Isaac remains disorganized

By: Dr. Jeff Masters , 8:29 PM GMT on August 23, 2012

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Tropical Storm Isaac has strengthened slightly, data from the hurricane hunters show, but the storm remains disorganized and difficult to forecast. If you have to make decisions based upon what Isaac will do, I highly recommend that you wait until at least Friday morning to make a decision, if at all possible, as the forecasts then should be of significantly higher accuracy. Isaac continues to have a large area of light winds about 50 miles across near its center. This makes the storm subject to reformations of the center closer to areas of heavy thunderstorms that form, resulting in semi-random course changes. Until Isaac consolidates, the lack of a well-defined center will make forecasts of the storm's behavior less accurate than usual. An Air Force Reserve hurricane hunter aircraft is in Isaac this afternoon, and has found that surface tropical storm-force winds on the east side of the storm, south of Puerto Rico, have undergone a modest expansion. These winds were mostly in the 40 mph range, with a few areas of 45 mph winds. The surface pressure remained fairly high, at 1004 mb. Infrared and visible satellite loops show that Isaac has fairly symmetric circular cloud pattern, with developing spiral bands that are contracting towards the center, which suggests intensification. However, the storm has a very clumpy appearance, and is a long way from being a hurricane. Given the storm's continued reluctance to organize, Isaac is unlikely to reach hurricane strength before encountering Haiti and Cuba. An analysis of upper level winds from the University of Wisconsin CIMSS shows an upper-level outflow channel well-established to the north, and an intermittent outflow channel to the south. Radar imagery from Puerto Rico shows some weak low-level spiral bands that haven't changed much in intensity or organization this afternoon. NOAA buoy 42060 reported 1-minute mean winds of 35 mph and a wind gust of 40 early this afternoon. At St. Thomas in the Virgin Islands, wind gusts up to 45 mph were observed early this afternoon. Isaac's rains caused major flooding last night in Trinidad and Tobago, the southernmost islands of the Lesser Antilles chain, according to the Trinidad Express. Isaac's rains have not been heavy enough today to cause flooding problems on other islands.


Figure 1. True-color MODIS image of Isaac taken at 1:40 pm EDT August 23, 2012. Image credit: NASA.

Latest model runs for Isaac
The latest set of 12Z (8 am EDT) model runs have shifted to the west compared to the previous set of runs. The models continue to show a west-northwestward track to a point on the south coast of Hispaniola, then across eastern Cuba and into the Florida Straits between Florida and Cuba. A trough of low pressure is then expected to pull Isaac to the northwest and then north, towards the Florida Panhandle. The big news in this model cycle is that both of our top models--the GFS and ECMWF--predict that 5 - 6 days from now, the trough of low pressure pulling Isaac to the north may not be strong enough to finish the job. These models predict that the trough will lift out and a ridge of high pressure will build in, forcing Isaac more to the west. The GFS predicts this will occur after Isaac makes landfall in the Florida Panhandle, resulting in Isaac moving slowly to the west over land, from Georgia to Alabama. The ECMWF predicts the westward motion will happen while Isaac is in the northern Gulf of Mexico, resulting in an eventual landfall near the Louisiana/Texas border on Thursday. There are some huge issues to resolve to make an accurate long-range track forecast for Isaac. Where will its center consolidate? How will the interaction with the mountains of Hispaniola and Cuba will affect it? Where will Isaac pop off the coast of Cuba? Hopefully, the data being collected by the NOAA jet this afternoon will give us a more unified set of model forecasts early Friday morning. For now, pay attention to the cone of uncertainty. If you're in the cone, you might get hit.



Figure 2. Predicted 5-day rainfall total ending at 8 am EDT Tuesday August 28 from Tropical Storm Isaac. Graphics were generated from the 12Z (8 am EDT) August 23, 2012 run of the HWRF model (top) and GFDL model (bottom). The heaviest rainfall is expected to occur in a 50 - 80 wide wide swath along and to the right of where the center tracks. Amounts in excess of 8 inches (yellow colors) are predicted for portions of the Dominican Republic and Haiti from the HWRF model, but not the GFDL model. Given the current disorganization of Isaac, these rainfall amounts are probably at least 20% too high. Image credit: Morris Bender, NOAA/Geophysical Fluid Dynamics Laboratory.

