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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Early 1200z runs - pay attention points west of NOLA. BAM models good short term early models for weak tropical systems.
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Quoting TXCWC:
hummm...0Z EURO does not show Isaac making landfall until TOMORROW NIGHT - 48hrs



Yeah I saw that and farther west. I haven't seen any other model like that though.
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And this track will be adjusted further west.
And it is a hurricane, 86 knots at flight level is enough.

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Quoting MAweatherboy1:

Its taken in a little dry air on the NW side though, it shows up well on radar and water vapor.



Its apparent that its dealing with dry air

surge may be higher because of the slow down
Member Since: June 17, 2011 Posts: 11 Comments: 6461
2849. Dunkman
Quoting MAweatherboy1:

Its taken in a little dry air on the NW side though, it shows up well on radar and water vapor.


This storm could find dry air from 1000 miles away and drag it into the core. I'm pretty sure it's absorbed every patch of dry air in the Atlantic basin.
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Quoting MAweatherboy1:

Its taken in a little dry air on the NW side though, it shows up well on radar and water vapor.



He is about to close it off I believe check out the rapid scan. That water vapor loop is 30 minutes old.


Link
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2847. GetReal
i
Member Since: July 4, 2005 Posts: 204 Comments: 8806
Quoting weatherh98:
did carl parker just say wishcaster....


Lol. Local met said blob earlier in Isaac's life.
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2845. TXCWC
hummm...0Z EURO does not show Isaac making landfall until TOMORROW NIGHT - 48hrs

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Good Morning. It appears that Isaac is undergoing CWI (Constant Wind Intensification) right now. This means that peak wind speed of the storm stays constant, but the area with those peak winds becomes larger and larger!
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Quoting iceman100:
Will everybody stop even mentioning rapid intensification please? This story will not intensify before hitting land. Period. Have you even paid attention to the history of THIS storm? Everyone is brining up OTHER storms that this reminds them of. Well guess what? This isn't those other storms. This is the same storm that hasn't grown strong in about 5 days.



no we wont


this storm starting too rapid intensification recon and now noaa are finding a lot of 80 too 85kt fight level winds this storm is really starting too get it act togeter and will do so in tell it makes land fall
Member Since: May 21, 2006 Posts: 5091 Comments: 114712
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2841. kwgirl
Good morning from Key West. The winds have finally laid down after Isaac's passing. It felt like an autumn day yesterday with the breezes and dry feel to the air. A lot different from the humidity that Isaac brought. Everyone on the Gulf Coast should be prepared for a hurricane, including boarding windows and evacuating to higher ground if need be. Listen to your Emergency management people. Prepare for the worst! Stay safe everyone.
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2839. Dunkman
One thing Isaac will bring is relentless storm conditions...it will take forever for that huge area of 60-70mph winds to finally dissipate.
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Quoting weatherh98:
closing off the dagger


Its taken in a little dry air on the NW side though, it shows up well on radar and water vapor.

Member Since: February 11, 2012 Posts: 82 Comments: 7612
Quoting mcluvincane:


6mph is not a good pace :)


I know. I want him to speed up. :)
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Quoting olihomer:
Spectacular one-minute visible satellite animation showing the sun rising over Isaac:

Link



That is firing up some big thunderstorms nw of center.
Wrapping round . Luckily it is not too far till landfall so it doesn't have much time.
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Will everybody stop even mentioning rapid intensification please? This storm will not intensify before hitting land. Period. Have you even paid attention to the history of THIS storm? Everyone is brining up OTHER storms that this reminds them of. Well guess what? This isn't those other storms. This is the same storm that hasn't grown stronger in about 5 days.
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Quoting LAlurker:

It can only enter Lake P. through it's natural passes at the Rigolets and Chef Menteur.


Thank You!
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did carl parker just say wishcaster....
Member Since: June 17, 2011 Posts: 11 Comments: 6461
2832. MahFL
I hope the person who has they keys to the big pumping station, hasn't mislaid them, lol.......
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2831. Dunkman
Quoting FLPandhandleJG:


Im talking about how they keep on saying it was going to be near a cat 3 or so.. But we all have different opinions and I watch TWC a lot and I have seen the difference.. No1 is perfect but all I am saying now days, its about getting viewers to watch u.. My friend works for NBC and he told me this.. So we choose to what to believe.. U have urs and have mine.. It's a blog..

On the side note: if u want to hear more reason of y i think TWC isn't what it used to be.. Let me know..


