A low pressure system in the Mid-Mississippi Valley will gradually move eastward Wednesday and Thursday.
As a result, widely scattered showers and thunderstorms are expected from the Upper and Mid-Mississippi Valley to the Great Lakes and Ohio Valley on Wednesday, reaching the Mid-Atlantic and Southeast on Thursday. In particular, a slight risk of severe thunderstorms is expected from the Lower Ohio and Tennessee valleys into eastern Arkansas, including Nashville, Memphis and Little Rock areas. The main threat will be damaging winds, hail and isolated tornadoes.
Meanwhile, a beautiful day is in store for the East Coast on Wednesday as a transitional high pressure moves through before the next system hits Thursday and Friday.
Out West, a front will develop over the northern Rockies and move through the northern Plains and central Rockies, accompanying light rain and thunderstorms. Farther south, fire conditions will ease up a bit in the Four Corners as winds become weaker. Unhealthy air will primarily be confined in northeastern New Mexico. However, winds are expected to pick up again Thursday with humidity dropping to 5 to 15 percent, leading to possible fire weather. Otherwise, a ridge of high pressure will build over much of the West Coast, bringing warmer and sunny weather at least into Thursday and Friday.
Temperatures in the Lower 48 states Tuesday ranged from a morning low of 28 degrees at Stanley, Idaho, to a high of 108 degrees at Pecos, Texas.