During the past 7-days, a series of slow-moving cold fronts traversed the eastern two-thirds of the Nation, triggering numerous and widespread showers and thunderstorms. Areas that recorded over 2 inches of rain for the week included portions of the central Plains, Midwest, Tennessee Valley, lower Delta, the Appalachians, most of Florida, the coastal Carolinas, and the mid-Atlantic. A northward surge of monsoonal moisture into the Southwest brought welcome rainfall to portions of the Four Corners States and Nevada, including more than 2 inches in southern and eastern Arizona, western New Mexico, and eastern Colorado. Unfortunately, hot and dry weather enveloped much of the Far West, including California. In the Northwest, temperatures averaged 8 to 12oF above normal with highs in the 90’s and 100’s, and numerous wild fires were reported. In Puerto Rico, scattered showers fell across the northern and eastern sections of the island, but dry weather prevailed in the southwest as D0 developed there. Scattered showers on Hawaii were enough to maintain conditions.
Southern and Central Plains
Similar to the middle Missouri Valley (e.g. Nebraska), southeastward moving thunderstorms dumped heavy rain (>2 inches) on swaths of central Kansas into eastern Oklahoma and western Arkansas, providing improvement where the greatest rains fell. In central Kansas, D2 replaced D3 as both short and medium-term (to 6-months) surpluses existed. In Oklahoma, D3 and D2 were improved by 1-category in the northeast, D2 was chipped away in central sections, and D0 was eliminated in eastern Oklahoma and western Arkansas. However, the southwestern section of Oklahoma observed dry and warm weather, justifying a small expansion of D2 there. In Texas, it was a relatively dry week, following a wet May and near-normal June. Accordingly, only small changes were made, with a slight reduction of D4 and D2 in the Panhandle, some trimming of the D0 along the western Gulf Coast, and slight downgrades in southwestern, south-central, and extreme south Texas. Although Oklahoma’s winter wheat crop was estimated to be the smallest since 1957 (51 million bushels) and its 17 bushels per acre yield matched 1967 (due to drought and freezes), summer row crops and pastures were rated much better, with the worst conditions in the west. Similarly, Texas crops were doing okay, with oats, cotton, and sorghum rated 28, 23, and 9% poor or very poor, respectively, and pastures and ranges at 22%, generally better off than the past several years.
Southwest and Great Basin
With much of California in either D3 or D4 and May-September normally dry, there is not much more room for further deterioration, at least during the dry season. With that said, however, further investigation of the long-term (36-month) deficits in southern California east of San Diego were similar to conditions to the north, along with overall impacts. Therefore, D3 was expanded east of San Diego to include the mountains, and to cities such as Riverside and San Bernardino. With June in the books, NCDC rankings for California for the July 2013-June 2014 period were the warmest and 3rd driest since 1895. The only drier July-June periods were in 1923-24 and 1976-77. This is the first time California experienced 3 consecutive years in the top 20 for dryness: 2011-12 ranked 20th, 2012-13 ranked 18th, and statewide precipitation has averaged 67% of normal during this 3-year period, and was just 56% of normal in 2013-14. Fortunately California’s reservoirs hold more water than they did in 1977 when the state experienced its 4th and 2nd driest years on record from July 1975-June 1977. However, a recent study estimated that this drought will cost California $2.2 billion in 2014, with a loss of over 17,000 agricultural jobs.
In contrast, a robust start to the July southwest monsoon was seen in parts of the Southwest. More than 2 inches of rain fell on central and southeastern Arizona, much of western and central New Mexico, and most of southern and eastern Colorado. Totals were much lower (<0.5 inches) in southwestern Arizona, southeastern California, most of Nevada and Utah, western Colorado, and southeastern New Mexico. Since this was the first wet week in Arizona, only small improvements were made where the largest rains fell (southern sections). In New Mexico and Colorado, wetter weather back in May and June, plus this week’s rains, allowed for larger and more significant 1-category improvements as both short and medium-term (to 180-days) surpluses existed, albeit somewhat tempered in New Mexico and southeastern Colorado by 2- and 3-year deficits. Fortunately, over 2 inches of rain fell on D4 areas of eastern Crowley, northeastern Otero, and northwestern Bent counties, improving conditions to D3 there, while just to the south, similar totals upgraded conditions from D3 to D2 (southern sections of Otero and Bent and northern Las Animas). Eastern Colorado and adjacent western Kansas also saw a 1-category improvement with additional rains this week. Elsewhere, status-quo prevailed.
During July 17-21, moderate to heavy rains are expected from the central Rockies southeastward to the lower Delta, and then into the Southeast during Days 6-7. Florida should also see moderate rains. The largest amounts (3 to 6 inches) for the 5-day period are forecast for the Red River Valley and eastward into Arkansas. The West will be seasonably dry, and the southwest monsoon is predicted to be quiet, with only light totals (<0.5 inches) in eastern Arizona and New Mexico. The northern Rockies and Plains, plus the Midwest, should be mostly dry. Subnormal temperatures are forecast for the West Coast and eastern half of the Nation, with above-normal readings expected in the Rockies and northern Plains.
For the ensuing 5-day period, July 22-26, the odds favor above-median precipitation in the eastern half of the U.S., Pacific Northwest, and northern Alaska, with below-median rainfall likely in the Great Basin, Rockies, High Plains, and south Texas. Temperatures are expected to average below normal in the Pacific Northwest and Alaska, but likely to be above-median in the Southwest, Rockies, Plains, Great Lakes region, and New England.