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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Chance of precipitation is 80% now in WPB!!! :/ no
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Water vapor images from GEOS-14 shows that dry air began disrupting the core again around 10:30am est, giving the NHS good reason not to upgrade to a hurricane.

LINK

However the storm's northward jog has caused a large increase in wind speed the buoy on the southern tip of the mississippi delta:

LINK

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Quoting Patrap:
Allison..still the Only Tropical Storm to have been Retired.

It dosent have to be a Major for the er, Impact to be deadly. It only has to Linger


Yup. I found out the hard way. Come back to GLP so we can make fun of you.
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Quoting jpsb:

Look at the huge expanding band of dry air to his north. I wonder where that is coming from? Must be sinking air from high in the atmosphere, bad news for Issac, good news for the gulf coast.


Considering the bad situation for NOrleans, feel good to see that we don't have a Katrina or one of the Cat3 or more posted here two nights ago... by comparing models....
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To all of you advocating objectivity, rationality and sensibility:

Isn't it a little early for y'all to be drinking so heavily?!
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Quoting Neapolitan:
I'm not quite sure why some seem to be upset that Isaac hasn't been officially classified as a hurricane. After all, people living in and around New Orleans aren't going to be able to tell the difference between a 64-knot tropical storm and a 65-knot hurricane; any damage that occurs will occur whether or not Isaac's map symbol is hollow or filled in; the winds will be just as windy and the rains will be every bit as wet whether landfall is made by Tropical Storm Isaac or Hurricane Isaac. And the families of those lost to Isaac on Hispaniola probably don't feel any less sense of heartbreak just because their loved ones were killed by a tropical storm and not a full-fledged hurricane.

It may help to keep this in mind: the hurricane classification is a man-made and arbitrary one; the cyclone spins on and does what it does regardless of what we call it.


I think you're about to set the blog record for most (+) with this comment.

Your Stephanie Abrams comment yesterday was right-on as well.
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Quoting Bluestorm5:
How the heck that's not a hurricane yet? Ugh... hopefully my school ends sooner, but that's two hours away.

Exactly, later today then it should be a hurricane. Still going to have the same impacts from Isaac.
Member Since: March 16, 2012 Posts: 123 Comments: 7887
3697. Patrap
Quoting cheaterwon:
I have to leave Houston tomorrow morning to be in Jacksonville Florida by 7am for a State Farm assignment. Do you all think I-10 will be okay to travel tomorrow? I didn't think about driving through the storm before excepting the assignment.


I-12 is a much better Route as its N of Lake P.

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3696. WxLogic
I see NHC kept it at 70MPH. Based on the discussion dry air still at it.

Like I mentioned before... it might try again to regenerate a well defined eye, but I do believe it will be the last attempt.
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3695. sar2401
Quoting Terradad:



My thoughts exactly!


No. They upgrade based on measurable data. They don't do it so people will take it seriously. Do you think anyone who knows Isaac is at 70 mph and not taking it seriously will suddenly start to prepare 12 hours before landfall if it was 75 mph? All the watches and warnings have been up for days. Those who paid attention are in good shape. For the others, well, you can't cure stupid, even if was a cat 5.
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Quoting Matt74:
What's with the Reed and Cybr teddy bashing? Two good informative bloggers IMO .


Haters going to Hate....some were after Taz last night..

I guess their "Ignore" doesn't work or they just are trying to pad their comments....I love the newbie that registered Aug 19th and already has nearly 500 comments. Must be trying for a prize...
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Quoting Patrap:


Well, Henry's Bar on Magazine St. is Open, so that could be a factor.


Wonder if soul food cafe is open off magazine...

man i love that place!
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Quoting MississippiWx:


HA. They'll come up with some other excuse. Meanwhile, the Louisiana coast will be getting pounded by those hurricane force winds mixing down to the surface from land friction.


The forecast is still a hurricane at landfall and west of NOLA. That is what we are prepared for.
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Quoting Neapolitan:
I'm not quite sure why some seem to be upset that Isaac hasn't been officially classified as a hurricane. After all, people living in and around New Orleans aren't going to be able to tell the difference between a 64-knot tropical storm and a 65-knot hurricane; any damage that occurs will occur whether or not Isaac's map symbol is hollow or filled in; the winds will be just as windy and the rains will be every bit as wet whether landfall is made by Tropical Storm Isaac or Hurricane Isaac. And the families of those lost to Isaac on Hispaniola probably don't feel any less sense of heartbreak just because their loved ones were killed by a tropical storm and not a full-fledged hurricane.

