Isaac approaching hurricane strength

By: Angela Fritz , 9:14 PM GMT on August 27, 2012

Share this Blog
58
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 2204 - 2154

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76Blog Index

Hoping this doesn't get upgraded simply to see disappointment spread across the faces of WU users. ;)
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting nofailsafe:


With how lopsided Isaac is right now I would chalk this up as a wobble. Wait for the next fix or two.


Yeah, I know, but these wobbles can add up.
Member Since: Posts: Comments:
2201. sar2401
Quoting playapics:
Hey gang, long time lurker here. Would it be reasonable to suggest that Isaac may actually weaken given that his slow forward motion is causing cool water to well up starving him from fuel?


He may weaken at some point or just stay as weak cat 1 until landfall. I'm pretty sure that, no matter what, we can turn the rapid intensification flag for Isaac to a permanent OFF now. :)
Member Since: Posts: Comments:
Product: Air Force Temp Drop (Dropsonde) Message (UZNT13 KNHC)
Transmitted: 28th day of the month at 05:51Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 309)
Storm Number: 09
Storm Name: Isaac (flight in the North Atlantic basin)
Mission Number: 29
Observation Number: 15

Part A...

Date: Near the closest hour of 6Z on the 28th day of the month
Highest Mandatory Level For Which Wind Was Reported: 850mb
Coordinates: 27.3N 87.8W
Location: 220 miles (354 km) to the S (189°) from Pensacola, FL, USA.
Marsden Square: 081 (About)

Level Geo. Height Air Temp. Dew Point Wind Direction Wind Speed
978mb (28.88 inHg) Sea Level (Surface) 27.8°C (82.0°F) 27.6°C (81.7°F) 215° (from the SW) 2 knots (2 mph)
Member Since: Posts: Comments:
Quoting MississippiWx:


He's currently on the forecast line, but he's just wobbling around a bit as he attempts to get the inner core established.


Gotta love cycloid motion!
Member Since: Posts: Comments:
This storm has had a zig-zag or stair-step pattern for several days now, so it really hasn't followed any model very well.

I am just really REALLY glad that it has never become a hurricane, for whatever reasons.

This storm will be analyzed for years to come - why were ALL the models so bad? Which ones did best, and when, and why?

And after this one is done, we will have another in the pipeline in less than a week, perhaps.

O Joy

Member Since: December 21, 2009 Posts: 0 Comments: 93
Whatever Isaac does or doesn't manage to do, he's been trying like crazy. He's looked a lot better ever since his FL blob really left and even more since it fell apart. Might pull it off this time.

It's just so funny to think that _again_.
Member Since: Posts: Comments:
Quoting mobhurricane2011:
This thing would have to make a sharp turn north to hit the Ms Coast looks like to me, you think that's still possible?


He's currently on the forecast line, but he's just wobbling around a bit as he attempts to get the inner core established.
Member Since: Posts: Comments:
Quoting MississippiWx:
Peak (10s) Flt. Lvl. Wind: 75 knots (~ 86.2 mph


Possibly suspect 62 kts from SFMR...now do they upgrade at 2AM or chalk it up as too small of a sample size?
Member Since: Posts: Comments:
2194. sar2401
Quoting MississippiWx:
Peak (10s) Flt. Lvl. Wind: 75 knots (~ 86.2 mph


Please, please, let this be a hurricane on the next update. This is like a blind date that never ends. :)
Member Since: Posts: Comments:
Quoting weatherboykris:



Even back when it was east of the antilles islands, environmental conditions were good for it to get it's act together. The storm simply never has. There are some type of internal dynamics that have been present since the beginning that have prevented it from taking advantage of seemingly great environmental conditions. Had it strengthened as expected at the start, it likely would have taken the original expected path into Southeast Florida. BTW, we didn't exactly escape Isaac's wrath here in Palm Beach county...the urban flooding here is unbelievable


He's been a weird storm, for sure. But he's been sucking dry air since he left Africa, and that's been a major impediment to development, yet he's survived to this point.

Clearly, he was a rainmaker in S. Fla., and in fact the whole peninsula. But he hasn't been the bomb that he could have been. Jeff Masters talked about the relatively low heat content in the GOM - which is really unusual for this time of the year. That, combined with the somewhat crazy ULL's that have impacted Isaac have (and will continue to) impede his development.
Member Since: Posts: Comments:
Hey gang, long time lurker here. Would it be reasonable to suggest that Isaac may actually weaken given that his slow forward motion is causing cool water to well up starving him from fuel?
Member Since: Posts: Comments:
2191. sar2401
Quoting animalrsq:


I will support a "Bring Back Taz" online demonstration. I know Taz is misunderstood by those who have not been on here for years. I almost never post, just absorb all the great info that others post and still trying to learn, but feel strangely protective of Taz as I would a little brother.


