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Posted at 09:25 PM ET, 08/28/2012

Hurricane Isaac battering southeast Louisiana, northern Gulf Coast


Hurricane Isaac at 9:45 p.m. ET (NOAA)
10:30 p.m. (last update): Relentless bands of torrential rain and powerful wind will continue to pound southeast Louisiana - including New Orleans and coastal Mississippi and Alabama throughout the night and into tomorrow. And storm surge will continue to push water onshore, with levels cresting through at least one more high tide cycle. A tornado risk exists as well.

The long duration of this event means the impacts may not be immediately apparent but will manifest themselves gradually as rainfall totals mount and increase flooding and winds continuously weaken trees and vulnerable structures. The storm appears as strong and healthy as it has been and there are no signs of imminent weakening.

We will resume our coverage tomorrow morning - as this storm will remain a force through the day, at least. Here are some links to follow the progress of Isaac overnight:

New Orleans radar

Southeast Louisiana current conditions

Storm surge levels

National Hurricane Center

10:00 p.m.: Winds at New Orleans International and Lakefront Airport are gusting to 62 and 67 mph. Over 60,000 customers are without power in the Crescent City and 190,000 in Louisiana.

9:50 p.m.: Location very close to Grand Isle, Louisiana measured sustained wind of 67 mph with gust to 85 mph at 8:12 p.m. ET.

9:45 p.m.: Rainfall so far in SE Louisiana around 1-3”, but this is just the beginning. 8-12”, locally 20” possible by Thursday.

9:30 p.m.: The Weather Channel reports the surge up the Mississippi River is testing the levees in Plaquemines Parish on its west bank. Fortunately, mandatory evacuations were issued in that area of extreme southeast Louisiana well south of New Orleans.

9:25 p.m.: This storm is just crawling, meaning New Orleans and southeast Louisiana will get slammed by wind and rain for at least another full day. The storm is likely to make a second landfall near Grand Isle later tonight. One adjective for this storm you’ll keep hearing: relentless.


High resolution satellite image of hurricane Isaac earlier today. (NASA)
Overview: Conditions are deteriorating along the northern Gulf Coast as Hurricane Isaac - packing sustained winds to 80 mph - draws closer. Its forward speed has slowed, meaning the landfall process will be prolonged through much of the night into Wednesday.

The storm’s deceleration is bad for two reasons: 1) it keeps the storm over warm waters, increasing the window for additional intensification 2) it adds to the amount of time for the coast to be raked by powerful winds to tropical storm and hurricane force and inundated by storm surge (up to 6-12 feet in southeast Louisiana and Mississippi) and torrential rain (8 to 12 inches, with isolated totals to 20”). The maximum storm surge will occur at high tide which, unfortunately, may occur two or three times before the storm pushes far enough inland.

Keep reading for earlier updates...


Radar view of hurricane Isaac at 8:45 p.m. Notice extreme band edging into New Orleans.
9:15 p.m.: Storm surge has reached 10 feet at Shell Beach, Louisiana.

9:00 p.m.: Winds gusting to 56 to 60 mph at airports in New Orleans.

8:55 p.m.: Power outages are quickly mounting in New Orleans. Up over 55,000 now. Almost 130,000 outages in Louisiana.

8:40 p.m.: Landfalling hurricanes carry with them a tornado risk. A tornado watch covers southeast Louisiana, southern Mississipi and Alabama and the western panhandle of Florida through 7 a.m. CT Wednesday morning.

8:35 p.m.: Band coming into New Orleans now could produce 70 mph wind gusts. This is similar to June 29 derecho in DC, but with heavier rain and of longer duration potentially.

8:25 p.m.: Isaac’s pressure is still dropping. Although it has “officially” made landfall, it remains over tidal waters where it can sustain itself and even grow. Its pressure is down to 967 mb. This morning it was 978 mb.

8:20 p.m.:: Eric Fisher of the Weather Channel says gusts at the New Orleans airports just reached 61-63 mph.

8:15 p.m.: New Orleans International Airport reported a wind gusts of 55 mph at 8:00 p.m. and the Lakefront Airport gusted to 62 mph. CNN reports over 100,000 residents without power in Louisiana.

8:10 p.m.: Storm surge has reached 8.8 feet at Shell Beach in Louisiana and 5.5 feet in Waveland, Mississippi.

8:05 p.m.: The National Hurricane Center says Isaac officially made landfall at 6:45 p.m. CT at mouth of Mississippi River (as I suggested was occurring in update below).

8:00 p.m.: Conditions in New Orleans proper will deteriorate rapidly in next 30 minutes as a super-intense band in Isaac’s core envelops the area. Dangerous wind gusts and torrential rain capable of producing flash flooding are possible. Anticipate power outage numbers will rapidly increase as this band moves in.


Radar view of hurricane Isaac at 6:45 p.m. ET (Radarscope)
6:55 p.m.: The landfall of hurricane Isaac looks like it’s about to occur (or is occurring) at the mouth of the Mississippi river. Radar imagery (to the right) shows the eye over the southernmost tip of the Louisiana delta. Having said that, the storm may well remain primarily over Gulf waters for several hours before truly coming inland. So the storm could maintain strength or even intensify a bit in that window.

Isaac currently has maximum winds of 80 mph and a central pressure of 970 mb.

(Note this live blog will take a short intermission and resume around 7:30-8 p.m.)

6:45 p.m.: Dramatic image of Isaac’s waves coming ashore at Navarre Beach in Florida. Another image of the surge taking out the parking lot at the casino in Waveland, Mississippi.

6:30 p.m.: 40,000+ customers are already without power around New Orleans (based on Entergy website, numbers seem to be fluctuating).

6:15 p.m.: Waters have risen 1-2 feet in last several hours in Lake Pontchartrain at West End: Graph. At West Pointe à la Hache along the Mississippi, the water has risen more than 7 feet today.

6:10 p.m.: At the Apache Corp oil platform (279 feet above water level) offshore southeast Louisiana, the wind gusted to 105 mph at 5:35 p.m.

6:00 p.m.: It’s starting to blow very hard in the Big East. 6 p.m. (5 p.m. CT) gust to 53 mph at New Orleans Lakefront Airport. At 5 p.m., it gusted to 67 mph in Boothville near mouth of Mississippi.

5:55 p.m.: The storm surge at Shell Beach, Louisiana has reached 8 feet and continues to rise.

5:50 p.m.: Something to monitor - some track models want to keep the center of Isaac offshore through the night and not move it ashore until sometime during the day Wednesday a bit further west than current projections.

Related Link: Afternoon live blog

Useful Links:

Washington Post Interactive tracking map

Interactive map for tracking tides/storm surges

Webcams along northern Gulf Coast

Isaac radar loops

By  |  09:25 PM ET, 08/28/2012

Categories:  Latest, Tropical Weather

 
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