Summary

For the second consecutive week, moderate to heavy rainfall brought additional drought relief from the Midwest southward across the central Plains into Texas. Meanwhile, drought conditions prevailed from California into the central and southern Rockies.

Alaska, Hawaii, and Puerto Rico

There were no changes made to the drought depiction in Alaska and Hawaii this week. In Alaska, cool weather and locally heavy showers were noted across much of the state, with streamflows in the northern Abnormal Dryness (D0) areas exhibiting some recovery. Additional rainfall over the ensuing weeks would likely warrant some D0 reduction. In Hawaii, some areas of leeward dryness are developing but remained fairly localized. In Puerto Rico, D0 was expanded into the northeastern quarter of the island where 90-day rainfall deficits (50 to 70 percent of normal) has resulted in streamflows drooping locally below the 10th percentile.

Central Plains

Conditions remained largely unchanged on the central High Plains during the monitoring period, as hot weather (readings as high as 100°F) offset the light to moderate showers (0.1 to 1 inch) which dotted western portions of the region. A small expansion of Extreme Drought (D3) in southwestern Kansas reflected increasingly poor vegetation health as indicated by satellite, with potential for additional degradations in this area if rain fails to materialize soon. Farther east, however, locally heavy downpours — with totals averaging 2 to locally more than 4 inches — resulted in some removal of Moderate (D1) and Severe (D2) Drought in central and southwestern Nebraska. In these areas, precipitation over the past 30 days has averaged 150 to 260 percent of normal. In Kansas, showers were mostly too light to warrant any additional improvement on top of last week’s drought reduction, though locally heavy downpours (2 to 4 inches) allowed for minor decrease of Extreme Drought (D3) in southern portions of the state.

Delta

After last week’s beneficial showers, mostly dry, warm weather prevailed in the Moderate (D1) and Severe (D2) Drought areas of southwestern Louisiana. Soil moisture remains limited in these locales due to pronounced dryness over the past 90 days (locally less than 50 percent or normal). The rest of the Delta remained free of drought. NOTE: At the end of the period, locally heavy showers and thunderstorms developed over the Delta’s drought areas, and the resultant benefit —if any — will be addressed in next week’s U.S. Drought Monitor.

Mid-Atlantic and Northeast

Drier-than-normal conditions prevailed over eastern portions of the region during the monitoring period, which coupled with declining streamflows led to an expansion of Abnormal Dryness (D0) in southeastern New Hampshire and neighboring locales. Precipitation over the past 60 days has totaled 50 to 70 percent of normal in the D0 areas, and streamflows have likewise dipped below the 20th percentile. In contrast, showers dotted the Mid-Atlantic region, with locally more than 2 inches of rain bordering areas with little — if any — rainfall. Overall, soil moisture remained adequate to abundant for pastures and summer crops.

Midwest

Moderate to heavy rainfall further reduced or eradicated drought but submerged low-lying fields and caused additional river flooding in western and central portions of the region. Persistent showers and thunderstorms doused areas from central Nebraska into Iowa and northern Illinois with 2 to 4 inches of rainfall, with locally higher amounts. The rain was more than sufficient to warrant additional 1-category improvements over the western half of the Corn Belt. Despite the additional heavy downpours, long-term precipitation deficits linger (less than 70 percent of normal over the past 12 months) in west-central and southeastern Iowa; consequently, a small area of Moderate Drought (with a Long Term, or “L”, designation) remained where shortfalls are most pronounced. In contrast, short-term dryness (90-day rainfall averaging 50 to 70 percent of normal) led to a small increase of Abnormal Dryness (D0) in southeastern South Dakota.

Ohio Valley and Southeast

Pronounced short-term rainfall deficits and above-normal temperatures led to an expansion of Abnormal Dryness (D0) in Kentucky and along the Ohio River. In the expanded D0 area, 30-day rainfall has totaled locally less one-third of normal, which coupled with temperatures up to 7°F above normal caused a rapid decline in soil moisture and streamflows. Farther south, locally dry conditions from east-central Georgia northward into western South Carolina warranted D0 expansion, with precipitation over the past 60 days tallying 35 to 60 percent of normal. Localized dryness and declining streamflows also led to the introduction of a small D0 area south of Asheboro, NC, where streamflows have dropped below the 10th percentile. In Florida, another round of locally heavy showers and thunderstorms (generally 1 to 4 inches, with some reports as high as 7 inches) facilitated the removal of the remaining D0 in southern-most portion of the state. The rest of the southeastern quarter of the nation saw scattered showers and thunderstorms, which were sufficient to prevent any introduction or expansion of D0.

