Unanswered questions concerning Hurricane Isaac

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

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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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Leslie is well developed with a full anticyclone and amazing funktop presentation.

Probably gets upgraded later tonight.

I don't know if the trough will pull it quite as hard as the official forecast shows, but I guess we'll find out soon enough.
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Quoting trHUrrIXC5MMX:


That 1938 Long Island Express seems a little bit too dangerous...I'm right over its path ...
I have to agree, as I am on the 'dirty' side of that track.
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Who thinks at least TS watches should go up for the N Antilles?
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Quoting Felix2007:









That 1938 Long Island Express seems a little bit too dangerous...I'm right over its path ...
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468. VR46L
Quoting presslord:
Who's in charge here?!?!?!


Don't know haven't seen any of the blog bosses on ...until recently

anyway cute Kirk not so cute now



And neither is this one



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Quoting bassis:


Hey Press
What's the significance of Janice joplin in your avatar now.

Is Kirk still a cane at this point


no significance, really...I just love Janis...
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More







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I don't buy the GFS for now on leslie, maybe I'm gun shy, but I'd advise anyone on the Florida east coast to keep a tleast one eye on this sucker.

GFS shows what looks like a 4 or 5 day stall to the east of Florida, that means it's probably picking up on a tricky steering situation that no human is quite smart enough to figure out, and possibly a bad turn going to happen IRL instead of a stall.

We'll have to watch that one too.


BAMM says it turns west on the 4th and 5th day, and what do you know? It's the third best model on day 4 and 5, and was with the GFS on spamming a mostly correct solution almost every run for Isaac.
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Leslie is probably a hurricane right now. CIMSS ADT is at T3.9 and they initialized the center at the wrong place.

Member Since: July 6, 2010 Posts: 113 Comments: 33456
Quoting CosmicEvents:
Hard to believe, but after an hour and a half nobody's posted the 5PM NHC discussion on TS Leslie.
.
.
000
WTNT42 KNHC 312037
TCDAT2

TROPICAL STORM LESLIE DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122012
500 PM AST FRI AUG 31 2012

THE STORM LOOKS A LITTLE BETTER ORGANIZED ON VISIBLE IMAGERY THIS
AFTERNOON WITH AN INCREASE IN CONVECTION IN ADDITION TO MICROWAVE
OVERPASSES SHOWING THE CENTER BECOMING MORE EMBEDDED IN THE
OVERCAST. INTENSITY ESTIMATES...HOWEVER...ARE UNCHANGED...SO THE
INITIAL WIND SPEED IS KEPT AT 55 KT. WHILE THE VERTICAL SHEAR IS
EXPECTED TO REMAIN LIGHT-TO-MODERATE IN THE SHORT TERM...MOST OF
THE GLOBAL MODELS ARE NOW SHOWING AN INCREASINGLY HOSTILE
ENVIRONMENT AFTER THAT TIME. THESE CONDITIONS ARE DUE TO AN
UPPER-LEVEL HIGH MOVING WEST OF THE CENTER...CAUSING AN INCREASE IN
NORTHWESTERLY SHEAR. MOST OF THE INTENSITY GUIDANCE NOW SHOW
LESLIE ONLY AS A CATEGORY ONE HURRICANE IN A FEW DAYS TIME. THE
OFFICIAL FORECAST IS REDUCED SLIGHTLY FROM THE PREVIOUS ONE...IN
BEST AGREEMENT WITH A BLEND OF THE INTENSITY CONSENSUS AND THE LGEM
MODEL. THERE IS SOME CHANCE OF LESLIE FINDING A MORE FAVORABLE
ENVIRONMENT IN THE LONG TERM...BUT ITS LIKELY SLOW MOTION AT THAT
TIME COULD CAUSE UPWELLING UNDER THE STORM...SO THE NHC FORECAST
WILL STAY CONSERVATIVE.

