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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2504. Patrap
This Large CV Ballerina has finally pulled Her/His arm's in and well,..these LARGE System's don't fade, nor wind down easily.

A LOT of water is now being put into Motion N to Nw and that alone is GOING to create a substantial event for many, in 3 States easily.

The Time for ACTION will be first Light to Noon CDT and I urge all with preps outside to carefully,but prudently get those done.

The winds are beginning to pick up and they will only increase to Tropical Storm Strength and Greater in the Warned area's from the Coastal regions to well inland.
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There are clouds in the eyewall topping 54k ft according to radar out of NOLA... cant see anything more then a few "showers" on radar but thats because of how far the eye is from land still
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Quoting Patrap:


I have a lil time to post before I'll have to disengage to deal with a few things when First Light allows.

One has to be VERY careful now with any chores as one bad accident, fall, or other can be dangerous for the event as things are pretty well locked down here, or in Level 1 Emergency status.




Sorry you had to cut your vacation short but I'm glad you are back. Trust your post. My family left. Wanted to get the older generation out and the young kids. Just to be safe. Be Careful and you guys stay safe also.
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Quoting MAweatherboy1:
Don't get too excited... There's only so much a storm can strengthen with no north side, lol.



NHC forecast seems very reasonable right now.


Last year Noel didn't even have a north side when it became a hurricane. Dry air to the north causing this, but there's little doubt in my mind right now that Isaac is a hurricane.
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2500. MahFL
I think Isaac is heading to MS anyways, just west of Mobile, AL.
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Product: NOAA Vortex Message (URNT12 KWBC)
Transmitted: 28th day of the month at 10:21Z
Aircraft: Lockheed WP-3D Orion (Reg. Num. N42RF)
Storm Number & Year: 09L in 2012
Storm Name: Isaac (flight in the North Atlantic basin)
Mission Number: 30
Observation Number: 09
A. Time of Center Fix: 28th day of the month at 9:31:45Z
B. Center Fix Coordinates: 27°30'N 87°59'W (27.5N 87.9833W)
B. Center Fix Location: 208 miles (336 km) to the SSW (193°) from Pensacola, FL, USA.
C. Minimum Height at Standard Level (Undecoded): NA NA
D. Estimated (by SFMR or visually) Maximum Surface Wind: 62kts (~ 71.3mph)
E. Location of the Estimated Maximum Surface Wind: 47 nautical miles (54 statute miles) to the E (99°) of center fix
F. Maximum Flight Level Wind Inbound: From 180° at 75kts (From the S at ~ 86.3mph)
G. Location of Maximum Flight Level Wind Inbound: 66 nautical miles (76 statute miles) to the E (94°) of center fix
H. Minimum Sea Level Pressure: 977mb (28.85 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 14°C (57°F) at a pressure alt. of 2,437m (7,995ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 18°C (64°F) at a pressure alt. of 2,440m (8,005ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 15°C (59°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Poorly Defined
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: Other - Not surface, 1500ft, 925mb (if vortex is newer than about mid 90's; see note for more), 850mb, 700mb, 500mb, 400mb, 300mb or 200mb
Remarks Section:
Maximum Flight Level Wind: 75kts (~ 86.3mph) in the east quadrant at 9:14:32Z
Maximum Flight Level Wind Outbound: 60kts (~ 69.0mph) in the west quadrant at 9:52:27Z
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2498. nolajet
Just wanted to wish everyone a safe day! Won't be getting home from work until most likely the power is out. Welcome back Patrap! Looks like the "eyeball" has finally made an appearance. Let's hope for the best. :)
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2497. GetReal
Quoting louisianaweatherguy:
an eye popped out, but NOW... if the north side don't fill in, his eye could possibly GO AWAY... this is really sad LOL!!!!


IMO this is the first time the eye has been centered in the CDO... Like a classic 977MB hurricane would look. THE DONUT HOLE LOOK!
Member Since: July 4, 2005 Posts: 204 Comments: 8898
Don't get too excited... There's only so much a storm can strengthen with no north side, lol.



NHC forecast seems very reasonable right now.
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I think for the first time we have a ligit eye forming. Now does it hold together for more that a few slides. This could be bad for souther lousiana.
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Yup, that's an eye. Not much of one...

Member Since: January 25, 2012 Posts: 33 Comments: 1520
2493. Patrap
Quoting jazzygal:


I think his eye is here to stay. He looks much better this AM. Pat are you back? Could have used you here a few nights ago. Too many on here not liking N.O.


