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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Could this be Isaac Part 2?
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Still moving NW to my eye. The Norther component is a illusion of the dry air intrusion cutting into the North.
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652. Caner
Quoting FL1980:
It's funny. Half say the storm is looking better and organizing, the other half says it looks ragged, does anyone know what they are talking about in here?


A storm can look 'ragged' and 'better' at the same time, the terms are not mutually exclusive...

I note that no one says the storm looks 'good', 'well-formed', 'symmetrical' or 'excellent'.

A storm can look like absolute crap and still look 'better' than it did when it looked like an utter piece of %$@#!...

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Quoting moonlightcowboy:


Ha! LOL. This has been tough going. Poor ol' models have to be worn slap out - they're gonna need some new wiper blades!!! ;P
Sure do appreciate your inputs keep em coming please. Keeping a watchful eye out to south from destin
Member Since: August 22, 2008 Posts: 0 Comments: 755
Quoting snow2fire:
The NHC has Isaac slowing to 5 mph around the time it makes landfall...

According to my figuring:
From 24hr to 36hrs: 14 hours - 86.8miles => 6.2mph
From 36hr to 48hrs: 14 hours - 69.4miles => 5.0mph
From 48hr to 72hrs: 24 hours - 146 miles => 6.1mph
From 96hr to 120hrs: 24 hours - 247miles => 10.3mph

... so what happens if it slows down before that???


I don't want to be flippant about it but if it slows down get a big big boat. That slow and that much rain could be worse than a cat2 that move right through.
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GFS stalls Issac out over Louisiana for a few days....
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Quoting truecajun:
does anyone know the best way to prep a wooden swingset for a storm? i'm so sick of having to fix the swingset after storms. we've repaired it twice. it always gets tumbled over and a beam breaks in the process. any suggestions?? my husband is a city boy, so he's not too handy



yah....sink it in the ground with concrete footings....easy as that....but that should have been done before the storm.....and it would permanently attach it to the ground for the most part, or at least make it a semi-permanent app. struct.
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Quoting FL1980:
It's funny. Half say the storm is looking better and organizing, the other half says it looks ragged, does anyone know what they are talking about in here?
Ragged, but getting organized?
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Quoting mitthbevnuruodo:


Can't believe you were SO naughty!! ;p
Someone had to tell the truth..
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Quoting CaneHunter031472:
GFS 324 hrs.



Deja Vu....... all over again
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642. 7544
hmmmm is he about to stall ?
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Quoting CybrTeddy:


That is Allison.


Wiki says as a subtropical storm, which I believe is inaccurate. As far as I know, she was post-trop at the time.
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Quoting HoustonTxGal:


Patron, straight up :o)


Rum and Patron.. I like the way y'all think!

Being a sailor, always have to have some rum. ;)
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IMHO the storm is not stalling at all. It is so darn big it makes it hard to see a motion small relative to its size.
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Quoting angiest:


And this was not a tropical storm at the time.


yeah its hurricane katrina, and they do have this pic on allison on wiki, but its for sure not allison...she didnt even have an eye at landfall let alone 4 days after it was over land when it moved in the miss/al
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Quoting washingtonian115:
For backing considerable off of my intensity forecast.I'm forecasting a 90mph storm.I said that the Gulf dodged a bullet in terms of a major cane coming for them..and that just set the flames to the gasoline.


Can't believe you were SO naughty!! ;p
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Quoting moonlightcowboy:


Good obs! :) Slowing usually indicates a bend starting. He will miss the largest area of the warmest waters of the loop eddy. The high has retreated northeastwards with the 1016mb line far inland now, meaning there will be less resistance. Zeroing in between NOLA and Mobile, most likely over Gulport/Biloxi if it strengthens any. Just won't intensify as much as I'd previously thought. Cat 3 won't happen unless there is a significant stall. But a stall also eventually upwells cooler waters. So any peak intensity won't last long and it'll weaken as it comes ashore.



wow and they just dropped the warnings for the extreme western panhandle from pcola-destin....wonder if this might be a slight mistake...
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Excellent news.... Dry air still affecting Isaac.... It still looks fighting its surroundings, trying to keep together...

