In the West, a cold front crossing the northern Intermountain region is interacting with the Southwestern monsoon circulation, helping to generate scattered showers. However, rain has largely bypassed the Northwest, where small grain harvest and wildfire containment efforts continue.
On the Plains, hot weather across the northern half of the region contrasts with relatively cool conditions in Oklahoma and Texas. In Montana, isolated showers are causing minor small grain harvest delays.
In the Corn Belt, warm conditions are returning, following an extended period of cool weather. For example, Des Moines, Iowa, last experienced an above-normal daily average temperature on August 8. In addition, there is an elevated wildfire danger today in the middle Missouri Valley due to very warm, dry, breezy conditions.
In the South, showery weather continues from the central Gulf Coast region to the southern Atlantic coastal plain, maintaining generally favorable conditions for pastures and immature summer crops. Extremely dry conditions persist, however, in the Mid-South, including much of Arkansas and the Bootheel of Missouri.
Outlook: During second half of the week, a surge of moisture associated with the monsoon circulation will interact with a pair of cold fronts crossing the Plains and Midwest. Five-day rainfall totals could reach 1 to 3 inches from the Four Corners States into the middle Mississippi Valley. Meanwhile, mostly dry weather in the Mid-Atlantic and Northwestern States will contrast with possible 1- to 2-inch rainfall totals in the upper Midwest and along the Gulf and southern Atlantic Coasts. By early next week, Tropical Storm or Hurricane Isaac will likely be in the vicinity of Florida’s peninsula, threatening the southern Atlantic States with the possibility of high winds, heavy rain, and a storm surge. Isaac’s strength upon reaching the southeastern U.S. will be partly dependent on prior interactions with the Greater Antilles, including Hispaniola and Cuba. The NWS 6- to 10-day outlook for August 27-31 calls for near- to above-normal temperatures nationwide, except for cooler-than-normal conditions in coastal California and the Pacific Northwest. Meanwhile, near- to below normal rainfall from the Pacific Coast to the Mississippi Valley will contrast with wetter-than-normal weather across the eastern one-third of the U.S.