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: 2554 - 2504

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

Not to downplay the wind and the storm surge too much, it seems that Isaac is destined to be more of a rainfall / flood event. If it manages to track close to the mississippi for 24 hrs+ and drops 10-15 inches of rain, how will this compare with the 2011 floods?
Member Since: Posts: Comments:
nothing is in impossible
Member Since: Posts: Comments:
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..



You think this storm was seeded?

Member Since: Posts: Comments:
2551. Patrap
The time for Track concerns is fading fast as the Steering is well established, and the lack of it inland tonight, or going "Null" is a great concern,'

Do not dismiss what is out there.

You could be deadly wrong.

New Orleans
NEXRAD Radar

Base Reflectivity 0.50° Elevation
Range 248 NMI


Storm Tracks are active



Member Since: Posts: Comments:


Morning everyone... this map of Isaac is prolly the most useful of all this a.m....

Stay safe out there...
Member Since: Posts: Comments:
Here is my Daily Briefing video blog for Tuesday Link
Member Since: Posts: Comments:
Quoting GetReal:



This is very likely the real thing!!!


The only question now will this be the beginning of a RI period... Hope not.

With no N side RI would be impossible i think
Member Since: Posts: Comments:
Quoting Patrap:
After we Lose power today, I will be sending Presslord or a few others info thru the Local Emg Mgmt BIG Loop to be disseminated here and on FB.

If it work's..It's dropping in and out sporadically here on my end and hopefully that glitch will be resolved.

I urge all to Tune in to the Official NHC Advisories as well as TWC with Met's Brian Norcross and Jeff Masters...at 50 minutes past every Hour.






Good to see you post Patrap. Been wondering if you were ok and still around. Stay safe.
Member Since: Posts: Comments:
I might be getting a mist/sprinkle from that tiny band. Hold up let me go check.
Member Since: Posts: Comments:
2545. ugajag
Not a bad morning here in Mobile..Winds about 15mph..My concern here is rain..We have had so much since June and are expecting 10-15" with Isaac.. Also the ground is so moist that 40-50 mph winds will bring down trees
Member Since: Posts: Comments:
6z GFS has come more in line with the Euro solution on our potential future storm, recurving it well before it gets to the US... If this verified Bermuda would be hit pretty hard though.

Member Since: Posts: Comments:
Quoting Thundercloud01221991:


your animated loop makes it look like the convection is trying to cover the eye again


Thats because it did i think.
Thats what has been keeping it so weak for so long seems all the rain is on the wrong side for a storm like this but looks can fool ones eyes so stay alert on this if your in the effected areas even a TS can get bad around here
Member Since: Posts: Comments:
2542. LargoFl
scenes like this up and down the southeast coast of florida..
Member Since: Posts: Comments:


Here comes Isaac watch out!!
Member Since: Posts: Comments:
2540. WxLogic
Isaac is about 130 miles from land. So far Isaac has been able to moisten things up to the N of him (at least temporarily), but he doesn't have much time as he'll be approaching the N GOM shelf waters.

Here's the sounding for LIX @ 00Z:



and now at 06Z:



But appears to be only temporarily since now Isaac is dealing with some dry air now at multiple layers:

At low levels:



Finally from 300MB all the way down to 600MB; you can see the dry air to the NE and N/NW of it:



Dry air entrainment will be experienced if Isaac doesn't create a solid eye wall at ALL levels. Else the short the eye it was finally able to clear will collapse once more.

Intensity wise... I would keep it at/under 85MPH as is being kept in check by current environmental conditions.
Member Since: August 14, 2008 Posts: 4 Comments: 5038
2538. Patrap
Quoting flcanes:

patrap, what's the situation in nola now?


Weather wise Uptown.

Quiet, but Ominous..as one can sense the storm easily as the Wind is just now making a few "Moan's" as it wind's thru the Power Lines here.

Haven't heard that since Gustav 4 years ago.


NOLA wu page

( If I don't respond here to every post inquired, know that I will Plus it as I can, as I'm doing a few multi task duties,,as I shake off the Down Time "Rust"


Member Since: Posts: Comments:
06z HWRF.

