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: 204 - 154

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 cat6band:



ALL of them!!


In the Mobile area, we just have that ticker thing at the bottom of the screen.
Member Since: Posts: Comments:
Quoting StormSurgeon:


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


Grand Bay here....waiting for the power to go out...for a week!!!
Member Since: Posts: Comments:
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?...
Member Since: Posts: Comments:
Quoting flcanes:

he's drawing it in off the yuc.


He has an expanding moisture field, and he's moving away from the Yucatan.
Member Since: Posts: Comments:
Just saw on local news that they are confirming the 14 inches of rain that fell over Sunrise, Tamarac, Lauderhill, Coral Springs area of North Western Broward.

Those wondering if they should or shouldn't prepare because they are outside of the cone, please keep in mind how far we in Broward are from the center of Isaac and what we experienced, you might not get winds, but you might get flooding rains and power outages.
Member Since: Posts: Comments:
Quoting auburn:


left 2-8 dead in Haiti..


Unfortunately you can have the same results with a tropical wave or depression in Haiti Auburn...
Member Since: Posts: Comments:
Quoting jpsb:
Yeah, but the dry air is definitely having an effect. Tops are warming in his core. I expect him to remain a TS over night.
I knew he was going to be a dud.
Member Since: Posts: Comments:
Quoting washingtonian115:
Who is still predicting a major hurricane....



me
Member Since: Posts: Comments:
196. auburn (Mod)
Quoting Thing342:
Actually, I belive it has jumped to about 19, so 21 total.


might have..hard to get official #s
Member Since: Posts: Comments:
Who is still predicting a major hurricane....
Member Since: Posts: Comments:
Quoting auburn:


left 2-8 dead in Haiti..

Didn't you read the blog entry ? It's up to 19 now.
Member Since: Posts: Comments:
Quoting auburn:


left 2-8 dead in Haiti..


Total's up to 21 dead now. I think he's done more than enough damage already.
Member Since: Posts: Comments:
192. auburn (Mod)
Quoting GeoffreyWPB:


Are any TV stations up there having wall-to-wall coverage of Isaac as of now?


Link to some nice live cams in NOLA
Member Since: Posts: Comments:
Quoting auburn:


left 2-8 dead in Haiti..
Actually, I belive it has jumped to about 19, so 21 total.
Member Since: Posts: Comments:
Quoting auburn:


left 2-8 dead in Haiti..


21 dead so far...sad...
Member Since: Posts: Comments:
189. jpsb
Quoting washingaway:


He's mixing it out though.

Yeah, but the dry air is definitely having an effect. Tops are warming in his core. I expect him to remain a TS over night.
Member Since: Posts: Comments:
Really slowing down now, will he stall?
Member Since: Posts: Comments:
Quoting auburn:


left 2-8 dead in Haiti..

how much damage so far?
i'll go check and report back
Member Since: Posts: Comments:
Quoting CaneHunter031472:


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


NHC typically shows a new track every 6 hours. There are exceptions, but mainly if there is a rapid intensity change upward. They do issue a new graphic evey three hours just to show the updated position.

With a storm the size of Isaac, a 20 mile move will make little difference in the preparation zone
Member Since: Posts: Comments:
Quoting GeoffreyWPB:


Are any TV stations up there having wall-to-wall coverage of Isaac as of now?



ALL of them!!
Member Since: Posts: Comments:
Quoting mojofearless:


They're evacuating Gautier? My Mom has a house off of Graveline on Bayou Pierre. Is that being evacuated?


Graveline, IDK, but if they are she will be informed. The board of supervisors are meeting right now to make it official. This is what a police officer told me other than that I already saw the National Guard driving around. Tell her to go to the WLOX website they should have more info there or the City of Gautier Website.
Member Since: Posts: Comments:
Quoting GeoffreyWPB:


Are any TV stations up there having wall-to-wall coverage of Isaac as of now?

probably
Member Since: Posts: Comments:
182. auburn (Mod)
Quoting GetReal:


I would like to see him do some work first before retiring...


left 2-8 dead in Haiti..
Member Since: Posts: Comments:
Quoting cat6band:
Bob Breck here in NOLA just did a run of the GFS and it showed 115 mph winds here in NOLA on Wed morning...That's more wind than we had with Katrina. I don't know if should laugh or cry....hahaha!!


Are any TV stations up there having wall-to-wall coverage of Isaac as of now?
Member Since: Posts: Comments:
This hasnt change very much in the last couple of days except its starting to tighten up some that i noticed.


Member Since: Posts: Comments:
Quoting Hurricane12:


Definitely don't want to see a catastrophe, though.


