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: 3604 - 3554

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

Heavy rain 50 mph wind gust!!
Member Since: Posts: Comments:
A really high storm surge with this track might push salt water all the way back up to Baton Rouge, or maybe at least half way there, since the river level is only like 4 feet at Baton Rouge last I heard...


Anyway, with this kind of forward speed we are going to see very wide spread 10 inch or greater totals, I think.Morning All...Agree the rain could be problematic but 4ft river level at Baton Rouge.....don't think so....you could walk across the river. You must be talking about depth amount that is needed for fully loaded barge/ship transport.?
Member Since: Posts: Comments:


http://www.tpcg.org/view.php?f=main&p=nws

Flash Flood Watch Issued by NWS New Orleans (Southeastern Louisiana)
Alert:

...FLASH FLOOD WATCH IN EFFECT FROM 7 AM CDT THIS MORNING THROUGH
7 PM CDT WEDNESDAY...

.WIDESPREAD HEAVY RAIN IS EXPECTED TO BEGIN LATER MORNING AND
CONTINUE THROUGH LATE WEDNESDAY AFTERNOON AS SLOW MOVING ISAAC
AFFECTS THE REGION. MANY AREAS ARE LIKELY TO RECEIVE 10 TO 15
INCHES OF RAINFALL OVER A 36 HOUR PERIOD WITH LOCALLY UP TO 20
INCHES POSSIBLE.

...FLASH FLOOD WATCH REMAINS IN EFFECT FROM 7 AM CDT THIS MORNING
THROUGH WEDNESDAY EVENING...

THE FLASH FLOOD WATCH CONTINUES FOR

* PORTIONS OF SOUTHEAST LOUISIANA AND SOUTHERN MISSISSIPPI...
INCLUDING THE FOLLOWING AREAS...IN SOUTHEAST LOUISIANA...

ASCENSION...ASSUMPTION...EAST BATON ROUGE...EAST FELICIANA...
IBERVILLE...LIVINGSTON...LOWER JEFFERSON...LOWER LAFOURCHE...
LOWER PLAQUEMINES...LOWER ST. BERNARD...LOWER TERREBONNE...
NORTHERN TANGIPAHOA...ORLEANS...POINTE COUPEE...SOUTHERN
TANGIPAHOA...ST. CHARLES...ST. HELENA...ST. JAMES...ST. JOHN
THE BAPTIST...ST. TAMMANY...UPPER JEFFERSON...UPPER
LAFOURCHE...UPPER PLAQUEMINES...UPPER ST. BERNARD...UPPER
TERREBONNE...WASHINGTON...WEST BATON ROUGE AND WEST FELICIANA.
IN SOUTHERN MISSISSIPPI...AMITE...HANCOCK... HARRISON...
JACKSON...PEARL RIVER...PIKE...WALTHALL AND WILKINSON.

* FROM 7 AM CDT THIS MORNING THROUGH WEDNESDAY EVENING

* HEAVY RAINFALL IS EXPECTED AS ISAAC MOVES SLOWLY NORTHWESTWARD
TODAY THROUGH WEDNESDAY AFTERNOON. RAINFALL TOTALS ARE EXPECTED
TO RANGE BETWEEN 10 AND 15 INCHES OVER A 36 HOUR PERIOD WITH
LOCALLY UP TO 20 INCHES POSSIBLE.

* RAINFALL RATES MAY OVERWHELM DRAINAGE SYSTEMS AND PUMPS...
RESULTING IN RAPID RUNOFF AND STREET FLOODING. LOW LYING AND
FLOOD PRONE AREAS MAY EXPERIENCE FLASH FLOODING CAPABLE OF
STALLING CARS AND THREATENING HOMES AND BUSINESSES.


Instructions:

A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION. YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION SHOULD FLASH FLOOD WARNINGS BE ISSUED.



Target Area:




Ascension
Assumption
East Baton Rouge
East Feliciana
Iberville
LAZ069
Livingston
Lower Jefferson
Lower Lafourche
Lower St. Bernard
Lower Terrebonne
Northern Tangipahoa
Orleans
Pointe Coupee
Southern Tangipahoa
St. Charles
St. Helena
St. James
St. John The Baptist
St. Tammany
Upper Jefferson
Upper Lafourche
Upper Plaquemines
Upper St. Bernard
Upper Terrebonne
Washington
West Baton Rouge
West Feliciana

Member Since: August 23, 2008 Posts: 0 Comments: 1918
Great work so far is doing the HAARP with Isaac XDD
Member Since: Posts: Comments:
3600. ncstorm
Quoting TomballTXPride:
Crow anyone?

LOL


still looking like Ike?
Member Since: Posts: Comments:
3599. VR46L
Getting very close now ......