I have a lil time to post before I'll have to disengage to deal with a few things when First Light allows.

One has to be VERY careful now with any chores as one bad accident, fall, or other can be dangerous for the event as things are pretty well locked down here, or in Level 1 Emergency status.


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Good Morning Isaac! He is waking up!
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an eye popped out, but NOW... if the north side don't fill in, his eye could possibly GO AWAY... this is really sad LOL!!!!
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That eye just popped out of no where and it looks good. Might see some significant development with that now appearing.
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2489. GetReal
Taz just signed off 20 minutes ago, and is missing the show.
Member Since: July 4, 2005 Posts: 204 Comments: 8898
oh boy...
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2487. GetReal


Eye held together for a second frame....
Member Since: July 4, 2005 Posts: 204 Comments: 8898
2486. WxLogic
Good Morning
Member Since: August 14, 2008 Posts: 4 Comments: 5038
2485. GetReal
Quoting Carnoustie:


it looks like an eye,but is it?



This is very likely the real thing!!!


The only question now will this be the beginning of a RI period... Hope not.
Member Since: July 4, 2005 Posts: 204 Comments: 8898
Quoting GetReal:
Post the best pic of Isaac eye... Blog goes dead. Hmmm LOL


I think his eye is here to stay. He looks much better this AM. Pat are you back? Could have used you here a few nights ago. Too many on here not liking N.O.
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2483. LargoFl
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Good Morning
Best nights sleep in a long time.
Pressure still falling.
Eye like feature.
Very impresive visible sat.
90 mph flight winds
still a TS.....
WOW What the...... is he doing and how is he doing it?
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2481. Patrap
A eye has cleared out as TS Isaac nears graduation to a Hurricane soon.

RainbowTop Loop


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This morning I noticed some convection start to build near 29 and 86 around 7:15 utc than it not only disappears but then become a dry slot of air on the water vapor by 9:45utc. I haven't studied up on seeding and whether it is ligit or not, but definitely looked wierd. Nevver seen convection build like that and then become so dry so quick. Does anyone notice what I did first? And second does anyone have a more logical explanation of how that could occur so quickly over a tropical system that is trying to develope?
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I think I see a pinhole eye.



ROFLMAO.

It's an eye.

But not much more than the eye wall itself on the N and NW directions. Literally no feeder bands except a few scattered clouds that probably don't even have real precipitation in them.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
2478. GetReal
Quoting Patrap:
TS Isaac RGB Loop




Now that is an impressive looking donut hole!!!

Isaac over the northern part of the Gulf Loop now....
Member Since: July 4, 2005 Posts: 204 Comments: 8898
2477. LargoFl
Quoting GetReal:
Well just a note of interest my barometer is down this morning to 29.55 inches and falling... I am located on the south side of metro NOLA.
a couple of days ago the NHC said it was going to hit around the mouth of the mississippi river..lets see where he does come in..stay safe up there ok
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2476. MahFL
Wow an eye just popped out !
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2475. Patrap
Quoting aislinnpaps:
Morning, Pat. I hope you were able to get some sleep last night. You stay safe!


G' more over dere, rest was a nice thing as it's been a rare event for me and others with this one.

But rest was achieved and the Java is flowing as we await Dawn.

As well as Isaac's move.

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2474. LargoFl
Quoting CCkid00:

okay....i live an hour northwest of NOLA (between Baton Rouge and Hammond). if this takes the EURO route, will we still get heavy winds and rain? because all of the convection is on one side, i can't figure what we will get here.
guess we will have to see what happens today and where he heads to, usually with a land falling storm the worst is on its northeast side, which spreads eastward i guess, we'll see what happens..this storm has quirks that confound the experts...stay prepared and stay safe ok
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2473. GetReal
Well just a note of interest my barometer is down this morning to 29.55 inches and falling... I am located on the south side of metro NOLA.
Member Since: July 4, 2005 Posts: 204 Comments: 8898
Quoting GetReal:



Seen this before.... However this time the eyewall looks pretty impressive, but can it hold together?!?!


it looks like an eye,but is it?
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2471. Patrap
TS Isaac RGB Loop

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Quoting GetReal:
Post the best pic of Isaac eye... Blog goes dead. Hmmm LOL


Everybody burned out, got trolled one too many times by ISAAC.
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Good morning. Isaac sure is a weird storm, I have a feeling its probably a hurricane, new recon is on the way and they should figure it out.