Jeff Masters

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LOL --- no, I'm not worried!
Just kidding because you said you knew me from years back! You Mossy Head Stalker! Please tell me you don't know who I "really am"! hahaha
Quoting shmdaddy:


Why? Because I'm from Mossy head? lol Never BF...I'm a good guy. No worries. :)
Member Since: July 10, 2005 Posts: 157 Comments: 29391
Quoting HoustonTxGal:
The bad thing about this whole mess is with not having a good bead on where Isaac is going to end up yet is people will sit by and not prepare, then once the balloon goes up everyone will be panicking and running to the stores and or clogging up the roadways trying to get out at the last minute.

End game is... if you or your loved ones are i the cone of possibility, go ahead and prepare now, get a plan together now... If you don't need it, great, you will be ready the next time. But if you need it, you are all ready and prepared.



Starting to think the storm surge may be the biggest story with Isaac but we'll have to wait and see. I'm trying to post any good wave/surge models I can find for people who may be near the coast.
Member Since: Posts: Comments:
Gulf water temps are roughly average in general, but with the center of the Gulf being a full 1C or more above normal.




So no, it's not cooler than normal.

It is normal or above.

Here is the latest maximum hurricane intensity predictor map...

Member Since: Posts: Comments:
2221. Grothar
Quoting yoboi:


gro what is that blob in the gom going to do??



Not much at this time, but it does look good. The inevitable question always comes up...."Have there ever been two hurricanes in the Gulf at the same time?"



Member Since: July 17, 2009 Posts: 71 Comments: 27565
Looks like Isaac is getting ready to dance

Member Since: September 18, 2007 Posts: 0 Comments: 1074
Quoting wxchaser97:

My forecast track that I just made not even seeing yours.

yep I think that could happen
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2218. amd
Good to see so many from the original 2005 crew posting on here tonight.

Looking at Isaac and it's future path, I have no clue what to expect with the storm. It's clear that there is a LLC around 16.7 according to recon and the NHC, but will that stay the dominant LLC?

One theory I have is that the LLC at 16.7 North continues to head to the WNW, interacts with Hispanola, dissipates, and a new LLC forms near the MLC which is quite a bit farther south. This could lead to a final outcome of Isaac making a final landfall on the Central to Western gulf coast (LA or Upper TX).

Or, the LLC and MLC actually align tonight, Issac develops a legit inner core, and after interaction with Hispanola and Eastern Cuba, Isaac ends up tracking very close to Florida or even goes up the east coast.
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Ok, now there might be a big difference at 90 hrs. Shortwave over Ky might be eating the ridge. Storm is a little closer to Tampa.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Quoting centex:
Forecast track sure seems to suggest NW turn on system that has already blown past that. Now looking at Cuba being first landfall. Maybe hear this from NHC center tomorrow. The overall system is still tracking west, the weak LLC is not going to change that. Funny how we focus on ill defined LLC. I watch the dominate in these forming systems. If your following the east FL prognosticators maybe you will learn a lesson. NHC dropped that yesterday.


yes
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Hi. Could someone please direct me to where I could find the longest possible satellite loop of Isaac... I would love to see this relatively small loop of images in a larger perspective, possibly back to the genesis of the system... is that possible? tyia
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Quoting KEEPEROFTHEGATE:


Okay this is new maybe further north
Member Since: August 29, 2006 Posts: 22 Comments: 1352
2213. KEEPEROFTHEGATE (Mod)
Member Since: July 15, 2006 Posts: 187 Comments: 58172
Quoting moonlightcowboy:


LOL, me too. Beelllll has that atmosphumerous touch! ;P



lol indeed!
Member Since: August 21, 2008 Posts: 0 Comments: 8699
2211. KEEPEROFTHEGATE (Mod)
Member Since: July 15, 2006 Posts: 187 Comments: 58172
Quoting WPBHurricane05:
Passing over the middle keys at 75 hrs. Pretty much the same as the 18Z.
As far as location, just about...maybe a little further north. Much more intense though. 00z up top, 18z below. Juxtapose the amount of closed isobars and the more intense convection.



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2209. Ryuujin
Quoting MiamiHurricanes09:
This run is going to have a serious outcome. Category 1 hurricane affecting southern Florida in about 3 days, probably the most intense run to date, and now it's headed into the Gulf.


