Thursday, July 28, 2016

National Drought Summary for July 26, 2016

Summary

Despite heat and high humidity levels, parts of the Midwest received significant rain. Specifically, showers and thunderstorms produced at least 2 to 4 inches of rain in parts of the upper Mississippi Valley and environs. However, rain mostly bypassed some Midwestern locations, including the lower Great Lakes region. Outside of the Midwest, showers were generally light and scattered, although spotty rainfall provided local relief from hot weather in the Four Corners States and the lower Southeast. Late in the drought-monitoring period, coverage and intensity of shower activity increased in the Gulf Coast region as a weak disturbance over the Gulf Mexico moved inland and helped to focus rainfall. Most of the remainder of the country experienced hot, mostly dry conditions, leading to an expansion of short-term drought in the south-central U.S. and contributing to an increase in wildfire activity in parts of the West. Temperatures above 100°F were commonly observed early in the period on the Plains, but Midwestern temperatures above 95°F were limited to the southwestern fringe of the major corn and soybean production areas. Late in the period, heat replaced previously cool conditions in the Northwest, while temperatures fell to near- or below-normal levels in much of the Plains and Midwest.

Northeast

Despite spotty showers, the general trend was toward worsening drought, in part due some of the hottest weather of the season. Daily-record highs for July 23 reached 99°F in Williamsport, PA, and 97°F in Bridgeport, CT. On July 24-25, Pennsylvania locations such as Reading (96 and 97°F) and Allentown (95°F both days) posted consecutive daily-record highs. All of the major airports in the Washington, D.C. area hit 100°F (and noted daily-record highs) on July 25, marking the first triple-digit heat in all three locations since July 2012. For several Mid-Atlantic locations, including Newark, NJ (99°F), and Philadelphia, PA (97°F), highs on July 25 broke daily records originally set in 1999—just weeks before the U.S. Drought Monitor made its public debut in the midst of an Eastern drought in August of that year.

Impacts of the Northeastern drought were obvious in the agricultural sector, with the U.S. Department of Agriculture (USDA) rating topsoil moisture at least half short to very short on July 24 in Rhode Island (97%), Connecticut (85%), Massachusetts (80%), New Hampshire (70%), Pennsylvania (63%), and New York (54%). In New York, USDA noted that “corn [was] starting to curl and yields are expected to be low… [There was] little to no re-growth in pastureland and hayfields. Soybeans [were] in bloom and showing signs of stress.” One-quarter of New York’s soybeans were rated in very poor to poor condition on July 24. Meanwhile, more than half of the pastures were rated very poor to poor in Connecticut (69%) and Rhode Island (60%). The Northeastern drought was also apparent in low streamflows, particularly across western New York, southern New England, and parts of Pennsylvania. Buffalo, New York, received 1.80 inches of rain during the first 26 days of July, 68% of normal, following its driest April-June period since 1941. Buffalo’s precipitation totaled just 4.42 inches (44% of normal) in April-June 2016.

Southeast

Occasional showers also provided local drought relief in the Southeast. Nevertheless, core areas of severe to extreme drought (D2 to D3) remained intact from Mississippi to the southern Appalachians, with expansion noted in several areas. Late in the drought-monitoring period, rain began to fall more heavily in portions of the Gulf Coast region. From June 1 – July 26, Southeastern precipitation totals were less than one-half normal in numerous locations, including Chattanooga, Tennessee (2.85 inches, or 35% of normal), and Macon, Georgia (3.58 inches, or 43%). Short-term rainfall deficits were also mounting along Florida’s Atlantic coast, where June 1 – July 26 rainfall totaled 4.28 inches (40% of normal) in Daytona Beach. Chronically hot Southern conditions have aggravated the effects of dryness and drought; in Meridian, Mississippi, July 26 was the 63rd consecutive day with an above-normal daily average temperature—a streak that began on May 25. In recent days, triple-digit daily-record highs were reported in Southeastern locations such as Columbia, South Carolina (102°F on July 26), and Athens, Georgia (101°F on July 25).