Stay safe on the Gulf Coast for the next couple days.
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Morning, Pat. I hope you were able to get some sleep last night. You stay safe!
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2467. GetReal
Quoting Patrap:
Was a good thing taking time off,

,,,thanx.


Will be a long couple of days along the Northern Gulf Coast.

We ready as rain you could say maybe?

But things sometimes have a way of working out for the better.





Good morning Pat, glad to have you back for posting the widest source of images on the WU.
Member Since: July 4, 2005 Posts: 204 Comments: 8898
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.
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Quoting Skyepony:


The storm is so big it is going to take a lower pressure to get the same winds. The high in the Atlantic is only ~1024mb as well. You need pressure gradient for winds. It's why the WPAC has a different chart converting mb to winds than the Atlantic.

That being said I traveled from GA to FL yesterday & chemtrails were everywhere in the SGA/NFL area. Another interesting note is how everyone is saying they have never seen a lunar halo or halo around the sun so bright as today in those areas. These sort of sightings are common with certain types of seeding.

If this goes the right way it could save the fall planting up the middle of the country..

Thanks for your explanation and opinion. Have a great day.
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2464. Patrap

Tropical Storm ISAAC NESDIS Satellite | NDBC Obs | Storm Archive

...ISAAC ON THE VERGE OF BECOMING A HURRICANE...SIGNIFICANT STORM SURGE AND FRESHWATER FLOOD THREAT TO THE NORTHERN GULF COAST... ...U.S. Warnings in Effect...


4:00 AM CDT Tue Aug 28
Location: 27.5°N 88.1°W
Moving: NW at 12 mph
Min pressure: 977 mb
Max sustained: 70 mph
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Quoting LargoFl:
according to the GFS we may be..dealing with yet another tropical system in the gulf in just about 135 hours or so, save those supplies etc..hurricane season isnt over yet, and..i do not like..where the GFS sends this next storm


Probably in the clear now.

The "cone" on that one will shift about a thousand miles before it's all said and done.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
i have a feeling alot of people are underestimating this storm
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2461. Patrap
www.nola.com
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2460. LargoFl
Quoting RTSplayer:
Storm is in annoying weak/pathetic shape.

You can see from Mobile and Slidell radar that there are almost no western rains at all this morning.


Oh yeah, Adjusted Euro is 971mb.


I don't know what this is, but the name "Isaac" seems appropriate, because right now it seems like a joke.

There has literally been stronger 990mb storms before.
well we all saw..what happened to eastern florida yesterday..some places got over 12 inches of rain, and when all that water filters into the rivers lakes and streams..flooding is coming for sure, with issac..dont focus on the winds, tornado's and tons of rain are coming, and god forbid he slows down or even stops for a day or two..over land or worse, just off shore.
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2459. GetReal
Post the best pic of Isaac eye... Blog goes dead. Hmmm LOL
Member Since: July 4, 2005 Posts: 204 Comments: 8898
Isaac is certainly a weird looking system. It looks cut in half, lol.

Nevertheless, it is also full of rain and probably a little bit stronger (in what damage it can do) than how it was when it impacted south Florida.
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2457. LargoFl
Quoting Chicklit:
Isaac is an odd duck. The storm has been contorted and unpredictable. The best we can do at present is use supercomputerized models that indicate where a system is going based upon current observations. It is nobody's 'fault' that Isaac didn't go up the state of Florida as initially the models indicated.

Anyway, sorry about the sour grapes over not getting hit with a storm but believe me, the expense would have been far greater for people had they been hit. And they can now use the supplies for another storm or else consume what they bought.
according to the GFS we may be..dealing with yet another tropical system in the gulf in just about 135 hours or so, save those supplies etc..hurricane season isnt over yet, and..i do not like..where the GFS sends this next storm
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2456. Patrap
Was a good thing taking time off,

,,,thanx.


Will be a long couple of days along the Northern Gulf Coast.

We ready as rain you could say maybe?

But things sometimes have a way of working out for the better.

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2455. GetReal



Seen this before.... However this time the eyewall looks pretty impressive, but can it hold together?!?!
Member Since: July 4, 2005 Posts: 204 Comments: 8898
Gotta go to work at 9 (no idea why I'm still up -_-), but I thought I'd link to the blog I just finished on Isaac. Didn't have time for Ileana.
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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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