A SERIES OF MICROWAVE PASSES GIVES A GOOD INITIAL MOTION ESTIMATE OF
295/16. THERE HAS BEEN A SUBTLE WESTWARD SHIFT IN MOST OF THE
RELIABLE MODEL GUIDANCE DURING THE FORECAST PERIOD...PERHAPS
INITIALLY DUE TO THE RIDGE BETWEEN KIRK AND LESLIE BEING A BIT
STRONGER THAN EXPECTED. THE GLOBAL MODELS ARE CONSISTENT IN
FORECASTING A BREAK IN THE SUBTROPICAL RIDGE IN A FEW DAYS
TIME...WHICH SHOULD CAUSE LESLIE TO TURN NORTHWESTWARD AND
NORTHWARD IN 3 TO 4 DAYS. BY THE END OF THE FORECAST...LITTLE
MOTION IS EXPECTED AS THE CYCLONE IS CAUGHT IN LIGHT STEERING
CURRENTS TO THE SOUTHEAST OF BERMUDA. THE OFFICIAL NHC PREDICTION
IS SHIFTED WESTWARD TO COME CLOSER TO THE DYNAMICAL MODEL
CONSENSUS... ALTHOUGH THE MODEL CONSENSUS IS STILL A BIT WEST OF
THE NEW FORECAST.


FORECAST POSITIONS AND MAX WINDS

INIT 31/2100Z 16.7N 51.0W 55 KT 65 MPH
12H 01/0600Z 17.7N 53.2W 60 KT 70 MPH
24H 01/1800Z 18.9N 55.9W 60 KT 70 MPH
36H 02/0600Z 20.1N 58.1W 65 KT 75 MPH
48H 02/1800Z 21.5N 60.0W 70 KT 80 MPH
72H 03/1800Z 24.1N 62.0W 70 KT 80 MPH
96H 04/1800Z 26.0N 62.5W 70 KT 80 MPH
120H 05/1800Z 27.0N 63.0W 75 KT 85 MPH

$$
FORECASTER BLAKE


no one wanted to plagiarize NHC data I guess
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This is so bad...



Lost about 1/5th to 1/6th each of the remaining values on these...in one year...



This is not gonna last much longer.



melted..

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Quoting presslord:
Who's in charge here?!?!?!


Hey Press
What's the significance of Janice joplin in your avatar now.

Is Kirk still a cane at this point
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Quoting Neapolitan:
That's quite an unusual statistic. It may be coincidence, but even coincidences need to sometimes be explained.


Interesting... I wonder if you make a circle 400 miles in diameter over the eastern caribbean that can include the path of all of these storms, what the average water temp (or heat content) has been in august and september... for the last 15 years. I looked online and all I could find was a 2010 research paper with data going to 2005:

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Quoting presslord:
Who's in charge here?!?!?!


No one's in charge here....something you might know something about yourself. Someone please take charge of him :)
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458. JeffM
Quoting Tazmanian:





why post it too where they can go too the nhc site and this look it up and all so why did you bold it i call that yelling


facepalm
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Well, Colorado state and others forecast some rediculously low number, like 11 named storms, and we are already at 12 named storms with 10/11 days remaining before the peak/middle of the season.

I called 15 to 16 named during the preseason, but I got no clue now.

Look at this:




The central MDR is back to a full degree above average, while the easter Nino zones are average or below average again. Of course over all the E.Pac near the equator is warmer than average, but not everywhere.

Looks like we'll continue to have neutral/positive conditions to barely el nino conditions for possibly the remainder of the season.


I'm betting on at least one more Eastern U.S. coast "retrograde" pop-up system gets named, and probably 5 to 10 more MDR storms and Gulf/Caribbean pop-ups get named before it's all said and done.


So now I'll revise my forecast for the whole season..

18 to 23 named storms....
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456. 7544
leslie u boring everybody go west get some excitment going will ya
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Nobody's in charge. I don't see any badges.
The rules of the site apply.
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Nick Walker on TWC just said that there's still Hurricane Watches up, and he said that it's still a depression, lol.
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Quoting islandgirls:


You can say that again. Antiguaboy where exactly are you located?
Am in Antigua, right in the most northeast of athe antilles.
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no.much.going.on....surfers.wax.up
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Who's in charge here?!?!?!
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Quoting GetReal:



Here is the most striking similarity of Leslie to Isaac:



That 1016mb isobar is stretched nearly straight east to west AGAIN, with Leslie being guided by it as was Isaac. Hope for a change...


And look at that low pressure off Africa.
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Quoting seer2012:
I agree but I see some similarities in the steering that remind me of what isaac was doing when he was out there in that area.This storm is stronger though and may begin to behave differently and may begin the turn soon. The northern Antilles isn't out of the picture just yet,though.



