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: 504 - 454

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

Quoting washingtonian115:
Gordon in 1994 was not taken off the list in.He killed 1000+.Hanna in 2008 killed 800 and as you can see will be back for 2016...
Is that always the case with a storm that goes over Haiti that the government chooses not to call for retirement?
Member Since: Posts: Comments:
Quoting LargoFl:
..good pic there ty..i dont think anyone ever knew east florida would get hit so bad as it did today..all that was supposed to be what we here on the gulf side were expecting, im lucky if i got a whopping 2-3 inches of rain today..we will see once the totals come in


I thought the wind would have been an issue. Not so much though. The feeder bands were training in my area last night for a good while. Today we had the same thing from the south though. That's why northeast broward and palm beach counties got some of the worst rainfall totals. Impressive how large this system is.
Member Since: Posts: Comments:
NNW jog? Will they get off N/O or are they stuck on it because of Katrina? What happens if it does slide east?
Member Since: Posts: Comments:

Wind Direction (WDIR):

NNE ( 30 deg true )

Wind Speed (WSPD):

31.1 kts

Atmospheric Pressure (PRES):

29.68 in

Buoy 64 nm south of Dauphin Island, AL
Member Since: Posts: Comments:
Quoting washingtonian115:
Gordon in 1994 was not taken off the list in.He killed 1000+.Hanna in 2008 killed 800 and as you can see will be back for 2016...


I hope you are right... Because that would mean the levees in NOLA held up.
Member Since: Posts: Comments:
Quoting stormchaser19:
For the people who are questioning about El NINO..He stalled Again SOI values are positive 9 of the last 11 days


SST Anomalies along the Pacific aren't too impressive either. SST Anomalies
Member Since: Posts: Comments:
498. FOREX
Quoting GTcooliebai:
I use Allan Huffman's Page. Link


Thank you, and I really enjoy reading what you write.
Member Since: Posts: Comments:
Quoting Dakster:


I bet Haiti asks that he is retired. 21 deaths and counting.
Gordon in 1994 was not taken off the list in.He killed 1000 .Hanna in 2008 killed 800 and as you can see will be back for 2014...
Member Since: Posts: Comments:
Quoting LargoFl:

I don't see how can make any other landfall except Miss/Ala at noon tomorrow as a TS.
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting GTcooliebai:
Well looks like Isaac will be back for another run in 2018. Baring some unexpected RI.


I bet Haiti asks that he is retired. 21 deaths and counting.
Member Since: Posts: Comments:
Quoting huntsvle:


umm...whats your overlay there...because your wind radii do not match your storm track?!!?


nevermind!!! i didn't ask that...the text showed up late.
Member Since: Posts: Comments:
Quoting washingtonian115:
The models bombed Isaac out as a major.Didn't happen.This is why you must always be skeptical when it comes to models runs.Was entertaining to see what they did with Isaac though.
Well looks like Isaac will be back for another run in 2018. Baring some unexpected RI.
Member Since: Posts: Comments:
Isaac has slowed down and taken a more Northen jog, Im not saying it will continue.... but on the Vis Sat it is obvious. Isaac will swallow that dry air and give it a shower.
Member Since: Posts: Comments:
Quoting HoustonTxGal:


Where did that come from? The writting at the bottom was too small.
Member Since: Posts: Comments:
Quoting HoustonTxGal:


umm...whats your overlay there...because your wind radii do not match your storm track?!!?
Member Since: Posts: Comments:
Quoting bucyouup68:


Not Much at all here
..yes its the same here..it rains for a few minutes then stops we get a dry spell and it rains again for a few minutes, most of the winds have died down now too
Member Since: Posts: Comments:
Honestly, I stopped watching The Weather Channel several years ago when they decided to become weather-tainment rather than weather.

