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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Quoting wxmod:
2 ships moving across the Arctic Ocean leaving clouds a thousand miles long. MODIS satellite photo.


hmm wow epic

and on other good news TD Isaac is not TD anymore

..TROPICAL DEPRESSION ISAAC HAS LOST TROPICAL CHARACTERISTICS WHILE MOVING ACROSS MISSOURI...FLASH FLOOD THREAT DIMINISHING...
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Quoting lobdelse81:
Poll time:) Some of you guys have commented on how long it has been since the US has seen a major hurricane (7 yrs already) and have been talking about the persistent troughs and Texas death ridges protecting the East coast and Gulf coasts, respectively, from major strikes. I as well as some others believe while this is remarkable that we have held onto this pattern for so long, we are truly living on borrowed time. But now I am willing to propose a poll about our next major hurricane strike.
The next time a major hurricane makes a landfall in the United States will be....
(a) sometime in the remainder of the 2012 season
(b) 2013
(c) 2014
(d) 2015
(e) some other year after 2015

I will go with C. Here is why: It looks like based on some of the models, the East coast is in for some major troughs coming through that should protect us through the peak of this season and by the time we get to October, the developing El Nino should shut down the season early. By the time we get to 2013, full El Nino effects should be in place to keep that season in check. However, I noticed looking back at history, it seems like the midpoints of most decades have featured a return of major hurricane strikes (1954/55, 1965, 1974/75, 1985, 1995, 2004/05).
Well..I'm not quite ready to write off the remainder of '12 or '13, even if it does become an El Nino period. Troughs or no troughs, the Western Carribean is still toasty enough that if a moderate storm was to get through, it could still explode.  Plus, there's always the occasional home grown storm forming off the dying cold fronts in the Gulf of Mexico.

And remember...Andrew formed during an El Nino year. It only takes one.

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Quoting Tropicsweatherpr:


Yep,I posted it at 9:40 AM on page 23 but that is fine.
Agreed, because I hadn't seen it then and had actually forgotten it was supposed to be out today....

I'm supposing your page 23 would be page (23/4 + 1) for me... so page 6?
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Quoting HurrMichaelOrl:
I have just read Dr. Masters' most recent blog entry and I am wondering if any theories have been ventured as to the very large, low end (and with unusually low barometric pressure, relative to wind speed) hurricanes have been hitting the US recently? Is it most likely a coincidence or part of a natural qualitative variance (cycle) in storm activity? Climate change? Or might the US be engaging in some sort of cloud-seeding operation since, say, Hurricane Wilma in '05? Maybe cloud seeding could somehow result in larger canes with actual pressures closer to what the wind speed should have been naturally?

I also wanted to share my observation from this past Wednesday (8/29). I came to my car (I am north of Orlando) around 3:00 pm and noticed sand particles falling from the sky (there was a fine layer on the car too) as well as a very light drizzle. I thought it was either an isolated SAL-related event or somehow related to Hurricane Isaac. Either way, it is the first time I have ever observed sand falling from the sky.

Sounds like Isaac had SAL imprinted within his circulation.
Member Since: July 6, 2010 Posts: 113 Comments: 33295
Quoting HurrMichaelOrl:
I have just read Dr. Masters' most recent blog entry and I am wondering if any theories have been ventured as to the very large, low end (and with unusually low barometric pressure, relative to wind speed) hurricanes have been hitting the US recently? Is it most likely a coincidence or part of a natural qualitative variance (cycle) in storm activity? Climate change? Or might the US be engaging in some sort of cloud-seeding operation since, say, Hurricane Wilma in '05? Maybe cloud seeding could somehow result in larger canes with actual pressures closer to what the wind speed should have been naturally?

I also wanted to share my observation from this past Wednesday (8/29). I came to my car (I am north of Orlando) around 3:00 pm and noticed sand particles falling from the sky (there was a fine layer on the car too) as well as a very light drizzle. I thought it was either an isolated SAL-related event or somehow related to Hurricane Isaac. Either way, it is the first time I have ever observed sand falling from the sky.


