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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Member Since: March 16, 2012 Posts: 127 Comments: 7972
Quoting WxNerdVA:
...ISAAC TAKING AIM ON THE NORTHERN GULF COAST...SIGNIFICANT STORM SURGE AND FRESHWATER FLOOD THREAT EXPECTED... ...U.S. Warnings in Effect...
10:00 PM CDT Mon Aug 27
Location: 27.1°N 87.0°W
Moving: NW at 10 mph
Min pressure: 979 mb
Max sustained: 70 mph


see...not a hurricane... It took a whole day to increase mere 5 mph...
dumb storm!
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Evening All,

Prayers go out to those to the North in the path of Isaac.

I was able to get many pictures of the flooding in Wellington, FL and will make a blog post tomorrow morning. I had to forge quite an interesting route however, I was able to get my Mother In-Law home through the back entrance to her subdivision. Many areas heavily flooded. The rains just disappeared all of a sudden this afternoon and not a moment too soon as things were quickly getting out of control. National Guard has been deployed to the area and flood waters are reported to be snake infested. Stay out of the water, lol.
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10:00 PM CDT Mon Aug 27
Location: 27.1°N 87.0°W
Moving: NW at 10 mph
Min pressure: 979 mb
Max sustained: 70 mph
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No cane

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Quoting JLPR2:
If this keeps up we will end up having a 960mb tropical storm by morning. xD


Maybe then we'll have a cat 1! A 960mb 75mph cat 1!
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979mb TS
ESTIMATED MINIMUM CENTRAL PRESSURE 979 MB
MAX SUSTAINED WINDS 60 KT WITH GUSTS TO 75 KT.
Member Since: March 16, 2012 Posts: 127 Comments: 7972
Quoting HurrikanEB:


PORT-AU-PRINCE -- The death toll from Tropical Storm Isaac rose Monday to 19 in Haiti where disaster officials warned the number could increase, and donors continued efforts to assess damage to crops and homes.

Link


By God.... I really feel bad for Haiti. RIP for those who died.
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No hurricane this advisory, as expected.
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1493. txjac
Quoting EcoLogic:
Land falling cyclone...first time in three weeks that I. Have refreshed my browser to reveal no new posts...freaky

Really blowing in gulf breeze...headed to bed.



G'night ...bit first, what kind of animal is that you are holding in your avatar?
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1491. keno66
Quoting jake436:
I'm very familiar with Buras, and no doubt your area was demolished. However, "imagine driving into an area in which you spent 38 years and not knowing where you were because there weren't any recognizable landmarks"...you DO realize the same could be said for the entire MS coast, right? I mean, people that lived several blocks north of the beach had CASINOS where their houses used to be. It's not a competition. Katrina took a lot from a lot of people. I live in MS, but was born and raised in LA. I grow tired of Mississippians whining about getting more of Katrina's wrath than NOLA, and vice versa. The storm tore up a lot of stuff, and ruined a lot of lives. Does it really matter who's life it ruined first?

First, we all know the dangers of where we live, so no one should need sympathy for a decision we consciously made. Second, I understand Mississippians "whining" because NOLA's disaster was truly "man-made." However, I can empathize with everyone who lost everything. We all had to pick ourselves up, dust ourselves off, and move on with our lives. With that being said, I apologize if my comment offended you.
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Quoting guygee:
A little too cute for me. That is like saying there are two kinds of empires, those that have fallen and those that will fall...there are two kinds of buildings, those that have crumbled and those that will crumble...there are two kinds of species, those that are extinct and those that will be extinct...ad infinitum...ad nauseum...


But all of those examples are true....
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Quoting JLPR2:
If this keeps up we will end up having a 960mb tropical storm by morning. xD

Another Irene the difference that Irene was a hurricane that weaken to a ts but Isaac haven`t strength into one.maybe that is why the HWRF or whatever the model name is present low pressure with Isaac.
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Quoting BaldwinStorm:






Yea...that aggravated me too. "Mobile Bay, MS"...Really? Alabama coast is always forgotten.



Alabama and Mississippi are often forgotten in the mainstream media. They are always seemingly New Orleans or the Florida Panhandle...we just fill the 'flyover state'. But this was really exposed following the Katrina aftermath, I think everyone could agree with that.

So this is rich:

Riddle me this... Channel 5 in Mobile:

"We are expecting to receive between 10-20 inches of rain"

then 60 seconds later:

"We have a 90% chance of rain Wednesday"


HAHAHA!!! C'mon. At least local Fox moments ago called for 100% rain Wed.

Member Since: August 23, 2012 Posts: 0 Comments: 21
So much for the 100 mph winds in the south of the circulation... This thing is just way too broad. The fact that there were low pressures and high winds that far from the center and in no convection was a sign that there was no tight inner core. Either that or this thing was a major cane, and we all no its not the 2nd option.
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Quoting southernstorm:


hes trying to be cute...its his role here.
I have never seen the cuteness. Wishing for a Cat 3 just does not strike me as cute.
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Cyan ring on TWC now
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I gotta head out, folks... I hope everybody from LA to MS to AL to FL get their stuff together before the winds start to pick up... I have meetings tomorrow so don't know how much time I will be able to spend online, but know my thoughts and prayers are with you guys.

