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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3204. 7544
anyone in la or ms have a link to the live coverage of issac thanks
Member Since: May 6, 2007 Posts: 0 Comments: 6618
Patrap, based on what you posted showing Isaac spinning, it looks to be just basically sitting there or moving just verrry slightly westward, but not toward Grand Isle area or northwestward. Is this what you see as well?
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3201. Patrap




,,please Handle us with care.

We family.

We've been beat up and battered 'round
Been sent up, and we've been shot down
You're the best thing that we've ever found
Handle Us with care

Reputations changeable
Situations tolerable
Baby, you're adorable
Handle Us with care

I'm so tired of being lonely
I still have some love to give
Won't you show Us that you really care

Everybody's got somebody to lean on
Put your body next to our's, and dream on

We've been fobbed off, and we've been fooled
We've been robbed and ridiculed
In day care centers and night schools
Handle Us with care

Been stuck in airports, terrorized
Sent to meetings, hypnotized
Overexposed, commercialized
Handle Us with care

I'm so tired of being lonely
I still have some love to give
Won't you show Us that you really care

Everybody's got somebody to lean on
Put your body next to our's, and dream on

We've been uptight and made a mess
But we'll clean it up ourselves, I guess
Oh, the sweet smell of success
Handle Us with care
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Looking at WV loop seems dry air has come outta nowhere far out in an arc fashion away from the core around from the East all the way around the West.
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3199. Pastey
Quoting HimacaneBrees:


Lol. I'm actually in Watson (with a Denham address) that's y I say Denham lol cuz nobody knows where Watson is, even mapquest lol. Yes it's gonna be very funky here later. We are definitely on the worst side. Looks like the center may pass directly over us.



I'm not in a terribly flood prone area which is a plus. Generator is ready, beer is cold...I just hope Demco is on their game and ready to do some repairs. I love my A/C. Best of luck over there in Watson...stay dry.
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Quoting HimacaneBrees:


Had our 1st shower here in Denham Springs about 0730. It's actually nice out ATM, won't be later tonight and tomorrow though


Zachary, Here, will be with ya, till power goes out,,,,,, generator not working, but have a ext cord to hook up to neighbors,,lol
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3197. LargoFl
Quoting GeorgiaStormz:
Isaac has a MASSIVE sphere of influence, im about to get a big band up in GA.

is this rain going into the drought area's of georgia?
Member Since: August 6, 2011 Posts: 4 Comments: 33281
3196. GEAUXDS
Denham Springs, LA here...Loooooong time lurker. Thanks everyone for the constant updates. Looking like things here will start to go downhill early evening tonight and stretch until tomorrow. Very interested in what this slow down in forward speed will bring.
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73 mph wind gust reported from buoy SE of New Orleans. windgust
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ADT agrees with the intensification process:
CI# /Pressure/ Vmax
3.6 / 987.1mb/ 57.0kt


Final T# Adj T# Raw T#
3.6 4.0 4.8

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Isaac has a MASSIVE sphere of influence, im about to get a big band up in north GA.

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Another shot of dry air to the core of Isaac. Was definitely too bullish on Isaac last night...

Pressure apparently steady too at the moment.
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Quoting hydrus:
These are potent waves. I would bet almost all of them form, if so we will have another impressive year for the record books. So much for El-Nino. Maybe when winter arrives.


WOW ...
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Quoting Patrap:
Quoting Patrap:


Scary-Slow mover.
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3187. CJ5
Were is yall's eye wall now? Some of you have to learn to quit jumping the gun based on a few sat/radar loops. He doesn't have a clear well formed eye and he never has.
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This could technically be worse for New Orleans especially in the city limits if this does RI into a near category two hurricane, Isaac is coming in at the worst possible time for the City of New Orleans. We are getting astronomical high because of the full moon tommorrow. The angle at which the storm is moving (parallel and just to the South of New Orleans) puts New Orleans in the worst right front quadrant with 10-12 feet of storm surge possible. Plus, Isaac is moving much slower than even Katrina so the rain and repeated high tides are going to cause problems. I hope people in New Orleans are not like people in Key West having a Hurricane Party because "it is ONLY a tropical storm"
God Bless them on the 7th year anniversary of Katrina
FM
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North Movement?
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Kermit and HH passing very close to each other.
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3182. LargoFl
"Winds will be an issue initially when Isaac makes landfall with gusts up to 80 mph. Forecasters say the big threat will be the storm surge around New Orleans and Biloxi, Miss., where water might rise six to nine feet. The slow-moving storm is forecasted to hover over the Gulf Coast and could punish coastal areas with up to 20 inches of rain, which was one of the big concerns"
Member Since: August 6, 2011 Posts: 4 Comments: 33281
3180. KRL
Pic of Wellington FL flooded from TS Isaac.