It may help to keep this in mind: the hurricane classification is a man-made and arbitrary one; the cyclone spins on and does what it does regardless of what we call it.


I agree, but I think it might matter for insurance reason? Maybe? Not sure but I can see that being the case with the way insurance companies love to dodge actually paying out for things.
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lots.of.surfers.in.el.salvador..best.time.of.the.yr
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3689. ncstorm
Quoting AtHomeInTX:


Yeah, I've had to be talked off that ledge a time or two myself. lol. I find sleep helps tremendously with patience.


LOL..this season in tropical forecasting has debunked a lot of experts..its a tough job for them and they can have it
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3688. Patrap
For the record..

Storms don't have Ear's nor wi-fi last we looked.

Impact counts, not any, er,..."Phrasing".



ISAAC RainbowTop Loop


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The weeping and wailing and blaming the NHC this morning is hilarious. Reminds me of that time in kindergarten where one kid spilled his chocolate milk on another kid's blankie...

Quoting CJ5:
LOL I see a lot of people that needed to be talked away from the ledge. The NHC just got removed from a lot of xmas card lists.

If you were being objective and looking at all of the data you would see that he just has not been able to sustain enough energy to be named a hurricane. He has never been able to close off the eye. He has looks no better than he did 4 days ago. The only change in the past 4 days is a pressure drop. The winds just never caught up and he was never able to spin up tight enough. This is good news to those in his path.
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Quoting wxchaser97:

Hey Blue, HH found 100mph flight level winds, 81mph surface winds from the dropsonde, and 976-975mb pressure. My school doesn't ban WU as well.
How the heck that's not a hurricane yet? Ugh... hopefully my school ends sooner, but that's two hours away.
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Quoting Patrap:


Thats the eye well kindof
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Quoting MississippiWx:


Eating crow has to be the most overused/annoying phrase on this blog. And no, I will not. I stick by my statement.


A close second is "NHC will make it a Hurricane in their 10AM update"
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Quoting nrtiwlnvragn:
Interpretation of dropsonde at NHC








This is good info, so thanks. I knew that they would like to see the average over the boundary layer, but if you do that this is still a HU.

Slight kink, but a much higher wind speed bulge just above.


For those interested:

See below, select 12:25UTC reading at the top

Dropsonde Report
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Product: NOAA Vortex Message (URNT12 KWBC)
Transmitted: 28th day of the month at 15:08Z
Aircraft: Lockheed WP-3D Orion (Reg. Num. N42RF)
Storm Number & Year: 09L in 2012
Storm Name: Isaac (flight in the North Atlantic basin)
Mission Number: 30
Observation Number: 34
A. Time of Center Fix: 28th day of the month at 14:35:33Z
B. Center Fix Coordinates: 27°59'N 88°33'W (27.9833N 88.55W)
B. Center Fix Location: 165 miles (266 km) between the SE and SSE (146°) from New Orleans, LA, USA.
C. Minimum Height at Standard Level (Undecoded): NA NA
D. Estimated (by SFMR or visually) Maximum Surface Wind: 60kts (~ 69.0mph)
E. Location of the Estimated Maximum Surface Wind: 13 nautical miles (15 statute miles) to the WSW (254°) of center fix
F. Maximum Flight Level Wind Inbound: From 312° at 59kts (From the NW at ~ 67.9mph)
G. Location of Maximum Flight Level Wind Inbound: 54 nautical miles (62 statute miles) to the SW (233°) of center fix
H. Minimum Sea Level Pressure: 980mb (28.94 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 14°C (57°F) at a pressure alt. of 2,446m (8,025ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 19°C (66°F) at a pressure alt. of 2,437m (7,995ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 16°C (61°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Poorly Defined
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: Other - Not surface, 1500ft, 925mb (if vortex is newer than about mid 90's; see note for more), 850mb, 700mb, 500mb, 400mb, 300mb or 200mb
Remarks Section:
MAX OUTBOUND FL WIND AND MAX FL WIND 90 KT E QUAD 14:50:00Z
SEC MAX FL WIND 68 KT BRNG:43 deg RNG:96 nm
SLP EXTRAP FROM 8k ft
Member Since: May 21, 2006 Posts: 5089 Comments: 114066
Quoting Matt74:
What's with the Reed and Cybr teddy bashing? Two good informative bloggers IMO .


No one is bashing anyone, but to come on here and down-trod others as not being "mets" while missing the forecast repeatedly aka..won't get past 85W.., or having a 1400-mide wide cone at 5-days is noteworthy.