O.o

That's weird.. never knew sand fell from the sky. :O
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12z GFS doesn't have the parade of CV systems that had at 06z. Only one tries to develop.
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Quoting catastropheadjuster:
I'm just wondering, if Leslie goes down in strength will she track more west? I mean if much left of here the trough want have very much influence on her then she would go more west right? Or is it no matter what she is going out to sea or toward Bermuda? I see where it looks like part of her is being pulled or something toward the North.

Sheri

It should be pulled northward regardless of its strengh. Here is the steering for a storm with a pressure above 1000 millibars.

Member Since: July 6, 2010 Posts: 113 Comments: 33295
I'm just wondering, if Leslie goes down in strength will she track more west? I mean if much left of here the trough want have very much influence on her then she would go more west right? Or is it no matter what she is going out to sea or toward Bermuda? I see where it looks like part of her is being pulled or something toward the North.

Sheri
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Quoting TropicalAnalystwx13:

The day he was designated as a tropical depression to the time he dissipated per by the HPC.

Isaac was active from August 21-September 1.


thanks for the clarification
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I have just read Dr. Masters' most recent blog entry and I am wondering if any theories have been ventured as to the very large, low end (and with unusually low barometric pressure, relative to wind speed) hurricanes have been hitting the US recently? Is it most likely a coincidence or part of a natural qualitative variance (cycle) in storm activity? Climate change? Or might the US be engaging in some sort of cloud-seeding operation since, say, Hurricane Wilma in '05? Maybe cloud seeding could somehow result in larger canes with actual pressures closer to what the wind speed should have been naturally?

I also wanted to share my observation from this past Wednesday (8/29). I came to my car (I am north of Orlando) around 3:00 pm and noticed sand particles falling from the sky (there was a fine layer on the car too) as well as a very light drizzle. I thought it was either an isolated SAL-related event or somehow related to Hurricane Isaac. Either way, it is the first time I have ever observed sand falling from the sky.
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Still waiting for a thirsty cane.

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Member Since: July 12, 2007 Posts: 0 Comments: 6069
Quoting sar2401:


If I'm not mistaken, Isaac had some flight level winds that were about 115 knots, and those never mixed down to the surface, even at landfall. In large storms with poorly defined centers, that may happen more often than not. I don't think we know enough about that kind of wind transport to include it in a rating scale with any confidence.

What seems to make sense to me is rating storms based on their total kinetic energy. The larger a storm is (in terms of area), how long it lasts from genesis to landfall, and the amount of water being pushed along with a storm, combined with wind speed, should alow us to come up with a total kinetic energy rating scale, which may be a better rating in terms of a storm's impact on land.


Actually I didn't word it as intended ... I meant to say that some of the flight level wind would get to the surface (not all of it). Perhaps this still is incorrect, maybe it would just be occasional gusts... but of course gusts do the most damage.

The kinetic energy rating -- you have seen the link I posted to the NOAA Ike scale page. The question I have about this is, how long does it take to calculate IKE? Are there situations where IKE will not be known for several hours because we don't have enough data to calculate it?

I like the idea of "integral kinetic energy", or maybe even better, TKO for "Total Kinetic Output." I was hoping there would be a simple way to guestimate that. Maybe based on the diameter of the tropical storm wind field multiplied by the overall wind speed.

Is there any study which shows how surge relates to longevity of a storm? I thought it would only relate to how many hours a strong storm existed in the 24 hours or so prior to landfall... the surge is not getting created until the final approach to the coast? (Of course, the shape of the coast has a lot to do with this too.)
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comeback.for.leslie.starting
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Don't tell me Leslie is pulling a Emily(2011) part two!.
Member Since: August 14, 2010 Posts: 10 Comments: 18673
Quoting wunderkidcayman:
looking on vis loop Leslie's LLCOC if full exposed and the overall LLC is nearly fully exposed starting to look like Chris (06) all over again
Good catch Cayman:

Visible loop shows the exposed center to the NW of the convectiom, interesting to see what happens later today if it can fire up new convection near the center.