Adjusted landfall intensity 970mb
Member Since: Posts: Comments:
Quoting blsealevel:

Good Morning looks like he found his path
Might make a high end cat 1 at land fall thats bad but could of been alot worse thank you dry air Iseec is a big one though

http://derecho.math.uwm.edu/models/al092012_inten .png





your animated loop makes it look like the convection is trying to cover the eye again
Member Since: Posts: Comments:
2535. flcanes
Quoting Masquer08er:
Patrap, Glad to see you're still here at WU. I was on here as SaymoBEEL 2003-2008 and enjoyed your posts so much.

patrap, what's the situation in nola now?
Member Since: Posts: Comments:

Good Morning looks like he found his path
Might make a high end cat 1 at land fall thats bad but could of been alot worse thank you dry air Iseec is a big one though

http://derecho.math.uwm.edu/models/al092012_inten .png



Member Since: Posts: Comments:
2533. flcanes
Quoting unc70:


My original question came from looking at Isaac trying to cut off dry air near west coast of Florida. If that outer band stretching almost to Texas doesn't tighten a lot, it looks almost capable of smacking almost the entire coast from about Tampa to Alabama.

I know that is unlikely, but that band is big trouble for wherever it rotates ashore.


TRUE DAT
Member Since: Posts: Comments:
Quoting Patrap:
After we Lose power today, I will be sending Presslord or a few others info thru the Local Emg Mgmt BIG Loop to be disseminated here and on FB.

If it work's..It's dropping in and out sporadically here on my end and hopefully that glitch will be resolved.

I urge all to Tune in to the Official NHC Advisories as well as TWC with Met's Brian Norcross and Jeff Masters...at 50 minutes past every Hour.




Patrap, Glad to see you're still here at WU. I was on here as SaymoBEEL 2003-2008 and enjoyed your posts so much.
Member Since: Posts: Comments:
2531. unc70
Quoting KRL:


Not sure, but it's crazy with Isaac closing in on New Orleans all the way up in the GOM, we're still getting rain from him here in Palm Beach County this morning.

PBC schools are closed again today due to so many major roads flooded out and reported flood damage at schools as well.


My original question came from looking at Isaac trying to cut off dry air near west coast of Florida. If that outer band stretching almost to Texas doesn't tighten a lot, it looks almost capable of smacking almost the entire coast from about Tampa to Alabama.

I know that is unlikely, but that band is big trouble for wherever it rotates ashore.

Member Since: Posts: Comments:
According to my math, storm is actually only about 15 to 16 hours from closest approach to NOLA.

With that track forecast, NHC must be expecting it to slow down by another 3 or 4 miles per hour within then next 2 advisories to make up for it's current speed...
Member Since: Posts: Comments:
Quoting RTSplayer:
"Isaac" is spelled with one "S" and two "A"'s.


Well, heck, guess I need a second cup of coffee. Hands one to RTSplayer as well.
Member Since: August 22, 2009 Posts: 0 Comments: 3167
2528. Patrap
Stay off streets during Tropical Storm Isaac, Jefferson Parish officials warn
Published: Monday, August 27, 2012, 7:55 PM



Jefferson Parish officials issued a stern warning to anyone who dares tread outside during Tropical Storm Isaac. "If you create damage, you are going to jail,'' Sheriff Newell Normand said during a news conference that just wrapped up.

Parish President John Young said that while the parish is in its best position ever to handle the massive amounts of rainfall that Isaac is sure to bring, communities outside the hurricane protection levee have to contend with the surge the storm is sure to bring. Officials believe the area could get from 10 to 15 inches of rain in a 36-hour period.

"We are much better protected today than at the time of Katrina hit. Over $10 billion has been invested in our hurricane risk reduction system,'' Young said.
Normand urged residents to stay inside for their safety. And motorists caught driving on flooded, barricaded streets will be arrested.

Authorities are also expecting massive outages given the size and the strength of the storm. Entergy has sought an additional 3,450 mutual aid workers to help restore power, said spokesman Manny Silver.