Here is the most striking similarity of Leslie to Isaac:



That 1016mb isobar is stretched nearly straight east to west AGAIN, with Leslie being guided by it as was Isaac. Hope for a change...
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Quoting wxgeek723:
Leslie better not pull something like this.
Pull that to the NNE, 100 miles, then imagine the media
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Quoting opal92nwf:
It has been drugery and embarassement for the Weather Channel to cover Isaac as if it's a Katrina as it makes landfall, but now they are covering it as if the damage is like Katrina's, which is absolutely unbelievably ridiculous!!!! Isaac is "child's play" compared to Katrina or a cat 4 or 5 storm. Save the hype for the real storm TWC!!!! Please tell me if you feel the same anyone out there.


====

Isaac hit less populated areas, so it's definitely not going to be as bad as Katrina in monetary losses. Isaac also did not have winds as strong as Katrina. Even Katrina's weak side winds were stronger than Isaac's strong side winds.

But Isaac has doubled and tripled Katrina's rainfall totals. Katrina was relatively dry in terms of rainfall totals, with only about 7.5 inches in this general area.
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Quoting antiguaboy396:
lols were used to it :)


You can say that again. Antiguaboy where exactly are you located?
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Quoting CosmicEvents:
Hard to believe, but after an hour and a half nobody's posted the 5PM NHC discussion on TS Leslie.


The Vegas odds were 10000:1. I wagered $100. Do the math. :)
Member Since: Posts: Comments:
Quoting CosmicEvents:
Hard to believe, but after an hour and a half nobody's posted the 5PM NHC discussion on TS Leslie.
.
.
000
WTNT42 KNHC 312037
TCDAT2

TROPICAL STORM LESLIE DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122012
500 PM AST FRI AUG 31 2012

THE STORM LOOKS A LITTLE BETTER ORGANIZED ON VISIBLE IMAGERY THIS
AFTERNOON WITH AN INCREASE IN CONVECTION IN ADDITION TO MICROWAVE
OVERPASSES SHOWING THE CENTER BECOMING MORE EMBEDDED IN THE
OVERCAST. INTENSITY ESTIMATES...HOWEVER...ARE UNCHANGED...SO THE
INITIAL WIND SPEED IS KEPT AT 55 KT. WHILE THE VERTICAL SHEAR IS
EXPECTED TO REMAIN LIGHT-TO-MODERATE IN THE SHORT TERM...MOST OF
THE GLOBAL MODELS ARE NOW SHOWING AN INCREASINGLY HOSTILE
ENVIRONMENT AFTER THAT TIME. THESE CONDITIONS ARE DUE TO AN
UPPER-LEVEL HIGH MOVING WEST OF THE CENTER...CAUSING AN INCREASE IN
NORTHWESTERLY SHEAR. MOST OF THE INTENSITY GUIDANCE NOW SHOW
LESLIE ONLY AS A CATEGORY ONE HURRICANE IN A FEW DAYS TIME. THE
OFFICIAL FORECAST IS REDUCED SLIGHTLY FROM THE PREVIOUS ONE...IN
BEST AGREEMENT WITH A BLEND OF THE INTENSITY CONSENSUS AND THE LGEM
MODEL. THERE IS SOME CHANCE OF LESLIE FINDING A MORE FAVORABLE
ENVIRONMENT IN THE LONG TERM...BUT ITS LIKELY SLOW MOTION AT THAT
TIME COULD CAUSE UPWELLING UNDER THE STORM...SO THE NHC FORECAST
WILL STAY CONSERVATIVE.

A SERIES OF MICROWAVE PASSES GIVES A GOOD INITIAL MOTION ESTIMATE OF
295/16. THERE HAS BEEN A SUBTLE WESTWARD SHIFT IN MOST OF THE
RELIABLE MODEL GUIDANCE DURING THE FORECAST PERIOD...PERHAPS
INITIALLY DUE TO THE RIDGE BETWEEN KIRK AND LESLIE BEING A BIT
STRONGER THAN EXPECTED. THE GLOBAL MODELS ARE CONSISTENT IN
FORECASTING A BREAK IN THE SUBTROPICAL RIDGE IN A FEW DAYS
TIME...WHICH SHOULD CAUSE LESLIE TO TURN NORTHWESTWARD AND
NORTHWARD IN 3 TO 4 DAYS. BY THE END OF THE FORECAST...LITTLE
MOTION IS EXPECTED AS THE CYCLONE IS CAUGHT IN LIGHT STEERING
CURRENTS TO THE SOUTHEAST OF BERMUDA. THE OFFICIAL NHC PREDICTION
IS SHIFTED WESTWARD TO COME CLOSER TO THE DYNAMICAL MODEL
CONSENSUS... ALTHOUGH THE MODEL CONSENSUS IS STILL A BIT WEST OF
THE NEW FORECAST.


