Isaac approaching hurricane strength

By: Angela Fritz , 9:14 PM GMT on August 27, 2012

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Isaac is walking the line of hurricane status this afternoon after a hurricane hunter mission investigated the storm and found winds of 80+ mph with the SFMR instrument, which looks down at the surface from the plane and estimates what wind speeds are. This instrument has a notoriously rough time in doing so when there's heavy rain, and since the strongest winds were recorded coinciding with the strongest rain, you can imagine that this region of high wind speed could be suspect. The hurricane hunter mission is still in the storm, so I imagine they will issue a special update if needed. Currently the best estimate of wind speed within the storm is 70 mph. Isaac's pressure has been dropping today as well and is now 981 mb. Isaac is moving northwest at 12 mph--no change since this morning. Satellite loops show that Isaac remains large, though asymmetric, with most of the strong thunderstorm activity on the west and southwest side. Isaac's southeast side continues to struggle with dry air and wind shear, which could help to moderate Isaac's intensity as it approaches the coast.

An oil platform in the northern Gulf of Mexico is reporting sustained winds from the north-northeast at 40 mph this afternoon. A buoy west of Tampa, Florida is recording sustained winds around 30 mph, and platforms south of Louisiana are recording winds from 35-40 mph. The widespread heavy rain of yesterday has lightened up in Florida, but a strong line of thunderstorms in one of Isaac's outer bands is training northward along and offshore of the east coast of Florida, affecting everyone from Miami to Jacksonville.

This afternoon the AP reported that Isaac's death toll in Haiti jumped to 19, which puts Isaac's total death count at 21. It appears most of the deaths in Haiti were due to collapsing structures.


Figure 1. Satellite imagery of Tropical Storm Isaac around 3pm EDT on Monday.

Track forecast:
Models seem to be coming into better agreement today on where Isaac will make landfall, closing in on Louisiana and New Orleans as most likely landfall point. The ECMWF, HWRF, and UKMET all suggest New Orleans as the landfall location. The GFS is only slightly west of that. The GFDL is the farthest west, predicting landfall near the Louisiana-Texas border. Landfall timing remains Tuesday night. Beyond landfall, Isaac is expected to move north toward the Midwest through the rest of this week, however, models are showing that the system will likely slow down around landfall time, prolonging impacts like surge and inland flooding.

Intensity forecast:
The closer Isaac gets to landfall without having formed an eye, the better it is for intensity at landfall. Isaac has strengthened only modestly in the past 24 hours, and is still struggling with a less-than-conducive atmospheric environment. The HWRF remains on the high end of the intensity spectrum, suggesting Isaac will be a weak category 2 upon landfall. Other models suggest it will be a strong category 1, but the difference is splitting hairs. The National Hurricane Center's official forecast is for Isaac to continue strengthening over the next day, reaching category 2 at landfall.


Figure 2. Tide gauge data from St. Petersburg, Florida. The green line shows the storm surge. As Isaac's counterclockwise winds blew offshore this morning, water levels feel two feet at St. Petersburg. The winds switched to onshore this afternoon as the center of Isaac moved more to the northwest, bringing a storm surge of two feet to the city.

Storm surge observations from Isaac
This morning, as Isaac's counter-clockwise winds brought offshore winds to the Tampa/St. Petersburg area, ocean waters fell two feet along the coast. This afternoon, winds have shifted to blow onshore, and a two foot storm surge has been observed at Naples, Fort Meyers, and St. Petersburg on the west coast of Florida. Water levels have also begun to rise along the coast of Louisiana, with a storm surge of 1.5 feet already occurring at Shell Beach on the east side of New Orleans in Lake Borgne.

Angela and Jeff

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Quoting wxhatt:
Isaac is struggling with dry air intrusion or maybe something has been dropped into the NE quadrant?



Here is PROOF! News Article written yesterday hinting about the upcoming project for Isaac!

Link

Thanks for showing me the most ridiculous thing I've seen all year.
Member Since: July 6, 2010 Posts: 113 Comments: 31981
That is a pretty small eye for such a big feller,if it is indeed a eye.
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<
Member Since: July 4, 2005 Posts: 204 Comments: 8868
Quoting gulfcoastmom:
Ok, I am not an expert by no means, but was looking at some maps and radars. Is this thing moving north? Should those of us east of MS be concerned?


Recon clearly shows NW movement. As to how concerned you should be, I have no idea.
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Quoting AllyBama:
Good evening to all of the Mobilians on here tonight! Guess we are still watching and waiting..


Hey, Ally, in Montgomery here so not as tense. Depending on how close you are to the Bay, storm surge could be an issue. Other than that, the northeast quadrant is unusaully dry for this big a storm, so rain totals look to be a lot less than yesterday at this time. Not out of the woods but the situation looks a lot more hopeful that Isaac will not be a big event for Mobile.
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Quoting TreasureCoastFl:
As you should be. Prayers to you! Stay safe!