LOL. I kind of feel the same way. Now we just need to figure out how to organize an on-line demonstration. :)
Member Since: Posts: Comments:
Peak (10s) Flt. Lvl. Wind: 75 knots (~ 86.2 mph
Member Since: Posts: Comments:
2189. KEEPEROFTHEGATE (Mod)
Taz has not been banned
his blog is still showing on page 3
of the members blog list
so he is just taking a break
maybe even sleeping
Member Since: Posts: Comments:
2188. sfranz
Hard to tell from just the satellites, but it looks like every time no-I-saac starts to close in that eyewall it wobbles over the top of it or outruns it with its forward motion and spits it out again.

Interesting storm to watch. Tough to forecast.

Member Since: Posts: Comments:
Quoting xtremeweathertracker:


Can i get the link to that model...i really like the windspeed field! Thanks
WeatherBELL
Member Since: Posts: Comments:
Highest winds found so far at 850 mb level:

05:47:30Z 27.717N 87.833W 842.9 mb
(~ 24.89 inHg) 1,375 meters
(~ 4,511 feet) 988.2 mb
(~ 29.18 inHg) - From 85° at 72 knots
(From the E at ~ 82.8 mph) 16.0°C*
(~ 60.8°F*) 16.0°C*
(~ 60.8°F*) 75 knots
(~ 86.2 mph) 60 knots
(~ 69.0 mph)
Member Since: Posts: Comments:
Quoting animalrsq:


I will support a "Bring Back Taz" online demonstration. I know Taz is misunderstood by those who have not been on here for years. I almost never post, just absorb all the great info that others post and still trying to learn, but feel strangely protective of Taz as I would a little brother.


Most people dont know this and im hesitant to post it here but Taz is a very special person with disabilities that has an obsession with tropical weather...this blog is his life...i mean who else here has over 100,000 comment posts!! I like Taz!! He means no harm to anyone!!
Member Since: May 31, 2011 Posts: 57 Comments: 572
Quoting washingaway:
Recon is indicating west.


With how lopsided Isaac is right now I would chalk this up as a wobble. Wait for the next fix or two.
Member Since: Posts: Comments:
Quoting MississippiWx:
Isaac has dropped another millibar. Center is still bouncing around as convection tries to wrap around.
This thing would have to make a sharp turn north to hit the Ms Coast looks like to me, you think that's still possible?
Member Since: Posts: Comments:
Trying to build an eye wall again.

Member Since: Posts: Comments:
2181. sar2401
Quoting weatherboykris:



Even back when it was east of the antilles islands, environmental conditions were good for it to get it's act together. The storm simply never has. There are some type of internal dynamics that have been present since the beginning that have prevented it from taking advantage of seemingly great environmental conditions. Had it strengthened as expected at the start, it likely would have taken the original expected path into Southeast Florida. BTW, we didn't exactly escape Isaac's wrath here in Palm Beach county...the urban flooding here is unbelievable


In the final analysis, I think south Florida and on up the east coast may actually have suffered the worst effects of Isaac, certainly in terms of rain. I'm sitting here in Alabama looking for those giant rainbands and...wait, there's a shower....oops, never mind, gone now.
Member Since: Posts: Comments:
Quoting WXGulfBreeze:


And that's a problem because...?

Never said it was a problem.
♬ ♫ ♪ |̲̅̅●̲̅̅|̲̅̅=̲̅̅|̲̅̅●̲̅̅| ♪ ♫ ♬
Member Since: Posts: Comments:
Quoting sar2401:


Thank you very much. I try. :)

I hope Taz hasn't been banned, and I can't imagine why he should compared to some others I've seen here. I will admit there are times I'm not quite sure what he's posting about, but he's a very entertaining and knowledgeable guy.


I will support a "Bring Back Taz" online demonstration. I know Taz is misunderstood by those who have not been on here for years. I almost never post, just absorb all the great info that others post and still trying to learn, but feel strangely protective of Taz as I would a little brother.
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.


I think that he did _also_ say that he was heading for bed in that post. So he might just be snoring away, completely and blissfully unaware of the discussion he has caused.

As for Isaac, I'm starting to really think that we're going to be able to figure out where he's going just about the time he gets there.

Ultimately, though, unless he really pulls it together pretty quickly, I suspect it's not going to matter too terribly much where the center, such as it is, actually goes -- he's going to cause a lot of rain and surge anywhere near there -- he's got breadth, it's about all he's ever had. There's a lot of energy there, it's just splatting around all over the gulf, so I have no idea how anybody can predict anything with much certainty.

Could still pull off really pulling himself together, but I've been thinking he's _just about there_ for the last several days. He's been plagued by disorganization and lack of focus, just like many people I know. Oh, the potential.