Yeah, this run doesn't look at all that welcoming. Clipping S Florida straight into the Gulf is not good, especially at a Cat 1 level.
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2208. Dunkman
Time for the big surprise of this run where it right turns into Tampa with the new data (just kidding).
Member Since: February 6, 2010 Posts: 0 Comments: 214
00z GFS has 1st landfall in South Florida... near the beginning of the Keys (where it connects to the Peninsula). Would cause lots of damage in SE Florida if a decent size Hurricane (in strength).
Member Since: July 6, 2005 Posts: 5 Comments: 580
Hey LWF :) Really great to see everyone out tonight!

Before you know it SQOTB will show up.

As for the infighting BF, I am not sure it will ever be as rough as it was in '05...lol
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Biggest difference vs 18Z:

A little slower and much stronger. Track looks to be about the same through 81 hrs.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
NHC - Gusts 40-50mph...??

Member Since: August 2, 2010 Posts: 21 Comments: 9888
Quoting MiamiHurricanes09:
This run is going to have a serious outcome. Category 1 hurricane affecting southern Florida in about 3 days, probably the most intense run to date, and now it's headed into the Gulf.


Wonder if being stronger will make it go further westward or poleward?
Member Since: August 29, 2006 Posts: 22 Comments: 1352
Quoting MiamiHurricanes09:
This run is going to have a serious outcome. Category 1 hurricane affecting southern Florida in about 3 days, probably the most intense run to date, and now it's headed into the Gulf.



Not good this could go under ri.
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2201. centex
Forecast track sure seems to suggest NW turn on system that has already blown past that. Now looking at Cuba being first landfall. Maybe hear this from NHC center tomorrow. The overall system is still tracking west, the weak LLC is not going to change that. Funny how we focus on ill defined LLC. I watch the dominate in these forming systems. If your following the east FL prognosticators maybe you will learn a lesson. NHC dropped that yesterday.
Member Since: August 10, 2007 Posts: 0 Comments: 3296
Quoting moonlightcowboy:
Quoting ProgressivePulse:

The horse has been beaten for a couple days now right? Only to wake up to a deflating mess once again. The image below is what we have to work with ATM which is not conduct of a strengthening cyclone...
class=/blogquote'>

Thank ye kindly!






The whole gall-darned mess is about 1/3 west and parallel and very south of Hispaniola still. And, I don't think it's scaring a palm leaf up there too much yet. Isaac better hurry up if'n he wants to shake things up on that island. Fun island, too. Was just there in February.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
Quoting DestinDave:
I HOPE you are wrong! Too close & wrong side of the storm!

I kinda hope I'm wrong since its bad for the gulf coast. But yet, Isaac will be in the GOM.
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Quoting Beachfoxx:
Should I be scared? LOL Please tell me you are not a stalker! hahaha

Just kidding!

Nice to meet you neighbor!


Why? Because I'm from Mossy head? lol Never BF...I'm a good guy. No worries. :)
Member Since: June 10, 2011 Posts: 0 Comments: 17
This run is going to have a serious outcome. Category 1 hurricane affecting southern Florida in about 3 days, probably the most intense run to date, and now it's headed into the Gulf.
Member Since: Posts: Comments:
The bad thing about this whole mess is with not having a good bead on where Isaac is going to end up yet is people will sit by and not prepare, then once the balloon goes up everyone will be panicking and running to the stores and or clogging up the roadways trying to get out at the last minute.

End game is... if you or your loved ones are i the cone of possibility, go ahead and prepare now, get a plan together now... If you don't need it, great, you will be ready the next time. But if you need it, you are all ready and prepared.

Member Since: September 18, 2007 Posts: 0 Comments: 1074
Passing over the middle keys at 75 hrs. Pretty much the same as the 18Z.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
2193. KEEPEROFTHEGATE (Mod)
Member Since: July 15, 2006 Posts: 187 Comments: 58172
Quoting Grothar:
Wow...
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Quoting chevycanes:

shocker. lol.

seriously though, you do know that the WP3 Orion has been flying around out there, right?

you keep saying this yet every time the advisory has been further north today.



