Weather Underground midday recap for Sunday, July 21, 2013.
Areas of active weather continued across the nation on Sunday as a frontal boundary extended across the Mid-Atlantic States through the Central U.S. The front reached across the Central Plains and into the Northern High Plains during the afternoon. A wave of low pressure along the boundary in the Northern High Plains began to lift northeastward toward Canada, allowing the western half of the boundary to begin to lift northward as a warm front. Moisture streaming inland from the Gulf of Mexico and energy near this system stirred up scattered showers and thunderstorms from the Gulf Coast northward through the Eastern Valleys and the Mid-Atlantic into the Upper Great Lakes. As the wave of low pressure began to lift northeastward, severe storms became possible in parts of the Northern Plains. The Storm Prediction Center issued a slight risk of severe thunderstorms development across parts of central and eastern North Dakota into northwest Minnesota through the evening hours.
Meanwhile, out West, showers and thunderstorms developed over parts of the Southwest and southern California. Monsoonal moisture and daytime heating also aided in showers and thunderstorms over parts of Southern Rockies on Sunday.
Temperatures in the Lower 48 states Sunday have ranged from a morning low of 32 degrees at Stanley, Idaho to a midday high of 99 degrees at China Lake, Calif.