Southern Plains and Texas

Despite temperatures in the 90s, rainfall during the week was sufficient to warrant modest to significant reductions in drought from northern and central Oklahoma southward into Texas. Showers and thunderstorms dropped 2 to locally more than 4 inches of rain from the eastern Oklahoma panhandle southeastward into central Oklahoma and east-central Texas. In particular, there were numerous reports of more than 3 inches west of Oklahoma City, and several totals in excess of 7 inches southwest of Dallas-Fort Worth. Consequently, drought intensity declined in areas where the heaviest rain fell, although long-term impacts continue (i.e. reservoir storage and ground water supplies). Farther south, a slow-moving disturbance drifted north from northeastern Mexico along the Rio Grande River Valley, dropping moderate to excessive rainfall (2 to 5 inches, with localized amounts in excess of 8 inches) from Laredo to the western Edwards Plateau. Likewise, a separate area of showers and thunderstorms (1 to 3 inches) swept across Texas’ Trans-Pecos region later in the week. These two areas of rain resulted in notable decreases in drought intensity and coverage across southern and western Texas.

Western U.S.

Variable conditions in the north contrasted with ongoing drought elsewhere. In addition, the return of hot weather in California and the Southwest accelerated moisture losses and increased irrigation requirements.

In northern portions of the region, a slow-moving Pacific storm generated locally heavy rain and mountain snow across the northern Rockies, with showers from this system (locally more than inch) spilling into northeastern drought areas of Washington. Consequently, modest reductions were made to drought intensity and coverage in the mountains and foothills of northeast Washington, where Water Year precipitation was mostly near normal (80-95 percent of normal). Appreciable rainfall bypassed southwestern portions of Columbia River Valley, where Moderate (D1) and Severe (D2) Drought were expanded to reflect poor crop conditions and much-below-normal Water Year precipitation (40-50 percent of normal). To further illustrate the drought’s impacts, the USDA-NASS reported Washington’s winter wheat slipped 1 percentage point to 27 percent poor to very poor as of June 22, with only 30 percent rated good to excellent.

Farther south, California and the Great Basin will most likely have to wait until the 2014-15 Water Year for drought relief. In northern and central California, Exceptional Drought (D4) reflected abysmal 2013-14 Water Year precipitation totals; from northern portions of the Coastal Range to Mt. Shasta, precipitation since October 1 totaled 30 to 50 percent of normal (deficits of 16 to 32 inches). The corresponding Standardized Precipitation Indices (SPI), which helps quantify precipitation in terms of drought and historical probability, are well into the Extreme (D3) to Exceptional (D4) categories. Similar precipitation rankings (D3 or D4 equivalent) are prominent for the past Water Year from San Francisco south to Santa Barbara and east to the Sierra Nevada, including most of the San Joaquin Valley.

In the central Rockies and Four Corners, there were no changes to this week’s drought depiction. Extreme Drought (D3) remains entrenched across west-central Arizona and along the Arizona-New Mexico border, with Water-Year precipitation in these locales totaling less than half of normal (locally below 30 percent of normal) .

Looking Ahead

Warm, humid, and unsettled conditions will persist from the central and southern Plains to the Mid-Atlantic and Southeast Coast. Embedded within this large area of unsettled weather, the greatest potential for heavy rain will be over the Upper Midwest and northern Plains as well as the central and western Gulf Coast region. Showers are also expected across the Northwest — though the rain is expected to once again bypass primary Northwestern drought areas — and in the Northeast. The NWS 6-10 day outlook for July 1-5 calls for wetter-than-normal conditions east of the Mississippi and from the Four Corners into the central Plains as well as southern Texas. Conversely, drier-than-normal weather is expected from the Northwest east to the northern Plains. Above-normal temperatures are anticipated across much of the nation, with cooler-than-normal conditions confined to the Upper Midwest, Texas, and the coastal Pacific Northwest.

Author(s):
Eric Luebehusen, U.S. Department of Agriculture