More than half a million customers remain without power in Louisiana from Isaac, while rain spreads northward across Arkansas and Missouri.
According to Entergy, 526,326 people were still in the dark in Louisiana as of 6:30 a.m. EDT Friday.
Meanwhile, Louisiana and Mississippi are still reeling from Isaac's deluge with multiple areas recovering from dam breaks or controlled releases of dams to prevent a disaster.
With fears of the breaching of the Percy Quin Dam south of McComb, Miss., due to being stressed by Isaac's heavy rainfall, evacuations were forced for Tangipahoa Parish in Louisiana on Thursday.
The Associated Press reports that a controlled breach of the Percy Quin Dam began late Thursday afternoon to prevent a failure of the dam that could send flood waters rushing south into communities such as Kentwood, La.
As a rainstorm, Isaac is now dousing Arkansas and Missouri with heavy rain today. While rainfall totals will not be as hefty as they were across Louisiana and Mississippi with Isaac's slow crawl, there could be localized flooding.
Rainfall amounts of 4-8 inches are possible across eastern Arkansas and eastern Missouri. That corridor of the heaviest rain will spread into southern portions of Illinois and Indiana.
Despite Isaac's weakening to a tropical rainstorm, the threat continues for locally severe storms that may spawn a tornado. The threat lies from Mississippi to southeastern Missouri.
4:35 p.m. EDT Thursday: Isaac has officially been downgraded to a tropical rainstorm. It continues to drench southeastern Louisiana and Mississippi with flooding rain and dangerous storm surge.
1:11 p.m. EDT Thursday: Fears of the failure of the Percy Quin Dam in Mississippi have forced evacuations from Kentwood to Robert, La., in Tangipahoa Parish. The Tangipahoa River runs under I-55, so if a breach occurs, floodwaters may rush over the interstate, according to AccuWeather Expert Senior Meteorologist Jim Andrews.
Google Earth image of the dam at risk for breaking south of McComb, Miss.
11:28 a.m. EDT Thursday: Thunderstorms associated with Isaac that are deluging eastern Mississippi and western Alabama are capable of spawning more tornadoes. So far today, there have been three tornado reports in Mississippi. One tornado was spotted on Market Street in Pascagoula, Miss., while another touched down and downed trees near Meridian, Miss. The third tornado damaged a home near Crandall, Miss.
9:48 a.m. EDT Thursday: Update to previous water level rise at Osyka if the Percy Quinn Park dam breaks: "Looks like if the dam breaks, there would be about a 2-3 ft rise at Osyka," tweeted the New Orleans NWS office.
9:30 a.m. EDT Thursday: Potential dam break at Percy Quinn Park on the Tangipahoa River, south of McComb, Miss. Severe flooding is expected downstream along the Tangipahoa River from west of McComb Airport and Magnolia to Osyka. Water levels are expected to rise near 8 feet below the dam to 6 feet at Osyka.
8:30 a.m. EDT Thursday: A fatality due to a tree falling on a car in Picayune, Miss., is being reported by the NWS.
7:45 a.m. EDT Thursday: Max sustained winds with Isaac are now 45 mph. Heaviest rain total so far (unofficial) 23.31 inches in Gretna, La.
5:40 a.m. EDT Thursday: Flash Flood Emergency issued for Slidell, La. Slidell Fire Department officials reported a surge of water pouring into the central and southern portions of the city from a breach in the railroad tracks along Highway 11.
5:29 a.m. EDT Thursday: According to Entergy, 682,648 customers are without power in Louisiana and 49,918 customers in Mississippi.
4:15 a.m. EDT Thursday: Storm total rainfall at the Remote Automatic Weather Stations (RAWS) in Marion County, Miss., has reported 13.06 inches and counting of rainfall.
3:55 a.m. EDT Thursday: Record rain of 7.86 inches fell on New Orleans Int'l Airport Wednesday from Isaac. This broke the previous record of 4.50 inches set in 2005 with Katrina.
3:00 a.m. EDT Thursday: National Weather Service in Jackson, Miss., said there are now 30 roads closed due to flooding across Lamar County.
2:05 a.m. EDT Thursday: Marion County, Miss., Sheriffs Office reported a foot of water flowing across Mississippi Highway 43 near Joe Magee Road.
1:55 a.m. EDT Thursday: Isaac continues to slowly weaken as it drifts inland across Louisiana. Maximum sustained winds have dropped to 50 mph; however, flooding rainfall and damaging wind gusts continue to batter much of Louisiana, southern Mississippi and southwestern Alabama.
12:00 a.m. EDT Thursday: President Obama declared the states of Louisiana and Mississippi as major disaster areas.
For older Isaac reports, click here.
Thunderstorms once again turn severe across the Ohio Valley and into the mid-Atlantic through Sunday night.
More summer-like conditions will return to the Boston area for a brief time before a front pushes through the region during the latter part of the weekend.
Tropical Rainstorm Matmo will bring heavy rain to Japan this weekend.
Dry weather across the western half of the country continues to spark wildfires, especially across Utah and the Northwest.
AccuWeather.com meteorologists are monitoring an area of thunderstorms east of the Philippines for potential tropical development.
Rounds of showers and thunderstorms will move through the Pittsburgh area this weekend with the threat of severe weather.
New Holstein, WI (2007)
Strong thunderstorm winds blew two airplanes into one another at the local airport.
New York/MA (1819)
Two simultaneous cloudbursts, 45 miles apart; A bucket survey claimed 15" of rain fell at Catskill, NY. Highways were completely washed out. One washout started west of the old Albany Post Road and spread eastward across the road until it was 190 feet wide and 80 feet deep in a distance of 160 paces. At Westfield Valley, "suddenly the windows of heaven seemed to have been opened and the rain fell in such torrents that in less than 5 hours, Westfield River rose at least 20 feet above its usual height at low water. The river overflowed its banks with great rapidity and violence, sweeping away every bridge, fence and building which opposed its current."
Pittsburgh, PA (1872)
Cloudburst of 30 minutes followed by a flash flood. Over 133 people drowned on the north side of Butcher Run and Wood's Run.