And then to insult the NHC for not hyping a 70 mph storm is the icing on the cake.
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3680. jpsb
Quoting sunlinepr:



Look at the huge expanding band of dry air to his north. I wonder where that is coming from? Must be sinking air from high in the atmosphere, bad news for Issac, good news for the gulf coast.
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Quoting ncstorm:


athome, you sound like you trying to talk people off the ledge..LOL..patience is wearing thin on this blog..


Yeah, I've had to be talked off that ledge a time or two myself. lol. I find sleep helps tremendously with patience.
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I have to leave Houston tomorrow morning to be in Jacksonville Florida by 7am for a State Farm assignment. Do you all think I-10 will be okay to travel tomorrow? I didn't think about driving through the storm before excepting the assignment.
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Quoting Bluestorm5:
What's going on with the storm? I'm on computer at school (at least WU is not banned...)

Hey Blue, HH found 100mph flight level winds, 81mph surface winds from the dropsonde, and 976-975mb pressure. My school doesn't ban WU as well.
Member Since: March 16, 2012 Posts: 123 Comments: 7887
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 28th day of the month at 15:09Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 306)
Storm Number & Year: 09L in 2012
Storm Name: Isaac (flight in the North Atlantic basin)
Mission Number: 31
Observation Number: 12
A. Time of Center Fix: 28th day of the month at 14:26:40Z
B. Center Fix Coordinates: 27°59'N 88°35'W (27.9833N 88.5833W)
B. Center Fix Location: 164 miles (264 km) to the SSE (147°) from New Orleans, LA, USA.
C. Minimum Height at Standard Level: 1,217m (3,993ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 53kts (~ 61.0mph)
E. Location of the Estimated Maximum Surface Wind: 38 nautical miles (44 statute miles) to the S (188°) of center fix
F. Maximum Flight Level Wind Inbound: From 283° at 61kts (From the WNW at ~ 70.2mph)
G. Location of Maximum Flight Level Wind Inbound: 42 nautical miles (48 statute miles) to the S (187°) of center fix
H. Minimum Sea Level Pressure: 976mb (28.82 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 19°C (66°F) at a pressure alt. of 1,525m (5,003ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 20°C (68°F) at a pressure alt. of 1,524m (5,000ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 20°C (68°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind: 89kts (~ 102.4mph) in the northeast quadrant at 13:17:00Z
Sea Level Pressure Extrapolation From: 850mb
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Quoting sunlinepr:
That's an Eye??




Hard to tell anymore could be some more dry air but it sure looks like one to me
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Has the Army Corps closed the big structure gates they built to stop storm surge? It would be cool to see those in action!
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3673. mbar62
Quoting prweatherwatcher:


They are completly wrong, there is not doubt that Isaac is now a Hurricane...


It's not a hurricane and is deteriorating on satellite. I seriously doubt it will achieve hurricane strength before landfall due primarily to dry air entrainment. We should all be rather happy about that.
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Quoting kidd5433:


Correct me if I'm wrong but building codes in NOLA call for windows that can withstand more than a Cat-1 force winds right?



not sure dont live in NOLA so i would not no that ask pat
Member Since: May 21, 2006 Posts: 5089 Comments: 114066
3671. Patrap
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Quoting SFLWeatherman:
Wellington on 8/28/12


What a flood and it extends to at least FT. Pierce.
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Quoting Patrap:


Well, Henry's Bar on Magazine St. is Open, so that could be a factor.


Ahh, I knew those antennas in Bourbon Street were strange....
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Quoting reedzone:
You know what Bob, I've had alot of respect for you, watched your videos and you have the nerve to make that statement.. Your not a MET, your a bully.. I did NOTHING to you and start bullying me on here. That's not professorial sir.


Says the guy with the "won't pass 85W" Isaac prediction and "1400 mile wide 5-day cones" last year.

I think the intensity forecast hurt the track forecast, because a stronger storm would have turned north by now.

Just my opinion.
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Quoting sunlinepr:
That's an Eye??




no, another dry slot.
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3666. sar2401
Quoting AllStar17:
I'm not sure if I really get that flight level winds of 100 mph or above aren't translating to at least 74 mph at the surface.


Because the flight level winds aren't reaching the surface due to the lack of a closed eye and the ever present dry air. Surface winds are extrapolated after removing contamination for rain also. Isaac may finally become a cat 1 just before landfall or he may remain a strong TS. The difference in actual effects on the ground are trivial. Props to the NHC for reporting the facts based on the science we have available. Given the fact they've been saying a hurricane for the last 5 days, they aren't playing CYA.
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Quoting CJ5:
LOL I see a lot of people that needed to be talked away from the ledge. The NHC just got removed from a lot of xmas card lists.

