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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2154. KEEPEROFTHEGATE (Mod)
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Hmmmm...HH headed back to center for another pass...guess we could get another VDM soon!
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Quoting Terradad:




But it is a model....

based on an extrapolation of the current heading, I believe.


But that is just my opinion....

In a way yes and in a way no. But no matter what Isaac has kind of been following it.
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2151. jake436
Quoting weatherh98:
This is idiocyand nitpicking

its all based on perspective. if you wanna look at 2 center fixes fine if you wanna make it 5 thats great too. you are both right according to perspectivepersonally the storm is making a few hundred s curves
That's my point. I do realize though, at such close range, wobbles matter in the grand scheme of things. It's just not enough to say it's going a certain direction, to me. There's been a lot of west or WNW over the past couple days, but in the long run, it's gone NW.
Member Since: August 31, 2006 Posts: 0 Comments: 271
Quoting Terradad:




But it is a model....

based on an extrapolation of the current heading, I believe.


But that is just my opinion....


When things get fuzzy just go with XTRP ((cough))
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Quoting desimundo:
It looks like Isaac can't make up its mind:



Hasn't been able to since he left the African coast.
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the euro would kick off soon and the gfs seems to have just stopped the run...
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Quoting washingaway:
I see a baby dinosaur.



I see a hitchhiking ghost?
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Quoting weatherh98:


By pat. hunker down. im going to bed goodnight folks

Good night 98, hope your prepared for what Isaac brings.
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Quoting wxchaser97:

I didn't get an easy storm to start out with. I started posting here in July so the first storm I tracked/forecasted was Ernesto. It hasn't been any easier this year after that.


He makes very good graphics and explains things in such a way that even I can understand. It really doesn't matter how brilliant a meteorologist is if they cannot effectively communicate what they think will happen.
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good for you Hunter.........spot on
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Quoting washingaway:


You're right, I didn't notice that.



He wants to go away to Texas!
Member Since: August 17, 2007 Posts: 0 Comments: 1098
GFS 66 hrs.

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Quoting Patrap:
To be sure,..

I'm very proud of how the flow has gone here.

Been a' lurking for a spell.


Will stop in tomorrow as I can.


Focus and rest is required as we may be out of touch for a day or so.

Keep up all the fine post and banter everyone.

The World is watching, know that.

Have a fine evening.

Peace.


By pat. hunker down. im going to bed goodnight folks
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Quoting mobilebayal:




......that appears to be hitch hiking .


You're right, I didn't notice that.
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Quoting Patrap:
If there's a bustle in your hedgerow, don't be alarmed now,
It's just a spring clean for the May queen.
Yes, there are two paths you can go by, but in the long run
There's still time to change the road you're on.
And it makes me wonder.



New Orleans
NEXRAD Radar

Base Reflectivity 0.50° Elevation
Range 248 NMI


great see you you back! many have asked about you, hoping for your input on isaac
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I have always wondered why college has debate class. Now I know. You guys make the most awesome weather people ever (but you should really consider taking a debate class - it is possible to have healthy debates without getting nasty with one another) There isn't ever a wrong or right posted on this blog; there are opinions supported by more or less facts. It is sometimes called west casing, wish casting etc. Perhaps it IS people with a bias believing that the storm will go one way or another as it would behoove them and then taking their hypothesis and attempting to support it with data. THAT IS what science is however, and weather IS a science. Hell, even the models have a bias. Most scientific instruments have weaknesses that are otherwise termed a "bias". This is how we learn and get better at predicting the weather. We DO NOT get better when good people get banned, or arguments happen that get people banned!

So Smile! It is just a blog and we are just talking about weather! lighten up all :) :) :)

I thoroughly enjoy reading all the casting on here - even those that catch fish!
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Quoting wxchaser97:

XTRP is not a model, its just an extrapolation of the current heading.




But it is a model....

based on an extrapolation of the current heading, I believe.


But that is just my opinion....
Member Since: Posts: Comments:
2135. sar2401
Quoting RTSplayer:


I'm already using that site, and it's not updating.


I think Isaac finally caused all the model runs to explode. :) It's not running right now so there's a glitch somewhere.
Member Since: Posts: Comments:
Quoting Patrap:
If there's a bustle in your hedgerow, don't be alarmed now,
It's just a spring clean for the May queen.
Yes, there are two paths you can go by, but in the long run
There's still time to change the road you're on.
And it makes me wonder.