Intensity forecasting is pretty awful. The NHC can barely beat the SHIPS Decay model (3 year average is a 10% improvement), and in fact got owned by it to the tune of 20% after 36 hours in 2011. 4 days ago this could have been a TS at landfall and it could have been a category 4. 2-3 was the most likely. If you err on the high side then less people die than when you err on the low side. What would you have them do?
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the recon is still finding a lot of fight level winds of 80 too 85kt even the noaa recon is now finding a lot of 80 too 85kt fight level winds


Member Since: May 21, 2006 Posts: 5091 Comments: 114712
Quoting ILwthrfan:


He's slowed down as well and seems to be finally completing his CDO. I'd say he's 75 knots based on the 85knot flight level winds found in the SE quad. CAT 2 is still a very real possibility, but up-welling may be a problem to at some point.

Isaac wrapping up now. Impressive image!

Link.


You guys might actually get some rain from Issac. So far here in FL since the end of May has been wet to say the least with some areas receiving 40" of rain over the last 90 days.


Link
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Quoting CajunMom2:
Long time (way, way before Katrina) lurker in Lafayette. Starting to get nervous here, news reports do not appear concerned and no one has board up that I could tell. Should we be concerned?
You should prepare for a long term rain event. It's still unclear if the storm will slide to the West.
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2827. CJ5
It looks like a fifth morning of waking up and seeing Isaac has failed to gain momentum. Good for those impacted.

My tin foil hat would suggest that the weather modification has worked perfectly for this storm. Lets review; South of Haiti he never could get his northern eye wall established. North of Cuba he could not get his Southern eye wall established. As he moved through the keys it was his northern eye wall again. As he moved up the west coast of Florida it was his east eye wall that sputtered. On now look, what a coincidence, as he moved towards the coast it is his Northern eye wall that cannot gain traction. Just saying....
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Quoting GetReal:



You know that you are bashing the new owners of this site...


I guess I will keep it hush hush then .. LOL Im so scared.. Its a blog and there is plenty other blogs out there.. I was just saying an opinion.. I thought u can base a opinion on this blog or any blog.. Where is the harm.. It's not like Im doing any harm.. Geesh!
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closing off the dagger

Member Since: June 17, 2011 Posts: 11 Comments: 6461
2824. MahFL
The northern half of the storm is now going to fill out on the IR, so basically your going to now have a regular rainy/windy large sized hurricane, raining onto a low lying land that is already saturated. Very bad.
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Quoting canehater1:


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
547 AM CDT TUE AUG 28 2012

.DISCUSSION...
TROPICAL STORM ISAAC VERY CLOSE TO BECOMING A HURRICANE THIS
MORNING...WITH LATEST SAT IMAGERY BEGINNING TO SHOW A RAGGED EYE.
NEVERTHELESS...ISAAC REMAINS A VERY LARGE CYCLONE...WITH TROPICAL
STORM FORCE WINDS EXTENDING 180 NAUTICAL MILES ACROSS THE NE & NW
QUADRANTS OF THE STORM. THUS...TROPICAL STORM FORCE WINDS ALREADY
INFRINGING ACROSS THE FAR SOUTHEASTERN COASTAL WATERS ZONES.
ALSO...ISAAC MADE A SLIGHT WNW JOG OVERNIGHT...WHICH MADE IT
NECESSARY TO ADJUST THE FORECAST TRACK A LITTLE WEST AS WELL.

FOR THE TWO REASONS ABOVE...THE TROPICAL STORM WARNINGS HAD TO BE
EXTENDED WESTWARD TO CAMERON...AND INCLUDES PARISHES FROM RAPIDES...
ALLEN...JEFF DAVIS...AND EASTERN CAMERON EASTWARD TO THE
ATCHAFALAYA RIVER. THE TROPICAL STORM WATCH WAS EXTENDED WESTWARD
TO HIGH ISLAND...INCLUDING JEFFERSON AND ORANGE COUNTIES IN SE TX
ONLY. THE TROPICAL STORM WATCH REMAINS UNCHANGED ACROSS WESTERN
CAMERON...CALCASIEU...BEAUREGARD...AND VERNON PARISHES.

Saw this coming ....as a mariner you can't help but
plot courses for storms too..lol


I think this is a lot like Gustav's path. Started looking that way on the models days ago.
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This storm is now starting to remind me of Hurricane Dolly(2008) and Hurricane Alex 2 yrs ago. Both had trouble with their inner cores getting organized, but eventually underwent some rapid intensification to Cat2 status, with relatively low pressures for their designation as well.
A more extreme case could be Hurricane Alicia in 1983, which underwent rapid strengthening to cat3 right up to landfall.
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I think it is ironic that Isaac has struggled so much due to moisture issues, but will probably be remember because of the copious amount of moisture it will create.
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Quoting TropicalAnalystwx13:

I've watched TWC since Isaac was a TD. There was no hype. Sorry.


