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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Peoples backyards are being washed into the drainage canals here. The cars on the road out front won't slow down and it pushes the water toward the yards and out the back and into the canal.
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Usually I am to the West and Dry side of tropical systems living in South Central Texas, the weather gets hot but there is little to no humidity for a few days so really it feels pretty good. A VERY DRY AND SUBSIDENT AIRMASS BETWEEN THE
UPPER LEVEL RIDGE OUT WEST AND TROPICAL CYCLONE ISAAC OVER THE
MISSISSIPPI VALLEY PRECLUDES RAIN CHANCES ON THURSDAY AND FRIDAY.
OVER THE LABOR DAY WEEKEND...SOUTHERLY LOWER LEVEL FLOW RETURNS
WITH SOME INCREASE IN MOISTURE. THIS MAY ALLOW THE SEABREEZE TO
GENERATE SOME SHOWERS AND THUNDERSTORMS NEAR THE COASTAL PLAINS.
AFTER NEAR OR SLIGHTLY ABOVE AVERAGE DAYTIME TEMPERATURES TUESDAY
INTO WEDNESDAY...WELL ABOVE AVERAGE DAYTIME TEMPERATURES ARE
EXPECTED THURSDAY THROUGH THE LABOR DAY WEEKEND WITH HIGHS IN THE
UPPER 90S TO NEAR 102 MOST AREAS. NIGHTTIME TEMPERATURES WILL BE
NEAR OR SLIGHTLY BELOW AVERAGE...EXCEPT SLIGHTLY ABOVE AVERAGE
ALONG THE RIO GRANDE.
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Quoting ABH4Life:
Taz, spelling B champion!


u bout to get cussed at
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting WXGulfBreeze:


So, what's the blob moving into the picture around 180 hours?
..thats storm number 2..going to the same place as issac according to the GFS
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Quoting hurrtracker1994:
Hello everyone just thought I would check in. Isaac is starting to develop a large CDO however wind shear continues to disrupt the CDO on the southwestern area of the storm. Also the dry air that Isaac was contending with earlier is finally starting to mix its way out. If the anticyclone can center itself over Isaac then we can start to see the storm intensify quicker. I would expect the storm to be a hurricane by the morning, if dry air and wind shear continue to lessen.



You can see the wind shear that is really making this system rather lopsided.


It's more likely already there... IMO
Member Since: July 4, 2005 Posts: 204 Comments: 8898
Dry slot to the west of the core is now filling in, isolating a pocket of dry air, which will eventually fill in.
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Taz, spelling B champion!
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I say 105 to 110 at landfall.
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Quoting Melagoo:


Thanks Taz ... I haven't seen that yet ... New Orleans is in big trouble again ... :c/


Right now they have it as a one just off the coast, I would be suprised if it became a 2 that close to land. That is just based on experience, not any technical mumbo-jumbo.
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Quoting KEEPEROFTHEGATE:


So, what's the blob moving into the picture around 180 hours?
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Quoting Masquer08er:
Avalon, my wife's cousin and his wife live on Brawood. I do sign language at St Ignatius.


Oh wow! I have seen you. That's great! I am really curious to see what this storm brings. I sure hope not much.
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Hello everyone just thought I would check in. Isaac is starting to develop a large CDO however wind shear continues to disrupt the CDO on the southwestern area of the storm. Also the dry air that Isaac was contending with earlier is finally starting to mix its way out. If the anticyclone can center itself over Isaac then we can start to see the storm intensify quicker. I would expect the storm to be a hurricane by the morning, if dry air and wind shear continue to lessen.



You can see the wind shear that is really making this system rather lopsided.
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Member Since: July 4, 2005 Posts: 204 Comments: 8898
Quoting mobilebayal:


I got the bay house ready to go yesterday. It was one of the prettiest days of the summer. Just beautiful. They had a big jubilee around Mullet Point today. For those that don't know, a jubilee is when lack of oxygen in the water in Mobile bay causes fish, shrimp, crabs..ect. to come up to the beach.
There was a jubilee last week too, right?
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Quoting mobilebayal:




So, are you cooking for all of the Mobile people on here? When should we come?
It did sound Good and this Hamburger Helper does not look good anymore if you know what I'm saying :o)

Taco :o)
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Quoting StormHype:
Was out to Siesta Key to shoot some video. One good training squall actually dried up coming ashore. This storm has a dry air issue. Gusty, but no winds to TS force. People out having fun in the wind and surf.