Stay safe, and good night.

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Land falling cyclone...first time in three weeks that I. Have refreshed my browser to reveal no new posts...freaky

Really blowing in gulf breeze...headed to bed.
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Quoting MississippiWx:


It's not over yet, my friend. Also, Haiti has reported at least 17 dead from Isaac.


PORT-AU-PRINCE -- The death toll from Tropical Storm Isaac rose Monday to 19 in Haiti where disaster officials warned the number could increase, and donors continued efforts to assess damage to crops and homes.

Link
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I guess we should be thankful it's struggling right now with dry air and shear cause it's circulation covers the entire GOM, and then stretches just east of FL...
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is it me (as a total amateur) or since a few hours isaac is seemingly going SW?
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Quoting TomballTXPride:
IMO, this is when he looked his best. A symmetrical CDO, vertically stacked MCL and LLC, not signs of mid-level dry air instrusion. Signs of an eye also. This is when I thought "Oh Crap", this is it.



On the other hand, this is when he began his demise. He constant fight with dry air, unable to win that battle. From here, he went downhill, never able to recover. We'll see what tonight brings though.

You are focusing on the past look at him now.



Pressure is dropping as well.
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1477. Gearsts
No Hurricane yet?
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979mb (28.91 inHg) Sea Level (Surface)
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1475. InPCola
Quoting Melagoo:

Looks like Isaac may be kicking out the dry air ...

I was wondering the same - it seems like the same dry air that it originally sucked up from the south hours ago, when the SE portion was the weakest-looking, just making its way around the circulation of the storm now. Was wondering if it'll finally expel it for good once it gets back around to the NW/W portion of the storm and be fully closed in at that point. Guess time will tell.
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1474. JLPR2
If this keeps up we will end up having a 960mb tropical storm by morning. xD

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Quoting RitaEvac:
flag Taz's post, he'll be perma-banned for good, and never be back.


The blog moves so fast it's hard to find a single post
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Quoting treehuggingsister:

And we're kinda balmy and breezy on the Westside.

Weather's a bear, isn't it?


Down by the port, it's decidedly UN-humid, but winds have picked up to maybe 20mph. Moon is ducking in and out of the clouds. Actually a nice night, though a bit on the breezy side. Only a few boats left in the marina.
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1470. ATCr
Quoting GeauxGirl:


Wonder what the winds are on Biloxi beach? I'm about 70 north of Biloxi and the breeze is picking up. It was hot, hot, hot today.
<
/blockquote>

KBIX 280243Z AUTO 03014G21KT 10SM FEW060 SCT170 BKN210 29/20 A2978 RMK AO2 RAB0232E0243 SLP087
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The Air Force just registered 979.4MB - and it's flying at 5k feet, closer to the surface than NOAA. That'll be the level for the 11pm.

And a NOAA dropsonde in the southern eyewall just picked up 50kts at the surface - but 70kts a few hundred feet above it.
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Quoting angiest:


Didn't that describe Alex as well?

The pressure difference with this one is insane though. Alex was the Ike of Mexico, in a way. Very low pressures (sub-950mb) with 110mph winds. Isaac has the pressure of a 90mph hurricane. I don't know what to think anymore.
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Quoting CloudGatherer:
Who cares? I mean, really, why are you posting 850 mb winds?

That's because the plane is at 850 mb?
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How is it that Ileana and all other EPac storms look so well-organized and the Atlantic continues to have issues? Even in the Southern Hemisphere basins that have hurricane seasons comparable to the Atlantic in terms of numbers, you still get better-looking storms most of the time. This baffles me!
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Quoting TomballTXPride:

Surprised that's been allowed to go on for so long.
Despite the "cutesy" Taz has mades some valuable contributions here over the years.
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Time: 02:31:00Z
Coordinates: 27.1167N 87.0W
Acft. Static Air Press: 842.6 mb (~ 24.88 inHg)
Acft. Geopotential Hgt: 1,326 meters (~ 4,350 feet)
Extrap. Sfc. Press: 979.4 mb (~ 28.92 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 206° at 1 knots (From the SSW at ~ 1.1 mph)
Air Temp: 21.4°C (~ 70.5°F)
Dew Pt: 16.6°C (~ 61.9°F)
Peak (10s) Flt. Lvl. Wind: 6 knots (~ 6.9 mph)
SFMR Peak (10s) Sfc. Wind: 22 knots (~ 25.3 mph)
SFMR Rain Rate: 4 mm/hr (~ 0.16 in/hr)
(*) Denotes suspect data
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Well, I'm off to bed. I'll be praying that Issac doesn't take the left hand side of the cone. Night all.
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1462. gecko
Quoting IMA:

I paid my $5 on the day I was notified to renew, have the PayPal receipt to prove it, but it still says "renew". I have sent multiple messages to support but have not had a reply. It's been 19 days since the first message was sent. I'm so disgusted right now! It's not about the ads, I have ABP, but not being able to get more than 6 frames on the animated radar & not getting assistance is maddening!


