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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Hello hurricane Issac
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Quoting weatherh98:


i may turn the tv off.


This is pertinent to weather how exactly? Why is it some cannot stop with the politics? WEATHER is the topic, not your tv viewing habits.
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Quoting MAweatherboy1:
I guess I was right about the dropsonde. Isaac should be declared a hurricane with 80mph winds at 11AM.





more proof.... i see the coc but show me actual recon data
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Quoting Kristina40:


I don't recall anyone calling it a hurricane either.


They've been calling for it to be a hurricane since it was in the Keys. It's 18 hours from landfall now and still a TS. This will finally be a Cat1 when it comes ashore.

The widely over-done hype is unfortunate because it will cause many to turn off the TV in 10 days when the next storm moves this way. I'm not against prep, just need to keep it sane and sensible. It's gonna be a cat1 like the NHC says.
Member Since: May 31, 2007 Posts: 0 Comments: 1204
Important: water vapor loop shows complete wraparound of moisture around a DEFINED EYE. This happened only in the last 30 minute, and here is the image 4 minutes ago:



If you want to see the full 30 frame animation, here is a LINK.

Also, replace "1311" (9:11am) with a later time to see newer images.
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Quoting Hhunter:


His eye was 50 miles wide but rapid scan shows it looks to be contracting and closing over the last hour as convection increases and closes off the last bit of eye wall building.

IMO this is going to be over water 12 more hours and looks to be an intensifying CAT 1/2 hurricane while making landfall. STAY SAFE!
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I guess I was right about the dropsonde. Isaac should be declared a hurricane with 80mph winds at 11AM.

Member Since: February 11, 2012 Posts: 83 Comments: 7835
2945. RickWPB
Quoting seflagamma:


It did not have a "ton of rain" in it over S Fla but if you were under one of those training bands with heavy rain for 2 days... 12.5" of rain is a lot of water.

and a few areas north of me got same amount.

Yep, if you happen to get under one of those "heavy moisture trains" you can get lots of rain. We got between 9 and 11 inches in two days here in Lake Worth. Out in Wellington FL they recv'd up to 15" of rain with some houses getting water in their houses.
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From Wellington
http://sphotos-b.xx.fbcdn.net/hphotos-ash4/293462 _406086826106605_1760106380_n.jpg
Quoting seflagamma:


my brother in law lives in Wellington and there are some low areas there.
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Quoting TcuFrogs:
I wish everyone east of Texas the best during this time, but if Isaac does continue to shift west and ramps up, there will be alot of unprepared people here in SE Texas. Just saying.


I don't know. Yesterday they were cleaning Walmart in Orange out of supplies. Which is actually good whether this one comes here or not. But yeah the majority aren't ready for anything.
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Quoting seflagamma:


It did not have a "ton of rain" in it over S Fla but if you were under one of those training bands with heavy rain for 2 days... 12.5" of rain is a lot of water.

and a few areas north of me got same amount.


For sure, I'm not knocking the fact FL got flooding rain. I'm just wondering if we're looking at a May 8th flood type situation.
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2941. TXCWC
Quoting Matt1989:
A lot of texas casters in here. Storm is not going toTexas..


GFS AND EURO SAY DIFFERENT - no NOT LANDFALL IN TX - BUT both say a TRACK INTO TX definitely possible

0Z EURO


06z GFS
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Quoting HimacaneBrees:
Well Obama will be speaking at 10 EDT about Isaac. Campaign tactic? Think I'd rather watch QVC.


i may turn the tv off.
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Quoting CloudGatherer:
988mb (Surface) 195° (from the SSW) 70 knots (81 mph)

That's a NOAA dropsonde.

Ladies and gentlemen, I give you Hurricane Isaac.



i dont believe
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Quoting seflagamma:


my brother in law lives in Wellington and there are some low areas there.


Can only imagine what it would be like without the canal system.
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2937. Hhunter
Crap...
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2936. hydrus
Quoting CajunMom2:
Long time (way, way before Katrina) lurker in Lafayette. Starting to get nervous here, news reports do not appear concerned and no one has board up that I could tell. Should we be concerned?
I would be. Isaac could pass right over you. Take the warnings seriously when they come your way, and if you have trees, board up before the wind. Check your hurricane prep list.
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Also good morning everyone, Isaac looks to be getting better organized.
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Quoting StormPro:
hey man....i'm on Carroll st...where are you?


montgomery. Ill be down on the lakefront today.
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Quoting StormTracker2K:


You guys might actually get some rain from Issac. So far here in FL since the end of May has been wet to say the least with some areas receiving 40" of rain over the last 90 days.


Link


The drought in Florida is DONE! lol, looks like its been an active spring and summer for ya.

We need the rain up here. Isaac dumping 1-4 inches over the entire state would be bliss, but he's looking like he going for a mean run this morning looking at recent trends. I hope people are ready for this storm.
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988mb (Surface) 195 (from the SSW) 70 knots (81 mph)

That's a NOAA dropsonde.

Ladies and gentlemen, I give you Hurricane Isaac.
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Quoting SFLWeatherman:
Wellington asks National Guard for help after getting nearly 14 inches of rain



my brother in law lives in Wellington and there are some low areas there.
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2929. Hhunter
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Quoting weatherh98:


reporting for ranting

gotta get the funktop in before it gets bad here


hey man....i'm on Carroll st...where are you?
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Quoting weatherh98:


reporting for ranting

gotta get the funktop in before it gets bad here


hey man....i'm on Carroll st...where are you?
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Quoting Beachfoxx:
Wow--- not seeing that over here just north of Destin on the bay, it might be up a little, but no where 6 feet.


