While Hurricane Irma pummeled Florida and (to a lesser extent) other parts of the Southeast, most other parts of the contiguous 48 states caught little if any precipitation, save for scattered moderate to isolated heavy precipitation in parts of the Northeast. Irma brought intense rains (approaching 1.5 feet in some spots) and powerful wind gusts (measured at 140 mph at one place on the West Coast of the Florida Peninsula) that removed any suggestion of dryness from the Southeast. Enough precipitation fell on part of eastern Maine to shave down areas of D0 and D1 from the west, but most of the country -- from the Ohio and lower Mississippi Rivers westward to the Pacific Coast – recorded little precipitation, if any. Only isolated patches in the eastern Great Lakes Region and the lower Colorado River Valley recorded more than an inch of rain.
Beneficial precipitation is expected during September 14 – 18, 2017 across much of the drought-afflicted areas in the northern Plains and Rockies. Between 1.5 and 3.5 inches are expected across all but the western and northern tiers of Montana, and central and southwestern sections of North Dakota. Moderate rains (0.5 to locally 1.5 inches) is expected in the Upper Midwest and the central Plains, as well as the far Pacific Northwest west of the Cascades. Light precipitation at best is anticipated in other areas of dryness and drought.
The ensuing 5 days (September 19 – 23, 2017) look to bring a reversal in the temperature pattern recently observed across the 48 states, with odds favoring cooler than normal weather from the northern High Plains and southern Rockies to the Pacific Coast, and warmer than normal conditions expected in the central and eastern parts of the county. There are enhanced chances for above-normal precipitation from central and northern sections of the High Plains westward to the Pacific Coast, most of the Great Plains north of Texas, and the middle and upper Mississippi Valley. Odds also favor above-normal precipitation in the Copper Basin of Alaska. Meanwhile, subnormal precipitation is favored in the East, Southeast, most of Texas, and the southern Rockies.
Another dry week led to broad development of D0 and more limited expansion of D1 to D3 conditions from Iowa and Missouri eastward through southern Wisconsin, Illinois, and adjacent Indiana. Precipitation totaled less than 2 inches over the past month in the D0 areas of southern Michigan, southern Wisconsin, eastern Iowa, much of Illinois outside a band across the middle of the state, southwestern Indiana, and parts of southern and eastern Missouri. Although below-normal temperatures have mitigated some potential impacts from the marked short-term dryness, declining streamflows and topsoil moisture have slowly become more evident