NOAA's P-3 was flying above there earler

the true is nothing has been flying near the surface since this morning

well ok this is how I see it if the LLCOC was really near 16.7N 68.7W I'd say ok it under the convection more stacked and all of it just took a curve/jog WSW to 16N 695W hmm I don't think so more likely though its located near 15.7N 89W moving W-WNW and the convection is now starting to wrap arond the COC

anyway overall I think its still messed up with possible multi-COC we will most likely have to wait till the next recon that will fly a low level mission and find and confirm the LLCOC that should be lifting off around 2 hours time I think (1am)
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Looks very close to the 18Z so far..now for the gulf!
Member Since: August 29, 2006 Posts: 22 Comments: 1352
Quoting shmdaddy:


I'm just North of you BF. I've 'known" you this whole time too! I'm in Mossy Head.


You're North of just about everyone in the Panhandle LOL!
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This gfs, if pans out has a lot really nasty looking weather on the, well nasty side. It's a little north of the last run, so far, but not much.
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Quoting j2008:
I might get alot of crow but my guess is the center is about 15N 68W. At least MLC is there, LLC cant be too far off though.......
Nah, we only give you a wing and maybe a drumstick for that...
Quoting LongIslandXpress38:


It's an infrared satellite pic. of Isaac..
Thanks... finally someone actually answered my question with a FACT.

LOL
Member Since: October 25, 2005 Posts: 19 Comments: 22874
2186. Grothar
Member Since: July 17, 2009 Posts: 71 Comments: 27565
Quoting wxchaser97:

My forecast track that I just made not even seeing yours.
I HOPE you are wrong! Too close & wrong side of the storm!
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2184. yoboi
Quoting Grothar:


gro what is that blob in the gom going to do??
Member Since: August 25, 2010 Posts: 8 Comments: 3205
Quoting WPBHurricane05:
Looks like the gap over Florida might be a little larger at 60 hrs vs. the 18Z.


It's going to be Sat / Sun before it's 100% for us.
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2182. yqt1001
New AMSUB pass. Unfortunately the resolution is too low to actually get much from it.

Member Since: November 19, 2010 Posts: 1 Comments: 1286
Quoting mynameispaul:
GFS North Atlantic Surface Pressure and Wind +180 Hours animated.

Link


That is 12z...that's 12 hours old...

We're waiting on 00z...
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72HR
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2179. Dunkman
Only difference in the end point through 72h is that it's a hell of a lot stronger than the 18z. 18z was 1000mb at this time, 0z is 994mb.
Member Since: February 6, 2010 Posts: 0 Comments: 214
2178. Michfan
Quoting RTSplayer:


That is 3 hours 40 minutes old.


It is but gives a good idea of how its trying to organize.
Member Since: September 7, 2007 Posts: 0 Comments: 1761
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Quoting schistkicker:
So, mountains typically act to disrupt a storm and knock the LLC and MLC out of alignment, yes?

What happens if going over some mountains actually treats Isaac like a trip to the chiropractor and finally fixes him up?

Then he will have to be back the next week for an additional alignment. And the next week after that as well, and after that . . . bring his wallet, of course.
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{{{Finn}}}}

I agree with every word she says! I love my WUBA friends!
Quoting LakeWorthFinn:
On luwkin' mode here, but had to post a Hi! to all my old friends :) Isaac has done one good thing - bringing the "Wild Bunch" back.... Sooo good to see you all!

I also want to welcome the new members who have joined and paid their membership to become part of this great WUBA community. If you can ignore the petty fights here, you'll have a great time, learn a lot and be prepared if/when a storm comes your way. To be prepared takes the fear away, so you can enjoy the weather discussions and watch the fascinating developments and behaviors of tropical cyclones, which to me is mind blowing. I appreciate the hours of work many people here put in their research and analysis, for which I'm personally very grateful :)

D. Masters has a great rainfall forecast map on his main blog entry. We should be getting 4-6" around my house, even more if the GFS's little Eastward "swing" by the tip of SFL pans out.

Don't forget that even the NHC cone s not written in stone yet, though it's usually very accurate.

Have fun and be safe!
Member Since: July 10, 2005 Posts: 157 Comments: 29391
Quoting WxGeekVA:


My unofficial forecast track for Isaac.

My forecast track that I just made not even seeing yours.
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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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