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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Watch Isaac still not become a hurricane.
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3453. Patrap
12z Early Cycle NHC model tracks
Isaac

Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)




Dynamic Models (More sophisticated models)




Early Model Wind Forecasts

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Quoting reedzone:


Me a troll?? Say that to the bloggers who enjoy my posts on here.. I have some haters but really a troll?? That's low man... I have a right to make predictions and maybe you haven't read my post one night saying I was WRONG in Isaac not busting the mid level ridge. I was WRONG in Isaac going up the East Coast. I was WRONG WRONG WRONG.. ok?

U crying there mate??? swear it sounds like it. LOL
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I believe Stewart's writing the advisory, so that's a good thing.
Member Since: February 11, 2012 Posts: 84 Comments: 7925
3450. wxmod
This is a satellite photo of cumulus cloud streets forming over the arctic ocean where there used to be ICE. Cumulus clouds require HEAT and would probably not form over solid arctic ice. As the ocean becomes warmer, these clouds will become bigger and will affect the type of storms that happen in the arctic.

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Quoting reedzone:


Me a troll?? Say that to the bloggers who enjoy my posts on here.. I have some haters but really a troll?? That's low man... I have a right to make predictions and maybe you haven't read my post one night saying I was WRONG in Isaac not busting the mid level ridge. I was WRONG in Isaac going up the East Coast. I was WRONG WRONG WRONG.. ok?


Ok champ, sport. Just calm down over there, maybe read an NHC discussion or something. LOL.
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Quoting Charliesgirl:

Edit Failed!

a beautiful pic taken by a friend over Lake Ponchartrain in Slidell, La. double good luck.


oh well, anyone know how to post a photo? I put it to my photos on here.
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Quoting Levi32:


He's been stacked. Dry air is his problem, making the eyewall ragged. However, he has been gradually deepening for the last 48 hours, and still is.


Can the dry air be ingested and expelled before landfall? Looking at the water vapor imagery I dont forsee dry air becomming an issue from this point on?
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3446. K8eCane
Quoting washingaway:


You know, every where you go, there's always an A hole.

if a-holes could fly, i swear sometimes this place would be an airport. never, ever underestimate a tropical system
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twc says it looks concentric and looks great
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting reedzone:


Me a troll?? Say that to the bloggers who enjoy my posts on here.. I have some haters but really a troll?? That's low man... I have a right to make predictions and maybe you haven't read my post one night saying I was WRONG in Isaac not busting the mid level ridge. I was WRONG in Isaac going up the East Coast. I was WRONG WRONG WRONG.. ok?


so you are saying you were Wrong?
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Quoting Patrap:
Earlier..


Hey Pat...mandeville here. Where would I find a good prediction of the surge level here? TIA
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Update: at buoy KMIS, just east of the tip of Louisiana, winds have already switched over to the SOUTHEAST, indicating it will pass well S of New Orleans. Storm was almost at 28 degrees north at 10:15am, with a pressure reading of 975.5. It will be interesting to see if it makes it much past 28 north.

Edit: this wind direction is suspect, looking at the history of the readings!

Take a look at this buoy for the greatest wind increase:
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Levi,

What do you think the deal with Isaac is? Do you ever remember seeing this happen before? Pressure keeps dropping but it's doing it without a complete eyewall. I can't remember ever seeing a TC drop this low without a complete eyewall. The COC doesn't even have a solid COD over it. Whatever method of strengthening Isaac is using is not typical of normal tropical cyclones.....at least in this hemisphere.
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the word "ignore" is right next the word "quote" and much easier to use. :)
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Isaac SHOULD be upgraded to a Hurricane at 11, but for some reason I don't think it will.
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Quoting Tazmanian:
11am better be good


Or else what?
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Quoting windwave:


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


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

Got to love the clowns too....... they add their specialness to the blog, and we get the laugh!
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GULP.

Thats the sound of a big chunk of dry air Isaac is now wrapping around his core. I dont see him strengthening much more than 85-90mph before landfall. Crazy low pressure though, someone is going to have fun writing a thesis about this one.
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Isaac must be pushing up a large surge... trolls are getting flooded out from under their bridges and up onto the blog. :-/
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Folks are starting to lose power in the Greater New Orleans area. It's starting.
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3433. divdog
Quoting reedzone:
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.
Weel we not u r not professional and made that statement out of frustration or something else going on in your head.85 w just remember
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Quoting Levi32:


He's been stacked. Dry air is his problem, making the eyewall ragged. However, he has been gradually deepening for the last 48 hours, and still is.


Its enough.....probably get that eye right over me.
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3431. SLU
All things being equal, 975mb would be able to support a 100mph cat. 2 hurricane ....
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3430. jpsb
Quoting weathermanwannabe:
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.