Up maybe a foot just West of Fort Walton Beach on the Sound. Noticed Isaac went more North than West at the last avisory and has really slowed down, could he be turning North sooner than they forecast or is this a jog? Guess we'll see at the next advisory if this trend continues!














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Quoting leelee75k:
When Isaac is all gone, I would love to discuss how and why he split over Florida if anyone is up for it. I found this particular action over Floria to be one of the strangest things I've ever seen a tropical cyclone do.


me too, there is still alot of "left over Isaac" off the east coast of Fla...
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Wellington asks National Guard for help after getting nearly 14 inches of rain

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2923. TXCWC
Quoting MAweatherboy1:
Looking at radar, I think Isaac has just about stalled, or at least slowed to under 5mph... It's just not going anywhere.


IF so would mean EURO may be more correct in showing more of a westward movement BEFORE landfall as opposed to AFTER as shown by GFS
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A lot of texas casters in here. Storm is not going toTexas..
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Quoting GeorgiaStormz:
Good Morning guys, i see as soon as i go to bed, and just before landfall(like all the storms this year) Isaac is finally trying to get it together...probably due to land friction


we got 18 hours till landfall
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Quoting Tazmanian:
they this found 968mb


Morning Taz...nice to see you survived the anti-Taz clan last night....I thought for sure you would have been tarred and feathered from the onslaught....(of course you may have liked that)....:)
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I think a NOAA dropsonde just got 81mph at the surface... I'm not great at reading those things though so someone correct me if I'm wrong.
Member Since: February 11, 2012 Posts: 83 Comments: 7835
I wish everyone east of Texas the best during this time, but if Isaac does continue to shift west and ramps up, there will be alot of unprepared people here in SE Texas. Just saying.
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what most ppl dont realize that hurricanes going over swamp area dont lose intesity for a very long time. anywhere else in the country a storm would be weakening. here off the Louisiana coast, where the swamps are already filled with water from local downpours. the storm has no problem to strengthen all the way to landfall
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Quoting DrMickey:
re: 2867
You have posted that photo twice and you made that chuildish remark about two meteorologists.
Enuff! POOF!!


Get a sense of humor Dr. Poof.
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I hope that new Inner Harbor Navigation Canal Surge Barrier (IHNC) works and keeps most of the storm surge out.
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Good Morning guys, i see as soon as i go to bed, and just before landfall(like all the storms this year) Isaac is finally trying to get it together...probably due to land friction
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2913. WxLogic
Quoting 9030mike:
Am I wrong in saying that it doesn't look like Isaac has a ton of rain with it on radar? A lot of green, not much yellow or red. Is the rain factor overhyped?


The dry air in the N and W peripheries is causing the lack of rain (in this case a bit more than usual). The E,NE, and SE will have the most rain.
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Quoting leelee75k:
When Isaac is all gone, I would love to discuss how and why he split over Florida if anyone is up for it. I found this particular action over Floria to be one of the strangest things I've ever seen a tropical cyclone do.


I think that is why Isaac didn't get it togather quicker as all the energy yesterday over eastern Florida robbed the center of alot of energy. Our worst weather in Broward and Palm Beach occurred in during the morning early afternoon with tropical storm conditions including heavy heavy rains and winds 50-60 SE winds.
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Quoting TropicalAnalystwx13:

They never said it was. In fact, last night, Carl Parker and Jim Cantore specifically said, "this is no Katrina".
My point was they are there In New Orleans for a reason. You see all these Katrina reminders. You see these flashbacks you hear all the time. It's the seventh Anniversary of Katrina. Katrina was a bad, bad, bad storm it was felt all the way over to here Alabama. I am not knocking this storm. They are pushing the issue though. They would be very foolish not to say this storm isn't a Katrina. They were hoping this was a Cat 2 or higher or they wouldn't have 4 reporters in N.O. I don't know it could be that there partnership with NBC has made it where they have to overhype about everything now.
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Quoting Tazmanian:



yep and it still has other 18 too 36hrs overe water


Hey TAZ! Morning! What you think of those 80 knot plus winds all over the place. Check out the lastest Visible on the rapid scan. It really looks like it wants to make a run for it. I don't want to hype it but it sure looks like its about to turn ugly. Like you said last night.

Link
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2909. ncstorm
I sense some bans coming soon..
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Looking at radar, I think Isaac has just about stalled, or at least slowed to under 5mph... It's just not going anywhere.
Member Since: February 11, 2012 Posts: 83 Comments: 7835
Quoting Tazmanian:



yep and it still has other 18 too 36hrs overe water

I smell an "Alex-like" situation with this thing coming in at a solid cat2 but with cat3/4 pressures if rapid intensification starts out
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Quoting leelee75k:
When Isaac is all gone, I would love to discuss how and why he split over Florida if anyone is up for it. I found this particular action over Floria to be one of the strangest things I've ever seen a tropical cyclone do.


It was like FL choked off his moisture source. Much of the day yesterday featured more convection over FL than over Issac. Some reports in C Palm Beach county of 25" of rain.

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Quoting lobdelse81:

Wouldn't this correspond to surface sustained winds at 85-90mph?
It should, but it seems Isaac is having trouble translating those down to the surface.
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Quoting 9030mike:
Am I wrong in saying that it doesn't look like Isaac has a ton of rain with it on radar? A lot of green, not much yellow or red. Is the rain factor overhyped?


It did not have a "ton of rain" in it over S Fla but if you were under one of those training bands with heavy rain for 2 days... 12.5" of rain is a lot of water.

and a few areas north of me got same amount.
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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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