Isaac pounding Louisiana, Mississippi, Alabama, and Florida
Hurricane Isaac continues to lumber slowly northwestwards at 6 mph, as it pounds Louisiana, Mississippi, Alabama, and Florida's Panhandle with torrential rains, high winds, and a damaging storm surge. The eye was partially over water for most of the 15 hours after Isaac's official landfall at 7:45 pm EDT Tuesday night, but New Orleans radar shows the eye of the storm is now fully ashore near Houma. The radar echoes show some weakening on the west side of the eyewall, where dry air has infiltrated the storm. Wind shear remains light, and upper level outflow over Isaac is as impressive as we've seen so far, with a strong outflow channel to the north, and a respectable one to the south, as well. Infrared and visible satellite loops show a very large, symmetric, and well organized storm, and Isaac is going to be able to stay near Category 1 hurricane strength all day today. This will allow Isaac to drop rainfall amounts of 15 - 20" in some areas of Louisiana before the storm is over. A few rainfall totals from Isaac through 11 am EDT:
9.26" New Orleans Lakefront Airport
5.59" Belle Chasse, LA
5.21" Mobile, AL
3.65" Hattiesburg, MS
3.42" Gulfport, MS
2.81" Biloxi, MS
Figure 1. Morning radar reflectivity image from New Orleans.
A dangerous storm surge event underway
Isaac is bringing a large and dangerous storm surge to the coast from Central Louisiana to the Panhandle of Florida. Late this morning was high tide along much of the coast, and the highest water levels of Isaac are likely being experienced at many locations. At 11:30 am EDT, here were some of the storm surge values being recorded at NOAA tide gauges:
8.0' Waveland, MS
8.2' Shell Beach, LA
2.0' Pensacola, FL
4.6' Pascagoula, MS
3.4' Mobile, AL
The peak 11.06' storm surge at 1:30 am EDT this morning at Shell Beach, which is in Lake Borgne, 20 miles southeast of New Orleans, exceeded the 9.5' surge recorded there during Category 2 Hurricane Gustav of 2008. In general, the storm surge heights from Isaac have been more characteristic of a strong Category 2 hurricane, rather than the weak Category 1 hurricane one might suppose Isaac is, based on its top sustained winds of 75 - 80 mph. The Saffir-Simpson Scale for ranking hurricanes is only a crude measure of their potential impacts.
A storm surge estimated at 12' moved up the Mississippi in Plaquemines Parish near Port Sulphur, LA, near 8:30 pm EDT Tuesday, causing overtopping of the levees and flooding of homes in the mandatory evacuation areas behind the levees. These levees were not part of the $14.5 billion levee upgrade New Orleans got after Hurricane Katrina, and were not rated to Category 3 hurricane strength, like the levees protecting New Orleans are. The surge continued upriver, elevating the water levels 10' in New Orleans (103 miles upstream from the mouth of the Mississippi), 8' in Baton Rouge (228 miles upstream), and 1.4' at Knox Landing, an amazing 314 miles upstream. The river was 7' low due to the great 2012 U.S. drought, and I suspect the near-record low flow rate of the river allowed the storm surge to propagate so far upstream. The salt water from the storm surge will be slow to leave the river, due to the continued winds of Isaac keeping the surge going, plus the very low flow rates of the river. One benefit of the heavy rains of 10 - 20 inches expected to fall over Louisiana over the next two days will be to increase the flow rate of the Mississippi River, helping flush the salt water out of the river. The low flow rates of the Mississippi had allowed salt water to move upriver to just south of New Orleans over the past few weeks, threatening the drinking water supply of Plaquemines Parish.
Figure 2. Tide gauge data from Waveland, Mississippi. The green line shows the storm surge. The red line is the storm tide, the height of the water above Mean Sea Level (MSL.) The storm tide at Waveland currently (9') is 2' higher than that of Category 2 Hurricane Gustav of 2008. Image credit: NOAA Tides and Currents.