Thank you Treasure! We've done everything we can do to prep, now we watch, wait and pray for everyone in the path.
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Quoting sunlinepr:
Looks like it will never develop a defined Eye....

So weird looking. Like the right half went NE over Fl and the left half is still moving NW.
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Isaac is struggling with dry air intrusion or maybe something has been dropped into the NE quadrant?



Here is PROOF! News Article written yesterday hinting about the upcoming project for Isaac!

Link
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New recon is in the air, it should get out there soon to replace the current one... You really can't say enough about the job they do, not just with Isaac but with every storm that threatens land.
Member Since: February 11, 2012 Posts: 83 Comments: 7777
Finally wind has backed off in the keys, we had a good day and a half of wind rain and gusts. East coast a couple of days of wicked crap and still counting. Good luck to you all in the gulf states no matter were you are. The storm is big you are going to get wind rain surge. Get away from the coast. God bless you lot
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Quoting weatherh98:
Beer sales unusually big for a Monday, guess people have their priorities


Rouses in New Orleans has announced they have broken all previous liquor sales.
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Quoting ncstorm:
when I last left this blog, it was declared that Isaac would be a hurricane at the 5pm update, its now two updates later and Isaac is still the impossible dream..where is Susan Boyle when you need her..


Lol. Susan Boyle can sing to me all she wants. She has a beautiful voice.
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922. forecaster1 12:40 AM GMT on August 28, 2012

Exactly, for the last day and half, it has never made sense to me how the forecast models have this this busting through the steering that is in place. In fact the hpc showed their forecast and it had Isaac moving NW right into the trough; that makes no sense
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Looks like it will never develop a defined Eye before landfall... Although there is time, conditions are there.... Dry air everywhere...

Member Since: August 2, 2010 Posts: 21 Comments: 9814
Quoting BahaHurican:
But this isn't the crap... this is the good stuff...



well then take it too other blog
Member Since: May 21, 2006 Posts: 5091 Comments: 115069
Quoting TropicalAnalystwx13:
Well, um...



lets see if it holds..this is about the 5th eye thats tried!
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Seems like a lot of people are forgetting this still has 24 hours or so over water, maybe longer than that if landfall is in Mississippi. Isaac wasn't supposed to be a hurricane until now according to the NHC forecast.
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Quoting Tazmanian:



keep the politics crap off this blog
But this isn't the crap... this is the good stuff...
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Quoting moonlightcowboy:


I don't know what modeling makes up this chart, but I keep coming back to it for some reason.

I'm not a big modeling person although I totally admit their necessity as a great tool - improvement have been great, especially the past couple of years it seems. I'm an old school hobbyist with an interest in these storms since I was a boy with Camille. All of these tools are great! I watch sats, sfc maps, the other charting; but this time, this time, I've paid even less attention to the modeling and even less attention to the CIMSS steering charts. Those charts fooled me with Ernesto, so I omitted them this time.

With Isaac moving wnw/nwest this rain chart reflects, imo, Isaac's eventual route inland, as it points directly to the upper west end point of the 1016mb which ends at the tail of the shortwave trough that has deepened and now extends into TX towards Ohio. IMO, currently, this direction points to the weakest escape route for Isaac inland.

Now, I'm starting to get concerned about his forward speed and the plains high closing in. Starting to think an inland stall is quite likely.


"Hurricane Camille was the third and strongest tropical cyclone and second hurricane during the 1969 Atlantic hurricane season. The second of three catastrophic Category 5 hurricanes to make landfall in the United States during the 20th century (the others being 1935's Labor Day hurricane and 1992's Hurricane Andrew), which it did near the mouth of the Mississippi River on the night of August 17. Camille and unofficially the Labor Day Hurricane were the only Atlantic hurricanes to exhibit recorded sustained wind speeds of at least 190 miles per hour (310 km/h) until Allen joined the club in 1980, and remains the only confirmed Atlantic hurricane in recorded history to make landfall with wind speeds at or above such a level. The actual windspeed of Hurricane Camille will never be known, however, as it destroyed all of the wind recording instruments upon making landfall. By central pressure, in turn, Camille was the second strongest U.S. landfalling hurricane in recorded history, second only to the Labor Day Hurricane in 1935. It was also the first modern Category 5 hurricane to ever receive a person's name when making landfall in the United States."
-- From Wikipedia

If I went through Camille I would want to know what makes these things tick, too.
Interesting post MLC.
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Quoting GetReal:


Again pinhole dry spot.... Same as earlier...

I don't think so. There's dry air in there but I think that's an eye.
Member Since: February 11, 2012 Posts: 83 Comments: 7777
Quoting keithneese:


Good evening Ally. Nervous night here in Mobile.
As you should be. Prayers to you! Stay safe!
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Quoting aislinnpaps:


He is the commander in Chief and can make these decisions. I just wonder if he looked at the maps...

Commander in chief Pffft. To him, it's just a job perk.
What about family, do they get to go? I'm sorry. As a veteran, I find this asinine. If your 150 miles inland from say, Pensacola. why in God's name, would He want you to drive to the coast?
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Well, um...