Did you totally log out and log back in again? It's been a while since I renewed but I thought that was in the instructions.
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Quoting MississippiWx:
Winds have certainly mixed down to the surface. Lots of 60+ mph readings north and west of the center.


Wonder what the winds are on Biloxi beach? I'm about 70 north of Biloxi and the breeze is picking up. It was hot, hot, hot today.
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1460. jake436
Quoting keno66:

The initial landfall was in Buras. That's where I grew up and lived until everything was completely and totally destroyed. Imagine driving into an area in which you spent 38 years living and not knowing where you were because there weren't any recognizable landmarks.
I'm very familiar with Buras, and no doubt your area was demolished. However, "imagine driving into an area in which you spent 38 years and not knowing where you were because there weren't any recognizable landmarks"...you DO realize the same could be said for the entire MS coast, right? I mean, people that lived several blocks north of the beach had CASINOS where their houses used to be. It's not a competition. Katrina took a lot from a lot of people. I live in MS, but was born and raised in LA. I grow tired of Mississippians whining about getting more of Katrina's wrath than NOLA, and vice versa. The storm tore up a lot of stuff, and ruined a lot of lives. Does it really matter who's life it ruined first?
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The salient portions of Kermit's most recent center pass, about to be superseded by two new readings, from NOAA and the Air Force:

Product: NOAA Vortex Message (URNT12 KWBC)
Transmitted: 28th day of the month at 01:53Z
Aircraft: Lockheed WP-3D Orion (Reg. Num. N42RF)
Storm Number & Year: 09L in 2012
Storm Name: Isaac (flight in the North Atlantic basin)
B. Center Fix Coordinates: 26°59'N 86°39'W (26.9833N 86.65W)
B. Center Fix Location: 241 miles (388 km) to the S (172°) from Pensacola, FL, USA.
C. Minimum Height at Standard Level: 2,981m (9,780ft) at 700mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 50kts (~ 57.5mph)
H. Minimum Sea Level Pressure: 981mb (28.97 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 12°C (54°F) at a pressure alt. of 3,061m (10,043ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 17°C (63°F) at a pressure alt. of 3,077m (10,095ft)
L. Eye Character: Poorly Defined
M. Eye Shape: Not Available
Maximum Flight Level Wind: 70kts (~ 80.6mph) in the southeast quadrant at 22:34:49Z
Maximum Flight Level Wind Outbound: 55kts (~ 63.3mph) in the south quadrant at 1:35:01Z
Remarks Section - Additional Remarks...
SLP EXTRAP FROM 10K FT
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flag Taz's post, he'll be perma-banned for good, and never be back.
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1457. angiest
Quoting WeatherNerdPR:

Isaac is essentially a WPAC storm in the Gulf. Most bizarre storm in a while.


Didn't that describe Alex as well?
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1455. Skyepony (Mod)
Product: NOAA Vortex Message (URNT12 KWBC)
Transmitted: 28th day of the month at 01:53Z
Aircraft: Lockheed WP-3D Orion (Reg. Num. N42RF)
Storm Number & Year: 09L in 2012
Storm Name: Isaac (flight in the North Atlantic basin)
Mission Number: 28
Observation Number: 36
A. Time of Center Fix: 28th day of the month at 1:16:47Z
B. Center Fix Coordinates: 26°59'N 86°39'W (26.9833N 86.65W)
B. Center Fix Location: 241 miles (388 km) to the S (172°) from Pensacola, FL, USA.
C. Minimum Height at Standard Level: 2,981m (9,780ft) at 700mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 50kts (~ 57.5mph)
E. Location of the Estimated Maximum Surface Wind: 62 nautical miles (71 statute miles) to the N (360°) of center fix
F. Maximum Flight Level Wind Inbound: From 96° at 59kts (From the E at ~ 67.9mph)
G. Location of Maximum Flight Level Wind Inbound: 56 nautical miles (64 statute miles) to the N (360°) of center fix
H. Minimum Sea Level Pressure: 981mb (28.97 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 12°C (54°F) at a pressure alt. of 3,061m (10,043ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 17°C (63°F) at a pressure alt. of 3,077m (10,095ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 12°C (54°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Poorly Defined
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 700mb
O. Fix Determined By / Fix Level (Undecoded): 1 / 1 nm
Remarks Section - Remarks That Were Decoded...
Maximum Flight Level Wind: 70kts (~ 80.6mph) in the southeast quadrant at 22:34:49Z
Maximum Flight Level Wind Outbound: 55kts (~ 63.3mph) in the south quadrant at 1:35:01Z
Remarks Section - Additional Remarks...
SLP EXTRAP FROM 10K FT
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Quoting MississippiWx:


It's not over yet, my friend. Also, Haiti has reported at least 17 dead from Isaac.

Oh' Lordy. Havent looked at it today...
Hearts go out to Haiti.
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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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