Member Since: Posts: Comments:
It's ssoo tempting to view this as an exact science...and it simply isn't...there's a lot of art to it...tropical meteorology is an attempt to approximate chaos....similar to parenting in that way...
Member Since: Posts: Comments:
Quoting MAweatherboy1:
I would be furious if I was on the plane that got the 81mph winds... You proved beyond any doubt that the system is a hurricane and they totally blow off your reading?


Why your getting paid. Is there a prize for being on the plane that "got the 81mph winds" Maybe this should be like the show "Bachelor Pad" and we kick off planes and their crews when they don't give us Hurricane force winds and have backstabbing and in-fighting. Made for TV!!
Member Since: Posts: Comments:
New readings from Kermit:

SFMR Peak (10s) Sfc. Wind: 63 knots (~ 72.4 mph)
-------------------

Time: 14:50:00Z
Coordinates: 28.1667N 87.4833W
Acft. Static Air Press: 753.4 mb (~ 22.25 inHg)
Acft. Geopotential Hgt: 2,371 meters (~ 7,779 feet)
Extrap. Sfc. Press: 989.7 mb (~ 29.23 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 164° at 90 knots (From the SSE at ~ 103.5 mph)
Member Since: Posts: Comments:
Quoting reedzone:
I have lost all confidence on the NHC... I'm done.


Yeah. It has 64kts or greater in both directions on the radar, and a dropsonde with 80mph surface winds, but it is NOT a hurricane, according to NHC...


Maybe it's a dust devil?

A Haboob?

What are they gonna call it next?
Member Since: Posts: Comments:
This storm will be forever known as "Isaac the Choker" never could get it together and was always choking on dry air
Member Since: Posts: Comments:
Quoting cheaterwon:


Don't always agree with you hardly ever and your avitar looks like a motorcycle cop (just joking), but you are not a troll you do not say stuff just to inflame people and you contribute greatly to the blog.


Really do appreciate that, thanks.
Member Since: Posts: Comments:
Quoting reedzone:
I have lost all confidence on the NHC... I'm done.


There is no way Isaac travels past 90W. Just no way.
Member Since: Posts: Comments:
Water has already begun to move into backyards along the the Bayou's on the coast of Gulfport. I really don't think some people around here understand storm surge has no relation to only wind and being a Hurricane. Water is 4 feet over the piers at this poing and the height of storm surge is at high tide in the morning and everyone stil have boats on trailors beside their house. Some people are going to be very suprised. The water has completely covered the beaches in some areas already and is lashing the old seawall.
Member Since: Posts: Comments:
3588. hydrus
I saw the long range models pick up on this over a week ago. Max Mayfield was concerned about this when Isaac was in the Atlantic.PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD
958 AM EDT TUE AUG 28 2012

VALID 12Z SAT SEP 01 2012 - 12Z TUE SEP 04 2012

MOST MEDIUM RANGE GUIDANCE CONTINUES THE THEME OF LESS AMPLIFIED
FLOW OVER SRN CANADA AND THE NRN CONUS... THOUGH A SUBTLE HINT OF
TROFFING DEVELOPS OVER ERN NOAM BY AROUND DAY 7 NEXT TUE. NOT
SURPRISINGLY MEANINGFUL DIFFS REMAIN WITH INDIVIDUAL FEATURES
WITHIN THIS LOWER AMPLITUDE MEAN PATTERN. IN ADDITION SOLNS ARE
STILL NOT AS WELL CLUSTERED AS DESIRED WITH THE ULTIMATE PATH OF
ISAAC WHICH SHOULD WEAKEN TO TROPICAL DEPRESSION STATUS BY EARLY
DAY 3 FRI AND TRACK INTO THE MIDWEST DURING THE WEEKEND. CONSULT
LATEST NHC DISCUSSIONS/ADVISORIES FOR FURTHER INFO REGARDING ISAAC.

AS FOR INDIVIDUAL FEATURES... THE 00Z UKMET OR A COMPROMISE
BETWEEN THE GEFS MEAN/CANADIAN PROVIDES THE CLOSEST REPRESENTATION
OF THE 09Z NHC ADVISORY TRACK FOR ISAAC THRU DAY 4 SAT. THE UKMET
TRENDS SLOWER AFTER DAY 4. AFTER DAY 5 SUN EXPECT THE REMAINING
REFLECTION OF ISAAC TO PROGRESS GENERALLY EWD IN RESPONSE TO
SLIGHTLY GREATER INFLUENCE FROM THE MEAN WESTERLIES ALOFT.
MEANWHILE BY MID-PERIOD THE 06Z AND ESPECIALLY 00Z GFS RUNS MAY
BECOME TOO SLOW AND WRAPPED UP WITH THE SYSTEM EJECTING FROM WRN
CANADA... IN LIGHT OF THE LOW AMPLITUDE NATURE OF THE MEAN FLOW.
ON THE OTHER HAND THE 00Z GEFS MEAN APPEARS TOO FLAT WITH FLOW
DOWNSTREAM FROM THAT EJECTING WRN CANADA SYSTEM EARLY-MID PERIOD.
THE 00Z ECMWF MAY BE A LITTLE SHARP/AMPLIFIED WITH ITS SHRTWV OVER
NEW ENGLAND/CANADIAN MARITIMES EARLY SUN. ALSO THE 00Z ECMWF
BECOMES MORE AMPLIFIED THAN THE GUIDANCE AVERAGE OR CONTINUITY
WITH ITS TROF REACHING WRN CANADA AND THE NRN ROCKIES BY DAY 7 TUE.

