It’s the continued rain that’s pushing the crest forecast for the Mississippi River at Vicksburg up and up, now to 50.5 feet a week from today.

That’s up almost another foot from the previous forecast and nearly within a foot of the 1973 crest.

“Northwest Arkansas has received up to 7 inches of rain in the past 48 hours, and the Memphis area, up to 4 inches,” said National Weather Service Senior Hydrologist Marty Pope. “If you look back on the past 30 days, areas in the Ohio and Mississippi River valleys have gotten 15 to 20-plus inches of rain. In some places, that’s about half of normal yearly rainfall.”

This morning at 7, the river was flowing at 49.1 past the Vicksburg gauge, up 0.2 feet in 24 hours and 6.1 feet above the official flood stage.

The new forecast means the river has another 1.4 feet to go in the next six days. It also means more farmland and homes in Warren County will flood and will stay flooded longer.

If the new forecast holds, the flood of 2008 will be the worst since 1973, when the river reached 51.6 feet at the city. However, flooding could be less severe this year compared to that historic flood for a number of reasons, said Robert Simrall, chief of water control for the U.S. Army Corps of Engineers Vicksburg Division.

“The tributary impacts aren’t as problematic this year. In ’73, we received over 12 inches of rain locally in the month of the flood, which had all the tributaries to the river really backed up. During this flood, we haven’t had hardly any rain locally, it’s all coming from widespread rainfall in areas far north of Vicksburg,” Simrall said.

Additionally, the dozens of oxbow lakes north of Vicksburg along the river are not topped out yet, as they had been in 1973 due to rainfall, said Simrall.

“All of those lakes were going over the spillway in ’73, and right now there’s still storage space in many of those reservoirs,” he said.

The heightened forecast does mean the National Weather Service is changing its classification of the flood effects in Vicksburg and Warren County from moderate to major flooding, said Pope.

“Right now, there’s already a lot of major impacts for some people, but when the river stages go above 50 feet those major impacts become much more widespread,” explained Pope.

The situation for farmers is going from bad to worse, said Warren County Extension Service Director John Coccaro.

“As for the amount of farmland affected right now, I’ve heard about a quarter of a million acres are flooded from Vicksburg on north into Yazoo County,” he said. “This is getting very comparable to the ’73 flood, and by the time they get through adjusting the crest level we may very well be at that level or beyond.”

Fields with standing wheat crops that have been inundated with water have virtually no chance of producing any harvest, Coccarro said. Farmers waiting for fields to dry out so they can plant summer crops such as cotton, corn and soybeans have already missed ideal planting times and will most likely not see fields ready for planting for at least a month.

“It’s a real dilemma, and the farmers really don’t know what to do,” said Coccaro.

Following the 1973 crest, Pope said it took more than a month for the river to reside below flood stage.

“It’s going to take a long time for the river to come down this time, too,” he said. “I wouldn’t say it will take quite as long, but at least three weeks after the crest if we keep on getting rainfall over the river basin.”

The longer the river stays high, the longer the gates of Steele Bayou Control Structure will have to remain closed.

The structure, near Mississippi 465, is the drainage point for roughly 4,000 square miles of timber and farmland enclosed by levees and known as the Yazoo backwater area. The structure’s gates have been closed since March 13 to keep out Mississippi River water, but the bathtub effect, including up to 4 inches of rain last week, is taking its toll.

With normal rainfall through Sunday, the Army Corps of Engineers Vicksburg District expects floodwaters on the landside of the Steele Bayou Structure to top out at 94 feet on May 10, said Simrall. With no rain over the Yazoo backwater area, the landside is forecast to top out at 91.5 feet on Tuesday.

With normal rainfall, the flood inside the Steele Bayou Structure would be one of the worst in recent history. The highest recorded water stage on the landside of the structure came in 1979, when a crest of 96.5 feet was recorded. The only other time a recording over 94 feet occurred in the Yazoo backwater area was in 1983, when the water stage crested at 95.8 feet.

More farmland south of Vicksburg was also being inundated daily. Tuesday, most of the 1,300-person work force of LeTourneau Technologies was laid off without pay. The company makes offshore oil rigs, but it’s bankside fabrication area has become an island.

Severe restrictions continue on river traffic. The high and swirling currents have caused at least five mishaps. Four tows have hit the U.S. 80 bridge and one broke up about 15 miles upstream.

Mississippi RiverCREST FORECAST50.5 feet on April 18TODAY’S STAGE:49.1 feetROSE:0.2 footFLOOD STAGE:43 feetPast high readingsGaugeYear51.6197349.3198349.1199748.0197547.9197947.0199546.0199445.8198445.4200244.5200544.4199144.2197443.6199643.6199343.6199843.0200342.8199042.2198541.7199941.0198940.5198039.9200139.8197839.7198239.3200437.8200736.5198736.4198835.1198634.4199232.5198132.4197632.4197731.6200629.32000Tracking the forecastsThe forecasts by the National Weather Service for the Mississippi River’s crest at Vicksburg have been altered eight times this year.March 2246 on April 5March 2446 on April 4March 2645.5 on April 4March 3146.5 on April 5April 146.5 on April 6April 348 on April 8April 449 on April 13April 949.3 on April 13April 1050.5 on April 18