FORECAST POSITIONS AND MAX WINDS

INIT 31/2100Z 16.7N 51.0W 55 KT 65 MPH
12H 01/0600Z 17.7N 53.2W 60 KT 70 MPH
24H 01/1800Z 18.9N 55.9W 60 KT 70 MPH
36H 02/0600Z 20.1N 58.1W 65 KT 75 MPH
48H 02/1800Z 21.5N 60.0W 70 KT 80 MPH
72H 03/1800Z 24.1N 62.0W 70 KT 80 MPH
96H 04/1800Z 26.0N 62.5W 70 KT 80 MPH
120H 05/1800Z 27.0N 63.0W 75 KT 85 MPH

$$
FORECASTER BLAKE





why post it too where they can go too the nhc site and this look it up and all so why did you bold it i call that yelling
Member Since: Posts: Comments:
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?



Don't forget Alex, even though it was stronger and missed the U.S., much the same M.O...doesn't intensify until it's half on land, a category or two lower pressure than average storm of the same wind speed, and takes up half the basin in size...
Member Since: Posts: Comments:
Hard to believe, but after an hour and a half nobody's posted the 5PM NHC discussion on TS Leslie.
.
.
000
WTNT42 KNHC 312037
TCDAT2

TROPICAL STORM LESLIE DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122012
500 PM AST FRI AUG 31 2012

THE STORM LOOKS A LITTLE BETTER ORGANIZED ON VISIBLE IMAGERY THIS
AFTERNOON WITH AN INCREASE IN CONVECTION IN ADDITION TO MICROWAVE
OVERPASSES SHOWING THE CENTER BECOMING MORE EMBEDDED IN THE
OVERCAST. INTENSITY ESTIMATES...HOWEVER...ARE UNCHANGED...SO THE
INITIAL WIND SPEED IS KEPT AT 55 KT. WHILE THE VERTICAL SHEAR IS
EXPECTED TO REMAIN LIGHT-TO-MODERATE IN THE SHORT TERM...MOST OF
THE GLOBAL MODELS ARE NOW SHOWING AN INCREASINGLY HOSTILE
ENVIRONMENT AFTER THAT TIME. THESE CONDITIONS ARE DUE TO AN
UPPER-LEVEL HIGH MOVING WEST OF THE CENTER...CAUSING AN INCREASE IN
NORTHWESTERLY SHEAR. MOST OF THE INTENSITY GUIDANCE NOW SHOW
LESLIE ONLY AS A CATEGORY ONE HURRICANE IN A FEW DAYS TIME. THE
OFFICIAL FORECAST IS REDUCED SLIGHTLY FROM THE PREVIOUS ONE...IN
BEST AGREEMENT WITH A BLEND OF THE INTENSITY CONSENSUS AND THE LGEM
MODEL. THERE IS SOME CHANCE OF LESLIE FINDING A MORE FAVORABLE
ENVIRONMENT IN THE LONG TERM...BUT ITS LIKELY SLOW MOTION AT THAT
TIME COULD CAUSE UPWELLING UNDER THE STORM...SO THE NHC FORECAST
WILL STAY CONSERVATIVE.

