Midwest: Drought areas of the Midwest —which extend from northwestern Iowa into northern portions of Minnesota and Michigan’s Upper Peninsula — reported another week of record-setting warmth (temperatures averaging 15 to 25°F, or more, above normal). Despite the arrival of a storm system in the region’s northern tier, rain amounts were generally disappointing (0.5 inch or less). However, isolated, locally heavy showers (1-3 inches) provided some relief from Moderate Drought (D1) in northern Minnesota. In contrast, Abnormal Dryness (D0) was introduced across central Illinois and the northeastern corner of Missouri, where increasing rainfall shortages (90-day precipitation locally less than 50 percent of normal) were noted. Illinois has also reported remarkably low streamflows for this time of year, with streams in the central portions of the state reporting flow rates in the lowest 5th percentile.
Western U.S.: Late-season storminess provided much-needed precipitation across western and northern portion of the region, while dry, unfavorably warm weather settled over central and eastern drought areas of the west.
In northern portions of the region, another in a series of late-season Pacific storms generated moderate to heavy rain and mountain snow (2-6 inches liquid equivalent), maintaining favorable spring runoff prospects from the Klamath Mountains northward into the Cascades. Snowpacks increased in northwestern Oregon and from northeastern Oregon into northern Idaho and northwestern Montana. However, the lingering Moderate Drought (D1) in central Washington received little if any precipitation, with only minor reductions made to southeastern portions of this area (where precipitation totaled more than half an inch). In northeastern Oregon, precipitation totaled locally more than an inch, resulting in additional reduction of D1 and D0.
In southern portions of the region, showers in the west contrasted with dry, increasingly warm conditions farther east. Rain and high-elevation snow fell in the Sierra Nevada, although snow-water equivalents remained in the lowest 5th percentile (indicative of D3 drought) in southern portions of the range, where Severe Drought (D2) persisted. A weakening disturbance produced 1 to 2 inches of rain along the southern California Coast, preventing – for the time being – any drought intensification in these locales. The Southwest was dry, with water-year precipitation totaling less than 30 percent of normal in the newly-expanded Severe Drought (D2) areas of southeastern California and neighboring portions of southern Nevada. Expansion of Extreme (D3) drought was noted in southwestern Arizona, as local assessment coupled with satellite-derived vegetation information indicated deteriorating conditions in this corner of the state. In Colorado, most of the state was now under Abnormal Dryness (D0) or worse, with Severe Drought (D2) introduced in the northwestern quarter of the state, where snow-water equivalents and water-year precipitation were in the lowest 5th percentile (generally 50 percent of normal or less).