By July 24, USDA indicated that topsoil moisture ranged from 40 to 74% very short to short in eight states stretching from Texas to South Carolina. In Texas, topsoil moisture rated very short to short climbed in the last week from 64 to 74%. Arkansas also noted a 10 percentage point weekly rise, from 58 to 68%. On July 24, pastures were rated at least one-fifth very poor in Georgia (36%), South Carolina (31%), Alabama (26%), and Tennessee (24%). Among row crops, Alabama’s corn was being hit especially hard by drought, with 35% of the crop rated very poor to poor. In addition to agricultural effects, Southeastern drought impacts were apparent in low streamflows and beginning to show in some lake levels. For example, Georgia’s Lake Lanier was 4.40 feet below full pool on July 27, 2016, and 4.07 feet below the level observed 2 years ago, on July 27, 2014.

Southern Plains

Hot, mostly dry weather persisted on the southern Plains, although showers wrapped around the region through the southern Rockies and the central Plains. Locally heavy showers also developed in the western Gulf Coast region. The general trend was for a large increase in abnormal dryness (D0), with moderate drought (D1) returning in some areas. On July 25, Midland, Texas, set a July record with its 19th day of triple-digit heat. Previously, Midland had recorded 18 days with high of 100°F or greater in July 1964. Midland also set a July record with 9 days of 105-degree heat—all from July 3-14—eclipsing its July 1995 standard of 6 days. By July 24, topsoil moisture rated very short to short had increased to 81% in New Mexico and 74% in Texas. On the same date, the Texas cotton crop was rated 17% very poor to poor, the highest in the nation ahead of Mississippi (11% very poor to poor).

Midwest

Significant rainfall chipped away at many of the remaining areas of abnormal dryness (D0) and moderate drought (D1). Rain was heaviest in the upper Mississippi Valley. The rain helped to offset the effects of a brief heat wave, leaving Midwestern corn and soybeans mostly in good shape. On July 24, USDA rated 76% of the U.S. corn and 71% of the soybeans in good to excellent condition. Only in the lower Great Lakes region and the westernmost Corn Belt were there heat- and/or drought-related concerns with major row crops. Michigan led the nation among the eighteen major production states with 13% of its corn rated very poor to poor, followed by Pennsylvania, South Dakota, and Texas—all at 11%. Michigan also led the Midwest in soybeans rated very poor to poor—13% on July 24—although Arkansas led the U.S. at 14%. Not coincidentally, Michigan also led the Midwest in pastures rated very poor to poor (26%), just ahead of Ohio at 25%. Ohio (62%) and Michigan (51%) also led the Midwest in topsoil moisture rated very short to short.

Northern Plains

Meanwhile, heat briefly compounded the effects of patchy drought across the northern and central Plains. In South Dakota, triple-digit, daily-record highs for July 20 soared to 108°F in Dupree and 107°F in Timber Lake. On July 24, South Dakota led the nation with 15% of its spring wheat rated in very poor to poor condition, followed by North Dakota at 10%. However, some areas received significant rain during the monitoring period, helping to trim drought coverage in parts of North Dakota and environs.

West

Several days of cool weather in the Northwest were followed by increasing heat. By July 25, daily-record heat returned to portions of the interior Northwest, where Yakima, Washington, posted a high of 102°F. Some of the West’s most significant short-term drought covered the Black Hills and adjacent areas, where moderate to extreme drought (D1 to D3) persisted. Portions of Wyoming also continued to note deteriorating short-term conditions. Farther south, heat also returned to southern California, where record-setting highs for July 23 rose to 110°F in Riverside and 108°F in Campo. By July 26, two wildfires in California were of particular concern: the 38,000-acre Sand fire near Santa Clarita and the 24,000-acre Soberanes fire near Big Sur. Farther east, monsoon-related showers were mostly confined to the Four Corners States, although rainfall in most cases was not heavy enough to result in improvement in the drought depiction. Still, Douglas, Arizona, received 2.92 inches of rain from July 17-24, with significant totals also observed in neighboring southwestern New Mexico. For much of the Southwest, however, the trend was toward increasing drought coverage and intensity, in part due to hot weather. On July 19, Salt Lake City, Utah, noted its first-ever minimum temperature above the 80-degree mark—the low was 81°F—with records dating to 1874.

