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 RTSplayer:
A little trigonometry shows it will pass a few tenths of a degree SW of NOLA's center coordinates using linear extrapolation.


Ah . . . linear extrapolation. Do you mean using the current direction, simply draw a straight line from Isasc to the shore? There should be simpler name for that, rather than "linear extrapolation." I'll think of something. To bad the xtrap is taken.
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Talked to my son earlier. He's currently at home but on alert to having to go into base. He's a disaster lead, so can't evacuate. However today Obama decided military cannot evacuate if they are within 150 miles of a military shelter. If there is a military shelter within that 150 miles, they have to go to it, basically to the closest shelter. Now for places like Hurlburt who are on the Gulf, literally, who cares about storm surge, etc.. Sorry, I'm ranting. I know my son has to stay, but the others who could be safer? Ugh.
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18z GFDL Isaac shifted east towards a southeast Louisiana landfall in 42 hrs:



Kirk comes into view in 5 days:

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Quoting TomballTXPride:

Sure looks like it's on it's way. Noticed your only a couple days signed up after me. Here's a couple great visible links to follow Isaac. Usually between now and sundown is the best time to watch these tops shoot and billow in the sky. Looks like Isaac is ready to put on a show for us.

Link

Link
Hey, Tomball, you belong in this blog... just joined a few days ago and already passing on what you know to the "new kid in town".... Good stuff!

Evening all... I'm just getting online to see what's happening with Isaac...
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Quoting StormHype:


TWC bought WU in July. What did you expect? Maybe Dr. Master's stays there, and Al Roker comes here. How you like them apples? lol



omg...did not know that...lol

and naaaa i would rather dr masters stay here and al can stay in NYC...lol
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Quoting flcanes:

alabama would need to watch out, though
Have my nose to the south facing window.
Member Since: August 16, 2007 Posts: 0 Comments: 397
Quoting allancalderini:
97L is still not out so don`t count him as dead.

Neither is the NHC.
A 1011 MB SURFACE LOW IS CENTERED NEAR 21N42W IN THE CENTRAL TROPICAL ATLC. THE LOW HAS BEEN MOVING NW AT ABOUT 15 KT. THE SYSTEM IS CURRENTLY SHEARED WITH CONVECTION EXTENDING NE OF THE LOW CENTER WHERE A CLUSTER OF STRONG CONVECTION IS FROM 23N-26N BETWEEN 38W-42W. FURTHER DEVELOPMENT OF THIS SYSTEM IS POSSIBLE OVER THE NEXT COUPLE OF DAYS.
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Quoting WetBankGuy:
Why We're Staying

A number of people have expressed surprise or dismay at the number of New Orleanians who are not leaving. There are several reasons for this, but primarily it is tied to former Mayor's Ray Nagin's poorly executed phased return policy.

Under this policy after Gustav (hardly a disaster for New Orleans) people were denied the ability to return and secure their homes from any damage on the theory that we couldn't possibly get by without full restoration of Cox Digital and a chance for the beer to get cold at Rouse's Supermarket.

We know how to get buy without power and with a boil water order. We're not going to grab a downed power line. We're not children, and the older of us have experience of this back to Betsy. Even the lead editorialist of the Times-Picayune (writing in a personal column) announced he would not leave for a mandatory evacuation order unless he thought it prudent and the phased return regime was eliminated.

It didn't help that FEMA went on national television promising to cover people's hotel bills, etc. during the whole phased return thing and then reneged on that promise.

We all watched anxiously during Gustav as the lake battered at the east side seawall of the Industrial Canal as a heroic few men secured a loose barge. Everything held.

We're not all throwing hurricane parties. We all learned that lesson from the people on the coast who died during Camille, thank you very much. People are hunkering down, well supplied (if they can afford it at the end of the month) in houses secured as best they can. We are following the directives of our local officials to shelter in place.

We are the survivors. We are the people who came home. We are not easily giving up what we have reclaimed.