OVERALL PREFER A BLEND OF 06Z GFS/00Z ECMWF/00Z ECMWF MEAN SOLNS
FOR DAYS 3-6 FRI-MON TO ACCOUNT FOR SPREAD WITH SYSTEMS AFFECTING
THE NRN CONUS AND SRN CANADA... WITH EACH INDIVIDUAL SOLN WEIGHTED
SUFFICIENTLY LIGHTLY TO DOWNPLAY ANY ISSUES DESCRIBED ABOVE. BY
DAY 7 TUE THE BLEND ADJUSTS TO A 70/30 RATIO OF THE 00Z ECMWF
MEAN/00Z GEFS MEAN AS THERE IS DECENT ENSEMBLE MEAN AGREEMENT IN
THE LARGE SCALE BY THAT TIME BUT THE GEFS MEAN BECOMES A LITTLE
MORE AMPLIFIED THAN OTHER GUIDANCE. THE INITIAL BLEND IS ADJUSTED
OVER THE E-CNTRL CONUS TO REFLECT THE 09Z NHC ADVISORY TRACK FOR
ISAAC.

RAUSCH

Member Since: Posts: Comments:
Quoting tkeith:
Yes maam :) The folks at the NHC are making me look a liilte smarter for staying and riding this one out. I still think it has time and will be a Cat 1 hurricane. The folks in the low lying areas are definately gonna get wet feet. But if Issac dont spawn alot of tornaos we should be ok :)

I hear ya. Stay safe :)
Member Since: Posts: Comments:
Quoting wxchaser97:

One would think so, I would love to hear the NHC reasoning behind this.

need that wind at the surface - that's where we all are...
Member Since: Posts: Comments:
Live coverage on WDSU in New Orleans. The on-air weatherman just said that rain amounts should not amount to much, and this will be a minimal tropical storm. Not sure where he is getting that information. Gonna be a lot of flooding in New Orleans.

Member Since: Posts: Comments:
Member Since: Posts: Comments:
What happened to the 81mph surface winds from the dropsonde?
REPORTS FROM AIR FORCE AND NOAA HURRICANE HUNTER AIRCRAFT INDICATE
THE CENTRAL PRESSURE HAS DECREASED TO ABOUT 976 MB SINCE THE
PREVIOUS ADVISORY...BUT IT HAS LEVELED OFF OVER THE PAST FEW HOURS.
THE MAXIMUM 850 MB FLIGHT-LEVEL WIND OBSERVED HAS BEEN 89 KT...
WHICH EQUATES TO A SURFACE WIND OF ABOUT 71 KT. HOWEVER...
BIAS-ADJUSTED SFMR SURFACE WINDS HAVE ONLY BEEN AROUND 60-62 KT...
WHICH CORRELATES WELL WITH DROPSONDE BOUNDARY LAYER-DERIVED SURFACE
WINDS. AS SUCH...THE INTENSITY OF ISAAC IS BEING MAINTAINED AT 60
KT...WHICH IS JUST BELOW HURRICANE STATUS.
Member Since: March 16, 2012 Posts: 127 Comments: 7940
Quoting TropicalAnalystwx13:
How are they going to ignore their own dropsonde.


They couldn't find any other instances of winds that fast. One reading could have been a localized gust or waterspout.
Member Since: Posts: Comments:
Quoting weatherh98:


reported for posting during school

You're the one texting me! Lol.
Member Since: July 6, 2010 Posts: 113 Comments: 31882
3580. Michfan
How did they not upgrade it? I'm not gonna go bashing them but this is really baffling. Recon data clearly showed it was a hurricane. /facepalm.
Member Since: Posts: Comments:
3579. Patrap
Hey..I gotz a good idea.

Maybe we can replace the NFL Replacement Referee's with Banned wunderblogger's ?

POLL ?
Member Since: Posts: Comments:
Quoting Thing342:
The discussion contradicts itself. SFMR SURFACE WINDS HAVE ONLY BEEN AROUND 60-62 KT...
WHICH CORRELATES WELL WITH DROPSONDE BOUNDARY LAYER-DERIVED SURFACE
WINDS. AS SUCH...THE INTENSITY OF ISAAC IS BEING MAINTAINED AT 60
KT...WHICH IS JUST BELOW HURRICANE STATUS.

