#Drought news: 1-category intensification of drought conditions across parts of W., S., and S.E. #Colorado

Click on a thumbnail graphic to view a gallery of drought data from the US Drought Monitor.

Click here to go to the US Drought Monitor website. Here’s an excerpt:

This Week’s Drought Summary

A strong cold front progressed southeast across the Great Plains, Mississippi Valley, and Southeast on April 28 and 29. This cold front was a focus for a severe weather outbreak from Oklahoma and eastern Texas east to the middle and lower Mississippi Valley. As this front shifted south, heavy rain (more than 2 inches) fell from the western Gulf Coast east to the Florida Big Bend and Florida Gulf Coast. A summer-like ridge of high pressure aloft led to an early and persistent heat wave across southern California and the Desert Southwest during late April into early May. Much above normal temperatures also affected the southern Rockies and southern Great Plains. To the north of this upper-level ridge, multiple low pressure systems along a nearly stationary front resulted in occasional thunderstorms with locally heavy rain (1 inch or more) to the central Great Plains, middle Mississippi Valley, and Ohio Valley. Onshore flow led to a wet start to May across the coastal Pacific Northwest, but little to no precipitation was observed across the Great Basin. Surface low pressure, centered across the Gulf of Alaska, resulted in light to moderate precipitation amounts to the Kenai Peninsula, southeast mainland Alaska, and the Alaska Panhandle. Rainfall was generally suppressed across the tropical central and eastern Pacific, including Hawaii, during late April into the beginning of May. This dry pattern over the tropics extended east to Puerto Rico…

High Plains

Increasing short-term precipitation deficits, exacerbated by above-normal temperatures recently and high evapotranspiration rates, support an expansion of abnormal dryness (D0), moderate drought (D1), and severe drought (D2) across Kansas. 60-day precipitation deficits range from 2 to 4 inches extending from southwest Kansas northeast to north-central Kansas. Russell, KS received only 0.40 inches of precipitation during April which was the 2nd driest on record (dating back to 1950) for the month. Russell’s normal April precipitation is 2.62 inches. Abnormal dryness was reduced in coverage across parts of South Dakota that received more than 1 inch of rainfall at the beginning of May. Recent heavy rainfall (more than 1 inch) also brought a 1-category improvement to the high Plains of northeast Colorado. Conversely, a 1-category intensification of drought conditions were necessary across parts of western, southern, and southeast Colorado. Southern parts of the San Luis Valley and southeast Colorado have experienced abnormal heat and high evaporative demand. SPI values on multiple time scales support the introduction of extreme drought (D3) to parts of the San Luis Valley and southeast Colorado. Farther to the north, abnormal dryness (D0) was expanded northeast Wyoming that missed the recent rainfall and where 60-day SPI values support it…

West

Precipitation for the water year to date (WYTD) , since Oct 1, 2019, has averaged less than 50 percent of normal across parts of Oregon, northern California, and the Great Basin. Based on 6 to 9-month SPI values, moderate (D1) to severe (D2) drought was expanded across parts of northern Nevada. Salt Lake City is coming off its driest April on record as it only measured 0.26 inches of precipitation (1.73 inches below normal). This dry April prompted an expansion of abnormal dryness (D0) north to include more of northern Utah. In contrast to the worsening conditions across the Great Basin, a wet start to May (1 to 3 inches, locally more) brought slight amelioration to extreme drought across coastal southwest Oregon and extreme northwest California. Intensifying drought conditions have occurred east of Cascades in Oregon and Washington. Based on poor WYTD precipitation (50 percent or less), severe drought was expanded across southeast Washington. Also, the lack of precipitation during April has adversely affected dryland farming in this part of the state. For similar reasons and support from SPI values on multiple time scales, moderate to severe drought expanded across eastern Oregon. Extreme drought (D3) was introduced to north-central Oregon and extends slightly north into south-central Washington…

South

Heavy rain (widespread amounts of more than 2 inches) at the end of April prompted a 1-category improvement to parts of the western and northern Gulf Coast, including southern Louisiana and southeast Texas. This recent heavy rain resulted in precipitation surpluses during the past 30 days and normal (25th to 75th percentile) 28-day streamflows. However, dating back 6-months, large precipitation deficits (more than 8 inches) remain across southeast Louisiana and the along the Mississippi Gulf Coast. In contrast to the improving conditions across southeast Texas, drought coverage/intensity remained nearly steady or worsened slightly across south Texas. Abnormal dryness (D0) was expanded across the Texas Panhandle and northwest Oklahoma due to increasing 30 to 60-day precipitation deficits, above normal temperatures (highs well into the 90s and low 100s), and periods of strong winds during late April into the beginning of May. These indicators along with impact reports (poor pastures, low ponds, and poor winter wheat quality) support the introduction of a small D1 area in northwest Oklahoma…

Looking Ahead

On May 7 and 8, a low pressure system is forecast to track rapidly east across the central and eastern U.S. with a swath of moderate rainfall (0.5 to 1 inch) across the central Great Plains, middle to lower Mississippi Valley, Ohio Valley, and mid-Atlantic. Behind this low pressure system, much below normal temperatures are forecast to overspread the east-central U.S. with at least a light freeze likely across the Great Lakes and eastern Corn Belt. Frost may extend south to the Shenandoah Valley and southern Appalachians. This late frost and/or freeze could damage vegetation in areas where the growing season has started. Meanwhile, a wave of low pressure is expected to develop along the tail end of a stationary front which could bring beneficial rainfall to southern Florida. The early and prolonged heat wave is forecast to ease across the Desert Southwest during the second week of May.

The CPC 6-10 day outlook (May 12-16) indicates that unseasonably cool temperatures are likely to persist into mid-May across the Corn Belt and much of the eastern U.S. A cooling trend is forecast across the western U.S., although above normal temperatures remain favored across the southern Rockies and southern Great Plains. The largest probabilities of above normal temperatures are forecast across Alaska. The evolving upper-level pattern favors above normal precipitation across much of the Great Plains and Mississippi Valley. These increased chances of above normal precipitation also cover much of the West.

US Drought Monitor one week change map ending May 5, 2020.

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