Wondering, last night we thought we could have a Cat3 / 4 into NOLA....

Isaac, a very unpredictable storm...

Hope Kirk or whatever is called the new storm, arrives surrounded by SAL and dry air....

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The NHC has Isaac slowing to 5 mph around the time it makes landfall...

According to my figuring:
From 24hr to 36hrs: 14 hours - 86.8miles => 6.2mph
From 36hr to 48hrs: 14 hours - 69.4miles => 5.0mph
From 48hr to 72hrs: 24 hours - 146 miles => 6.1mph
From 96hr to 120hrs: 24 hours - 247miles => 10.3mph

... so what happens if it slows down before that???
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Quoting 7544:
looks like isaac just jogged ne ?
Saw what you're talking about. Cant tell if it just the way the asymmetrical rotation appears.
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Quoting truecajun:


thanks. that's what we will do, and cross our fingers


is it better to stake or lay down? anyone have experience with both scenarios? it's too big to put in the attached storage room - slide, 3 swings, monkey bars and a little house thingy
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GFS 324 hrs.

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I have to say. In the last images of day light, he has a nice southern eye wall, and anotherstorm is building up in the center, as well as convection appearing to be developing to his east. If he can get a closed eye wall, I bet he explodes.
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Quoting washingtonian115:
For backing considerable off of my intensity forecast.I'm forecasting a 90mph storm.I said that the Gulf dodged a bullet in terms of a major cane coming for them..and that just set the flames to the gasoline.


yeah totally agree! unless it stall right now its just not going to make it over 100mph or even 90mph...this northwaqrd jog is kinda turning into more of a movement and not so much a jog at this point
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It's funny. Half say the storm is looking better and organizing, the other half says it looks ragged, does anyone know what they are talking about in here?
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The MJO is forecast to move into a phase unfavorable for African wave development in the Atlantic development not long after Labor Day. Look closer in for potential storms after that.

Quoting Chucktown:


Peak of the hurricane season is in 2 weeks. The African wave train is probably at its peak right now.
Member Since: July 8, 2005 Posts: 0 Comments: 44
BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
738 PM EDT MON AUG 27 2012

THE NATIONAL WEATHER SERVICE IN RUSKIN HAS ISSUED A

* TORNADO WARNING FOR...
NORTHERN HILLSBOROUGH COUNTY IN FLORIDA.
CENTRAL PASCO COUNTY IN FLORIDA.

* UNTIL 815 PM EDT

* AT 739 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
TORNADO NEAR THONOTOSASSA...OR 7 MILES EAST OF TEMPLE TERRACE...
MOVING NORTH AT 25 MPH.

* THE TORNADO WILL BE NEAR...
THONOTOSASSA.
HILLSBOROUGH RIVER STATE PARK.
WESLEY CHAPEL.
SAN ANTONIO.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU ARE IN THE PATH OF THE TORNADO GO TO A SMALL INTERIOR ROOM IN
A STRONG AND WELL CONSTRUCTED BUILDING. CARS AND MOBILE HOMES ARE NOT
SAFE. IF NO SHELTER IS AVAILABLE...LIE FLAT IN A DITCH OR CULVERT AND
COVER YOUR HEAD WITH YOUR HANDS.

TO REPORT SEVERE WEATHER TO THE NATIONAL WEATHER SERVICE PLEASE CALL
813-645-2323.
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625. Zero7
Quoting MAweatherboy1:
Why does TWC need 4 people reporting from New Orleans? I don't think its the only spot that's gonna feel impacts...


Because that is where NBC told them to be. Cantore had made a comment friday, when they asked him where he was going from Tampa. He replied "wherever NBC tells me to go."

