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 depalma13:


If the levees break, than New Orleans should be abandoned forever. This is a Tropical Storm/barely Cat 1 Hurricane. It is not a life or death situation. It's time for everyone to stop panicing because of a little water and and wind.


A TS or Cat 1 is not life or death? I'm guessing the people that already died as a result of this storm would beg to differ with your ill informed commentary. People like you are why I stopped coming to this blog.
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if you guys learn how too ues the ignore tools on here you can ignore all the dry air caster and make this blog a marh better place too blog
Member Since: May 21, 2006 Posts: 5091 Comments: 115074
3352. sar2401
Quoting TomballTXPride:

Exactly. And MS and AL likely will get severe impacts and perhaps even more rainfall out of this.


Well, it's sure not happening in AL. Had one squall line earlier today that dropped .16 of an inch. The rainbands coming off Issac look puny so far. We'll take some more rain if we can get it but it sure doesn't look like a major event for AL right now.
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Quoting reedzone:


NO ONE not even the NHC is taking Isaac seriously and lives will be lost.


The NHC is taking this plenty seriously.. if the news is disregarding the massive storm surge potential that's their fault.
SOUTHEAST LOUISIANA AND MISSISSIPPI...6 TO 12 FT

I've seen major hurricanes with that storm surge potential before.
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WPTV Live Video of WPB!!
Link
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It did get a little more western wobble not much but then again it dont take much does it

GOES GVAR sensor depicting the low cloud conditions

Link
Member Since: August 23, 2008 Posts: 0 Comments: 1918
3346. divdog
Quoting reedzone:


NO ONE not even the NHC is taking Isaac seriously and lives will be lost.
U ought to be banned for that statement mr won't pass 85w. Thai is ridiculous statement. Shame on u
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3345. Patrap
Earlier..

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3344. Michfan
I think this storm is going to teach us a lot of lessons once it is all said and done. Hopefully we will realize as well how lucky we were that this didn't blow up.
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Copious amount of weather porn here.
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3342. JasonRE
Quoting hurricanehanna:
Hey JasonRE - just saw this posted in the Advertiser's site:

Lafayette Consolidated Government is activating four sandbag sites today. The sites will open by noon and are at the following locations:
-LCG North District Barn 130 Shantel Road (old landfill)
-LCG South District Barn 1017 Fortune Road
-George Dupuis Center (Brown Park) 1212 E. Pont Des Mouton Road
-Robichaux Center (Neyland Park) 1919 Eraste Landry Road
Sand and shovels will be provided a these locations and residents will be required to fill their own bags (self-service). Lafayette Consolidated Government will provide the bags.


Thanks! I just got that info from a co-worker. Guess I will be here while the wife fights off water! I can't believe we're open tomorrow!
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Quoting reedzone:


NO ONE not even the NHC is taking Isaac seriously and lives will be lost.

From 8AM:

..SIGNIFICANT STORM SURGE AND FRESHWATER FLOOD THREAT TO THE NORTHERN GULF COAST..
Member Since: August 1, 2012 Posts: 0 Comments: 436
Quoting Levi32:


Yes, the turbulent mixing brings downbursts to the surface. This is why I am somewhat dumbfounded. Never have I seen 976mb, 85kt flight-level winds, and no hurricane. If they don't upgrade from the dropsonde 70kt observation, I won't know what to say.


Rick Knabb....
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Quoting RTSplayer:
Anyone know if it's actually raining in the greater NOLA area? or is the radar just out to lunch?

I ask because radar shows some light showers approaching my location.


I figure between the cable company, Intergy,and my own house, it's only a matter of time now before something breaks and I won't be on here any longer.

But maybe you NOLA people lose power first so I'll know ahead of time if the post rate drops to nothing.


Yes.

Bourbon Street Cam:
Link
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Quoting NGCSTSKS:
Found a cam of downtown NO and they are just walking around, Looks like its raining though


Did you expect to see wide spread panic in the streets?
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3337. emcf30
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3334. 7544
Quoting Wxouttacontrol:


I don't live there but here is a local news live feed

Link


thanks
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Quoting notifbutwhen:
Is it me, or does anyone else feel that they may not be taking the storm surge potential serious enough?

My concerns are especially for the non-levee protected areas. The average everyday people may have a false sense of security due to Isaac not making hurricane status in these final hours.

BTW - I'm from FL. Not a wish-caster...


NO ONE not even the NHC is taking Isaac seriously and lives will be lost.
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Quoting windwave:
and after this storm peters out i guess we can all look forward to the blog masters's fascinating "it's hot" posts. oh wait it's almost september. what ever WILL he write about lol


You know, every where you go, there's always an A hole.
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3331. Melagoo
... well we all know that DRY AIR can really impede on the development of any storm I don't think Isaac will be a Hurricane ... but a very impressive Tropical storm ... like the guy in New Orleans they interviewed said "It's just a big Thunder Storm" ... maybe they should remind him that it can still flood and spawn Tornados ... stay safe all affected!
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3329. Levi32
Quoting MississippiWx:
Land friction will also help a lot of these hurricane force winds mix down to the surface. With flight level winds in excess of 100mph, Isaac should easily be a hurricane at the 10am update.


