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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Starting to get the dmin affect.
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Recon headed back for the intense southern quadrant. They should find that Isaac has become a hurricane.
Member Since: July 6, 2010 Posts: 108 Comments: 30257
152. jpsb
Quoting scott39:
Isaac is going to put a show on tonight.
I doubt that, he is sucking in huge amounts of dry air.
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GFS really slows it down over NOLA. Then turns it west. Could be a major rain event.
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Quoting CaneHunter031472:


Gautier, MS by Pascagoula.


They're evacuating Gautier? My Mom has a house off of Graveline on Bayou Pierre. Is that being evacuated?
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149. Reb74
NW FL...three drops of rain. We missed a day of school/work for three drops of rain!
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Quoting TropicalAnalystwx13:
12z GFS:



We're barely going to have time to relax after Isaac as another storm should develop from the wave off the African coastline. While this is a long way out, Isaac is expected to be in the Midwest in five days, and this disturbance should be entering the Northern Leeward Islands by then, allowing for a more northerly track north of the Greater Antilles.

Now the gfs first predicted Isaac to go to the NE so track is not set in stone. This season is in a pretty active period right now. Hopefully the remnants of Isaac bring beneficial rain to the plains.
Member Since: March 16, 2012 Posts: 123 Comments: 7887
Quoting taco2me61:
Hey to you too are you "Ready" for the Flood we are going to get????

Taco :o)
Taco, Al, Got my Bayou La Batre Reeboks ready. BTW, My handle pre-Ivan until 2yrs ago was SaymoBEEL. Maybe TWC should practice saying moBEEL.
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Quoting StormSurgeon:
Oh Yea I forgot we are in "FL" Well I gess we need to go to Tampa Bay GA then :o)

Taco :o)
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Quoting MiamiHurricanes09:
MSLP has stopped it's free fall. Remains at 982mb with a surface wind of 8mph.

000
UZNT13 KNHC 272138
XXAA 77218 99264 70862 08166 99982 27612 13007 00665 ///// /////
92528 24204 10008 85269 20850 00000 88999 77999
31313 09608 82109
61616 AF306 2709A ISAAC OB 15
62626 EYE SPL 2643N08619W 2111 MBL WND 10508 AEV 20802 DLM WND 10
506 981843 WL150 11007 084 REL 2643N08618W 210902 SPG 2644N08618W
211013 =
XXBB 77218 99264 70862 08166 00982 27612 11861 21807 22850 20850
21212 00982 13007 11894 09508 22858 15503
31313 09608 82109
61616 AF306 2709A ISAAC OB 15
62626 EYE SPL 2643N08619W 2111 MBL WND 10508 AEV 20802 DLM WND 10
506 981843 WL150 11007 084 REL 2643N08618W 210902 SPG 2644N08618W
211013 =
;

I'm not surprised. The convection has really warmed recently.

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Anyone think Isaac will be retired?
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If it spins like a hurricane, wobbles like a hurricane, and has a 981mb pressure reading>>>>> It's not a hurricane!
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Quoting TropicalAnalystwx13:
12z GFS:



We're barely going to have time to relax after Isaac as another storm should develop from the wave off the African coastline. While this is a long way out, Isaac is expected to be in the Midwest in five days, and this disturbance should be entering the Northern Leeward Islands by then, allowing for a more northerly track north of the Greater Antilles.


Another one bites the dust? ;-)
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140. JLPR2
Quoting hydrus:
This should be interesting ..


Track looks like a compromise between the GFS and the EURO. Will be interesting to see which model ends up being right.
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Quoting taco2me61:
Hey to you too are you "Ready" for the Flood we are going to get????

Taco :o)



Lol Stormsurgeon! Taco, I am ready. The sun is now shining outside.
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12z GFS:



We're barely going to have time to relax after Isaac as another storm should develop from the wave off the African coastline. While this is a long way out, Isaac is expected to be in the Midwest in five days, and this disturbance should be entering the Northern Leeward Islands by then, allowing for a more northerly track north of the Greater Antilles.
Member Since: July 6, 2010 Posts: 108 Comments: 30257
Quoting TomballTXPride:


After 4 consecutive runs trending west, the last two runs (12Z & 18Z) have been east. Interesting to see if the others will follow suit later on.