TrueDat!!!!
Member Since: Posts: Comments:
Quoting Hurricane12:


Definitely don't want to see a catastrophe, though.

yep, another "K" storm would suck
Member Since: Posts: Comments:
Quoting SFLweatherBen:
Hey guys. I've been following the blog for a few years now. I've always appreciated all the helpful information. Now I've finally decided to join. Here is a picture of some flooding in Plantation, FL

post again, plz
Member Since: Posts: Comments:
Quoting taco2me61:
Oh Yea I forgot we are in "FL" Well I gess we need to go to Tampa Bay GA then :o)

Taco :o)


Heh heh.....got the panels up on the Island house yesterday and fridge cleaned out....better safe than sorry.
Member Since: Posts: Comments:
Quoting Masquer08er:
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.
I think you are Right maybe they need too :o)

Taco :o)
Member Since: Posts: Comments:
Quoting GetReal:


I would like to see him do some work first before retiring...


Definitely don't want to see a catastrophe, though.
Member Since: Posts: Comments:
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting StormSurgeon:


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


I am in the Springhill area and it rained a tiny bit about 35 minutes ago.
Member Since: Posts: Comments:
Quoting washingaway:


He's mixing it out though.


he's drawing it in off the yuc.
Member Since: Posts: Comments:
Hey guys. I've been following the blog for a few years now. I've always appreciated all the helpful information. Now I've finally decided to join. Here is a picture of some flooding in Plantation, FL
Member Since: Posts: Comments:
Bob Breck here in NOLA just did a run of the GFS and it showed 115 mph winds here in NOLA on Wed morning...That's more wind than we had with Katrina. I don't know if should laugh or cry....hahaha!!
Member Since: Posts: Comments:
Quoting wxchaser97:

I think a hurricane will be determined at 8/ 11 at the latest. New convection firing around the center so he is not going away.

definetly
Member Since: Posts: Comments:
Quoting jpsb:
I doubt that, he is sucking in huge amounts of dry air.


He's mixing it out though.

Member Since: Posts: Comments:
Quoting allancalderini:
Anyone think Isaac will be retired?


I would like to see him do some work first before retiring...
Member Since: Posts: Comments:
Quoting gusgelpi:
My research is showing 12(ish) feet of surge on the Mississippi Gulf Coast especially in the inland bays. Is this accurate for current forecast or did I miss something.


I think that's what the NHC was forecasting as well (12 feet).
Member Since: Posts: Comments:
Quoting FFtrombi:


Dropsonde dropped by kermit recorded 981mb with 16mph winds, so freefall is slowing, but wouldn't say it has stopped yet.

how could it
don't screw gravity, lol
Member Since: Posts: Comments:
Quoting TropicalAnalystwx13:
Recon headed back for the intense southern quadrant. They should find that Isaac has become a hurricane.

I think a hurricane will be determined at 8/ 11 at the latest. New convection firing around the center so looks like we can see the eyewall forming.
Member Since: March 16, 2012 Posts: 127 Comments: 7972
Dropsonde from Kermit says about 981 mb with 14kt surface winds, which means about 980mb.
Member Since: Posts: Comments:
Quoting mobilebayal:


I have a pair too. Used them for a costume party. I remember your old user name. I always laughed when I saw it.

lol
o_o
Member Since: Posts: Comments:
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 =
;


Dropsonde dropped by kermit recorded 981mb with 16mph winds, so freefall is slowing, but wouldn't say it has stopped yet.
Member Since: Posts: Comments:
Quoting Masquer08er:
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.


I have a pair too. Used them for a costume party. I remember your old user name. I always laughed when I saw it.
Member Since: Posts: Comments:
Quoting TropicalAnalystwx13:
Recon headed back for the intense southern quadrant. They should find that Isaac has become a hurricane.



Back to confirm the first pass, and the obvious IMO...
Member Since: Posts: Comments:
Quoting mobilebayal:



Lol Stormsurgeon! Taco, I am ready. The sun is now shining outside.


Hello all you fellow Mobilians! Just getting some sprinkles over on Hillcrest...
Member Since: Posts: Comments:
My research is showing 12(ish) feet of surge on the Mississippi Gulf Coast especially in the inland bays. Is this accurate for current forecast or did I miss something.
Member Since: Posts: Comments:
Starting to get the dmin affect.
Member Since: Posts: Comments:

Viewing: 204 - 154

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.

Local Weather

Overcast
30 °F
Overcast

JeffMasters's Recent Photos

Lake Effort Snow Shower Over Windsor, Ontario
Sunset on Dunham Lake
Pictured Rocks Sunset
Sunset on Lake Huron