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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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: 8898
Quoting AtHomeInTX:


Morning huntsvle. Yeah I don't see it coming any closer though. He's real close to landfall. Hopefully he'll keep moving at a good pace.


6mph is not a good pace :)
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2802. WxLogic
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


Almost there...
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Quoting StormHype:


Not only is this "no Katrina" it's "no hurricane" yet.


I don't recall anyone calling it a hurricane either.
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Good morning from Loxley Ala.We are getting some light winds with a misting rain right now.The sky is so strange looking.Especially when you dont see any birds flying.I hope everyone stays safe.Its not so much the winds I am worried about as the flooding potential this storm is gonna do.We have had so much rain here that the ground is moist and that alone with more rain and wind could possibly bring down a few trees and power lines.Praying for everyones safety in its path.
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Looks to me like the beginnings of cdo taking place??
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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.
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2797. 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
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Quoting huntsvle:


Good morning athome!! :)

It appears, that perhaps, the wobble...may not have been JUST a wobble.


Morning huntsvle. Yeah I don't see it coming any closer though. He's real close to landfall. Hopefully he'll keep moving at a good pace.
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2795. GetReal
Quoting RTSplayer:
Wow.

They updated the forward speed to just 6mph...

That changes everything now.

This will give more time for intensification initially, but up-welling may kill it later on.

Worst thing about this is those rainfall totals will come up higher if it stays moving so slowly as it approaches land.


Isaac is still located in some very deep warm water....
Member Since: July 4, 2005 Posts: 204 Comments: 8898
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..

I've watched TWC since Isaac was a TD. There was no hype. Sorry.
Member Since: July 6, 2010 Posts: 113 Comments: 32501
Good to find only two H's left....
Most probably should be 2S... or 1S and 1TD...
Anyhow, good news for NOLA

Member Since: August 2, 2010 Posts: 21 Comments: 9874
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Quoting TropicalAnalystwx13:

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


Not only is this "no Katrina" it's "no hurricane" yet.
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Quoting aislinnpaps:
Good morning, everyone. Looks like even us in west central LA will be getting a little bit of Issac. Last night our alert read we would receive tropical storm winds if it jogged at all west and the first thing I hear this morning is it appears to be jogging a little west. But I think pretty much everyone here is ready for the flooding and possible loss of electric. The town is out of batteries, flashlights, water, bread, etc..

It's weird that both us and my son in Fort Walton Beach are being effected by the same storm. Last weekend I was preparing for a bunch of people to be coming here from Hurlburt in Fort Walton Beach, now we're in almost the same boat.


Where are you from my friend? Alexandria here....
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not to many times twc predicts 65 mph winds!
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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..
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Quoting fredric1979:
Since someone probably told the TWC to casually mention the Mississippi coast. Can someone tell the over hype machine (TWC) no matter how hard they try to make it be. This is no Katrina.

They never said it was. In fact, last night, Carl Parker and Jim Cantore specifically said, "this is no Katrina".
Member Since: July 6, 2010 Posts: 113 Comments: 32501
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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.
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Quoting uncwhurricane85:
...the southwest eye will open now...its just pullin the convection that was on the sw to the ne....it will keep doing that


Not good, it looks like it will steadily strengthen until landfall. Could reach cat 2 imo 100 mph
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One hot tower on the north side makes tthe a strong cat 1 low cat 2
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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.

I don't believe the property damage will end up at more than 1% of the economic losses that occurred from disruptions due to cancellations and loss of productivity of people glued to this blog instead of working or going to school. lol ;-)


Hey!! I'M multitasking! LOL
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Quoting Pirate999:


Morning all...

Let's hope it's a wobble. Worse case for Nola and MS/AL is a slight move to the west and stalling or significant slowing. I'm worried about the flooding rains a stall or slow system will bring.
If you look at the radar AL/MS, mainly AL, will miss most the rain if it keeps this up.
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2780. Dunkman
Isaac may be a crappy hurricane but that is one of the best looking tropical storms ever.
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Quoting weatherh98:
like at the bowling ally... OPEN

Isaac is just spinning and spinning and spinning.He won't make up his damn mind....
Member Since: August 14, 2010 Posts: 10 Comments: 17472
Quoting CajunCrawfishhunter:
Question: With the Hurricane center shifted tropical storm watches further west into Texas, does this indicate they are thinking a possible west shift in the track.


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.
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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.

I don't believe the property damage will end up at more than 1% of the economic losses that occurred from disruptions due to cancellations and loss of productivity of people glued to this blog instead of working or going to school. lol ;-)
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Since someone probably told the TWC to casually mention the Mississippi coast. Can someone tell the over hype machine (TWC) no matter how hard they try to make it be. This is no Katrina.
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2775. WxLogic
Quoting SWLACajun:
Thanks WxLogic. What odds do you give this? I live around Lake Charles and they just up'd us from Tropical Storm Watch to Warning.


