Mississippi Gov. Haley Barbour said the combination of heavy rains from the violent storms that have hit Mississippi and high water levels on the Mississippi River could produce a flood that will be “monumental” in the annals of his state.

Speaking at a press briefing at the Capitol Building this afternoon, Barbour said as many as 900,000 acres of farmland, much of it in the South Delta, could go under water as the Mississippi and area streams continue to rise.

Barbour urged residents in areas that could be impacted by the flooding to begin preparing to evacuate now and to not wait for the projected crest of the floodwaters on May 18 “because the roads in and out of the areas could be flooded before then.

“People need to take this very seriously,” he said. “It will be much easier for people to remove themselves and their personal belongings now than it will be to mount a rescue operation later,” he said. “That’s particularly true for the elderly.” (He noted studies have shown that a number of elderly persons died during rescue operations following Hurricane Katrina.)

Updating reporters on the latest flood projections, Barbour said the Mississippi River at Vicksburg could reach 57.5 feet on May 20. The level would be higher than in the 1927 flood, the catastrophic natural disaster that prompted most of the flood control efforts undertaken in the lower Mississippi River Valley in the last 80 years.

He said the state has created several task forces that are working to evacuate residents from hospitals, nursing homes and other care facilities in areas that at risk of flooding.

Although exact levels could depend on the amount of rainfall over the next few days, Barbour said much of the area in the South Delta between the Yazoo and Mississippi Rivers and south of Mississippi Highway 14 could flood.

“We are preparing a map of the areas we expect to flood, but we are not ready to release that to the public yet,” he said.

An updated forecast released this morning indicates the flooding situation remains, well, fluid.

Although the Mississippi River Crest Forecast, provided by the Corps of Engineers, has not changed, the crest dates have shifted.

“Crest stages remain the same as the following May 2 projections: 57.5 feet at Vicksburg on May 20, 64.5 feet at Greenville on May 17, 53.5 feet at Arkansas City on May 16, 56 feet at Helena, Ark., on May 12 and 48 feet at Memphis on May 11. The current Mississippi River stages as of 10:30 a.m. today are 46.76 feet at Vicksburg, 54.65 feet at Greenville, 43.71 feet at Arkansas City, 51.66 feet at Helena and 44.13 feet at Memphis, all of which are above flood stage.

“At this projected stage, the Yazoo River Backwater Levee will be overtopped by 1.3 feet in some areas,” the report said.  “The Mississippi Levee Board is in the process of hardening portions of the levee projected to overtop to provide added strength in these stressed areas.  The overflow is projected to add an additional 0.5 feet of water to the Yazoo River Backwater Area.”