Nationwide
A pair of low-pressure systems tracked from the Southeast northward along the East Coast, bringing a swath of widespread precipitation (2 to 4 inches, locally more) to much of the East Coast at the end of April.
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During the final week of April, the Southern Great Plains, along with the Lower Mississippi Valley, also received widespread precipitation with amounts exceeding 2 inches across southeastern Colorado, northern and eastern Oklahoma, and northeastern Texas. Late April was mostly dry across the Central to Northern Great Plains and Middle Mississippi Valley.
Little to no precipitation was observed throughout the West, where a significant warmup at the end of April resulted in rapid snowmelt, runoff, and flooding along streams and rivers. In contrast to these above-normal temperatures, cooler-than-normal temperatures occurred across the Great Plains, Corn Belt, and much of the East from April 25 to May 1.
The West
30 to 60-day Standard Precipitation Index (SPI), along with soil moisture indicators, support an expansion of abnormal dryness (D0) and moderate drought (D1) across southeastern Montana. 30 to 90-day SPIs, recent warmth, and soil moisture led to a 1-category degradation in northwestern Montana.
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Following significant improvements across California and the Great Basin during the past few months, no changes were made this week after little or no precipitation. The drought of varying intensity is designated for parts of Oregon and northern Idaho, where precipitation averaged below normal for the Water Year to Date (October 1, 2022 to May 1, 2023).
The High Plains
Rainfall of 1.5-2 inches or more during the past week, along with SPI at various time scales and soil moisture, supported a 1 to 2-category improvement to southeastern Colorado.
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For similar reasons, a 1-category improvement was made to southwestern Kansas. However, 12-month SPI still supports D3-D4 across much of western and central KS. Wichita has only received 0.72 inches of precipitation from March 1 to April 30, which made it the 2nd driest March and April on record and the driest since 1936. Based on the National Drought Mitigation Center’s short and long-term objective blends and Climate Prediction Center’s (CPC) leaky bucket soil moisture, D1-D3 expansion was warranted for northern Kansas and south-central Nebraska.
Extreme drought (D3) was increased westward across west-central Nebraska following a very dry April. North Platte tied for the driest April on record. Degradations were also made to southeastern Kansas based on the 60 to 120-day Standardized Precipitation Evapotranspiration Index (SPEI). Abnormal dryness (D0) coverage increased in northeastern Wyoming based on recent dryness and declining soil moisture. A slight improvement was made to the southwest corner of South Dakota, based on a local report that was consistent with VegDri and objective drought blends.
The South
Balancing longer term SPIs and recent widespread rainfall (1-3.5 inches), a 1-category improvement was made to parts of Oklahoma and Texas.
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Improvements were also made to parts of central Texas along with the Texas Gulf Coast after more than 1.5 inches of rainfall this past week. CPC’s leaky bucket soil moisture and 90 to 120-day SPI supported a slight expansion of moderate (D1) to severe (D2) drought in west-central Texas. Based on soil moisture considerations and impact reports (very dry pastures), extreme (D3) drought was increased in coverage across the Texas Panhandle. The addition of abnormal dryness (D0) in east-central Tennessee was based on increasing 30-day deficits, SPEI, soil moisture, and 28-day average streamflows. — UNL Drought Monitor
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