I wouldn't go more than 20 miles or so to the west of NHC projected path. The C CONUS high is sitting there and not moving towards the E... in matter fact during the last 9 HRs it has been drifting back to the W so that would cause Isaac to turn NNW and then NE after making it inland.
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Quoting mcluvincane:


He's actually not far off.. recon has found 100 mph flight level winds eye is round and getting wrapped. Its stalling and allowing for modest strengthening
...the southwest eye will open now...its just pullin the convection that was on the sw to the ne....it will keep doing that
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like at the bowling ally... OPEN

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Quoting huntsvle:


Good morning athome!! :)

It appears, that perhaps, the wobble...may not have been JUST a wobble.


Morning all...

Let's hope it's a wobble. Worse case for Nola and MS/AL is a slight move to the west and stalling or significant slowing. I'm worried about the flooding rains a stall or slow system will bring.
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Quoting oceanspringsMS:


You are a joke


He's actually not far off.. recon has found 100 mph flight level winds eye is round and getting wrapped. Its stalling and allowing for modest strengthening
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2769. snotly
HRRR seems to think drifting west and better structure but still dealing with dry air

HRRR
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2768. Mikla
Hey SJ... THANKS for all you folks are doing!

Quoting StormJunkie:
Morning all, from Biloxi, MS. Gulf waters are already starting to rise at a fairly quick rate here. We will have the webcam running for at least the next 24 hrs.
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Quoting Tazmanian:
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 28th day of the month at 12:22Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 306)
Storm Number & Year: 09L in 2012
Storm Name: Isaac (flight in the North Atlantic basin)
Mission Number: 31
Observation Number: 04
A. Time of Center Fix: 28th day of the month at 11:38:20Z
B. Center Fix Coordinates: 27°51'N 88°13'W (27.85N 88.2167W)
B. Center Fix Location: 184 miles (297 km) to the SE (143°) from New Orleans, LA, USA.
C. Minimum Height at Standard Level: 1,224m (4,016ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 45kts (~ 51.8mph)
E. Location of the Estimated Maximum Surface Wind: 69 nautical miles (79 statute miles) to the WNW (303°) of center fix
F. Maximum Flight Level Wind Inbound: From 42° at 58kts (From the NE at ~ 66.7mph)
G. Location of Maximum Flight Level Wind Inbound: 78 nautical miles (90 statute miles) to the WNW/NW (304°) of center fix
H. Minimum Sea Level Pressure: 977mb (28.85 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 17°C (63°F) at a pressure alt. of 1,527m (5,010ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 21°C (70°F) at a pressure alt. of 1,527m (5,010ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 20°C (68°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Open from the south-southwest to the north-northeast
M. Eye Shape & Diameter: Circular with a diameter of 50 nautical miles (58 statute miles)
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind Outbound: 86kts (~ 99.0mph) in the southeast quadrant at 11:57:30Z





the new vorte is out see above
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Quoting washingtonian115:
Oh Aussie storm where art thou? :).


ditto
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last night twc said hh would fly through isaac till land fall...... wheres the info then????
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Quoting GetReal:
Winds have picked up over the last thirty minutes out of the NE gusting 30+ mph... Big increase in coverage of stratus clouds zipping south.




Mine is going up now
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Quoting GetReal:


Closer, almost there for a completely closed in eye wall.
LOOK at the goes 14 time lapse as the sun is rising on Isaac. Don't know if the eye is closed or not but convection at the eye is increasing.
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Morning all, from Biloxi, MS. Gulf waters are already starting to rise at a fairly quick rate here. We will have the webcam running for at least the next 24 hrs.
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Oh Aussie storm where art thou? :).
Member Since: August 14, 2010 Posts: 10 Comments: 17472
Quoting AtHomeInTX:


Don't tell him.


Good morning athome!! :)

It appears, that perhaps, the wobble...may not have been JUST a wobble.
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Thanks WxLogic. What odds do you give this? I live around Lake Charles and they just up'd us from Tropical Storm Watch to Warning.
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Quoting justsouthofnola:
there is the eye..... hes gonna make it.

i live in central lafourche parish the eye of this thing should pass over my house


Please stay safe and beware of the flooding issues....Hope you sandbagged where no needed to.
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2755. GetReal
Winds have picked up over the last thirty minutes out of the NE gusting 30+ mph... Big increase in coverage of stratus clouds zipping south.
Member Since: July 4, 2005 Posts: 204 Comments: 8898
Forecast didn't predict a stall, it's crawling at a snails pace, this has to change to forecast at 11
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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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