By Wendell Marsh

WASHINGTON (Reuters) - Severe weather including possible tornadoes, damaging winds, rain and hail were expected on Sunday from Texas to Wisconsin, forecasters said.

The severe weather continued for a second day after a large tornado, part of a volatile storm system caused by a springtime warm weather front, left significant damage in Iowa.

"As some residents of the Plains, Ohio Valley and Southeast found out on Saturday, the atmosphere is ripe for severe weather, including tornadoes," said Accuweather.com senior meteorologist Alex Sosnowski.

"This could prove to be a memorable event for the Heartland," he said.

Sosnowski warned that the atmospheric conditions could bring risks of loss of life over the next few days as the slow-moving system crawls across the eastern half of the United States until it reaches the Northeast on Monday night.

According to the Weather Channel, the cities in the peak tornado threat zone were Iowa City, Waterloo, and Dubuque in Iowa; Moline, Illinois; Rochester, Minnesota; and La Crosse and Madison in Wisconsin.

Iowa governor Terry Branstad was traveling around the state by helicopter on Sunday morning to survey damage from Saturday's storm.

The peak U.S. tornado season lasts from March until early July, the period when warm, humid air often has to thrust upward against cool, dry air.

This weekend's storm is being caused by a front of warm air surging northward across the country's midsection, bringing very warm temperatures with some areas posting possible record highs.

Another day of record-breaking heat into the 90s was forecast for Nashville and much of Tennessee. This after Saturday's temperatures hit an all-time record high for the date of 91 degrees in Nashville.

It also was the earliest date on record that Nashville had hit the 90-degree mark, according to Bobby Boyd, meteorologist for the National Weather Service in Nashville.

In the northern plains, the Red River on Sunday had started a gradual decline in the Fargo-Moorhead area of North Dakota after reaching a preliminary crest at the fourth-highest level on record with rain storms lighter than expected.

"Fortunately, most of the precipitation is coming in as pretty light," said Greg Gust, warning coordination meteorologist for the National Weather Service.

The Red River rose rapidly last week and appeared ready to threaten the 40.84 foot record crest at Fargo of two years ago. However, the rise had slowed considerably by Saturday.

The weather service said Sunday the river had reached a preliminary crest in the Fargo-Moorhead area at 38.75 feet Saturday night with prolonged flooding expected.

Wild Fires were also a threat from Texas and New Mexico to northwestern Missouri, the National Weather Service said.

(Additional reporting by Tim Ghianni in Nashville, Kay Henderson in Des Moines, and David Bailey in Minneapolis; Editing by Jerry Norton)