Dropsondes say 80mph.


NHC: "Nooooo we want this to be the strongest tropical storm EVAR! Gotta break some kind of record on the 'I' storm, right!!"
Member Since: Posts: Comments:
They just had live recon flight crew on while in storm. They reported that the winds at 8000 feet have not made way to surface. They could not find hurricane force winds at surface.
Member Since: Posts: Comments:
Wellington on 8/28/12


Member Since: Posts: Comments:
Windy and light rain bands this morning; sun shining right now; TS warning discontinued east of Destin, so looks like my area dodged a bullet.

And I got a day off from work!

Stay safe, everyone to the west. Back to lurk mode unless things change dramatically.
Member Since: Posts: Comments:
Quoting TropicalAnalystwx13:
How are they going to ignore their own dropsonde.

The NHC just used the ignore button on the dropsonde. We all don't know/get it.
Member Since: March 16, 2012 Posts: 127 Comments: 7940
Quoting mynameispaul:


I have 125 people on ignore now. lol

Anyway, GFS says eye wall of Isaac will be coming near me in SW LA.


So you should be on post #21... And Isaac is still N of Cuba....
Member Since: Posts: Comments:
Quoting reedzone:


Me a troll?? Say that to the bloggers who enjoy my posts on here.. I have some haters but really a troll?? That's low man... I have a right to make predictions and maybe you haven't read my post one night saying I was WRONG in Isaac not busting the mid level ridge. I was WRONG in Isaac going up the East Coast. I was WRONG WRONG WRONG.. ok?


Don't always agree with you hardly ever and your avitar looks like a motorcycle cop (just joking), but you are not a troll you do not say stuff just to inflame people and you contribute greatly to the blog.
Member Since: Posts: Comments:
HH'S Said that's the first time they found winds that high. it will take time to work to the surface.
Member Since: Posts: Comments:
Quoting presslord:


that's not their job...I get your point...but that just ain't what they do...

I'm not saying that they should make every named storm a hurricane, but Isaac is pretty much one right now, don't see why they haven't upgraded him.
Member Since: Posts: Comments:
Your telling me there are no 74 mph winds ANYWHERE in that storm? Don't buy it.
Member Since: Posts: Comments:
Quoting TropicalAnalystwx13:
How are they going to ignore their own dropsonde.


reported for posting during school
Member Since: June 17, 2011 Posts: 11 Comments: 6468
Only 70mph, not bad, gonna be the rain and tidal influx that will cause the issues
Member Since: Posts: Comments:
I would be furious if I was on the plane that got the 81mph winds... You proved beyond any doubt that the system is a hurricane and they totally blow off your reading?
Member Since: Posts: Comments:
Quoting TropicalAnalystwx13:
How are they going to ignore their own dropsonde.


Oh no they hit the "Ignore User" button on their dropsonde!!
Member Since: Posts: Comments:
3563. texasjo
I was hoping Isaac would jog more to the west and come up through Texas, and up into the DFW area. We need the rain! Hoping for the best for those affected by this guy though.
Member Since: Posts: Comments:
Not going to be good!!
Member Since: Posts: Comments:
Quoting sunlinepr:


Dry Air joker?


Dry Air Choker*
Member Since: Posts: Comments:
3560. tkeith
Quoting hurricanehanna:


lol. Hey tkeith! How are ya? Got the preps ready?
Yes maam :) The folks at the NHC are making me look a liilte smarter for staying and riding this one out. I still think it has time and will be a Cat 1 hurricane. The folks in the low lying areas are definately gonna get wet feet. But if Issac dont spawn alot of tornaos we should be ok :)
Member Since: Posts: Comments:
3559. JeffM
Quoting farupnorth:



Isaac will be interesting in post analysis. Big mystery why he couldn't get stronger in ripe conditions in the GOM.

Yeah Destin Jeff was a really funny guy. He should be lifetime member in my book. Don´t know if he was banned or just got bored here.



Must be global warming. As they said, we're going to see more intense hurricanes...oh, wait.
Member Since: Posts: Comments:
Where is the "ignore user" button for the NHC??
Member Since: Posts: Comments:
Quoting Felix2007:
Can't they just upgrade it to hurricane just so that people will take it seriously???


that's not their job...I get your point...but that just ain't what they do...
Member Since: Posts: Comments:
How are they going to ignore their own dropsonde.
Member Since: July 6, 2010 Posts: 113 Comments: 31882
HH' on TWC pretty cool. :)
Member Since: Posts: Comments:
Quoting Tazmanian:
i got a new name for Isaac


am calling Isaac the joker


Dry Air joker?

Member Since: Posts: Comments:

Viewing: 3604 - 3554

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.