Pic Link
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Just in the last hour storm has movied .16 degrees North and .29 degrees west.
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Quoting Patrap:
This Large CV Ballerina has finally pulled Her/His arm's in and well,..these LARGE System's don't fade, nor wind down easily.

A LOT of water is now being put into Motion N to Nw and that alone is GOING to create a substantial event for many, in 3 States easily.

The Time for ACTION will be first Light to Noon CDT and I urge all with preps outside to carefully,but prudently get those done.

The winds are beginning to pick up and they will only increase to Tropical Storm Strength and Greater in the Warned area's from the Coastal regions to well inland.



I use your ballerina explanation to friends, who can't understand why Isaac is taking so long...they love it..especially when they get the visual!
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3177. Patrap
Quoting LargoFl:
pat you in a safe area..away from what could be massive storm surge?


We live on the Audubon Ridge near Jefferson Ave and Magazine St.,,the Highest point in NOLA. 4 Blocks N of the River.

We are prepared, and safe.

NOLA is secure..our Spirits well, and this too will pass, but itsa going take a good while.


Im on first watch, 2 sleeping, 2 Jack Chi's with 4 Pups and one very pregnant Nola Roux.

: )

On Tchoupitoulas Street, New Orleans

Eastbound near Audubon Park, 7:30 am CDT 28 Aug 2012




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Hurricane Isaac

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3175. CJ5
Quoting IcemanMC:
Is the eye wall open or closed?


The "eye wall" is open, has been open and likely to stay open. This has been Isaac's problem for the past 5 days. He cannot close the deal.
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3174. divdog
Quoting FelixTheKat:
isaac look very poor right now even though winds are stronger
Go take a nap. U must be seeing things
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Quoting CybrTeddy:


I don't have the link.
ATCF
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Quoting CybrTeddy:


I don't have the link.

If you want/need the link: Link
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3171. Grothar
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3170. hydrus
These are potent waves. I would bet almost all of them form, if so we will have another impressive year for the record books. So much for El-Nino. Maybe when winter arrives.
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Quoting Tazmanian:




i can with my i pad


I don't have the link.
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Quoting rockymountaindreamin:
Everyone seems to be concentrating on the track storm surge & windspeed. All of these are great concerns. But as a former resident of the area, I am concerned with the amount of rainfall this will storm will generate. Do any of you have comments on this?


The eastern side of the storm will have much more flooding, so if your located to the east of its landfall, I'd be prepared for anything between 10-20 inches of rain in 2 days. BE SAFE!
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What are chances of Isaac stalling off the coast of LA? Other than the rain and surge...which are bad enough...what effect will that have on the winds? And is this possible?

Worried in MS
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Is the eye wall open or closed?
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New to this site. Does anyone know if Dr. M. will update at 11:00 or when??
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3161. LargoFl
on top of the upwelling storm surge itself..14 ft waves
Member Since: August 6, 2011 Posts: 4 Comments: 33281
Quoting Pastey:


I'm from Denham Springs as well. I just didn't post that because most people outside LA have no clue where that is. We'll be in for a ride but the storm is much weaker than it could have been.


Lol. I'm actually in Watson (with a Denham address) that's y I say Denham lol cuz nobody knows where Watson is, even mapquest lol. Yes it's gonna be very funky here later. We are definitely on the worst side. Looks like the center may pass directly over us.
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Quoting CybrTeddy:
Can't get to the ATCF on here, dang.




i can with my i pad
Member Since: May 21, 2006 Posts: 5089 Comments: 114049
Quoting TomballTXPride:

Only this time, the trajectory (angle) at which Isaac is coming in is SIGNIFICANTLY more dangerous than the angle Katrina ever was. Not saying this is another katrina. Hardly. But my point is the angle of the coast this thing is making on LA and the fact it will likely make landfall west of 90W is scary. I really am glad he stayed weak the last 24 hours and hope another punch of dry air will finish him off once and for all. Cloud tops are beginning to warm again which is a good sign but anything is still possible with still more than 18 hours over water.


That's what I was implying about getting dicey for NOLA earlier, if this thing were to hit 100mph at landfall, it might actually be worse for NOLA than K. Not predicting it, just implying the possibilities at hand.
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Quoting GeoffreyWPB:


If you have DirecTV...you can follow news coverage on Isaac on channel 349.
They're showing WDSU in NOLA
Member Since: August 16, 2007 Posts: 0 Comments: 393
3156. Patrap
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Quoting reedzone:
The thing is, it's a Category one with a pressure of a Category 2/Major Hurricane.. Like Alex in 2010. This means Isaac is a very dangerous and intense Hurricane despite the category and New Orleans should have evacuated, hopefully they did. Katrina aimed for New Orleans 7 years ago today.


Large diameter storms can have lower pressure at lower winds speeds. During it's New England area landfall, Irene had typical cat3 pressures but with low-end Cat1 gusts.
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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.

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