I don't think we will see a big shift in the track...I think they have a pretty good handle on that...I'm very much interested in seeing if the intensity is gonna follow the pressure drop....
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MSLP has stopped it's free fall. Remains at 982mb with a surface wind of 8mph.

000
UZNT13 KNHC 272138
XXAA 77218 99264 70862 08166 99982 27612 13007 00665 ///// /////
92528 24204 10008 85269 20850 00000 88999 77999
31313 09608 82109
61616 AF306 2709A ISAAC OB 15
62626 EYE SPL 2643N08619W 2111 MBL WND 10508 AEV 20802 DLM WND 10
506 981843 WL150 11007 084 REL 2643N08618W 210902 SPG 2644N08618W
211013 =
XXBB 77218 99264 70862 08166 00982 27612 11861 21807 22850 20850
21212 00982 13007 11894 09508 22858 15503
31313 09608 82109
61616 AF306 2709A ISAAC OB 15
62626 EYE SPL 2643N08619W 2111 MBL WND 10508 AEV 20802 DLM WND 10
506 981843 WL150 11007 084 REL 2643N08618W 210902 SPG 2644N08618W
211013 =
;
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Quoting mobilebayal:


The nerve of some people! Hey Taco!
Hey to you too are you "Ready" for the Flood we are going to get????

Taco :o)
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Quoting angelafritz:
Has anyone else noticed that I struggle most with simple figures of speech? First, it was the elbow of Florida. Now it's pulling hairs. :)


LOL. I thought pulling hairs was a pretty good analogy, considering the amount of hair pulling Isaac has already caused. :)
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Quoting taco2me61:
Well they were saying he was from Weatherunderground but I did not get the guys name but it was just a bit "Wrong" just saying....

Taco :o)

Hey Taco! You know we're really in FL
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getting close...
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Quoting taco2me61:
Well they were saying he was from Weatherunderground but I did not get the guys name but it was just a bit "Wrong" just saying....

Taco :o)


The nerve of some people! Hey Taco!
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Quoting weatherh98:


I'm more concerned with the latter

I hope nothing too serious happens but I still have that bad feeling.
New convection on the west side of Isaac.
Member Since: March 16, 2012 Posts: 123 Comments: 7887
Quoting scott39:
He looks like a 8 week old fetus.



Apt description. He really does!
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Quoting GTcooliebai:
LOCATION...26.4N 86.2W
ABOUT 320 MI...515 KM SSE OF MOBILE ALABAMA
ABOUT 255 MI...415 KM SE OF THE MOUTH OF THE MISSISSIPPI RIVER
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...981 MB...28.97 INCHES


TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 205 MILES...335 KM
FROM THE CENTER.


Thanks so much. It's not tropical force yet but we are getting gusty winds. Wow...this this is huge! I wondered where these cool winds were coming from.
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This should be interesting ..
Member Since: September 27, 2007 Posts: 1 Comments: 19537
Quoting txjac:


I say let her spend the night with her friend ...both of you need to stay safe

Well the decision was made for me - I just spoke to a friend driving this direction and apparently US1 is completely under water before I could even GET to the area I was concerned about. Good advice, though - if she wasn't on the phone crying that she wants to come home, I wouldn't have even been considering it.
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Quoting nrtiwlnvragn:



Tail Doppler Radar mission


Perfect, thanks man.
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Quoting TreasureCoastFl:
Ugh, dont know how to post photos correctly. Oh well... good luck to you all in this storms path!!
They can get there by clicking, no worries. Thank you for posting! :)
Mine are about the same so I am gonna' skip them. I am going to go over our security camera footage tonight and see if there is anything interesting. If so I'll upload it.
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Quoting TomballTXPride:
18Z GFS so far at 18 hours. Maybe 20 miles to the east of the 12Z GFS track.



I was afraid that would happen. NHC need to update tracks faster now I hope.
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Quoting wxchaser97:

I'll try not to but no promises. Lots of rain will be dumped and there will be a good amount of storm surge.


I'm more concerned with the latter
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Quoting Tazmanian:
man i new this was going too happen
Dont even think it!
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Quoting Tazmanian:
man i new this was going too happen


You knew what was going to happen?
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Quoting MiamiHurricanes09:
NRT, what's the NOAA2 aircraft doing?