Yes NHC has done an excellent job on Issac tract a little off on strenght but over all great job by the NHC. I was fooled by GFS into think a little more west, turned out NHC was correct and I am eating crow. lol.
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11am better be good
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Quoting windwave:
another epic embarrassment for the weather establishment. the moment they wrote off the storm in Southeast Florida, it began to rain massive amounts, the wind increased, tornadoes formed and roads were flooded, and this went on for almost 24 hours. The question is not are they wrong in their current forecast, but in what manner they are wrong. sad really.


I thought it was handled pretty well they forecasted 4-8 inches of rain with 12" in isolated areas. Winds were as expected 30-50 mph with gusts to 60 mph. The worst weather was expected from Sunday thru Monday. Yes some areas of PB got 15-20" but Miami got 4-5" Naples recieved about 3.5" Fort Lauderdale got 7" but other areas of Broward got 10+ inches. We got what was pretty much advertised the dirty side of a medium intensity tropical storm.
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Quoting SouthTXWX:


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.


Me a troll?? Say that to the bloggers who enjoy my posts on here.. I have some haters but really a troll?? That's low man... I have a right to make predictions and maybe you haven't read my post one night saying I was WRONG in Isaac not busting the mid level ridge. I was WRONG in Isaac going up the East Coast. I was WRONG WRONG WRONG.. ok?
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brace for the F5 hits...
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Quoting sar2401:


Well, it's sure not happening in AL. Had one squall line earlier today that dropped .16 of an inch. The rainbands coming off Issac look puny so far. We'll take some more rain if we can get it but it sure doesn't look like a major event for AL right now.
Quoting TomballTXPride:

Good news. Thanks for the update. Hopefully you are right!


"Right now" are the opoerative words;-)
Member Since: August 16, 2007 Posts: 0 Comments: 397
Wind startin' to howl...its movin' in. Really glad its not going to be another too bad....
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3423. Levi32
Quoting wayfaringstranger:
Levi is there a complete eye wall? Is Isaac better vertically stacked based on recon?


He's been stacked. Dry air is his problem, making the eyewall ragged. However, he has been gradually deepening for the last 48 hours, and still is.
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Even though it's not a Katrina sized storm, Isaac is still a big threat. People hopefully followed warnings and did what they needed to do.
EDIT: Tornadoes are another threat, Tornado watch issued in S LA, S MS, S AL, and NW FL Panhandle.
Member Since: March 16, 2012 Posts: 127 Comments: 7958




a beautiful pic taken by a friend over Lake Ponchartrain in Slidell, La. double good luck.
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Quoting CybrTeddy:
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.


Well, thank you guys very much for that - refreshing? - break. Now, back to weather.
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Quoting CybrTeddy:
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.


No problem CybrTeddy keep on keeping on
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3418. sar2401
Quoting CybrTeddy:


The NHC is taking this plenty seriously.. if the news is disregarding the massive storm surge potential that's their fault.
SOUTHEAST LOUISIANA AND MISSISSIPPI...6 TO 12 FT

I've seen major hurricanes with that storm surge potential before.


Let's put this into perspective. Katrina had a maximum storm surge of 27.8 feet at Pass Christian MS. Average storm surge was in the order of 15 to 18 feet. The Grand Isle LA area had a storm surge of 16.2 feet. 6-12 feet is still a lot of water but it's not Katrina.
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Quoting CybrTeddy:
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.


autocorrect=fail never use it myself
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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.


I must say, all storms such as this require respect and the truth is there is always the element of surprise and the unexpected development. That said, coverage intensity should be relative within reason to storm intensity and potential. All storms have potential of serious rain etc. Often its hard to predict. TWC coverage and intensity of coverage on a scale of one to ten is by far a ten. So how do you ramp up for a cat 2, 3, 4 or 5 hurricane from here. Its way wAy over kill and sensationalized. To watch abrahms try and convince nabb and get him to say this was a hurricane as she did a bit ago is damn right weird. I have never, in 40 years seen the media have so much negative dire coverage of a "tropical storm". They keep saying issac is no katrina but..... Well he is no katrina, lol, hello, how about a tropical storm. John hope would be apalled at this. He would have no part in this crap, way to much, bordering on plain weird.
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3413. Patrap


This is a quick view of the initial counties (WOU) product for WW 0591
Full watch page will be available shortly. Please check back soon.

