5/22 Drought Monitor: Most Of AZ/NM In Level 3 Or 4 Drought; D4 Growing In 4 Corners, Towards Phx

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South

Intensifying dryness from northeastern Texas to the central Gulf Coast contrasted with heavy rain and much-needed drought relief in western portions of the region. Despite isolated downpours (locally more than 4 inches) providing localized relief from Abnormal Dryness (D0) in coastal portions of Louisiana and Mississippi, most locales reported sub-par rainfall for the week. Over the past 30 days, many of the newly-expanded D0 areas have reported less than 25 percent-of-normal rainfall (locally less than 10 percent) with deficits over the same period totaling 2.5 to 5 inches. In northeastern Texas, locales from Dallas eastward have reported similar shortfalls over the past 30 days, with 60-day precipitation totaling less than 70 percent of normal. Meanwhile, 7-day rainfall totaled 1 to 3 inches (locally more) from central Texas northward into western Oklahoma, resulting in widespread reductions to this week’s drought intensity and coverage. Notable amounts included: 4.92 inches near Bertram, TX (north of Austin); 4.76 inches in Crowell, TX (west of Wichita Falls); 3.35 inches in Willow, OK (north of Altus). The rain was not only heavy, but also frequent. Childress, TX, saw measurable rainfall for 8 consecutive days from May 13 – 20; this ties the all-time record dating back to 1948. Despite the beneficial rain, Severe (D2) to Exceptional (D4) Drought persisted over much of the southern High Plains, where 6-month precipitation has totaled locally less than 25 percent of normal.

Midwest

Conditions were largely mixed over the region during the 7-day monitoring period, with generally dry weather in the north contrasting with additional rain in southern portions of the region. Moderate to heavy rainfall (1-4 inches, locally more) led to widespread reductions in Abnormal Dryness (D0) in central Missouri, with a report of 5.52 inches in Appleton City (north of El Dorado Springs). Similarly, moderate to heavy showers (1-2 inches) netted a modest reduction to D0 in southeastern Iowa. Conversely, rain largely bypassed locales from northeastern Missouri into west-central Illinois, with D0 expanded to capture areas reporting half of normal rainfall over the past 60 days. Farther north, the recent tendency toward unfavorable dryness continued, with D0 expanded across northern Wisconsin and environs to capture locales which have reported less than 50 percent-of-normal rainfall over the past 60 days. Nevertheless, rain amounts topping an inch in and around Red Lake in northern Minnesota led to small reductions to Moderate Drought (D1) and Abnormal Dryness (D0).

High Plains

The overall trend toward improving conditions in the south contrasting with increasingly dry weather in the far north continued, though some northerly areas benefited from locally heavy rain. In southern Kansas, another week with moderate to locally heavy showers (1-3 inches, as high as 3.72 inches in Longton, KS) led to widespread reductions of drought intensity and coverage. Nevertheless, 6-month precipitation in the state’s lingering Extreme Drought (D3) was less than half of normal, while the Exceptional Drought (D4) in the state’s southwestern corner stood at less than one third of normal over the same time period. Moderate to heavy rainfall (locally more than 3 inches) in northeastern Colorado likewise trimmed the coverage of Abnormal Dryness (D0). In south-central Nebraska and north-central Kansas, heavy rain (2-3 inches; Phillipsburg, KS, reported 3.95 inches) yielded a corresponding reduction of D0. In southeastern Nebraska, increasingly dry conditions over the past 90 days (40-60 percent of normal) led to a modest increase of Moderate Drought (D1) southwest of Lincoln. Farther north, sharply wetter conditions between Bismarck, ND, and Aberdeen, SD, (6.17 inches in Java, SD) resulted in a considerable reduction of D0. Beneficial rain (1-2 inches) was also reported in northeastern Montana, where D0 was reduced accordingly. Meanwhile, D1 and D2 were increased somewhat in North Dakota from Bismarck to the Canadian border, where 60-day rainfall shortfalls (locally less than 30 percent of normal) have added to the region’s lingering long-term drought.

West

Outside of beneficial rain in eastern-most portions of the region, lackluster water-year precipitation and unusual warmth have led to increasing drought despite the cool wet season having drawn to a close. Beneficial rain was reported during the period in northeastern portions of Montana and Colorado, resulting in reductions of Abnormal Dryness (D0) and as well as Moderate (D1) and Severe (D2) Drought. However, the overarching theme in the West continued to be the ongoing and intensifying drought in the lower Four Corners as well as the interior Northwest. In the latter region, Moderate and Severe Drought (D1-D2) were expanded over much of Oregon’s Harney Basin to reflect a sub-par water year (50-75 percent-of-normal precipitation, or 10-25th percentile) as well as protracted dryness over the past 60 days (less than half of normal). Farther south, Extreme (D3) and Exceptional (D4) Drought were expanded over Arizona. The numbers from the Four Corners Region as a whole tell a dire story, with water-year precipitation totaling a meager 10 to 30 percent of normal in the hardest-hit areas; the Standardized Precipitation Index (SPI), which puts these values in a drought-intensity equivalent, are D3- and D4-equivalent over much of central and northeastern Arizona. A sub-par snowpack and above-normal temperatures have left little water available through snowmelt. Furthermore, the satellite-derived Vegetation Health Index (VHI) — which incorporates both vegetation greenness and thermal stress — shows extremely poor conditions over most of Arizona as well as neighboring portions of southern California and southern New Mexico. This region will be in need of a robust Southwest Monsoon beginning in early July to help offset the impacts brought on by this season’s Extreme to Exceptional Drought in the lower Four Corners Region.

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http://droughtmonitor.unl.edu/DroughtSummary.aspx