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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Looks like dry air being pulled in on the east side of the eye.
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It's easy to try and second guess the NHC from the comfort of your home/work computer, but they have done a fine job with this storm and all interests in the Northern Gulf coast have been on notice for several days. Issac never blew up like may folks were expecting but possible Cat 2 has been on the table for several days as well..........Yesterday NHC specified that Issac would intensify up until landfall. The forecast was spot on............Whether folks heeded that advice and prepared accordingly is another matter.
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Quoting reedzone:


NO ONE not even the NHC is taking Isaac seriously and lives will be lost.


Dude you are a troll, you said the storm would never bust through a Ridge and Isaac would never cross 85W, yet it did. NHC takes it seriously, why do you think they have flown 31 missions into Isaac? Why do you think they update every few hours? Thank the lord you are not allowed anywhere near a NHC office, the entire East Coast of the US and now the Gulf coast would have been evacuated. Pipe down there champ, and learn your role as just another dude who works a day job and watches the weather from home.
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People like windwave are hilarious to me, I don't know about you guys.

Good trolls know basic grammar, I made a mistake due to auto-correct on the iPad. Windwave can't even make a sentence without 12 mistakes.
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3400. Patrap
Tornado Watch Issued for the Se Louisiana Area..

Image and Text to follow
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You know what Bob, I've had alot of respect for you, watched your videos and you have the nerve to make that statement.. Your not a MET, your a bully.. I did NOTHING to you and start bullying me on here. That's not professorial sir.
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Local met in New Orleans just profoundly said "Don't try to do any boating today....unless you've got a destroyer." Sheesh.
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3397. Melagoo
I think Isaac looks more symmetrical now not good ... :c(

I take back the non-Hurricane remark things look way more organized now

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Quoting windwave:
omg that taz guy is still here? doesn't he hold the record for number of threats to quit posting? well the circus is in town lol



Welcome to ignore you clown
Member Since: May 21, 2006 Posts: 5091 Comments: 114977
Quoting CybrTeddy:


I'm on a iPad, so I have an excuse. Welcome to ignore you clown.




heh heh heh LOL
Member Since: May 21, 2006 Posts: 5091 Comments: 114977
..
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3391. Caner
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3390. GetReal
Member Since: July 4, 2005 Posts: 204 Comments: 8858
Levi is there a complete eye wall? Is Isaac better vertically stacked based on recon?
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I can assure you: ALL the people in positions of responsibility and authority are taking this VERY seriously....
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3386. divdog
Quoting MississippiWx:
Recon finds 975mb readings now. Also, Isaac's center continues to move in wild directions.
Will a surprise course change be issacs last trick .?
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Quoting windwave:


while i'm "add it"? wow, how embarrassing . . . for you


I'm on a iPad, so I have an excuse. Welcome to ignore you clown.
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another little burst beginning on the southwest side.
Member Since: June 17, 2011 Posts: 11 Comments: 6482
975mb pressure and a wobble

Time: 14:27:00Z
Coordinates: 27.9667N 88.5667W
Acft. Static Air Press: 842.8 mb (~ 24.89 inHg)
Acft. Geopotential Hgt: 1,290 meters (~ 4,232 feet)
Extrap. Sfc. Press: 975.5 mb (~ 28.81 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 216° at 3 knots (From the SW at ~ 3.4 mph)
Air Temp: 21.0°C (~ 69.8°F)
Dew Pt: 21.0°C (~ 69.8°F)
Peak (10s) Flt. Lvl. Wind: 4 knots (~ 4.6 mph)
SFMR Peak (10s) Sfc. Wind: 15 knots* (~ 17.2 mph*)
SFMR Rain Rate: 2 mm/hr* (~ 0.08 in/hr*)
(*) Denotes suspect data
Member Since: March 16, 2012 Posts: 127 Comments: 7940
StormJunkie's live stream id really pretty cool. Sky is turning menacing and he just panned the beach to show rising water. Thanks StormJunkie and awesome work. Stay safe.
Link
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Quoting Beachfoxx:
Choctawatchee Bay just north of destin has risen maybe a foot in the past hour.