Im talking about how they keep on saying it was going to be near a cat 3 or so.. But we all have different opinions and I watch TWC a lot and I have seen the difference.. No1 is perfect but all I am saying now days, its about getting viewers to watch u.. My friend works for NBC and he told me this.. So we choose to what to believe.. U have urs and have mine.. It's a blog..

On the side note: if u want to hear more reason of y i think TWC isn't what it used to be.. Let me know..
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Quoting LAlurker:

It can only enter Lake P. through it's natural passes at the Rigolets and Chef Menteur.


the water entering lake p haha

Member Since: June 17, 2011 Posts: 11 Comments: 6461
2818. GetReal
Member Since: July 4, 2005 Posts: 204 Comments: 8806
Quoting weatherh98:
One hot tower on the north side makes tthe a strong cat 1 low cat 2


He's slowed down as well and seems to be finally completing his CDO. I'd say he's 75 knots based on the 85knot flight level winds found in the SE quad. CAT 2 is still a very real possibility, but up-welling may be a problem to at some point.

Isaac wrapping up now. Impressive image!

Link.
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Long time (way, way before Katrina) lurker in Lafayette. Starting to get nervous here, news reports do not appear concerned and no one has board up that I could tell. Should we be concerned?
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Spectacular one-minute visible satellite animation showing the sun rising over Isaac:

Link
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Quoting StormHype:
Not sure exactly how this will end up, but doesn't look to be that bad. There is no doubt this is the most over-hyped tropical storm since 2006 Ernesto.... all the way from last Thursday night until today. The media has been drooling for a disaster.

;-)


There is a reason why media exagerates... the look for Rating and that moves the economy... Wood, batteries, water, even expired food is sold...
Member Since: August 2, 2010 Posts: 21 Comments: 9693
This is a dog trying to chase its tail
Member Since: June 17, 2011 Posts: 11 Comments: 6461
2812. MahFL
Quoting TropicalAnalystwx13:

They never said it was. In fact, last night, Carl Parker and Jim Cantore specifically said, "this is no Katrina".


Unless a canal wall fails, you could never have another Katrina like event. A regular soaked and blown around by a Hurricane yes, but not a Katrina. Also those infamous places of last resort are not open.......
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Quoting jazzygal:
Anyone know if the water from Lake Borgne can get into Lake Pontchartrain or has that been closed off. Water in Lake Pontchartrain looked high. Worry about the North Shore since South side has been or will be closed off because of the new gates.

It can only enter Lake P. through it's natural passes at the Rigolets and Chef Menteur.
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Quoting SLU:

28/1145 UTC 28.0N 88.2W T4.0/4.0 ISAAC -- Atlantic
28/1145 UTC 23.2N 42.9W T1.5/1.5 97L -- Atlantic
We may have td 11 tomorrow night or after tomorrow.
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Quoting TropicalAnalystwx13:
It's funny how you guys are bashing the people that have degrees and have been doing this for decades. If you have a problem with them, don't watch it. We don't care if you think they're hyping.


reporting for ranting

gotta get the funktop in before it gets bad here


Member Since: June 17, 2011 Posts: 11 Comments: 6461
Quoting Kristina40:


I don't recall anyone calling it a hurricane either.


Actually, ESPN called it one right after the TB-Texas game around 11 PM. Had to shake my head at that one.
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2807. jpsb
Quoting AtHomeInTX:


I think they shifted slightly west earlier. But they said it was a temporary west motion and had it moving NW again. That was at 4. Don't know if it's still like that though.
Did not the GFS have several runs where Issac stalled right at the La coast and then slowly moved west all the way to Texas? Lets hope the that does not happen.
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It's funny how you guys are bashing the people that have degrees and have been doing this for decades. If you have a problem with them, don't watch it. We don't care if you think they're hyping.
Member Since: July 6, 2010 Posts: 113 Comments: 31441
Quoting CajunCrawfishhunter:
I will say this I have been lurking here for years and I am no where near an expert but i understand most thigns well enough but this storm has me stomped. I hear in the office we will only get a inch or so of rain and no winds to people saying we better hunker down. We live in Lafayette La and I have no idea what is going on.


There are alot of "Chicken Littles" on here who think the sky is always falling and consider themselves experts.
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2804. GetReal
Quoting FLPandhandleJG:


I bet TWC is saying thank you Isaac for slowing down b/c how we hype this storm for so long.. you come at the end to hopefully save our jobs or keep as much viewers to tune into our station.. Go Figure! Its always about the money.. It never an ending story..



You know that you are bashing the new owners of this site...
Member Since: July 4, 2005 Posts: 204 Comments: 8806

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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.

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