New Orleans
NEXRAD Radar

Base Reflectivity 0.50° Elevation
Range 248 NMI



Hey Pat! Good to see ya, Isaac is a coming for NOLA. Luckily he isn't as strong as the K storm or Gustav(except for the surge).
Member Since: Posts: Comments:
2133. Patrap
To be sure,..

I'm very proud of how the flow has gone here.

Been a' lurking for a spell.


Will stop in tomorrow as I can.


Focus and rest is required as we may be out of touch for a day or so.

Keep up all the fine post and banter everyone.

The World is watching, know that.

Have a fine evening.

Peace.
Member Since: Posts: Comments:
Quoting TexNowNM:



Unfortunate situation resulted in a post being made earlier tonight asking everyone to report Taz and get him permanently banned. There were a few who agreed and he has not posted since. Proud to say he had many defenders.

Also, I'd like to add you have posted some really interesting tidbits of information.


taz doesnt deserveto be banned.
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Quoting desimundo:
It looks like Isaac can't make up its mind:



It's all that oil gummin up the works. remember they were going to coat the ocean in front of the storm to knock it down in years past....Well BP has done it for us
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Quoting washingaway:
I see a baby dinosaur.





......that appears to be hitch hiking .
Member Since: August 17, 2007 Posts: 0 Comments: 1098
Quoting sar2401:


Why do you think "they" got Taz banned?



Unfortunate situation resulted in a post being made earlier tonight asking everyone to report Taz and get him permanently banned. There were a few who agreed and he has not posted since. Proud to say he had many defenders.

Also, I'd like to add you have posted some really interesting tidbits of information.
Member Since: Posts: Comments:
Quoting Patrap:
If there's a bustle in your hedgerow, don't be alarmed now,
It's just a spring clean for the May queen.
Yes, there are two paths you can go by, but in the long run
There's still time to change the road you're on.
And it makes me wonder.



New Orleans
NEXRAD Radar

Base Reflectivity 0.50° Elevation
Range 248 NMI


Welcome back :)
Member Since: Posts: Comments:


Bullseye New Orleans
Member Since: Posts: Comments:
Quoting Patrap:
If there's a bustle in your hedgerow, don't be alarmed now,
It's just a spring clean for the May queen.
Yes, there are two paths you can go by, but in the long run
There's still time to change the road you're on.
And it makes me wonder.



New Orleans
NEXRAD Radar

Base Reflectivity 0.50° Elevation
Range 248 NMI




You back?
Member Since: Posts: Comments:
Quoting Patrap:
If there's a bustle in your hedgerow, don't be alarmed now,
It's just a spring clean for the May queen.
Yes, there are two paths you can go by, but in the long run
There's still time to change the road you're on.
And it makes me wonder.



New Orleans
NEXRAD Radar

Base Reflectivity 0.50° Elevation
Range 248 NMI




YAY, Pat's back!!
Member Since: Posts: Comments:
Latest Vortex Message:
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 28th day of the month at 05:15Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 309)
Storm Number & Year: 09L in 2012
Storm Name: Isaac (flight in the North Atlantic basin)
Mission Number: 29
Observation Number: 10
A. Time of Center Fix: 28th day of the month at 4:26:50Z
B. Center Fix Coordinates: 27°17'N 87°27'W (27.2833N 87.45W)
B. Center Fix Location: 219 miles (352 km) to the S (184°) from Pensacola, FL, USA.
C. Minimum Height at Standard Level: 1,253m (4,111ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 52kts (~ 59.8mph)
E. Location of the Estimated Maximum Surface Wind: 25 nautical miles (29 statute miles) to the ENE (65°) of center fix
F. Maximum Flight Level Wind Inbound: From 137° at 60kts (From the SE at ~ 69.0mph)
G. Location of Maximum Flight Level Wind Inbound: 30 nautical miles (35 statute miles) to the ENE (63°) of center fix
H. Minimum Sea Level Pressure: 979mb (28.91 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 18°C (64°F) at a pressure alt. of 1,514m (4,967ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 22°C (72°F) at a pressure alt. of 1,519m (4,984ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 19°C (66°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Open in the southwest
M. Eye Shape & Diameter: Circular with a diameter of 40 nautical miles (46 statute miles)
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Levels (sfc and flt lvl centers are within 5nm of each other): Surface and 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind: 70kts (~ 80.6mph) in the east quadrant at 3:39:00Z
Maximum Flight Level Wind Outbound: 62kts (~ 71.3mph) in the southwest quadrant at 4:54:00Z
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Just went out side in Biloxi, and it feels like fall ... This weather is some crazy stuff.
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2122. KEEPEROFTHEGATE (Mod)
Quoting Patrap:
If there's a bustle in your hedgerow, don't be alarmed now,
It's just a spring clean for the May queen.
Yes, there are two paths you can go by, but in the long run
There's still time to change the road you're on.
And it makes me wonder.



