
IS EXPECTED TO BE AROUND 11 FEET.

THE CAMPGROUND ONE-HALF MILE DOWNSTREAM OF THE LOCK STRUCTURE IS
ESTIMATED TO GET ABOUT 10 FEET OF FLOOD WAVE. THIS CAMPGROUND AND
NEARBY RESIDENTS HAVE BEEN EVACUATED.

TRAVEL TIME OF THE FLOOD WAVE TO LOCK AND DAM NUMBER ONE...11 MILES
DOWNSTREAM...IS ESTIMATED TO BE ONE HOUR WITH A FLOOD WAVE ESTIMATED
TO BE 5.5 FEET. THIS STRUCTURE WILL OFFER SOME RESISTANCE TO FURTHER
TRAVEL DOWNSTREAM.

IF THE WAVE SHOULD CONTINUE BEYOND LOCK AND DAM NUMBER ONE...
AT INTERSTATE 59 AT THE PEARL RIVER...18 MILES DOWNSTREAM...A FLOOD
WAVE OF AN ADDITIONAL 2.5 FEET OF WATER LEVEL WOULD REACH THAT POINT
BETWEEN 2 AND 4 HOURS OF PASSING LOCK AND DAM NUMBER ONE.

THESE HEIGHTS AND TIMES ARE ESTIMATES AS COORDINATED WITH THE LOWER
MISSISSIPPI RIVER FORECAST CENTER. AT THIS TIME...THE STRUCTURE IS
STILL INTACT AND RELIEF VALVES HAVE BEEN OPENED TO LESSEN SOME
PRESSURE ON THE STRUCTURE.

PERSONS AND INTERESTS IN THIS WARNED AREA SHOULD NOT RETURN UNTIL
THE LOCAL OFFICIALS GIVE THE ALL CLEAR. THIS REMAINS A DANGEROUS
SITUATION WITHIN A LIMITED AREA NEAR AND DOWNSTREAM OF THE PEARL
RIVER DIVERSION CANAL BELOW LOCK AND DAM NUMBER TWO.
Member Since: December 31, 1969 Posts: Comments:
1836. VR46L
Quoting 7544:
hmm leslie looking good and 99l moving wsw is it going to slam into her


She definitely does ...I need to eat some Crow as I had her near written off yesterday but she is in a better environment now
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1835. K8eCane
what is a meme? i need to know so i dont accidentally post one
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1834. 7544
hmm leslie looking good and 99l moving wsw is it going to slam into her
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Quoting wxchaser97:


1. A SURFACE TROUGH INTERACTING WITH AN UPPER-LEVEL LOW IS PRODUCING AN
AREA OF SHOWERS AND THUNDERSTORMS ABOUT 1075 MILES NORTHWEST OF THE
CAPE VERDE ISLANDS. SOME SLOW DEVELOPMENT OF THIS DISTURBANCE IS
POSSIBLE OVER THE NEXT FEW DAYS AS IT MOVES WEST-SOUTHWESTWARD AT
10 TO 15 MPH. THIS SYSTEM HAS A LOW CHANCE...20 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

This could be interesting, wouldn't be much of a threat to land.


For anyone that's up late...I just did a special update on Invest 99-L tracing its origin. Its been something that I've tracked for a few days...but not something I gave special treatement to because I didn't think it would need any...

I guess we get suprise 99-L in the Atlantic...to counter suprise 99-E in the E-pac...LOL. The only reason I am up is because my sleep continues to be messed up...but oh well its Labor Day weekend. I briefly checked the NHC site when I just woke up now...and I was like "oh great...not another one to track"
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A cool picture of the yellow circles:

5 AOIs. October 5, 2007.
(There were actually 6 AOIs, but 5 are shown in this picture.)
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Leslie looks immensely better now than she did just a handful of hours ago, you go girl.
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Well if anyone is still on have a goodnight and fun tracking.
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Euro 144 hrs. also trended west with Leslie and also putting the NE quadrant over Bermuda which would be bad :

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I knew I was forgetting something.

Euro 24 hrs. also shows 99L:

Member Since: December 31, 1969 Posts: Comments:
I really need to rest now, night. Cool to see a new invest in the open Atlantic.
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1826. JLPR2
Quoting wxchaser97:

I think it might be time to rest the eyes. I still see the NW movement, unless it is me.


Heading to dreamland before I see some east movement. xD


Goodnight everyone!

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Quoting JLPR2:
With floater and everything.


Well we know they are serious in tagging this as an invest. Something to watch over the next few days if Leslie doesn't get her act together right now.
Quoting Bobbyweather:

Another Azores storm?

It's very possible and with the conditions out there we will have to wait and see.
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Quoting Bobbyweather:

Another Azores storm?
It seems so...that area has been a breeding ground for tropical systems this year, could have something to due with the warmer ssts.
Member Since: December 31, 1969 Posts: Comments:
Quoting JLPR2:
Could someone check if I'm going nuts or if Leslie seems to have added some west to her movement?



Thank you, if not, then it might be time to rest the eyes.

I think it might be time to rest the eyes. I still see the NW movement, unless it is me.
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1822. JLPR2
With floater and everything.

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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather

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