Quoting angelafritz:
No prob, Dr. Masters might be dropping in to add some more info about storm surge. You can imagine he's very busy at TWC. Has anyone caught him on air yet today?
Member Since: Posts: Comments:
Why does TWC need 4 people reporting from New Orleans? I don't think its the only spot that's gonna feel impacts...
Member Since: Posts: Comments:
Quoting LargoFl:
looks like its calming down some in florida, just cells of rain coming in around here..isolated not like over on the east coast, local weather met said for the next 2 days this is what we can expect..sun then rain,sun then rain etc


Not Much at all here
Member Since: Posts: Comments:
Member Since: Posts: Comments:
did i here the weather ch say Ivan lol
Member Since: May 21, 2006 Posts: 5091 Comments: 114719
Member Since: Posts: Comments:
Here is an awesome WV image with the current NHC forecast and 15z WRF forecast overlaid


Member Since: Posts: Comments:
Quoting FOREX:


How do you see the GFS? The site that I use it shows it hasn'rt run yet.
I use Allan Huffman's Page. Link
Member Since: Posts: Comments:
Quoting CaneHunter031472:


Chances are huge. Gfs shows it as well as the euro, but I rather stick to the official forecast.


the official missed the read on the influence of the High early on which makes it a bit unnerving to believe now.
Member Since: Posts: Comments:
Quoting Parkedinparker:
Just in from Panama City FL: I threw all the furniture in the pool yesterday. The good news- It looks like Isaac's path is going to my west. The bad news- My wife is not happy, apparently I wasn't supposed to throw in the couch from the living room.
Your comment brought me out of "long time lurking" ... rofl ... too funny! Sounds like something my hubby would do unfortunately.

Syn627
Lafayette LA
Member Since: Posts: Comments:
Stay safe WU bloggers on the Gulf Coast, this thing is coming your way.
Member Since: Posts: Comments:
Looks to be moving NNW now.
Member Since: Posts: Comments:
Quoting MAweatherboy1:

It's possible but unlikely... the center is nowhere close to the convection.

By the way I just looked at the vis. loop of 97L and it is so cool! Watch the two little circulations rotate around each other, especially in the first half of the loop before darkness.




is that jose back from the dead
Member Since: May 21, 2006 Posts: 5091 Comments: 114719
Quoting washingaway:


He's mixing it out though.



Are you "wishmixing"?
Member Since: Posts: Comments:


Terrebonne Parish Administration

Monday, August 27, 2012

Mandatory Evacuation Issued for Low-Lying Areas of Terrebonne Parish

Terrebonne Parish Consolidated Government is issuing a Mandatory Evacuation for the following low-lying areas of the parish.

These areas include:
• Dularge - South of Dr. Beatrous Rd. bridge near the Dularge Gym
• Grand Caillou - South of Woodlawn Ranch Rd.
• Little Caillou - South of Lacache Middle School
• Montegut - South of Montegut Fire Station
• Pointe aux Chenes - South of Pointe aux Chenes Elementary School

The following areas are under Voluntary Evacuation:
• Dularge - South of the Dularge overpass due to potential highway flooding near the beginning of LA Hwy 315
• Little Caillou - South of Duplantis Bridge to Lacache Middle School
• Areas south of the Klondyke bridge covering lower Bourg, upper Montegut, and upper Pointe aux Chenes

Terrebonne Parish opened a shelter at the Houma Municipal Auditorium located at 800 Verret Street. The shelter opened at 9:00 a.m. on Monday morning. Residents needing transportation to the parish shelter should contact the Terrebonne Parish Council on Aging at (985) 868-8411 beginning Monday morning. Those residents with medical special needs that require shelter should contact the Louisiana Department of Health at 1-800-228-9409. A temporary pet shelter will begin operations this afternoon at the West Houma Gym on Williams Avenue. This temporary shelter is ONLY available for the pets of those residents who will be staying at the parish shelter at the Municipal Auditorium.