New Orleans
NEXRAD Radar

Base Reflectivity 0.50° Elevation
Range 248 NMI


how was the scuba driving

are you home or still there
Member Since: Posts: Comments:
Quoting Patrap:
If there's a bustle in your hedgerow, don't be alarmed now,
It's just a spring clean for the May queen.
Yes, there are two paths you can go by, but in the long run
There's still time to change the road you're on.
And it makes me wonder.



New Orleans
NEXRAD Radar

Base Reflectivity 0.50° Elevation
Range 248 NMI



PAT GREAT YOURE BACK HAVENT SEEN A LONG RANGE NOLA RADAR IN A WEEK AND A HALF!!
Member Since: Posts: Comments:
I see a baby dinosaur.

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GFS has started running again.

Here's the 00Z 60hr Vorticity Plot, notice anything missing?



Never fear, the 63 hour data looks just fine though:



EDIT:

precip_ptot is bad past 54 hours though until 66 hours unfortunately. Not sure if that is going to effect later time steps, but it's likely. Additionally, not sure how this will affect any subsequent 3 hour plots...
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It looks like Isaac can't make up its mind:

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Quoting sar2401:


They can't find any high winds because Isaac is a large steaming pile of horse manure. This is a good example of pressure and wind not being correlated. The track models haven't done a great job but the intensity estimates have been absolutely terrible. How many times have we seen that Isaac was supposed to become a hurricane "in the next day or two" now? The next day or two has run out and they still aren't getting it right.


its coorelated, it is taking time. 979 isnt anything to sneeze at
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2116. nigel20
This would not be good were it to happen
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http://www.nhc.noaa.gov/2000leslie.html
Member Since: Posts: Comments:
Quoting Patrap:
If there's a bustle in your hedgerow, don't be alarmed now,
It's just a spring clean for the May queen.
Yes, there are two paths you can go by, but in the long run
There's still time to change the road you're on.
And it makes me wonder.



New Orleans
NEXRAD Radar

Base Reflectivity 0.50° Elevation
Range 248 NMI




Hey Pat!!!
Member Since: August 17, 2007 Posts: 0 Comments: 1098
Quoting weatherh98:


Yea i had a year to "work out the problems" your sharkbait

I didn't get an easy storm to start out with. I started posting here in July so the first storm I tracked/forecasted was Ernesto. It hasn't been any easier this year after that.
Member Since: Posts: Comments:
2112. Patrap
If there's a bustle in your hedgerow, don't be alarmed now,
It's just a spring clean for the May queen.
Yes, there are two paths you can go by, but in the long run
There's still time to change the road you're on.
And it makes me wonder.



New Orleans
NEXRAD Radar

Base Reflectivity 0.50° Elevation
Range 248 NMI


Member Since: Posts: Comments:
...i think i can i think i can...

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I am in Morgan City, La. Been lurking on here the past couple of days to see if anyone thinks it will come further west into central Louisiana were I am located. Most of the models shifted to la/ms border but i'm not seeing where it is moving NW enough for that. Just my thoughts.
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2108. sar2401
Quoting weatherh98:



It will steadily deepen through landfall, because the pressure could get as low as 970

the fact that the nhc cant find high winds is perplexing


They can't find any high winds because Isaac is a large steaming pile of horse manure. This is a good example of pressure and wind not being correlated. The track models haven't done a great job but the intensity estimates have been absolutely terrible. How many times have we seen that Isaac was supposed to become a hurricane "in the next day or two" now? The next day or two has run out and they still aren't getting it right.
Member Since: Posts: Comments:
2107. nigel20
Quoting wxchaser97:

Good morning Nigel. Isaac has been a "fun/interesting" storm to look at over the past few days.

Agreed.
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Quoting TexNowNM:



I'm really concerned they got him banned.


No! Admin, please cut Taz a break. He's an institution on here and he adds to the conversation if you know him.
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2105. nigel20
Ileana
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Quoting wxchaser97:

Right now I've just been stumped on Isaac. I decide to join WU this year and this is what I have to track/ forecast.


Yea i had a year to "work out the problems" your sharkbait
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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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