In the West, widely scattered showers extend northward from Arizona. Cool conditions are limited to areas along the Pacific Coast. Elsewhere, late-season heat favors small grain harvesting and other fieldwork.

On the Plains, hot, dry weather favors summer crop maturation but is maintaining severe stress on rangeland and pastures. Today’s high temperatures could exceed 100°F as far north as southern South Dakota.

In the Corn Belt, a band of showers stretches from the lower Great Lakes region into the middle Mississippi Valley. The rain is too late for many summer crops, especially corn, but is helping to revive pastures.

In the South, Tropical Storm Isaac is bearing down on the central Gulf Coast, a day after lashing southern Florida with rain squalls and gusty winds. At 8 a.m. EDT was centered 360 miles southeast of the mouth of the Mississippi River, moving toward the west-northwest at 14 mph. Maximum sustained winds are near 65 mph. Locally heavy showers continue across Florida’s peninsula, but warm, dry weather covers the remainder of the South.

Outlook: Isaac should strengthen and is expected to be a hurricane at landfall on the central Gulf Coast late Tuesday or early Wednesday. Due to some uncertainty in Isaac’s track, hurricane warnings have been issued along the Gulf Coast from the south-central Louisiana to western Florida, including New Orleans. In addition, Isaac should be a prolific rain-maker in the lower and middle Mississippi Valley. Along and near the storm’s path, rainfall could reach 6 to 12 inches, with isolated amounts in excess of 18 inches. Little or no rain will occur through week’s end across the remainder of the U.S., while a late-season heat wave will expand from northern portions of the Rockies and Plains into the Midwest and Northeast. The NWS 6- to 10-day outlook for September 1-5 calls for near- to above-normal temperatures nationwide, except for cooler-than-normal conditions in the Pacific Northwest and along California’s coast. Meanwhile, near- to below-normal rainfall across the South and West will contrast with wetter-than-normal weather from the Midwest into the Northeast.