Good luck with your Cat1 NOLA.





its forcast too be come a cat 2
Member Since: May 21, 2006 Posts: 5091 Comments: 115435
Whats going on with Isaac now, this is not a question:
Member Since: March 16, 2012 Posts: 127 Comments: 7972


New frame eye still clearing out, it should not be long now to be clearly visible.
Member Since: July 4, 2005 Posts: 204 Comments: 8898
Quoting KEEPEROFTHEGATE:
..keeper if it does follow that path, the huge rains could indeed help those midwest drought states alot huh
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Quoting Tazmanian:



yes its forcast too be come a cat 2


Thanks Taz ... I haven't seen that yet ... New Orleans is in big trouble again ... :c/
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Quoting mobilebayal:




So, are you cooking for all of the Mobile people on here? When should we come?
What time?
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Quoting GetReal:


Eye starting to clear out.... along with new burst on NW side eye wall.
It looks like Isaac has completely separated from the "blob" (to use the technical term) over Florida. Will this help him get stronger if he is now smaller? And what happens to the blob? Does it move the same direction as the storm or go its own way?
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Was out to Siesta Key to shoot some video. One good training squall actually dried up coming ashore. This storm has a dry air issue. Gusty, but no winds to TS force. People out having fun in the wind and surf.

Good luck with your Cat1 NOLA.
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Quoting TreasureCoastFl:
We were expecting 2-3 inches and got 11" so he's a wet one who stretches far out from center. I am on east coast of Fl.


I hear you, we got 12 1/2" here in my area.. we are swamped...


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Quoting mobilebayal:


Are you near Brawood?
Avalon, my wife's cousin and his wife live on Brawood. I do sign language at St Ignatius.
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Quoting barbamz:


Isaac and it's twin to the east (the rainband which hammered FL today) are looking like a mirroring image of the psychological Rorschach-Test right now (or a butterfly)



Two female samuri warriors putting out a fire with their feet?
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Quoting Tazmanian:
if you live in New Orleans, LA do not ride this storm out ues this day light now too get out of town if you do plan on staying your a nut this kiding this is forcast too be a cat 2 storm may be even a cat 3 storm if you do plan on staying i would have a lifejacket some kind of flotation on stan by you may need it if one of the leves fail and water starts poring in so if you have a ch get out of town now


Taz i rode out katrina, ill be just fine.
Member Since: June 17, 2011 Posts: 11 Comments: 6539
I heard earlier 80,000 customers in east florida were without power..wonder if they got power back yet?
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Quoting KEEPEROFTHEGATE:

Hot towers beginning to refire over center where dry air intruded.
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Isaac and it's twin to the east (the rainband which hammered FL today) are looking like a mirroring image of the psychological Rorschach-Test right now (or a butterfly)

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Quoting catastropheadjuster:


Yeah yesterday got all the boards cut for the windows around the house and screwed 2x4's around garage doors. Katrina sucked them in big time. Got a roast,potatoes,carrots and blackeye peas for supper tonight, Gotta have a good dinner before everything goes down hill.

sheri




So, are you cooking for all of the Mobile people on here? When should we come?
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271. Reb74
Quoting hydrus:
This should be interesting ..

Any thoughts to where it may go? GOM? East Coast?
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there have been no reports of tornado touchdowns, according to Bay News 9 Chief Meteorologist Mike Clay. However, a tornado has been reported in Indian River County, near Vero Beach, and damaged 20 mobiles home. There is no word as to injuries.
Local weather is expected to be rainy at times, with gusty winds for the rest of the day and night, Clay said. Thunderstorms could also develop quickly and produce torrential rainfall for the next few days.

In the last 72 hours, wind gusts as high as 49 mph were reported in the Bay area.
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Quoting taco2me61:
maybe 2 weeks if you know what I'm saying :o)

Taco :o)
During Katrina, after 2 weeks, Georgia power came by and got our power back, well half the house. One leg of the 220V wasn't hooked up and half the house (AC half) was powerless. I called about it. Three days later I saw a truck and ran out to meet them. They said, "We came out yesterday and rang the bell, but nobody came." I just stood there with my mouth open.

I let it go, when he realized. They had to be exhausted.
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Once the winds catch up to the pressure, I think we ma have RI very soon, Isaac definitely looks like he's a hurricane now.
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Quoting Melagoo:
Our news here said the NHC released a CAT 2 storm ... is that right?



yes its forcast too be come a cat 2
Member Since: May 21, 2006 Posts: 5091 Comments: 115435
Quoting TexNowNM:
Dr. Masters wrote that most in Haiti were killed by collapsed buildings. That means there are many more with terrible injuries. Hope and pray aid can get to them in time to ease their suffering. Makes you grateful for something as simple as Tylenol.