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1256. wxmod
2 ships moving across the Arctic Ocean leaving clouds a thousand miles long. MODIS satellite photo.

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1255. K8eCane
so leslie will MORE THAN LIKELY follow the models. it just isnt SET IN STONE. Therefore we must find her not guilty :[
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Quoting HurrikanEB:
Regarding Isaac:

Will his official existence dates be from the day he was designated as a TD until the HPC stops advisories, or will it stop at when the NHC stopped their advisories?

Because on in the NHC monthly summery which was issued today, have his start date, but no end date. Even though the NHC stopped advisories on the 30th.

The day he was designated as a tropical depression to the time he dissipated per by the HPC.

Isaac was active from August 21-September 1.
Member Since: July 6, 2010 Posts: 113 Comments: 33295
Here's a good example of track uncertainty with Leslie:



As you can see, there is a preferred track shared by most of the ensemble members between 55 and 60 W with some variation in timing (one slow cluster to the S and one faster and further N). There's also minority clusters that trend both to the east and to the west toward the Eastern Seaboard, but so far these are less likely in the model space. Of course, this is a 204 H forecast so it and 4 bucks will get you a latte.
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looking on vis loop Leslie's LLCOC if full exposed and the overall LLC is nearly fully exposed starting to look like Chris (06) all over again
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1251. K8eCane
i dont see how leslie could miss that big old trough
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Regarding Isaac:

Will his official existence dates be from the day he was designated as a TD until the HPC stops advisories, or will it stop at when the NHC stopped their advisories?

Because on in the NHC monthly summery which was issued today, have his start date, but no end date. Even though the NHC stopped advisories on the 30th.
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Quoting K8eCane:



11 nhc advisory discussion talks about that
Oh ok thanks I see it now.
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1248. K8eCane
Quoting GTcooliebai:
12z GFS is a full 5 degrees west at 156 hrs. than the 06z GFS for Leslie.



11 nhc advisory discussion talks about that
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Quoting Tropicsweatherpr:


Oh boy,dont remind me of that fiasco as I didn't sleep that night.

hmm Leslie just may be your girl lol

Quoting GTcooliebai:
Wasn't Chris expected to become a hurricane?

as far as I remember it did

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MONTHLY TROPICAL WEATHER SUMMARY
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM PDT SAT SEP 01 2012

FOR THE EASTERN NORTH PACIFIC...EAST OF 140 DEGREES WEST LONGITUDE..

TROPICAL CYCLONE ACTIVITY IN THE EASTERN NORTH PACIFIC BASIN DURING
AUGUST WAS SOMEWHAT BELOW AVERAGE. THREE NAMED STORMS FORMED...TWO
OF WHICH BECAME HURRICANES...BUT THERE WERE NO MAJOR HURRICANES.
BASED ON A 30-YEAR AVERAGE FROM 1981 TO 2010...THREE TO FOUR NAMED
STORMS DEVELOP IN THE BASIN EVERY YEAR DURING AUGUST...WITH TWO
REACHING HURRICANE INTENSITY AND ONE BECOMING A MAJOR HURRICANE.

IN TERMS OF ACCUMULATED CYCLONE ENERGY...ACE...WHICH MEASURES THE
COMBINED STRENGTH AND DURATION OF TROPICAL STORMS AND HURRICANES...
ACTIVITY SO FAR THIS SEASON IS VERY CLOSE TO THE LONG-TERM AVERAGE
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Quoting Tropicsweatherpr:


When I mean fiasco,is the decoupuling.
Yeah I knew what you meant, I think some folks went to bed expecting a hurricane when they woke up.
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12z GFS is a full 5 degrees west at 156 hrs. than the 06z GFS for Leslie.
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Quoting GTcooliebai:
Wasn't Chris expected to become a hurricane?