Yes, the turbulent mixing brings downbursts to the surface. This is why I am somewhat dumbfounded. Never have I seen 976mb, 85kt flight-level winds, and no hurricane. If they don't upgrade from the dropsonde 70kt observation, I won't know what to say. That is the most tangible data you can get from a recon.
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Couldn't have picked a worse time to strengthen. Stay safe everyone, praying for the best.
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3326. Patrap
Quoting Tazmanian:



i hop you are all boarded up pat with the windows so i would be get the last few things done why you can then chating here on the blog lasting time


Yes indeed Taz..just completed the last of all that and the rain has started my friend.

Will update here when we can..until we cant.

Im on first watch as 2 are Sleeping as this is going to be a LONG event.

A weather Alert Radio is a MUST as that's the fastest way to get TVS warnings real time.

Thanks for the concern Taz.

NOLA is ready..

Our motto,,,mostly heard among us Local's..wide and far,

"Never Again".


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Quoting FelixTheKat:


he eating massive amounts of dry air as we speak.


Go play at the playground kid
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Quoting windwave:


lol. i wouldnt take much of anything "Cyberteddy" says too seriously.


I wouldn't take anything with someone with two posts seriously either :)

Also, it's "CybrTeddy" buddy, not "Cyberteddy", need glasses?
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Is it me, or does anyone else feel that they may not be taking the storm surge potential serious enough?

My concerns are especially for the non-levee protected areas. The average everyday people may have a false sense of security due to Isaac not making hurricane status in these final hours.

BTW - I'm from FL. Not a wish-caster...
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Quoting Patrap:
Never be concerned about "landfall"..as at that time the Storm is fully half inland with effects already occurring Hours before that misused TERRIBLE wording.

My strongest objection always stated.

And a Fact.

So naaaaaaaaa.

: )


Nice call their Patrap
Member Since: August 23, 2008 Posts: 0 Comments: 1918
well look at that, the "eye" which I called a dry spot was in fact....a dry spot. It was obvious, the bloody thing was ROTATING around the COC, eyes don't rotate around the COC (exception for Wilma, that was bizarre). Isaac does have an eyewall, but it is only partial and may never clear out. The convection on the north side is too fragile and until Isaac builds a buffer against the dry air to the north, it will never complete an eyewall. Considering how close the coast is now to the north, I'm doubtful if it will ever complete it.

So what have we learned? Wait for more than a couple frames of sat imagery before jumping to conclusions and perhaps, don't jump on other bloggers for stating their opinion when you yourself have no more education (or this case, most likely less) than they do on the subject.
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Quoting FelixTheKat:


im doubt that his winds are still as strong he looking alot worse now. people seem to forget that the does this all the time starts to look better then he eat more dry air


Worse???


That's a Hurricane!
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Quoting FelixTheKat:


he eating massive amounts of dry air as we speak.
Frame-by-frame forecasting will get you nowhere.
Member Since: August 1, 2012 Posts: 0 Comments: 436
Quoting FelixTheKat:
isaac starting to look rather poor again.

dry air is once again destroying his little core lol. thank goodness he is such a pathetic little system.



does not matter much now,the surge has already built up and has to go somewhere.
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Quoting dogsgomoo:
You know... I'm not that old but I recall a time when live weather events and emergency news preempted most commercials and regular programming. But i guess when you're TWC and you want to treat everything as if it was an emergency and Cat 42 equivalent (complete with dramatic music) you'd never air another commercial again. ;)


You kidding?? This is TWC's money making time. Their ad buy costs go up dramatically when there's a significant weather event because they've got a lot of eyeballs watching, and they'll run as many as they can fit in.
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Land friction will also help a lot of these hurricane force winds mix down to the surface. With flight level winds in excess of 100mph, Isaac should easily be a hurricane at the 10am update.
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3314. GetReal



Isaac looks like he wants to come out of his shell and play.
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Quoting windwave:
another epic embarrassment for the weather establishment. the moment they wrote off the storm in Southeast Florida, it began to rain massive amounts, the wind increased, tornadoes formed and roads were flooded, and this went on for almost 24 hours. The question is not are they wrong in their current forecast, but in what manner they are wrong. sad really.


Didn't they have pretty much continuous Tornado Watches for south florida?
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-64kts and 50kts eye wall on the short range radar.


This is a category 1 hurricane.

New frame....very big mass of -64kts on N side of eye wall.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
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Quoting WeatherfanPR:
My thoughts and prayers with all in the path of Isaac. I hope the levees doesn't break this time.


If the levees break, than New Orleans should be abandoned forever. This is a Tropical Storm/barely Cat 1 Hurricane. It is not a life or death situation. It's time for everyone to stop panicing because of a little water and and wind.
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Quoting TomballTXPride:

Exactly. And MS and AL likely will get severe impacts and perhaps even more rainfall out of this.



Tomball do you think it might be bad here in Mobile,Al with the surge? I was looking at the image Pat put up and it looked like it took a very little north jog there for a second. Know I'm no pro so I may not know what I am talking about.

sheri
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Quoting CybrTeddy:


Do they go with GMT or UTC with those times? Would make sense since they release updates saying it came out at 12pm and it's only 9am.


GMT time. That is why you see 12:19 instead of 8:19.
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Good morning all...Kenner, La. here....our winds are gusting over 30mph right now and the rain just started..it's very creepy...we are "hunkered down"...and know it's gonna get pretty ugly around here for a couple days..will keep you all posted as we can.
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3304. Patrap
ISAAC RainbowTop Loop

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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.