Those going to the parish shelter should bring food, water, bedding and any other necessary supplies such as medications and baby supplies they will need to sustain themselves and their families for 72 hours (3 Days), as these items WILL NOT be provided at the shelter








Member Since: Posts: Comments:
Quoting MAweatherboy1:

It's possible but unlikely... the center is nowhere close to the convection.

By the way I just looked at the vis. loop of 97L and it is so cool! Watch the two little circulations rotate around each other, especially in the first half of the loop before darkness.



Invest 97L not developing opens the door for future 98L to go more west as the ridge expands.
Member Since: April 29, 2009 Posts: 75 Comments: 14009
TROPICAL STORM ISAAC FORECAST/ADVISORY NUMBER 27
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
2100 UTC MON AUG 27 2012

CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY...

THE HURRICANE WARNING FROM THE FLORIDA-ALABAMA BORDER TO DESTIN HAS
BEEN CHANGED TO A TROPICAL STORM WARNING.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A HURRICANE WARNING IS IN EFFECT FOR...
* EAST OF MORGAN CITY LOUISIANA TO THE ALABAMA-FLORIDA BORDER...
INCLUDING METROPOLITAN NEW ORLEANS...LAKE PONTCHARTRAIN... AND LAKE
MAUREPAS

A HURRICANE WATCH IS IN EFFECT FOR...
* INTRACOASTAL CITY TO MORGAN CITY LOUISIANA

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* FROM THE ALABAMA-FLORIDA BORDER TO THE AUCILLA RIVER
* INTRACOASTAL CITY TO MORGAN CITY LOUISIANA

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* EAST OF SABINE PASS TO WEST OF INTRACOASTAL CITY LOUISIANA

A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED
SOMEWHERE WITHIN THE WARNING AREA. PREPARATIONS TO PROTECT LIFE AND
PROPERTY SHOULD BE RUSHED TO COMPLETION.

A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE
WITHIN THE WATCH AREA.

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

TROPICAL STORM CENTER LOCATED NEAR 26.4N 86.2W AT 27/2100Z
POSITION ACCURATE WITHIN 15 NM

PRESENT MOVEMENT TOWARD THE NORTHWEST OR 305 DEGREES AT 10 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 981 MB
MAX SUSTAINED WINDS 60 KT WITH GUSTS TO 75 KT.
50 KT....... 50NE 15SE 15SW 50NW.
34 KT.......150NE 150SE 80SW 180NW.
12 FT SEAS..180NE 180SE 180SW 150NW.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 26.4N 86.2W AT 27/2100Z
AT 27/1800Z CENTER WAS LOCATED NEAR 26.1N 85.9W

FORECAST VALID 28/0600Z 27.4N 87.5W
MAX WIND 70 KT...GUSTS 85 KT.
64 KT... 20NE 0SE 0SW 20NW.
50 KT... 60NE 20SE 20SW 60NW.
34 KT...165NE 150SE 80SW 180NW.

FORECAST VALID 28/1800Z 28.6N 89.0W
MAX WIND 80 KT...GUSTS 100 KT.
64 KT... 20NE 20SE 0SW 20NW.
50 KT... 60NE 50SE 30SW 60NW.
34 KT...180NE 150SE 80SW 180NW.

FORECAST VALID 29/0600Z 29.5N 90.0W...NEAR THE COAST
MAX WIND 85 KT...GUSTS 105 KT.
64 KT... 30NE 20SE 10SW 20NW.
50 KT... 60NE 60SE 40SW 60NW.
34 KT...180NE 150SE 80SW 150NW.

FORECAST VALID 29/1800Z 30.3N 90.7W...INLAND
MAX WIND 75 KT...GUSTS 90 KT.
50 KT... 60NE 60SE 40SW 40NW.
34 KT...180NE 150SE 80SW 110NW.

FORECAST VALID 30/1800Z 32.2N 91.8W...INLAND
MAX WIND 35 KT...GUSTS 45 KT.
34 KT... 60NE 130SE 30SW 40NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 175 NM
ON DAY 4 AND 225 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY

OUTLOOK VALID 31/1800Z 35.9N 92.1W...INLAND
MAX WIND 25 KT...GUSTS 35 KT.