A SERIES OF MICROWAVE PASSES GIVES A GOOD INITIAL MOTION ESTIMATE OF
295/16. THERE HAS BEEN A SUBTLE WESTWARD SHIFT IN MOST OF THE
RELIABLE MODEL GUIDANCE DURING THE FORECAST PERIOD...PERHAPS
INITIALLY DUE TO THE RIDGE BETWEEN KIRK AND LESLIE BEING A BIT
STRONGER THAN EXPECTED. THE GLOBAL MODELS ARE CONSISTENT IN
FORECASTING A BREAK IN THE SUBTROPICAL RIDGE IN A FEW DAYS
TIME...WHICH SHOULD CAUSE LESLIE TO TURN NORTHWESTWARD AND
NORTHWARD IN 3 TO 4 DAYS. BY THE END OF THE FORECAST...LITTLE
MOTION IS EXPECTED AS THE CYCLONE IS CAUGHT IN LIGHT STEERING
CURRENTS TO THE SOUTHEAST OF BERMUDA. THE OFFICIAL NHC PREDICTION
IS SHIFTED WESTWARD TO COME CLOSER TO THE DYNAMICAL MODEL
CONSENSUS... ALTHOUGH THE MODEL CONSENSUS IS STILL A BIT WEST OF
THE NEW FORECAST.


FORECAST POSITIONS AND MAX WINDS

INIT 31/2100Z 16.7N 51.0W 55 KT 65 MPH
12H 01/0600Z 17.7N 53.2W 60 KT 70 MPH
24H 01/1800Z 18.9N 55.9W 60 KT 70 MPH
36H 02/0600Z 20.1N 58.1W 65 KT 75 MPH
48H 02/1800Z 21.5N 60.0W 70 KT 80 MPH
72H 03/1800Z 24.1N 62.0W 70 KT 80 MPH
96H 04/1800Z 26.0N 62.5W 70 KT 80 MPH
120H 05/1800Z 27.0N 63.0W 75 KT 85 MPH

$$
FORECASTER BLAKE
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162 hours
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At this time I am leaning heavily towards the left side of the forecast cone, and a much closer pass at the NE Antilles.
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Quoting GetReal:



If Leslie is going to follow the script, and start turning NW, she should begin showing a more poleward movement about now.... IMO


But as we all know, sometimes tropical systems just do not follow the forecast script...

I agree but I see some similarities in the steering that remind me of what isaac was doing when he was out there in that area.This storm is stronger though and may begin to behave differently and may begin the turn soon. The northern Antilles isn't out of the picture just yet,though.
Member Since: July 30, 2012 Posts: 4 Comments: 614
144 Hours
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"Gloom of The N.H.C". : Complete Ver. (9:17)

Look what I found on some japanese video game album track list...
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Quoting washingtonian115:
It's the 4Qing living dead on right now.

Any who if I was in the Antillies and saw what was coming from the east I know i'll be a little freaked out.I don't know how those people can do it.
lols were used to it :)
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Quoting stormpetrol:
Leslie appears bouncing along westward just above the 16N latitude line.




If Leslie is going to follow the script, and start turning NW, she should begin showing a more poleward movement about now.... IMO


But as we all know, sometimes tropical systems just do not follow the forecast script...

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114 hours
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430. VR46L
Quoting Articuno:

Kirk almost looks like he's spinning like he's on the other hemisphere. o_o or is it just my eyes playing tricks?


Well I guess because he is starting his long journey north east his spin looks totally different to Leslie who is moving West...

Kirk


Leslie
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The model entertainment begins.Let's not forget about that tiny island in the Atlantic a few hundred miles off the U.S east coast..
Member Since: August 14, 2010 Posts: 10 Comments: 18873
Quoting prcane4you:
What a bunch of bore people

???

You talking to me?
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Quoting washingtonian115:
Men have always been good when it comes to strength but women have always had the smarts.Lol.

They haven't had the smarts if they can't figure out how to stay alive... lol.
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18z GFS running

102 hours
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Quoting wxgeek723:
Leslie better not pull something like this.





It won't. Do you know how rare it is for a hurricane to take that track into NJ from the sea. (yes I am aware of Irene "sideswiping" Jersey last year....so save you breath before spouting that example as it is not the same thing

The track above just doesn't happen for hurricanes but once every freak of nature.
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Quoting Articuno:

Kirk almost looks like he's spinning like he's on the other hemisphere. o_o or is it just my eyes playing tricks?
What a bunch of bore people
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Quoting washingtonian115:
Men have always been good when it comes to strength but women have always had the smarts.Lol.


-______-
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Leslie satellite imagery shows that the mid level circulation is not aligned with the low level circulation. There is a displacement between circulations and convection is not over the LLC the way it needs to be to strengthen into a hurricane.
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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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