Weather Underground Forecast for Sunday, May 26, 2013.

Expect more severe showers and thunderstorms to develop over the High Plains again on Sunday, stretching into the Central Plains and Mississippi River Valley. A low pressure system continues spinning over the region as is slowly moves off the Rockies and into the Plains. Flow around this system will continue to create a warm front that stretches from eastern Montana through Nebraska and into the Mid-Mississippi River Valley. The heaviest rainfall and strongest storms are most likely to develop from southeastern Montana and northeastern Wyoming through northeastern Nebraska, moving into western Iowa Sunday night. These areas may see large hail and isolated tornadoes. Another region of heavy rainfall with scattered thunderstorms will develop just east of this system, starting the day over Iowa and Illinois, moving eastward into the Midwest and Lower Ohio River Valley by Sunday night.

In the Southern Plains, heavy rainfall will continue winding down on Sunday for Texas. However, the combination of onshore flow from the Gulf of Mexico and a wave of low pressure will continue triggering rain showers from southern Texas through Oklahoma. This will allow for flooding to remain a concern, especially for the San Antonio area.

Out West, a trough of low pressure moves over the Pacific Northwest, bringing scattered showers to Washington and Oregon on Sunday. Some moisture from this system will reach into northern California and northern Nevada, bringing a few light rain showers Sunday afternoon into Monday.