I'm seeing the same thing just West of Fort Walton Beach on the sound too. Waves are now hitting the deck of the dock and the water is about a foot from going over the dock.
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Quoting CybrTeddy:


Maybe you could sidelong some grammar lessons and basic computer typing skills while you're add it.

:)



LOL
Member Since: May 21, 2006 Posts: 5091 Comments: 114977
Last large, slow moving storm to make landfall near here was Lee, and he caused near $2B in damage.
Member Since: August 1, 2012 Posts: 0 Comments: 436
3375. will40
Quoting Tazmanian:
if you guys learn how too ues the ignore tools on here you can ignore all the dry air caster and make this blog a marh better place too blog


everyone has their own opinion Taz
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With the state of emergency
Florida Price Gouging laws are in effect.
Too bad it has to be a qick hike in prices because they are gouging already.

Cam shot of NO didn't look like heavy rain yet. Nice link, Montana.
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I think ppl in MS are letting their guard down a little bit and that is not a good thing. Just a reminder of what's to come. This will be felt all the way to Mobile and beyond.

Member Since: August 1, 2007 Posts: 0 Comments: 178
3372. Levi32
Pressure a millibar or so lower than the last pass:

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Recon finds 975mb readings now. Also, Isaac's center continues to move in wild directions.
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Oh yes.

New frame.

Plus 64kts and minus 64kts.

It's gotta be a hurricane now.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Quoting MississippiWx:
Well, Isaac seems to finally have his act together. He will strengthen all the way through landfall.


Strange to think that the reason its finally sterengthening is actually land interaction, allowing the storm to finally consolidate its core.
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Quoting windwave:


ok i will post 1,000 times today so i can be considered cool by Cybertebby lol


Maybe you could sidelong some grammar lessons and basic computer typing skills while you're at it.
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3366. GetReal
Member Since: July 4, 2005 Posts: 204 Comments: 8858
Quoting Levi32:


Yes, the turbulent mixing brings downbursts to the surface. This is why I am somewhat dumbfounded. Never have I seen 976mb, 85kt flight-level winds, and no hurricane. If they don't upgrade from the dropsonde 70kt observation, I won't know what to say. That is the most tangible data you can get from a recon.


Maybe their waiting an hour or two to see if it stays
Member Since: August 23, 2008 Posts: 0 Comments: 1918
Quoting FelixTheKat:


yea, keep wishcasting away.


Downplaying this storm is foolish, this storm will cause billions in damage and effect millions of people with strong winds and floodin due to its slow pace. No wishcasting here just facts. I believe i hear ur mom calling you, better go c what she wants
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Quoting reedzone:


NO ONE not even the NHC is taking Isaac seriously and lives will be lost.


Dumbest statement of year award!
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Quoting JasonRE:


Thanks! I just got that info from a co-worker. Guess I will be here while the wife fights off water! I can't believe we're open tomorrow!

Chances are once Joey declares a state of emergency for Lafayette Parish, businessowners will heed the warning...it's a wait and see.
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Quoting MontanaZephyr:


Yes.

Bourbon Street Cam:
Link


Ok, nothing too heavy yet apparently, just a drizzle.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Just hit the ignore button on guys like Felixthecat, save the board from his jibberish
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To all those ready to downplay this storm
WAKE UP this is a HUGE storm and whether the winds are 65 or 85 is of little significance.
statistically the real killers are surge and rain. Isaac will have plenty of both
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Quoting windwave:
Do not confuse media with meteorological organizations and employees. I don't recall anyone in the "weather establishment" exactly writing off this storm. I recall the media shifting it's attention because it wasn't giving them ratings or living up to their established "Live TV-Friendly Deadly Hurricane" trope fast enough.

Most mets and professionals have been saying that this storm is big, moving large amounts of atmosphere and can and will still bring large amounts of rain and flooding and that people need to be prepared for that.
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I think Isaac just got punched in the gut again with dry air?
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Quoting depalma13:


If the levees break, than New Orleans should be abandoned forever. This is a Tropical Storm/barely Cat 1 Hurricane. It is not a life or death situation. It's time for everyone to stop panicing because of a little water and and wind.


A TS or Cat 1 is not life or death? I'm guessing the people that already died as a result of this storm would beg to differ with your ill informed commentary. People like you are why I stopped coming to this blog.
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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.