OUTLOOK VALID 01/1800Z 38.7N 89.3W...INLAND
MAX WIND 20 KT...GUSTS 30 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 26.4N 86.2W

NEXT ADVISORY AT 28/0300Z

$$
FORECASTER STEWART
Member Since: Posts: Comments:
Quoting CosmicEvents:
You're doing fine. Thank you.
I recall my then fiancees first dinner/meeting with family when she jumbled her words regarding preferring one part of calamari to another. She swung and missed on tentacles.


My ex-wife did that all the time. My favorite was "mean as a yardstick". Her uncle looked at her and said, "We've had a yardstick lying around the house for years and it never hurt anyone."
Member Since: Posts: Comments:
Quoting gustaveye:
Looks to me that dry air is destroying Isaac. I don't see it getting stronger....just the opposite! NHC says CAT 2 at landfall....i think it will be a weak tropical storm! Is it just me?


The storm has been steadily strengthening. Sure the dry air is impeding speedy development but it will not completely inhibit. Strengthening into a hurricane is very likely, now whether it be a Cat 1,2,or 3 is yet to be known. Intensity is the hardest thing to predict. Personally I think a strong Cat 1/weak Cat 2 is the most likely.
Member Since: Posts: Comments:


Member Since: Posts: Comments:
Quoting KEEPEROFTHEGATE:
only a few vis frames to go till darkness falls



It looks as though the entrained dry air issue is resolving (finally).
Member Since: Posts: Comments:
For the people who are questioning about El NINO..He stalled Again SOI values are positive 9 of the last 11 days
Member Since: Posts: Comments:
The models bombed Isaac out as a major.Didn't happen.This is why you must always be skeptical when it comes to models runs.Was entertaining to see what they did with Isaac though.
Member Since: Posts: Comments:
Quoting Pirate999:


Memories of Allison flooding Houston. That's not what NOLA needs. Slowing down and no intensification could be just as bad as a cat2 (or worse)


Its not the wind..its the water...Repeat 3 x..click your
heels if you want....
Member Since: Posts: Comments:
Maybe the XTRP model will end up being the best for Isaac. ((cough))
Member Since: Posts: Comments:
Here in LaPlace directly in the path. Thanks for all the discussion. It has helped a lot. Dr. Jeff: ... been a subscriber for years, from early Win 3, and supported the page. It's the best... the one I trust.
Member Since: Posts: Comments:
Quoting MAweatherboy1:
He's in huge trouble now... Watch the last frame or two... convection has weakened significantly in the N/NE quadrant, worse than it already was... I think he's swallowed a ton of dry air... Anything more than a minimal hurricane seems unlikely to me now. Feel free to bash me, but that's what I'm seeing.


Had a few peaks of sunshine now another squall about to come through from Isaac here in Bradenton... Skies look ominous.
Member Since: Posts: Comments:

One of the last rgb loops - til tomorrow. Storm really struggles.
Member Since: Posts: Comments:
Quoting FOREX:


it is 6pm central right now.


Correct - I'm saying the next bulletin is due out at 7:00 Central Time which is in 59 minutes
Member Since: August 21, 2011 Posts: 0 Comments: 143
Quoting Hurricane12:


Well, the NHC has been using CDT for their advisories now for a while.

Probably cause he was expected to move into that time zone
Member Since: Posts: Comments:
Looks to me that dry air is destroying Isaac. I don't see it getting stronger....just the opposite! NHC says CAT 2 at landfall....i think it will be a weak tropical storm! Is it just me?
Member Since: Posts: Comments:
Quoting LargoFl:
GFS at 252 hours..oh oh...........


.....sooooo we'll get isaac landfalling and follow until dissipated and then start it all over again.
Member Since: Posts: Comments:

Viewing: 504 - 454

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.