When I mean fiasco,is the decoupuling.
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Quoting allancalderini:
Yep it was.
I bet everyone was shocked to what they woke up too.
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Quoting GTcooliebai:
Wasn't Chris expected to become a hurricane?
Yep it was.
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Quoting Tropicsweatherpr:


Oh boy,dont remind me of that fiasco as I didn't sleep that night.
Wasn't Chris expected to become a hurricane?
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Quoting GTcooliebai:

2006 TS Chris:



Oh boy,dont remind me of that fiasco as I didn't sleep that night.
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Quoting GTcooliebai:

2006 TS Chris:



mighta been it...
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Quoting Grothar:


This may be a good question to ask Bryan Norcross on his blog. The one thing I do remember that was different, is that it was an incredibly strong high which moved Andrew on an almost due west motion. I do not see that happening here.

Thank you for your responses.
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Quoting Unfriendly:
I remember a storm either last year or a few years ago... might have been Lee? Or Fay? Dunno.

Anyways, shear exploded it, and the MLC went one way, and the LLC went another, and stripped to her skivvies. Any chance of a MLC forming a LLC under it if this scenario occurs?

2006 TS Chris:

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Before I leave, I found something funny to post-

Anton Johnson: Tips for live coverage of minimal hurricanes.
1. Wear loose-fitting rain gear, preferably with an open hood to better accentuate wind gusts.
2. Stand with feet sholder width apart and knees bent. Lean torso and head into the direction of the wind for effect.
3. Use minimal wind-screen on microphone, speak loudly as if straining.
4. Position shot to include a fluttering small diameter palm, and a dilapidated structure with flapping corrugated metal.
5. Adjust light filter for gloomy effect.
6. Cut to animated overly-enhanced color radar during lulls.
7. Pan to blowing fronds, leaves and trash if possible.


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1234. Grothar
Quoting opal92nwf:
Does anyone have any thoughts, comparisons, etc. on my last comment?


This may be a good question to ask Bryan Norcross on his blog. The one thing I do remember that was different, is that it was an incredibly strong high which moved Andrew on an almost due west motion. I do not see that happening here.
Member Since: July 17, 2009 Posts: 71 Comments: 27378
I remember a storm either last year or a few years ago... might have been Lee? Or Fay? Dunno.

Anyways, shear exploded it, and the MLC went one way, and the LLC went another, and stripped to her skivvies. Any chance of a MLC forming a LLC under it if this scenario occurs?
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Quoting opal92nwf:
Does anyone have any thoughts, comparisons, etc. on my last comment?

I do see the similarities, but that low to the ESE of Bermuda, is it supposed to split off and retreat southwestward? And is the high pressure of the SE coast supposed to build back eastward? Would definitely be something interesting to keep an eye on.
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Quoting opal92nwf:
Does anyone have any thoughts, comparisons, etc. on my last comment?
I think, this is just my opinion, in order for this to happen we need high pressure to the northwest of it to build in from the east and a high over the northeast to develop and bridge the gap, these highs need to be strong too and no weakness to escape.
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1230. Grothar
Notice the high cirrus clouds to the Northeast of Leslie.

Member Since: July 17, 2009 Posts: 71 Comments: 27378
Does anyone have any thoughts, comparisons, etc. on my last comment?
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1228. Grothar
Quoting unknowncomic:
Wilma first formed in the middle carribean sea.


That is exactly where she formed. Took a few by surprise.