If you were being objective and looking at all of the data you would see that he just has not been able to sustain enough energy to be named a hurricane. He has never been able to close off the eye. He has looks no better than he did 4 days ago. The only change in the past 4 days is a pressure drop. The winds just never caught up and he was never able to spin up tight enough. This is good news to those in his path.
Yes! And I for one am grateful...
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Quoting sunlinepr:
Maybe the Highest winds are 74.99999 mph so it will never achieve hurricane status...

Just, maybe! Maybe!
They are refraining from the upgrade as it will reduce the panic mode by a few percent and that will in turn reduce all the associated problems with the panic mode.
As its going to continue at about the level it is now for another day or so they can always upgrade it later and claim "afterthought" Happened before.
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Quoting Felix2007:
Can't they just upgrade it to hurricane just so that people will take it seriously???



My thoughts exactly!
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Quoting AllStar17:
I'm not sure if I really get that flight level winds of 100 mph or above aren't translating to at least 74 mph at the surface.

I'm trying to think of why they aren't but not much comes to mind. Some people could be in for a surprise with a hurricane coming ashore.

Quoting MississippiWx:


HA. They'll come up with some other excuse. Meanwhile, the Louisiana coast will be getting pounded by those hurricane force winds mixing down to the surface from land friction.

Don't even mention that:) Some people here would get really mad if that happens.
Member Since: March 16, 2012 Posts: 123 Comments: 7887
Not only does NHC bust the forecast, now they bust the "now" cast.

Lol.

It was going Big Bend area for center line 36 hours ago, and now it's SW of NOLA.


It's inside my cone from 8 days ago...
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Quoting Tazmanian:
there nothing boarded up in down town New Orleans, LA there is going too be a lot of windows blowing out on the higher levels


Yup, just because the winds haven't gone down to surface level doesn't mean it doesn't get more fun the higher up one goes...
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Quoting JeffM:
Did anyone just see the guy on TWC in NOLA acting like he was having a hard time standing straight up due to the wind while folks were walking by him with zero issues?


I was just laughing at that. Reminds me of the broadcast from Irene where the kids were goofing around in the background while the guy was trying to show how severe the storm was.
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I'm not quite sure why some seem to be upset that Isaac hasn't been officially classified as a hurricane. After all, people living in and around New Orleans aren't going to be able to tell the difference between a 64-knot tropical storm and a 65-knot hurricane; any damage that occurs will occur whether or not Isaac's map symbol is hollow or filled in; the winds will be just as windy and the rains will be every bit as wet whether landfall is made by Tropical Storm Isaac or Hurricane Isaac. And the families of those lost to Isaac on Hispaniola probably don't feel any less sense of heartbreak just because their loved ones were killed by a tropical storm and not a full-fledged hurricane.

It may help to keep this in mind: the hurricane classification is a man-made and arbitrary one; the cyclone spins on and does what it does regardless of what we call it.
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That's an Eye??


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Quoting Tazmanian:
there nothing boarded up in down town New Orleans, LA there is going too be a lot of windows blowing out on the higher levels


Correct me if I'm wrong but building codes in NOLA call for windows that can withstand more than a Cat-1 force winds right?
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All times in GMT. Derived from NHC_ATCF data for TropicalStormIsaac for 28August12pm
27Aug.06am , 24.9n83.7w
27Aug.12pm , 25.8n84.8w , 312.2*NW @ 24.8km/h (15.4mph) 13.4knots , 55knots , 987millibars , TS
27Aug.06pm , 26.1n85.9w , 287.0*WNW@19.2km/h (11.9mph)10.4knots , 60knots , 984millibars , TS
28Aug.12am , 26.7n86.5w , 318.1*NWest @ 14.9km/h (9.3mph) 8.0knots , 60knots , 981millibars , TS
28Aug.06am , 27.4n87.7w , 303.4*WNW @23.7km/h(14.7mph)12.8knots , 60knots , 978millibars , TS
28Aug.12pm , 27.8n88.2w , 312.0*NWest @ 11.1km/h (6.9mph) 6knots ,_, 60knots , 976millibars , TS
2TA5-PortO'Connor :: HUM-Houma :: KAXO-GrandIsle :: 17LA-Venice :: 5LA6-SouthwestPass,MississippiRiver :: EYW-KeyWest

The kinked line is TS.Issac's path on its 6th day as a TropicalStorm
The southeasternmost dot on the longest straight line is TS.Isaac's most recent position