The Tragedy of St. Bernard

-- Mark Folse
ToulouseStreet.net
Well said sir. I totally respect and admire you. I totally understand where you are coming from after surviving Erin, Opal, Ivan and Dennis (and a few smaller in between). Kudos to you! Hope you fair well and my prayers are with you and yours in this trying time.
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Isaac looks to be moving due north right now, still not sold on a Louisiana landfall
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This is the same set up when young Isaac came off Africa as the second wave:
...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 22N21W TO A 1011 MB SURFACE LOW AT 11N22W MOVING W NEAR 12 KT. THE WAVE/LOW COINCIDES WITH A LARGE SURGE OF DEEP LAYER MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. BROAD LOW-LEVEL CYCLONIC FLOW IS ALSO ABOUT THE WAVE
AND LOW...BUT IS NOT WELL ORGANIZED. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 9N-12N BETWEEN 23W-32W.

A CLUSTER OF SCATTERED STRONG CONVECTION IS ALSO MOVING OFF THE COAST OF AFRICA BEHIND THE WAVE FROM 11N-15N BETWEEN 13W-18W.
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Quoting odinslightning:
TWC stole Dr. Masters from us :(


TWC bought WU in July. What did you expect? Maybe Dr. Master's stays there, and Al Roker comes here. How you like them apples? lol
Member Since: May 31, 2007 Posts: 0 Comments: 1204
Quoting nola70119:




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.
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Quoting WxNerdVA:


No, this is Hurricane Isabel, I have no idea what avatar they had though.



WxgeekVA you no the rules


Do not circumvent a ban. Most bans last 24 hours or less, please accept the ban. If you create a new username to circumvent a ban, you will be blocked from the site completely.
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Quoting Tropicsweatherpr:
More trouble for Issac.

VORTEX DATA MESSAGE AL092012
A. 27/23:11:00Z
B. 26 deg 36 min N
086 deg 24 min W
C. 850 mb 1285 m
D. 48 kt
E. 136 deg 42 nm
F. 239 deg 68 kt
G. 134 deg 65 nm
H. 982 mb
I. 18 C / 1534 m
J. 21 C / 1536 m
K. NA / NA
L. NA
M. NA
N. 1345 / 8
O. 0.02 / 1 nm
P. AF306 2709A ISAAC OB 22
MAX FL WIND 74 KT SW QUAD 19:52:30Z
MAX FL TEMP 24 C 142 / 15 NM FROM FL CNTR
EYEWALL RAGGED AND BROKEN APART
Hes working on gulping in that dry air and moistening it up. He will be a hurricane soon.
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everyone in mobile and along the miss. gulf coast better be prepared to not be traveling for the next 2-3 days since we will get the right front quad and this storm looks back loaded to dump out across us over and over.....regardless of where this lands it's is gonna stretch across the gulf coast to the tip of louisiana into fla panhandle with effects for days.....

im in mobile near tillmans corner....there is a dark omnious look in the sky right now....clouds are moving in different directions on different strata of the atmos...feels like tornado weather big time.....
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Quoting weatherman410:


Huge shift? What in the world are you talking about?

The GFDL was taking Isaac to around the Sabine Pass the last few runs, well west of most of the other models.
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Quoting GTcooliebai:
Is that always the case with a storm that goes over Haiti that the government chooses not to call for retirement?

Too poor to send a rep to the WMO
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Quoting flcanes:

it's obviously the same avatar
No its not. That is my old avatar.
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This storm should be intensifying faster than it is, and I believe this is why its not..
Member Since: September 27, 2007 Posts: 1 Comments: 21409
A little trigonometry shows it will pass a few tenths of a degree SW of NOLA's center coordinates using linear extrapolation.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Quoting weatherman410:


Huge shift? What in the world are you talking about?
well almost 200 miles from west louisiana to new orleans is a big shift
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Quoting syn627:

LOL...glad I'm not the only one noticing that. It's very confusing...like the blog has a "split personality" or somethin like dat.

So what's wrong with a split personality? You may never agree on anything, but you'll always have someone interesting to talk to.
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Quoting CaneHunter031472:


I agree, but I do not see the NHC accepting this. I'm afraid this will be a nasty surprise to the coast.


How can it be a surprise if they are in the track cone?
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Quoting WxNerdVA:


Nope, not them. Sorry.

it's obviously the same avatar
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More trouble for Issac.