Alaska, Hawaii, and Puerto Rico

Heavy precipitation soaked much of southeastern Alaska, necessitating the removal of the recently introduced area of abnormal dryness (D0). Flooding was reported in a few spots, including near Skagway, where the Taiya River crested a foot above flood stage on July 23. In southeastern Alaska, July 21-26 rainfall totaled 4.86 inches in Yakutat. Meanwhile in western Alaska, some D0 was removed along the southern edge of the Seward Peninsula due to heavy precipitation. Nome received 1.58 inches of rain from July 17-23.

The passage of Tropical Storm Darby through the Hawaiian Island chain led to heavy surf, gusty winds, and significant rainfall. From July 22-24, peak wind gusts on the Big Island were clocked to 61 mph at Kohala Ranch and 53 mph at the Waimea-Kohala Airport. The Lanai Airport reported a gust to 48 mph. Meanwhile, some of the heaviest rain fell on Oahu, where several locations received in excess of 10 inches of rain. In fact, 24-hour totals on July 24-25 reached 10.56 inches in Luluku and 8.68 inches at the Manoa Lyon Arboretum. Although the heaviest showers largely bypassed Hawaii’s lingering areas of dryness and drought, enough rain fell to eliminate the Big Island’s remaining area of extreme drought (D3).

Puerto Rico received some heavy rain, mainly across the western half of the island. However, only light rain fell across southeastern Puerto Rico, leading to no change in the drought depiction.

Looking Ahead

During the next few days, an active weather pattern will feature the interaction between a disturbance in the Southeast and cold fronts crossing the Plains and Midwest. As a result, 5-day rainfall totals could reach 2 to 4 inches or more from the Mississippi Delta into the Mid-Atlantic States. Surrounding areas, including the northern and central Plains and the Midwest, could see 1- to 2-inch totals in a few spots. In the West, showers will be heaviest across Arizona and New Mexico, with most other areas remaining hot and dry. Elsewhere, lingering heat will be mostly confined to the lower Southeast, although hot weather will build eastward and return to the High Plains during the weekend.

The NWS 6- to 10-day outlook for August 2 – 6 calls for the likelihood of above-normal temperatures across the eastern half of the U.S., while cooler-than-normal conditions can be expected in parts of the Northwest and Southwest. Meanwhile, odds will be tilted toward above-normal rainfall in much of the Southeast, Southwest, and the upper Great Lakes region, while drier-than-normal weather should occur in the Northeast, Northwest, and south-central U.S.

Author(s):
Brad Rippey, U.S. Department of Agriculture


Dryness Categories

D0 ... Abnormally Dry ... used for areas showing dryness but not yet in drought, or for areas recovering from drought.

Drought Intensity Categories

D1 ... Moderate Drought

D2 ... Severe Drought

D3 ... Extreme Drought

D4 ... Exceptional Drought

Drought or Dryness Types

S ... Short-Term, typically <6 months (e.g. agricultural, grasslands)

L ... Long-Term, typically >6 months (e.g. hydrology, ecology)

The National Drought Mitigation Center | 3310 Holdrege Street | P.O. Box 830988 | Lincoln, NE 68583–0988
phone: (402) 472–6707 | fax: (402) 472–2946 | Contact Us | Web Policy

Department of Commerce
NOAA
Copyright 2016 National Drought Mitigation Center