WOUS64 KWNS 281443
WOU1

BULLETIN - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH OUTLINE UPDATE FOR WT 591
NWS STORM PREDICTION CENTER NORMAN OK
945 AM CDT TUE AUG 28 2012

TORNADO WATCH 591 IS IN EFFECT UNTIL 700 PM CDT FOR THE
FOLLOWING LOCATIONS

ALC003-053-097-290000-
/O.NEW.KWNS.TO.A.0591.120828T1445Z-120829T0000Z/

AL
. ALABAMA COUNTIES INCLUDED ARE

BALDWIN ESCAMBIA MOBILE


FLC005-033-059-091-113-131-133-290000-
/O.NEW.KWNS.TO.A.0591.120828T1445Z-120829T0000Z/

FL
. FLORIDA COUNTIES INCLUDED ARE

BAY ESCAMBIA HOLMES
OKALOOSA SANTA ROSA WALTON
WASHINGTON


LAC051-057-071-075-087-089-095-103-105-109-117-290 000-
/O.NEW.KWNS.TO.A.0591.120828T1445Z-120829T0000Z/

LA
. LOUISIANA PARISHES INCLUDED ARE

JEFFERSON LAFOURCHE ORLEANS
PLAQUEMINES ST. BERNARD ST. CHARLES
ST. JOHN THE BAPTIST ST. TAMMANY TANGIPAHOA
TERREBONNE WASHINGTON


MSC039-045-047-059-109-131-290000-
/O.NEW.KWNS.TO.A.0591.120828T1445Z-120829T0000Z/

MS
. MISSISSIPPI COUNTIES INCLUDED ARE

GEORGE HANCOCK HARRISON
JACKSON PEARL RIVER STONE


GMZ530-532-534-536-538-550-552-555-557-630-650-655 -750-290000-
/O.NEW.KWNS.TO.A.0591.120828T1445Z-120829T0000Z/

CW

. ADJACENT COASTAL WATERS INCLUDED ARE

LAKE PONTCHARTRAIN AND LAKE MAUREPAS

MISSISSIPPI SOUND

LAKE BORGNE

CHANDELEUR SOUND

BRETON SOUND

COASTAL WATERS FROM PORT FOURCHON LA TO LOWER ATCHAFALAYA RIVER
LA OUT 20 NM

COASTAL WATERS FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER
TO PORT FOURCHON LOUISIANA OUT 20 NM

COASTAL WATERS FROM BOOTHVILLE LA TO SOUTHWEST PASS OF THE
MISSISSIPPI RIVER OUT 20 NM

COASTAL WATERS FROM PASCAGOULA MISSISSIPPI TO STAKE ISLAND OUT 20
NM

MOBILE BAY

COASTAL WATERS FROM PENSACOLA FL TO PASCAGOULA MS OUT 20 NM

COASTAL WATERS FROM DESTIN TO PENSACOLA FL OUT 20 NM

COASTAL WATERS FROM APALACHICOLA TO DESTIN FL OUT 20 NM

ATTN...WFO...MOB...TAE...LIX...
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3412. kwgirl
Quoting sar2401:


Well, it's sure not happening in AL. Had one squall line earlier today that dropped .16 of an inch. The rainbands coming off Issac look puny so far. We'll take some more rain if we can get it but it sure doesn't look like a major event for AL right now.
Once the storm starts pulling North you will probably feel the worse side. As someone said on here, the Florida newscasters said the storm was over then we got our worst rains and winds. The winds just started lying down today in the keys, but if you look at satelitte, we are still getting weather from Isaac being pulled over us. It's a big lopsided storm. Key West was on the "dry" side at first. Yesterday we had surge in the streets after he passed us by. Don't write it off yet and if it is nothing in your area, count your blessings.
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3411. yoboi
Quoting presslord:
I can assure you: ALL the people in positions of responsibility and authority are taking this VERY seriously....



hey press i talked to junkie this morn...if i hear something will pass it along, just at a wait and see now...
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How ironic that a storm that was once moving at 23mph has now crawled to the pace of a snail.
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Hi to all,
Just observations from my location..northern Calcasieu parish SWLA. Winds out of NNW this am, and now winds out of NE w SLIGHT gusts out of E. Lower cloud movement....barely moving looking overhead. My dad always told me just as a "lay WX person", follow the winds in your own back yard, and on a rough scale, you can tell the location IN GENERAL of any storm. These are only observations..no predictions as I am not qualified for this. My bottom line is...I am amazed after following hurricanes since I was a kid w my dad, we are feeling the effects of Isaac, no matter how small they may be, but already. Just saying. Thank you for the people on this blog for your insight and comments. We are lucky to have this blog as well as those who are so knowledgeable in meteorology!
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3408. jpsb
Quoting emcf30:
Issac has stalled, nice pic.
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3407. ryang
What's with all these trolls this morning? -_-
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Stay safe John....
Choctaw Bay is rising, slowly. Up maybe 1 1/2 feet now. Looks like the dry air is riding over the FL Panhandle, no rain, no wind other than a minor gust every so often.

Everyone else in Isaacs path stay safe!
Quoting UnobtrusiveTroll10:
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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they always look better on vis:)
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Looks like dry air being pulled in on the east side of the eye.
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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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