Member Since: July 6, 2010 Posts: 113 Comments: 31981
He's a pretty big feller,isn't he? Isaac that is.
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when I last left this blog, it was declared that Isaac would be a hurricane at the 5pm update, its now two updates later and Isaac is still the impossible dream..where is Susan Boyle when you need her..
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927. Caner
Quoting Vipertec:



and this has what to do with the current weather situation? This blog has gone so far downhill.


Had more to do with the weather than your inane comment.

*POOF*
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926. FOREX
Quoting gulfcoastmom:
Ok, I am not an expert by no means, but was looking at some maps and radars. Is this thing moving north? Should those of us east of MS be concerned?


looks like it is going North to me, but many on this blog tell me that it is an illusion. So it probably isn't moving North.
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Quoting GBguy88:
Going to try and drive to Waveland, MS from Pensacola before conditions are too nasty to drive in...hoping to get some good footage of the eyewall.
Stay safe!
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Quoting AllyBama:
Good evening to all of the Mobilians on here tonight! Guess we are still watching and waiting..


Good evening Ally. Nervous night here in Mobile.
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Quoting MAweatherboy1:
Lol, eye just became very obvious on satellite.



Again pinhole dry spot.... Same as earlier...
Member Since: July 4, 2005 Posts: 204 Comments: 8868
Quoting shred3590:


Here is the reason for the LOL. The storm has been moving NW since the Keys. Current recon says NW movement. All of the models show NW movement to landfall. The NHC is forecasting continued NW movement. The steering layers call for NW movement until landfall, but some disagreement as to speed of advancement. In short, all knowledgeable sources say NW movement. You come in and say due north with absolutely no justification for your statement.

If you explain your comment with support from the available data, then you will get disagreement, but actual discussion. Off the wall statements with no support get LOLs.


The support is there. tell us how the storm will bust through the bondry to the north. The only thing if conditions stay the same is #1 storm stalls #2storm goes north then ne.
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Quoting GBguy88:
Going to try and drive to Waveland, MS from Pensacola before conditions are too nasty to drive in...hoping to get some good footage of the eyewall.
Good luck looking forward to the pics. We need/have to drive to Belle River or Gonzales LA this weekend. Let me know how it goes. I'm in Gulf Breeze.
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Lol, eye just became very obvious on satellite.

Member Since: February 11, 2012 Posts: 83 Comments: 7777
When the models were "bombing" out Isaac in the gulf they underestimated the dry air.
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Quoting trinigal:


Is this why every time I visit the site, I am bombarded with 'Vote Obama' ads? No political bias here, eh?


That would suggest something about your browsing habits, not the site's biases.
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Beer sales unusually big for a Monday, guess people have their priorities
Member Since: June 17, 2011 Posts: 11 Comments: 6487
Quoting TomballTXPride:

No eye. Not even close. Watch the loop back 30 frames. Still not convinced? Go back till 2 PM today. That's how much time I wasted with this storm.


He's had an eyewall today. His southern eyewall also had a huge convective burst earlier. It wouldn't take much for an eye to form.
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A tad more eastward movement from his 11am til 8pm location. Maybe from 305 to a 320 degree heading.Will need to keep an eye on it to see if it continues.
Sorry if it's been posted already,I am behind a bit.
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Quoting SrChiefFan1:


The son is spinning it to fuzz up his momma...there is no directive from POTUS... Still base commanders directive.


Well, then the base commander is. My son has no reason to.
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Quoting WeatherfanPR:
I think Isaac has just formed an eye !!!


I think your right!

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Quoting washingtonian115:
With the rate Isaac is going I don't think he'll ever be a hurricane.


It's gonna be close. As soon as it give the illusion it has started to get its act together, something goes wrong. It most probably will never hit Cat2, which is good. Still going to suck back for that area if it stalls out however.
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Pinhole dry air spot????
Member Since: July 4, 2005 Posts: 204 Comments: 8868
Quoting leelee75k:


looks like the blob that was Isaac's east side broke off and is now off the east coast of Florida. I notice that the clouds in South Florida are no longer racing to the Northwest. Not sure if he will be able to wrap any of that up into his circulation.
He's been needing to shuck that since he was south of Hispaniola. Maybe the "much anticipated" ramp up will actually happen this time...
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Ok, I am not an expert by no means, but was looking at some maps and radars. Is this thing moving north? Should those of us east of MS be concerned?
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Quoting aislinnpaps:


As I said, this just came down this morning.


Active duty here...This just not make any sense!..Obviously the conditions don't warrant a mass evac...they have to pay for gas, lodging, per diem...full for adults half for kids, and mileage on the vehicle, so I understand why they won't evac everyone but...neither Hulburt Field nor Eglin AFB really have the facilities to house all military members and their dependents. Literally, they do not..lol I guess stick everyone up in hangers at Duke Field
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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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