Substantial precipitation improves conditions in the Midwest; drought continues in High Plains region

A series of storms dropped moderate to heavy precipitation on much of the eastern half of the country, with 3 to locally 6 inches of rain falling on a swath from central Alabama to central South Carolina, near the Mississippi and Ohio Rivers confluence, areas from the Delmarva Peninsula to southeastern New York state, and portions of the Cascades and coastal areas in Washington and portions of Oregon.

Temperatures did not average far from normal except in the southwestern and northeastern parts of the country. The Southwest, the Great Basin, most of California, and New England experienced temperatures up to 5 deg. F in spots. In addition, episodes of low humidity and strong winds worsened dryness across much of the Plains and adjacent Rockies.

South

Only limited areas recorded light to moderate precipitation, with most sites reporting little or none. Between 2 and 4 inches fell on small areas in northeastern Oklahoma, northeastern Arkansas, and northwestern Tennessee. Most other areas of northern Tennessee observed 1.5 to 2.5 inches, and similar amounts fell on much of northern Arkansas and parts of eastern Louisiana. Several tenths of an inch were measured in the rest of Tennessee and central Louisiana, but a majority of the region—including almost all of Texas and Oklahoma—experienced a precipitation-free week.

In general, dryness and drought worsens moving from northeast to southwest across the South Region. Eastern Oklahoma, central and northern Arkansas, and almost all of Tennessee are free of significant dryness. In sharp contrast, D2 to D4 drought covers southern Louisiana, most of the western half of Oklahoma, and the central and eastern reaches of Texas. Exceptional drought (D4) covers several sizeable areas in the western half of Texas and the Oklahoma Panhandle. Only a few tenths of an inch of precipitation has fallen at best since early February across central and south-central Texas, with 17 sites reporting rainfall totals among the driest 2 percent of the historical distribution for the period, as did a few sites in northwestern Texas outside the Panhandle.

For the past half-year as a whole, less than 10% of normal precipitation has been observed in part of west-central Texas, including much of the Big Bend, while less than 25 percent of normal fell on most of the western half of Texas and the Oklahoma Panhandle. In addition, episodes of low humidity and strong winds worsened the situation across the already-parched region, leading to high wildfire danger and areas of blowing dust.

Midwest

Several weeks of substantial precipitation have progressively improved conditions, and now lingering long-term D0 and D1 conditions are confined to areas west of Lake Michigan. This past week, 1 to 2 inches fell on a few patches across the northern tier of the Midwest Region. Six-month precipitation totals between 2 and 5 inches below normal exist only across northern Iowa, a band from southeastern Iowa to central Missouri, and a few patches on the Michigan Upper Peninsula, west-central lower Michigan, southwestern Wisconsin, and northwestern Illinois. There are higher deficits in small parts of southern and western Missouri on the fringes of the large drought area that has enveloped most of the western half of the country.

High Plains

An inch or two of precipitation fell on northwestern South Dakota, a small part of eastern North Dakota, and the highest elevations of north-central Colorado. Elsewhere, a few areas of 0.5 to 1.0 inch was observed in parts of the central and southern Dakotas, northwestern Nebraska, and several swaths scattered across Wyoming. A few tenths of an inch, at best, fell elsewhere.

Dryness and drought cover a large majority of the High Plains Region; only the east-central and northeastern Dakotas and eastern Kansas are free of any significant dryness. D2 to D3 cover central and western parts of the region, including all of Wyoming, Colorado, and most of Nebraska. Slow intensification and expansion has been noted across many areas over the past several months, and D3 expanded to cover additional portions of north-central Wyoming, central Nebraska, and an area near the western Kansas/Nebraska border. Elsewhere, few changes were introduced. Recently, strong winds and low humidity have made dryness more acute, especially in southern parts of the Region.

West

The West region endured another dry week, with the heaviest precipitation falling along and west of the Cascades in Washington and northern Oregon (generally 1.5 to 3.5 inches, with isolated amounts reaching 6 inches in the highest elevations). This is one of two areas free of dryness and drought (northwestern Montana and adjacent Idaho is the other). D2 and D3 cover a large majority of the West Region, and exceptional drought (D4) has become entrenched in the Oregon Cascades, south-central Nevada, parts of southern New Mexico, and northeastern New Mexico.

Slow worsening and expansion continued, with noticeable deterioration in parts of New Mexico, Nevada, and California this week. Water storage in the two largest reservoirs in the west—Lake Powell along the central Arizona/Utah border, and Lake Mead farther downstream along the Colorado River—has dropped to unprecedented levels. In early April, the combined storage was only 44% of the average since 1964, and less than 75% of the storage in Lake Mead alone just before Lake Powell started to fill.