Tropical Storm Kirk in the Central Atlantic
Tropical Storm Kirk formed Tuesday night in the Central Atlantic. Kirk's formation at 03 UTC on August 29 puts 2012 in 4th place for earliest formation date of the season's 11th storm. Only 2005, 1995, and 1933 had an earlier formation date of the season's 11th storm. Kirk should stay well out to sea and not trouble any land areas.
Figure 3. Morning satellite image of Tropical Storm Kirk.
Invest 98L in the Eastern Atlantic
A tropical wave (Invest 98L) is about 750 miles west-southwest of the Cape Verde Islands, and is moving west to west-northwest at about 15 mph. In their 8 am EDT Tropical Weather Outlook, NHC gave 98L a 50% chance of developing by Friday morning. Several of the models develop 98L into a tropical depression by this weekend, but none of the reliable models foresee that 98L will be a threat to the Lesser Antilles. The storm may be a threat to Bermuda next week, but it is too early to say if it may threaten the U.S.
Jeff Masters
Reader Comments
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Someone's gotta do it when Keeper isn't around!
RMKS/1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE
WITHIN 100 NM EITHER SIDE OF A LINE FROM 13.6N 37.6W TO 15.1N 45.7W
WITHIN THE NEXT 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 20 TO 25 KNOTS. METSAT
IMAGERY AT 291830Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 13.5N 37.5W. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 20
KNOTS.
2. REMARKS: CURRENT MODEL GUIDANCE IS DEPICTING INTENSEIFICATION OF
A TROPICAL WAVE LOCATED ABOUT 700 MILES WEST-SOUTHWEST OF THE CAPE VERDE
ISLANDS. AT 291830Z, VISIBLE SATELLITE IMAGERY INDICATED AN AREA
OF MODERATE CONVECTION THAT HAS PERSISTED OVER THE LAST 24 HOURS.
WARM SEA SURFACE TEMPERATURES OF 80 TO 82 DEGREES FAHRENHEIT IN
CONJUNCTION WITH A FAVORABLE UPPER AIR ENVIRONMENT MAY ENHANCE
DEVELOPMENT OF THIS SYSTEM INTO A TROPICAL CYCLONE.
3. THIS ALERT WILL BE UPGRADED TO WARNING OR REISSUED AS REQUIRED
BY 301900Z.//
This morning, the NHC re-evaluated&altered their ATCF coordinates such that Isaac's center missed the Mississippi crossing.
That re-evaluation also led to a landfall ~8hours later directly over PortFourchon (immediately west of LA49) instead of the ~4miles(6kilometres) to the ENEast before their correction.
HUM-Houma :: LA49-PortFourchon :: KGNI-GrandIsle :: LS12-Buras :: 17LA-Venice :: 5LA6-SouthwestPass,MississippiRiver
Also a link to an older previous mapping for continuity, cuz I somehow failed to record any newer one.
These guys get paid for their opinions.
Link
I ultimately agree with you, but right now is a pretty poor time to get into broad political debates, IMO. They're unlikely to convince anyone of anything, they get really pissy, and there are still a whole lot of folks really struggling with this thing. Specific things -- like politics around current floodwaters or response or whatever -- I can see the point to a degree, but I don't see much point right now to sprawling arguments about the national political situation or elections or how anybody is responding outside of the local governments that are responsible for public safety at the moment.
And I say all of that as somebody who pays a lot of attention to politics.
Those who would like to have those discussions now can probably find any number of political blogs discussing it as I type.
This space should stay focused on what's going on with the still-developing and destructive situation unfolding, IMO, with some additional glances at the newer storms that might cause more destruction soon.
My two cents.
The statistics I stated are for return period for Hurricanes and can be found on the NHC website. By prone I meant prone more frequently to another hit or near pass, not by how dangerous a tropical cyclone would be for one area or another. Sorry for the confusion. I am well aware the Gulf coast is quite a bit more prone to storm surge damage than say the East coast of Florida is.