The longest line is a straightline projection through TS.Isaac's 2 most recent positions to its closest approach (within 18miles or 29kilometres) to an inhabited coastline
27Aug.12pm: TS.Isaac had been headed for passage over Venice,Louisiana (middle,17LAblob)
27Aug.6pm: TS.Isaac had been headed for passage over Seadrift(PortO'Connor)Texas (not shown)
28Aug.12am: TS.Isaac had been headed for passage 7.6miles(12.3kilometres)NEast of Venice (top,17LAblob)
28Aug.6am: TS.Isaac was heading for a 9:30pm passage 17.8miles(28.7kilometres)SSWest of Dulac,Louisiana (bottom,nearHUMdumbbell
28Aug.12pm: TS.Isaac was heading for a 29Aug.9:29am passage over GrandIsle,Louisiana in ~[]hours from now (when this was posted) after passing 11.5miles(18.5kilometres)SWest of the E8TankBattery near the SouthwestPass shipping entrance/exit for the MississippiRiver

Copy&paste hum, 29.382n90.714w-29.161n90.868w, kaxo, 5la6-28.894n89.436w, 17la-29.268n89.322w, 17la-29.347n89.263w, 24.627n82.873w, eyw, 23.9n81.5w- 24.0n82.5w- 24.9n83.7w- 25.8n84.8w- 26.1n85.9w, 26.1n85.9w-26.7n86.5w, 26.7n86.5w-27.4n87.7w, 27.4n87.7w-27.8n88.2w, 27.4n87.7w-29.215n90.022w, 5la6-28.825n89.513w into the GreatCircleMapper for a larger map and other information
The previous mapping for comparison
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3654. Patrap
Tropical Storm ISAAC Public Advisory

Home Public Adv Fcst Adv Discussion Wind Probs Graphics Archive

US Watch/Warning

000
WTNT34 KNHC 281458
TCPAT4

BULLETIN
TROPICAL STORM ISAAC ADVISORY NUMBER 30
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
1000 AM CDT TUE AUG 28 2012

...ISAAC STILL JUST BELOW HURRICANE STRENGTH AS IT CONTINUES
NORTHWESTWARD...


SUMMARY OF 1000 AM CDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...28.1N 88.5W
ABOUT 80 MI...125 KM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 165 MI...260 KM SE OF NEW ORLEANS LOUISIANA
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...976 MB...28.82 INCHES


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

THE HURRICANE WARNING HAS BEEN REPLACED WITH A TROPICAL STORM
WARNING FROM THE MISSISSIPPI-ALABAMA BORDER EASTWARD TO DESTIN
FLORIDA.

THE TROPICAL STORM WARNING HAS BEEN DISCONTINUED EAST OF DESTIN.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

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

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

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

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

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

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

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

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

FOR STORM INFORMATION SPECIFIC TO YOUR AREA INCLUDING POSSIBLE
INLAND WATCHES AND WARNINGS...PLEASE MONITOR PRODUCTS ISSUED BY
YOUR LOCAL NATIONAL WEATHER SERVICE FORECAST OFFICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1000 AM CDT...1500 UTC...THE CENTER OF TROPICAL STORM ISAAC WAS
LOCATED NEAR LATITUDE 28.1 NORTH...LONGITUDE 88.5 WEST. ISAAC IS
MOVING TOWARD THE NORTHWEST NEAR 10 MPH...17 KM/H. A NORTHWESTWARD
MOTION AT A SLIGHTLY SLOWER SPEED IS EXPECTED OVER THE NEXT DAY OR
TWO. ON THE FORECAST TRACK...THE CENTER OF ISAAC SHOULD REACH THE
COASTLINE OF SOUTHEASTERN LOUISIANA AS EARLY AS THIS EVENING.

MAXIMUM SUSTAINED WINDS ARE NEAR 70 MPH...110 KM/H...WITH HIGHER
GUSTS. ISAAC IS EXPECTED TO BECOME A HURRICANE BEFORE MAKING
LANDFALL...AND BEGIN TO SLOWLY WEAKEN AFTER THAT.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 185 MILES...295 KM
FROM THE CENTER.

THE LATEST MINIMUM CENTRAL PRESSURE REPORTED BY HURRICANE HUNTER
AIRCRAFT WAS 976 MB...28.82 INCHES.


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

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

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

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

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

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

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


NEXT ADVISORY
-------------
NEXT INTERMEDIATE ADVISORY...100 PM CDT.
NEXT COMPLETE ADVISORY...400 PM CDT.

$$
FORECASTER STEWART
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.