TWC is owned by a consortium of NBC Universal, The Blackstone Group,and Bain Capital
Link
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Tornado Warning for Hillsborough and Pasco Counties in FL until 8:15 PM EDT
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623. FOREX
Quoting STXHurricanes2012:

Dont come out saying that...winds are just about there for a hurricane!!!!


If this so called Failed storm stalls over NOLA, I would expect 30 inches of rain, which the new levees will not contain and many lives might be lost.
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Quoting uncwhurricane85:


that is not allison


That is Allison.
Member Since: July 8, 2005 Posts: 259 Comments: 23663
I live in Mary Esther and we have been in a drought since 2006. We are finally close to normal. Any flooding will be from the rivers, but the ground here can take an amazing amount of water. I saw what happened in NJ last year when they got ten inches of rain. We get that over a weekend sometimes. The sands just suck it right up.
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KOTG - Looks like it stalled the past hour of that loop.
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Quoting uncwhurricane85:


what were you getting bashed for?
For backing considerable off of my intensity forecast.I'm forecasting a 90mph storm.I said that the Gulf dodged a bullet in terms of a major cane coming for them..and that just set the flames to the gasoline.
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Quoting washingtonian115:
Where are all the people that were bashing me this morning at?


I missed your morning...what was all the hubbub bub?!
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Quoting angiest:


You forgot the rum.


Patron, straight up :o)
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616. wpb
Quoting Pirate999:
Hurricant or TS.. just hope it moves out and doesn't slow down. Rain for LA/MS/AL is the issue.

Remember Allison. This is her over LA/MS with an eye. (source: wikipedia)

faye over fla too
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Isaac has always been a night bloomer

I expect later he will start his "night moves"
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Methinks we owe forecaster Pasch an apology.
Member Since: August 30, 2008 Posts: 0 Comments: 43
Quoting Pirate999:
Hurricant or TS.. just hope it moves out and doesn't slow down. Rain for LA/MS/AL is the issue.

Remember Allison. This is her over LA/MS with an eye. (source: wikipedia)



that is not allison
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last few minutes of daylight fades
Member Since: July 15, 2006 Posts: 169 Comments: 53308
Quoting scott39:
Isaac is going to moisten up that East side. He looks to be barley moving NNW.....that is not good!



Yes......that east side is filling in a bit.
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Quoting shoreacres:


MLC! Good to see you - saw your post re: surface obs yesterday but the blog was moving too fast to say hi. Best wishes with this thing.


Hello, Linda! ;) We're all ready here! Only bad news is garbage folks didn't come today, not tomorrow either. So many houses have projectile missiles just hanging out there waiting to get airborne!
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Quoting Pirate999:
Hurricant or TS.. just hope it moves out and doesn't slow down. Rain for LA/MS/AL is the issue.

Remember Allison. This is her over LA/MS with an eye. (source: wikipedia)



And this was not a tropical storm at the time.
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608. Mikla
Issac finally appears to be putting it together:
- SSTs are decent (link)
- Shear is low/low-moderate (link)
- Starting to get feeders on all sides (RGB link)
- Venting/outflow is good to the NW
- Vorticity is well stacked (link)
It still is dealing with some dry air getting pulled in from the SW that has prevented the eye from closing off, but appears to be dealing with it better than it has up to this point.
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Quoting Masquer08er:
vodka or gin? I can't decide, so one of each it is.


You forgot the rum.
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Quoting moonlightcowboy:
Good evening, geeks! ;) Y'all got this thing figured out?


Yup

Cold beer and a tropics blog. It's all good.

Of course my life and property are not in any danger.
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Hurricant or TS.. just hope it moves out and doesn't slow down. Rain for LA/MS/AL is the issue.

Remember Allison. This is her over LA/MS with an eye. (source: wikipedia)

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Quoting HoustonTxGal:


I DID NOT CREATE IT... I was only sharing for those who might like to see it.. Trust me, I have o desire for the storm to come to TX.

We can dream
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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.