Nationwide
A strong area of mid-level low pressure near the West Coast resulted in anomalously wet weather during the first week of May throughout the Pacific Northwest, Northern Rockies, Great Basin, and California. Scattered thunderstorms brought pockets of heavy rainfall (more than 2 inches), from May 2 to 8, to parts of Texas, central Nebraska, and the Midwest. However, much of Kansas, Missouri, and southern Nebraska missed out on this beneficial rainfall.
{{tncms-asset app=”editorial” id=”90713c56-f009-11ed-854f-f3ba774624e3″}}
Following a wet end to April across the East, drier weather prevailed this past week from the Mid-Atlantic south to Florida. 7-day temperatures, ending on May 8, averaged below normal across most of the East along with California, the Great Basin, and Desert Southwest. Weekly temperatures averaged above normal across the Great Plains.
{{tncms-asset app=”editorial” id=”8623fdba-f009-11ed-8810-83443aff8fa4″}}
The West
Anomalously wet, cool weather prevailed across the West at the beginning of May. A 1-category improvement was made to parts of northern California after the wet start to the month and this improvement was also consistent with the 24-month Standardized Precipitation Index (SPI), National Drought Mitigation Center (NDMC)’s long-term drought blend, and NASA’s Gravity Recovery and Climate Experiment (GRACE) groundwater. It should be noted that Trinity Reservoir in northern California remains at half of its historical average.
{{tncms-asset app=”editorial” id=”8f5f53d4-f009-11ed-9bcf-6fc5de5d71d7″}}
A 1-category improvement was also warranted for parts of Oregon based on 24-month SPI, GRACE 1-meter soil moisture, and the wet first week of May. A decrease in abnormal dryness (D0) across parts of Washington was supported by SPI at multiple time scales, 28-day streamflow, and GRACE soil moisture.
Based on 60-day SPI and longer time scales, moderate drought (D1) was reduced in coverage across southwestern Wyoming. D1 was changed to long-term abnormal dryness (D0) in northeast Montana based on SPI at multiple time scales and a favorable soil moisture response this spring down to 20 inches this spring. Severe drought (D2) was removed from central Utah due to a lack of support from long-term indicators.
The High Plains
Convective rainfall, typical for early May, occurred this past week across parts of Kansas and Nebraska. In areas such as central Nebraska, which received more than 2 inches of rainfall and a lack of support from SPI at various time scales and NDMC’s objective drought blends, a 1-category improvement was made.
{{tncms-asset app=”editorial” id=”8ee2ec22-f009-11ed-ad4f-cf8fd119677c”}}
However, in areas that missed out on this rainfall, a 1-category degradation was necessary for parts of southern Nebraska and central to eastern Kansas. According to the USDA, 64% and 68% of the pastures and ranges for Kansas and Nebraska, respectively, are rated poor to very poor.
Abnormal dryness (D0) was expanded westward near and along the Colorado Rockies based on SPIs at various time scales. An increase in severe drought (D2) coverage was justified for parts of the High Plains of eastern Colorado that missed out on the recent heavier precipitation. Based on multiple indicators, including Condition Monitoring Observer Reports, abnormal dryness (D0) was reduced across northern parts of North Dakota.
The South
This past week, a mix of degradations and improvements were made to the Southern Great Plains, western Gulf Coast, Lower Mississippi Valley, and Tennessee Valley. Severe drought (D2) was slightly expanded in southeast New Mexico, based on 90-day SPI and USGS 28-day average streamflows falling below the 10th percentile along parts of the Black River. Based on declining soil moisture indicators, extreme drought (D3) was expanded westward across the Edwards Plateau.
{{tncms-asset app=”editorial” id=”8e7e9128-f009-11ed-ae0e-77e2b529e013″}}
More than 1.5 inches of rainfall this past week resulted in a 1-category improvement to parts of central and northwest Texas, the Texas Panhandle, and central Oklahoma. According to NDMC’s long-term objective drought blend, a sharp gradient remains between extreme to exceptional drought (D3-D4) in northwest Oklahoma to anomalously wet conditions in southeast Oklahoma. An increase in abnormal dryness (D0) was warranted for parts of northwest Arkansas based on increasing 30-day precipitation deficits and 28-day average streamflows below the 30th percentile.
The D0 coverage was modified across Tennessee after central parts of the state received more than 1.5 inches of rainfall. However, D0 was expanded to include more of western and northeastern Tennessee, based on 30 to 60-day SPI and 28-day average streamflows. Recent heavy rainfall and 120-day SPI supported the elimination of D0 in coastal Mississippi and a slight D0 decrease in southeastern LA. Also, moderate drought (D1) coverage decreased across southeastern Louisiana. A small area of D0 was added to central Louisiana, where 30 to 60-day precipitation deficits are increasing. — UNL Drought Monitor
{{tncms-asset app=”editorial” id=”878494a8-f009-11ed-bb8f-73ee187661c7″}}
{{tncms-asset app=”editorial” id=”8bca18bc-f009-11ed-9942-5765516f9f6b”}}
