Weather Underground Forecast for Tuesday, March 20, 2012. The slow moving cold front that kicked up active weather over the Plains on Monday will advance eastward through the Mississippi Valleys on Tuesday. Moisture streaming in from the Gulf of Mexico will spread northward across the nation¼'s mid-section, aiding in the development of more rain and thunderstorms from parts of the Southern Plains and Lower Mississippi Valley through the Upper Mississippi Valley. Stronger storms in southeastern Texas, the Arkansas-Louisiana-Texas region, and the Ozarks may turn severe with tornadoes, large hail and strong to damaging wind gusts. In addition to chances of severe weather development, expect possible flooding to continue in the eastern regions of the Central and Southern Plains and the Lower and Mid-Mississippi Valley due to the slow moving nature of this disturbance. Thunderstorms activity from this front is expected to advance into the Upper Great Lakes into Wednesday. Meanwhile, temperatures ahead of this front will remain quite warm on Tuesday as daytime highs are expected to remain well above normal. For the West, rain, heavy at times, and high elevation snow will continue in the Pacific Northwest on Tuesday. Expect precipitation to spread into parts of northern California, the Northern Intermountain West and the Northern Rockies. Temperatures in the Lower 48 states Monday have ranged from a morning low of 7 degrees at Leadville, Colo. to a high of 90 degrees at Laredo, Texas