There are many Aid Organisations and Workers and Warehouses - even hospitals etc in place - do not think that any more would help. I have little doubt, sadly, that more fatalities may be found and now a further outbreak of cholera looks very likely.
Looking down line slightly. it would appear that more potential Caribbean Weather systems are also imminent.
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Quoting Beachfoxx:
But they are closing Destin Commons tonight at 6:00pm & tomorrow!


Closing the Commons?.....Oh NOESSSSSS
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Quoting Masquer08er:
Yeah, finally something tropical. I'm afraid it's downhill from here. BTW I'm down the hill from St.Iggy off Springhill AV. If it floods, we might change the name to Spring Island.


Are you near Brawood?
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Quoting allancalderini:
Anyone think Isaac will be retired?
Yes I think it will be. Multiple deaths already, mostly in Haiti. Sad.
It will also be rembered as one of the strangest storms from path and intensity confusing everyone so much to the size of this thing.
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262. ARiot
Direct TV running NOLA local news mix
Ch. 349

Good coverage if interested.
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261. Reb74
Quoting greene47:
Any Okaloosa County residents on tonight? I saw on the weather channel that the surrounding counties (South Walton, Escambia/FL, and Santa Rosa) issued mandatory evac (I'm assuming for coastal areas) Is Okaloosa still a hold out with volunteer?...

I do know for SR and ES counties, it was an evac of low-lying areas. They turned off water and sewer to Perdido Key and Pensacola Beach. But I have not heard about OK county.
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260. auburn (Mod)
Quoting SherwoodSpirit:


Doubtless there will be more as they find them. I'm sure things are a complete mess in the tent cities. They'll probably be finding the dead for days.


I didn't want to say that..but I think you are probably right.
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Our news here said the NHC released a CAT 2 storm ... is that right?
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Quoting STXHurricanes2012:

Agreed I have it around 105 mph.


Yes i think the same 105-110 mph....specially we are talking about a 981 Mb storm
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Quoting StormSurgeon:


Hello all you fellow Mobilians! Just getting some sprinkles over on Hillcrest...


Same here on Dawes
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anyone experiencing coastal flooding from storm surge etc?.................COASTAL FLOOD ADVISORY NOW IN EFFECT FOR COASTAL TAYLOR AND
DIXIE COUNTIES THROUGH 8 PM EDT TUESDAY...

.MINOR COASTAL FLOODING IS ANTICIPATED ALONG THE TAYLOR AND DIXIE
COUNTY COAST AS TROPICAL STORM ISAAC MOVES NORTHWESTWARD ACROSS
THE NORTHERN GULF OF MEXICO.

FLZ128-134-281200-
/O.NEW.KTAE.CF.Y.0002.120827T1542Z-120829T0000Z/
COASTAL TAYLOR-COASTAL DIXIE-
1142 AM EDT MON AUG 27 2012

...COASTAL FLOOD ADVISORY IN EFFECT UNTIL 8 PM EDT TUESDAY...

THE NATIONAL WEATHER SERVICE IN TALLAHASSEE HAS ISSUED A COASTAL
FLOOD ADVISORY...WHICH IS IN EFFECT UNTIL 8 PM EDT TUESDAY.

* COASTAL FLOODING...TIDES ARE EXPECTED TO RISE AS MUCH AS 1 TO 2
FEET ABOVE NORMAL. THIS WILL RESULT IN MAXIMUM WATER LEVEL RISES
OF 2 TO 4 FEET ABOVE MEAN SEAN LEVEL AROUND THE TIME OF HIGH
TIDE.

* TIMING...THE ONSET OF HIGH WATER WILL BEGIN AFTER MIDNIGHT
TONIGHT AND MAXIMIZE AROUND THE TIME OF HIGH TIDE AROUND NOON ON
TUESDAY.

* IMPACTS...MINOR COASTAL FLOODING IS ANTICIPATED THAT WILL BE
CAPABLE OF FLOODING LOW LYING COASTAL ACCESS ROADS AND
POTENTIALLY IMPACTING UNPROTECTED STRUCTURES RIGHT ALONG THE
COASTLINE AROUND THE TIME OF HIGHEST TIDE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A COASTAL FLOOD ADVISORY INDICATES THAT COASTAL FLOODING IS
ANTICIPATED BUT IS ONLY EXPECTED TO CAUSE A MINOR IMPACT WITHIN
THE ADVISORY AREA.

&&

$$
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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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