VORTEX DATA MESSAGE AL092012
A. 27/23:11:00Z
B. 26 deg 36 min N
086 deg 24 min W
C. 850 mb 1285 m
D. 48 kt
E. 136 deg 42 nm
F. 239 deg 68 kt
G. 134 deg 65 nm
H. 982 mb
I. 18 C / 1534 m
J. 21 C / 1536 m
K. NA / NA
L. NA
M. NA
N. 1345 / 8
O. 0.02 / 1 nm
P. AF306 2709A ISAAC OB 22
MAX FL WIND 74 KT SW QUAD 19:52:30Z
MAX FL TEMP 24 C 142 / 15 NM FROM FL CNTR
EYEWALL RAGGED AND BROKEN APART
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Buildups 40 E LCH as seen frm Port Arthur, TX. We're dodging a bullet here - it's been raining alot (no drought this year) since April. I don't need another Rita, Ike, Humberto. I'm a controller, not a fence-builder. I hope the damage is minimal wherever this thing comes in - and that people have heeded the warnings.
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Quoting TomballTXPride:
I'm beginning to think NOLA will be spared the worst impacts, being that it's becoming more evident this storm will make landfall east of there. JMO.


I agree, but I do not see the NHC accepting this. I'm afraid this will be a nasty surprise to the coast.
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769. FOREX
Quoting Skyepony:


Curved Band...


Schooners.com has an awesome view of the Gulf here inPanama city Beach.
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Quoting WxNerdVA:


Nope, not them. Sorry.

._.

you told me earlier on the chat..
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Quoting TomballTXPride:
HUGE shift to the East for the GFDL.



Huge shift? What in the world are you talking about?
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Quoting syn627:

LOL...glad I'm not the only one noticing that. It's very confusing...like the blog has a "split personality" or somethin like dat.

lol
o_o
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Quoting aislinnpaps:
Evening all, sorry, came home and turned on the tv and came here and the first thing I hear is Dr. Master's talking about Issac taking a Gustav track.

Things are heating up here near Fort Polk, no water or regular bread to be found here or the surrounding towns. My son went into town to get just a few 'extras' as we are already prepared and Walmart marked down their 'fancy' bread when regular was gone.

This is our new weather alert.
As Tropical Storm Isaac Moves Closer...The Threat For Sustained
High Winds Is Likely To Increase. The Latest Forecast Is For
Winds To Remain Below Tropical Storm Force. However...A Slight
Jog To The West May Put Sustained Tropical Storm Winds Into The
Area From Lake Charles To Fort Polk To Alexandria.


Saw him too. He said Cat1 tops at landfall but long duration event may pile Gustav like surge into SE LA.
Member Since: May 31, 2007 Posts: 0 Comments: 1204
Quoting clickBOOM:
Isaac is basically a CAT 1 and he is slowing down which gives him more time to reach CAT 2 status before landfall.

oh no, large intensifying cat 2= IKE DOOM
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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?

LOL...glad I'm not the only one noticing that. It's very confusing...like the blog has a "split personality" or somethin like dat.
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761. Caner
Hmmmmm...

Dunno, looking at the latest water vapor...

It has finally managed to close off that stubborn pocket of dry air to the north east that has been one of its primary hindrances thus far...

Once it completely consumes that, taken into account with the fact that its about to move off of the cold water loop and into some warmer coastal waters, i think it actually could buck its previous trend and develop a little more strength and symmetry overnight.

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Quoting msphar:
What are the coastal tides for the next 36 hours ??
NOLA to Mobile (Mobeel for you Alabamians)

idk, probably at least a foot higher, though
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Isaac is basically a CAT 1 and he is slowing down which gives him more time to reach CAT 2 status before landfall.
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Quoting WxNerdVA:


Who's that? I signed up yesterday because a friend suggested I should, and that handle was already taken. And no, I don't know that "Geek" person either.
I don't normally put people on blast.But I'm about to with you.You e-mailed me yesterday talking about you were "WxGeekVa" and how that person got banned because of posting the Simpson's doom chart.Saying you made another account and what not.And now you come on talking about you don't know who that is?.FOHWTS!.Are you sure your WxGeekVA?.
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Tuesday School Closings WPB!!!
Link
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Quoting WxNerdVA:


Who's that? I signed up yesterday because a friend suggested I should, and that handle was already taken. And no, I don't know that "Geek" person either.

Stop playing with us. :P

We know you are Wxgeek
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Quoting msphar:
What are the coastal tides for the next 36 hours ??
NOLA to Mobile (Mobeel for you Alabamians)


Lol!!!
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TWC stole Dr. Masters from us :(
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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.