000
URNT15 KWBC 272121
NOAA2 2809A ISAAC HDOB 11 20120827
211130 2714N 08537W 7518 02469 9957 +173 +102 120045 046 036 001 00
211200 2713N 08539W 7518 02468 9956 +173 +103 115044 044 036 002 00
211230 2712N 08540W 7515 02469 9960 +166 +103 115046 046 037 001 00
211300 2710N 08541W 7519 02466 9954 +172 +106 117046 046 037 001 00
211330 2708N 08543W 7519 02464 9947 +178 +104 116048 048 039 003 00
211400 2706N 08544W 7519 02464 9948 +176 +102 112048 048 040 002 00
211430 2705N 08545W 7517 02461 9947 +173 +100 112047 047 039 002 00
211500 2703N 08546W 7520 02458 9948 +170 +108 111046 047 040 003 00
211530 2701N 08547W 7517 02458 9945 +169 +118 115047 047 042 005 00
211600 2659N 08548W 7518 02456 9948 +161 +126 110047 049 042 005 00
211630 2658N 08549W 7515 02455 9941 +167 +122 113047 048 042 005 00
211700 2656N 08550W 7519 02447 9938 +167 +115 112050 051 045 004 00
211730 2654N 08551W 7517 02445 9936 +164 +124 118051 052 045 004 00
211800 2652N 08553W 7518 02441 9937 +158 +134 120049 051 044 005 00
211830 2651N 08554W 7517 02439 9934 +155 +141 121047 048 046 004 00
211900 2649N 08555W 7517 02436 9928 +156 +149 124049 050 046 005 00
211930 2647N 08556W 7517 02432 9926 +155 +146 126050 050 048 003 00
212000 2646N 08557W 7519 02428 9923 +157 +136 126048 049 048 003 00
212030 2644N 08558W 7517 02427 9915 +162 +141 126049 049 047 004 00
212100 2642N 08559W 7520 02422 9907 +167 +148 125047 050 048 003 00



Tail Doppler Radar mission


Member Since: September 23, 2005 Posts: 13 Comments: 10466
Quoting Thing342:
Kermit finding 990mb at the edge of the CDO
Went down to 986mb.

212430 2631N 08608W 7520 02401 9860 +195 +137 123022 025 029 001 00
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Quoting Stormbugn:
I am about 50 miles inland from Gulfport, MS and I think we are feeling the first winds (very light) from the storm. Is that even possible????


Sure is. I'm in Montgomery AL and we have 14 mph from the ENE. We also have the first storms from the FL rainbands moving into far SE Alabama. The pressure here is 29.89 compared to 28.97 in the center of Isaac, so that's a pretty steep pressure gradient.
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man i new this was going too happen
Member Since: May 21, 2006 Posts: 5089 Comments: 114054
Quoting ChaseyChasinStorms:


Where do you live?


Gautier, MS by Pascagoula.
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Quoting catastropheadjuster:


Quoting taco2me61:
I could not beleive they called Mobile Bay in MS.... OMG this guy is on Weatherunderground but was in Mobile Bay MS and showing the USS Alabama....
Come on folks at least get the city Right :o)

Taco :o)




Taco r u for real. what the TWC has people here already or something?

sheri
Well they were saying he was from Weatherunderground but I did not get the guys name but it was just a bit "Wrong" just saying....

Taco :o)
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Is recon heading home or going for a farther out pass?
Member Since: March 16, 2012 Posts: 123 Comments: 7887




Time to "Wrap it up" Isaac.
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Quoting scott39:
He looks like a 8 week old fetus.
Lmao!!!
Member Since: June 21, 2011 Posts: 0 Comments: 329
Quoting CaneHunter031472:
Dry air?


Eye.

L. Eye Character: Open in the north
M. Eye Shape & Diameter: Circular with a diameter of 20 nautical miles (23 statute miles)
Member Since: July 6, 2010 Posts: 108 Comments: 30257
Quoting scott39:
Isaac is going to put a show on tonight.


I just hope he's not trying to do an Andrew impersonation.
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About JeffMasters

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