I feel ya, Isaac. I never know where I'm going or what I'm doing in this handbasket either. :P
Member Since: Posts: Comments:
Recon is indicating west.
Member Since: Posts: Comments:
Quoting HurricaneHunterJoe:


Can i get the link to that model...i really like the windspeed field! Thanks
Member Since: May 31, 2011 Posts: 57 Comments: 572
2175. sar2401
Quoting KEEPEROFTHEGATE:


Son of a gun....Isaac now looks just like Miss Piggy. Look at that nose and hair. :)
Member Since: Posts: Comments:
Quoting lopaka001:

Great now I am going be singing Zeppelin all night..


And that's a problem because...?
Member Since: Posts: Comments:
Isaac has dropped another millibar. Center is still bouncing around as convection tries to wrap around.
Member Since: Posts: Comments:
Quoting WXGulfBreeze:


I think you're about right. Isaac's been struggling, wants to put on the big boy britches, but just can't quite get there. Too many environmental factors going against him.



Even back when it was east of the antilles islands, environmental conditions were good for it to get it's act together. The storm simply never has. There are some type of internal dynamics that have been present since the beginning that have prevented it from taking advantage of seemingly great environmental conditions. Had it strengthened as expected at the start, it likely would have taken the original expected path into Southeast Florida. BTW, we didn't exactly escape Isaac's wrath here in Palm Beach county...the urban flooding here is unbelievable
Member Since: Posts: Comments:
GFS is back online out to 108 hrs. now. Link
Member Since: Posts: Comments:
Has anything more ever been said about Bill Gates' Hurricane Control Patents from 2007? After watching Isaac, the thought has crossed my mind that perhaps the government has begun testing his theories, although I realize what a massive effort and expense would be needed to implement such a plan. Just an attempt to explain away the erratic behavior of this storm in particular.

But like with anything, I suppose they could have developed it into a more manageable system. It would be really neat to explore but that would be interfering with nature ...

Anyone have any updated information on his hurricane control plans??
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



Great now I am going be singing Zeppelin all night..
Member Since: Posts: Comments:
2168. will40
wonder what the 2 update will say
Member Since: September 19, 2005 Posts: 2 Comments: 4266
2167. nigel20
Member Since: Posts: Comments:
Time: 05:37:30Z
Coordinates: 27.2667N 87.7167W
Acft. Static Air Press: 842.8 mb (~ 24.89 inHg)
Acft. Geopotential Hgt: 1,322 meters (~ 4,337 feet)
Extrap. Sfc. Press: 978.8 mb (~ 28.90 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 192° at 4 knots (From the SSW at ~ 4.6 mph)
Air Temp: 21.0°C* (~ 69.8°F*)
Dew Pt: 21.0°C* (~ 69.8°F*)
Peak (10s) Flt. Lvl. Wind: 9 knots (~ 10.3 mph)
SFMR Peak (10s) Sfc. Wind: 22 knots* (~ 25.3 mph*)
SFMR Rain Rate: 2 mm/hr* (~ 0.08 in/hr*)
Member Since: Posts: Comments:
Quoting weatherboykris:
Folks, I have news for you. With a 46 mile wide eye, this storm is not strengthening significantly at all before landfall. 85mph is about the ceiling for this one, IMO.


I think you're about right. Isaac's been struggling, wants to put on the big boy britches, but just can't quite get there. Too many environmental factors going against him.
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting weatherh98:


taz doesnt deserveto be banned.


I agree and I don't know if that happened. I don't mean to start a rumor. He may have just decided to go to bed or something. I am hopeful he will be back tomorrow.
Member Since: Posts: Comments:
Member Since: Posts: Comments:
2161. sar2401
Quoting weatherboykris:
Folks, I have news for you. With a 46 mile wide eye, this storm is not strengthening significantly at all before landfall. 85mph is about the ceiling for this one, IMO.


Agreed, and that's why the NHC is only showing a cat 1 at landfall....and they're probably a little nervous about that call right now. :)
Member Since: Posts: Comments:
Member Since: Posts: Comments:
2159. sar2401
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.


Thank you very much. I try. :)

I hope Taz hasn't been banned, and I can't imagine why he should compared to some others I've seen here. I will admit there are times I'm not quite sure what he's posting about, but he's a very entertaining and knowledgeable guy.
Member Since: Posts: Comments:
Folks, I have news for you. With a 46 mile wide eye, this storm is not strengthening significantly at all before landfall. 85mph is about the ceiling for this one, IMO.
Member Since: Posts: Comments:
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




Glad you're here, Pat!!
Member Since: Posts: Comments:
Welcome back Pat!

I thought you were going to be gone for longer, but what go I know?
Member Since: December 21, 2009 Posts: 0 Comments: 93
2154. KEEPEROFTHEGATE (Mod)
Member Since: Posts: Comments:

Viewing: 2204 - 2154

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

JeffMasters's Recent Photos

Lake Effort Snow Shower Over Windsor, Ontario
Sunset on Dunham Lake
Pictured Rocks Sunset
Sunset on Lake Huron