Member Since: July 17, 2009 Posts: 71 Comments: 27378
Quoting wunderkidcayman:

wow well sept oct and nov is our peak of hurricane season yep every country island and state had ist own peak in the season ours is in sept oct nov
Same here ours on the West Coast of FL. is during the 3rd week in Oct. That's when you get storms like Wilma and Tampa Bay Hurricane of 1921.
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Quoting seer2012:
Last night the shear forecast map showed an area of shear off to the NW.The storm track was heading right for it.It appears to have made contact with said shear.
I see Northwesterly Windshear, must be from the TUTT.

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Quoting GTcooliebai:
I don't know if anyone posted this already, but after Leslie the GFS shows 3 storms rolling off of Africa with one entering the Caribbean.


wow well sept oct and nov is our peak of hurricane season yep every country island and state had ist own peak in the season ours is in sept oct nov
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If the situation was any different with Leslie and her potential track, then I would not post this, but here it is-
National Hurricane Center Preliminary Report Hurricane Andrew

The depression was initially embedded in an environment of easterly vertical wind shear. By midday on the 17th, however, the shear diminished. The depression grew stronger and, at 1200 UTC 17 August, it became Andrew, the first Atlantic tropical storm of the 1992 hurricane season. The tropical cyclone continued moving rapidly on a heading which turned from west to west-northwest. This course was in the general direction of the Lesser Antilles.

Between the 17th and 20th of August, the tropical storm passed south of the center of the high pressure area over the eastern Atlantic. Steering currents carried Andrew closer to a strong upper-level low pressure system centered about 500 n mi to the east-southeast of Bermuda and to a trough that extended southward from the low for a few hundred miles. These currents gradually changed and Andrew decelerated on a course which became northwesterly. This change in heading spared the Lesser Antilles from an encounter with Andrew. The change in track also brought the tropical storm into an environment of strong southwesterly vertical wind shear and quite high surface pressures to its north. Although the estimated maximum wind speed of Andrew varied little then, a rather remarkable evolution occurred.....Significant changes in the large-scale environment near and downstream from Andrew began by 21 August. Satellite imagery in the water vapor channel indicated that the low aloft to the east-southeast of Bermuda weakened and split. The bulk of the low opened into a trough which retreated northward. That evolution decreased the vertical wind shear over Andrew. The remainder of the low dropped southward to a position just southwest of Andrew where its circulation enhanced the upper-level outflow over the tropical storm......And Later.... At the same time, a strong and deep high pressure cell formed near the U.S. southeast coast. A ridge built eastward from the high into the southwestern Atlantic with its axis lying just north of Andrew. The associated steering flow over the tropical storm became easterly. Andrew turned toward the west, accelerated to near 16 kt, and quickly intensified



^^^^^Does this map not look somewhat similar, there is a low/trough near Bermuda and the high pressure could bridge together with the one over the Southeast Coast of the US.
Now I know not everything is the same as in this situation, but very similar, and I don't know if the troughs were as strong during this time in August of 1992 as now, that would be interesting to know.
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Poll time:) Some of you guys have commented on how long it has been since the US has seen a major hurricane (7 yrs already) and have been talking about the persistent troughs and Texas death ridges protecting the East coast and Gulf coasts, respectively, from major strikes. I as well as some others believe while this is remarkable that we have held onto this pattern for so long, we are truly living on borrowed time. But now I am willing to propose a poll about our next major hurricane strike.
The next time a major hurricane makes a landfall in the United States will be....
(a) sometime in the remainder of the 2012 season
(b) 2013
(c) 2014
(d) 2015
(e) some other year after 2015

I will go with C. Here is why: It looks like based on some of the models, the East coast is in for some major troughs coming through that should protect us through the peak of this season and by the time we get to October, the developing El Nino should shut down the season early. By the time we get to 2013, full El Nino effects should be in place to keep that season in check. However, I noticed looking back at history, it seems like the midpoints of most decades have featured a return of major hurricane strikes (1954/55, 1965, 1974/75, 1985, 1995, 2004/05).
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Good morning...Leslie looks kind of ragged and there is plenty of dry air ahead of her.

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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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