Officials also warned residents that the window of opportunity for leaving the area is quickly shrinking.
"The message is we're prepared for the worst but we're hoping and praying for the best,'' Young said.
Member Since: Posts: Comments:
Been looking at MIMIC imagery and radar. I noticed a westward jog. But, it appears, to the eye, to be headed to the MS coast. If I lived there, I'd be very cautious no matter what the forecast says (I know it's inside the cone). I just don't see the 305 direction. Maybe I'm wishing a better solution for NOLA ;-)
Member Since: Posts: Comments:
2526. LargoFl
Member Since: Posts: Comments:
Quoting aislinnpaps:
TWC now says that is the eye of Issac.


I think everyone exect the NHC thinks its a hurricane.

It aint a cane till they say its a cane, correct?
Member Since: August 29, 2008 Posts: 0 Comments: 480
2524. LargoFl
Quoting Patrap:
After we Lose power today, I will be sending Presslord or a few others info thru the Local Emg Mgmt BIG Loop to be disseminated here and on FB.

If it work's..It's dropping in and out sporadically here on my end and hopefully that glitch will be resolved.

I urge all to Tune in to the Official NHC Advisories as well as TWC with Met's Brian Norcross and Jeff Masters...at 50 minutes past every Hour.




stay safe up there pat and good luck ok
Member Since: Posts: Comments:
2523. LargoFl
Quoting RTSplayer:


The right-most band of large storms is always like that.

Florida may end up getting more rain than Louisiana or Mississippi, regardless of the exact track from here on out.
simply amazing this storm is, hope those people in south florida make out ok, what a mess is left when the flood waters recede huh..
Member Since: Posts: Comments:
2522. Patrap
After we Lose power today, I will be sending Presslord or a few others info thru the Local Emg Mgmt BIG Loop to be disseminated here and on FB.

If it work's..It's dropping in and out sporadically here on my end and hopefully that glitch will be resolved.

I urge all to Tune in to the Official NHC Advisories as well as TWC with Met's Brian Norcross and Jeff Masters...at 50 minutes past every Hour.




Member Since: Posts: Comments:
"Isaac" is spelled with one "S" and two "A"'s.
Member Since: Posts: Comments:
TWC now says that is the eye of Issac.
Member Since: August 22, 2009 Posts: 0 Comments: 3167
Quoting LargoFl:
what is south florida..300 miles away from issac?..maybe more?..and still getting its flooding rains..the northern gulf states..heed your warnings ok...his flooding rains can be FAR away from where he lands and goes..this is one HUGE storm in area huh


The right-most band of large storms is always like that.

Florida may end up getting more rain than Louisiana or Mississippi, regardless of the exact track from here on out.
Member Since: Posts: Comments:
2518. LargoFl
THE NATIONAL WEATHER SERVICE IN MIAMI HAS EXTENDED THE

* FLOOD WARNING FOR...
EASTERN BROWARD COUNTY IN SOUTHEAST FLORIDA...
THIS INCLUDES THE CITIES OF...TAMARAC...SUNRISE...POMPANO BEACH...
PLANTATION...PEMBROKE PINES...MARGATE...HOLLYWOOD...FORT
LAUDERDALE...DEERFIELD BEACH...DAVIE...CORAL SPRINGS...
EASTERN PALM BEACH COUNTY IN SOUTHEAST FLORIDA...
THIS INCLUDES THE CITIES OF...WEST PALM BEACH...RIVIERA BEACH...
LAKE WORTH...JUPITER...DELRAY BEACH...BOYNTON BEACH...BOCA RATON...

* UNTIL 830 PM EDT TUESDAY

* FAR OUTER RAIN BANDS FROM ISAAC SHOULD DEVELOP OVER THE EAST
COAST METRO AREAS TODAY AND MOVE NORTHWARD WHICH CAN PRODUCE
LOCALLY HEAVY RAINFALL. ANY ADDITIONAL RAINFALL THAT DOES OCCUR
TODAY OVER BROWARD AND PALM BEACH COUNTIES WILL AGGRAVATE THE
FLOODING PROBLEMS. THEREFORE...THE FLOOD WARNING FOR EASTERN
BROWARD AND EASTERN PALM BEACH COUNTIES HAVE BEEN EXTENDED UNTIL
830 PM THIS EVENING. A FLOOD WATCH IS ALSO IN EFFECT UNTIL 8 PM
THIS EVENING.
Member Since: Posts: Comments:
mornin.

isaac has been, and will die being, a weirdo.
Member Since: Posts: Comments:
2516. LargoFl
what is south florida..300 miles away from issac?..maybe more?..and still getting its flooding rains..the northern gulf states..heed your warnings ok...his flooding rains can be FAR away from where he lands and goes..this is one HUGE storm in area huh
Member Since: Posts: Comments:
Good Morning! Wasted an hour checking updates. Saw Cantore on Canal St in NOLA waiting for the "teeth" of the storm. OK! Here we go for another day.
Member Since: Posts: Comments:
2514. KRL
Quoting unc70:
How far out will that outer band reach when it rotates 180 degrees?