Good answer... however even in winter this blog shuld b free of politics... not just wehn Isaac is kicking... he wuld b dissapointed in us :p
Just like what TS Lee did to us this time last year, ignited all those fires in Bastrop and Steiner Ranch.
and we would be tied with the 2005 hurricane season in terms of named storms at the end of August, of course Maria formed on September 1st
Oh i know. Been around long enough to know your sarcasm. So far it looks like it will go just north of the antilles. May dodge this one.
I very largely agree, unless there is a really specific political situation relating directly to tropical weather etc.
But I _care less_ at other times. Right now, it seems spectacularly silly.
Yes it has trended a bit to the west. Now it has leslie crossing 60W at around 20.5N... which is not good if the trend continues at 00z. Remember 2010 EARL...
It's way too early to tell whether 98L will threaten major land areas. Most models move the subtropical ridge east and bring it into the weakness NE of the islands, but this can change over the next few days.
By the way, a terrible tragedy in Braithwaite last night and this morning. Many of these residents lost everything in 2005 or 2008, and it has happened again. My best wishes go out to all the families who have suffered this beast of a storm. And there is still much in the way of heavy rainfall and strong winds to come tonight in SE-ern LA.
So you missed the Isaac fun (sorta)...
Anyways, glad to see you in the blog. And I agree that OBX and south Florida are usually good hurricane or storm targets. Although I have no data to back it up...
I thought this was a Weather blog???
Which means that we arent going to exactly get Michael by September 1st. With Leslie only being in the Western portion of the Central Islands and Kirk recurving... We will probably not see Michael until Leslie reaches the Turks(If Forecast Verifies).
It is... he was posting tropical weather model predictions
This was posted here yesterday
3308. depalma13 2:31 PM GMT on August 28, 2012 +1
Quoting WeatherfanPR:
My thoughts and prayers with all in the path of Isaac. I hope the levees doesn't break this time.
If the levees break, than New Orleans should be abandoned forever. This is a Tropical Storm/barely Cat 1 Hurricane. It is not a life or death situation. It's time for everyone to stop panicing because of a little water and and wind.
I would like to know what are the thoughts of depalma13 right now.
Yea..what's great are the thieves that carry old lawnmowers and replace them with the generators they rip off so you don't wake up during the night...
More like a recent graduate of the school systems that no longer teach geography and history.
Stop being a political hack with those kind of broadbrushes. Thanks.
Yes sir Mr. blog cop!
Dude that was uncalled for. Why tea party member? You think they go around wishing for disasters to affect fellow citizens? Not even most liberals would think that way. Please practice some critical thinking next time before making a comment or you will fall into the same category of the person who made that hateful comment in the first place. You see I am an active Tea Party Member or yeah and I am not an angry white male I'm a disgusted with the government Hispanic male. But I have been praying for New Orleans and if I need to shed some money to help I sure will as well. Don't judge.
It would likely be worse than that. There was a time went Isaac was forecast to come right up the center of the state and my first thoughts were of its impact on the lake. Much like, I am sure, those in Nawlin's worry about Lake Pontchartrain for the same reasons. There are a lot of similarities between the two lakes, how they are contained, and what nature does to defeat the aforementioned containment.
Okeechobee Lake Okeechobee Lake levels are not managed in the best interests of the citizens, it is managed from Orlando south by agriculture.. read big sugar.
E46 makes a great point about the vulnerability of the Hoover Dike. Had Wilma crossed the state at 8 miles per hour instead of the 30 mph it did, the dike would have breached. It was very close.
Maybe you would shed some $$ to help, however, what government program would you cut to offset the cost? That is the face of the tea party today & that is what I'm trying to point out.
Why don't you go to a political blog to point it out. This is not the place.
lol..it's Buffoon, you baffoon. Political comments were being made ways before mine. Just responding
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