Not sure, but it's crazy with Isaac closing in on New Orleans all the way up in the GOM, we're still getting rain from him here in Palm Beach County this morning.

PBC schools are closed again today due to so many major roads flooded out and reported flood damage at schools as well.
Member Since: Posts: Comments:
Quoting CybrTeddy:
Becoming better organized, expect this to be a hurricane today if not already one.


look at the blow up of convection on the east side... that will get wrapped around to the north soon
Member Since: Posts: Comments:
I guess the next frame will tell all.

Needs some red on funktop to wrap around the north side.

Based on radar observation, I doubt that has happened by the time the next satellite frame is available.
Member Since: Posts: Comments:
2511. LargoFl
cant believe this..still raining there, so far away from the storm....................
Member Since: Posts: Comments:
Quoting CybrTeddy:


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.

I agree, I just don't see much potential to go beyond the NHC forecast.
Member Since: Posts: Comments:
Becoming better organized, expect this to be a hurricane today if not already one.
Member Since: Posts: Comments:
Quoting Fl30258713:


Not really the time or place for a political discussion, but that being said, having lived in the North Central Gulf Coast for 47 years and having done my share of preparing for Hurricanes that didn't happen or that didn't come to me as a direct hit, all you can do for any Hurricane or potential hurricane, is plan for the worst and hope for the best.

As far as forecasting goes when a system/wanna be Hurricane is headed somewhere at 18 to 20 mph, the models give forecasters a good consensus of what storms will do for the next 2 to 3 day and beyond that time frame, the forecasting is less accurate, but far more accurate than it was 10 years ago.

I always plan based on my conception of the worst parts of the storm reaching me based on forecasting from many different sources to include my own opinion.

You can return unused batteries, 50 ft of unused rope or an unopened tarp and a roll of duct tape, but if you get your butt kicked by a Cat 4 Hurricane or a Tornado during a strong and rather large Tropical Storm, those items could be priceless if you need them.

All local government & media will lean to the side of caution, which happens to be the same side advertising & marketing that was pre-planned in case a storm occurred during hurricane season. It's just pre-planned marketing, not a conspiracy to rip people off.

People have to use common sense when planning for a hurricane's worst case scenario. Otherwise they have hurricane party's at the beach and try to go surfing. History has given us 911 recording of people calling for help in the middle of a hurricane because they didn't heed the warnings. Some of us see that as a pity and want to help but can't in the middle of a storm, others of us see that as a form of stupidity & natural selection.



Very well said, myfeelings as well but said better than I could say it.
Member Since: August 29, 2008 Posts: 0 Comments: 480
2507. LargoFl
....i wonder how our friends in eastern florida are making out this morning? has the flood waters receded yet? some had a foot or more of water in their homes
Member Since: Posts: Comments:
Quoting GetReal:


Eye held together for a second frame....


Aside from the fact that he's practically missing the north side, that is a fairly impressive satellite presentation compared to yesterday... he could have really become something had he become a hurricane over the Keys days ago.
Member Since: Posts: Comments:
2505. GetReal
The eaterly fetch of winds on the north side of Isaac should, interacting with the coastine of Mississippi and Se Louiisana should begin piling more moisture up in the atmosphere north of Isaac. I would not be surprised to see some serious convection firing off in that area later this morning, assisted by the heating of the sun. If that occurs that convection would assist Isaac in strengthening up to landfall.
Member Since: July 4, 2005 Posts: 204 Comments: 8898
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.
Member Since: Posts: Comments:

Viewing: 2554 - 2504

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.

Local Weather

Overcast
37 °F
Overcast

JeffMasters's Recent Photos

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