Heavy Rain Improves Drought In Localized Spots, Drying Persists Elsewhere
An active spring-like weather pattern occurred throughout the U.S. last week. However, any precipitation that fell was not distributed equally, causing some areas to stay unusually dry while locally heavy rain and mountain snow benefited other spots.
West
There was a sharp contrast between temperatures and precipitation throughout the West last week. Near to below normal temperatures and beneficial moisture occurred throughout the Northwest. Meanwhile, the Southwest had unseasonable warmth and dry weather.
A highly active storm track for most of Washington and parts of Oregon and Montana allowed for weekly rainfall totals of 1.5 to 3.5 inches, with localized totals in the Cascade Range exceeding 4.5 inches. Abnormal dryness (D0) and moderate to severe drought (D1-D2) saw improvements in Washington and northern Idaho. Abnormal dryness also contracted in northwestern Oregon and western Montana.
Conversely, widespread areas across California, Nevada, Arizona, New Mexico and parts of Idaho, Montana and Utah recorded negligible rainfall totals of less than one-tenth inch. Due to the climatological onset of the dry season in parts of the West, this lack of rainfall translated into modest negative departures for the week. Nonetheless, deteriorating conditions led to the expansion of exceptional drought (D4) in southern Idaho and extreme drought (D3) in parts of New Mexico, Arizona, Utah, Montana and southern Idaho. In addition, severe drought (D2) was expanded in Oregon, Montana and Arizona. Moderate drought (D1) expanded in parts of Idaho, Montana, Nevada and Arizona.
High Plains
Similar to the West, the High Plains saw a wide variety of weather impacts last week. Unseasonable warmth gripped the southern half of the region, including Kansas, Colorado and parts of Nebraska. Temperatures were largely nearly or slightly below average for the northern half of the region, including Wyoming and the Dakotas. Precipitation varied across the region, with extreme dryness across much of the region. However, there was a highly concentrated deluge across some southern areas.
Large portions of Wyoming, Colorado and western parts of the Dakotas, Nebraska and Kansas remained fairly dry last week. Weekly totals remained one-half inch, with extensive areas receiving less than one-tenth inch. This lack of precipitation and mounting precipitation deficits cause conditions to deteriorate for most areas. Extreme drought (D3) expanded in southwestern Kansas and south-central Colorado. Severe drought (D2) worsened in parts of Colorado and northeastern Wyoming, while moderate drought (D1) expanded in parts of South Dakota.
In opposition, intense thunderstorm activity generated a sharp corridor of heavy rainfall across eastern portions of Kansas and Nebraska as well as northern Colorado and southern Wyoming. Rainfall totals in these localized areas reached 2.5 to 5.5 inches. Improvements to moderate to exceptional drought (D1-D4) improved in Nebraska. Moderate to extreme drought (D1-D3) contracted in Kansas. Northern Colorado say improvements to severe to exceptional drought, while there was also a reduction of exceptional drought (D4) in southern Wyoming this week.
Midwest
While there was localized heavy rain in spots, the Midwest region largely saw dry weather last week. Temperatures also ended up being warmer than normal throughout the region.
The most significant rain occurred in southern Iowa, northern and central Missouri and west-central Illinois, where a series of storms dropped widespread rainfall totals of 2.5 to 5.5 inches, with a localized amount of 6.25 inches in south-central Iowa and north-central Missouri. Unfortunately, most of this beneficial moisture fell over spots already free of dryness and drought. Eastern Iowa did see some slight improvements to abnormal dryness (D0).
At the same time, the northern and eastern fringes of the region received less than one-half inch of rain. Much of Kentucky, however, reported less than one-tenth inch of rain for the week. Extreme drought (D3) expanded throughout much of Kentucky, with moderate to severe drought (D1-D2) increasing across far northern Kentucky. Abnormal dryness and moderate drought (D0-D1) worsened in localized portions southern portions of Missouri, Illinois, Indiana and Ohio. Abnormal dryness was added to northeastern Illinois, while a small portion of abnormal dryness increased in west-central Minnesota.
South
Below normal rainfall and above normal temperatures dominated the South last week. The vast majority of Texas, Oklahoma, Arkansas, Louisiana, Mississippi and Tennessee received less than one-half inch of rainfall. This resulted in the introduction of exceptional drought (D4) in the Oklahoma Panhandle, while exceptional drought expanded in parts of Arkansas and Mississippi. Severe to extreme drought (D2-D3) were expanded in parts of Oklahoma, Arkansas, Mississippi and Tennessee.
The major exception to this dry regime was concentrated in southern portions of the region, specifically southern Texas where thunderstorms delivered 1 to 3 inches of rainfall. This resulted in improvements to extreme drought (D3) in southern portions of Texas, Louisiana and Mississippi.
Southeast
There were the haves and the have nots throughout the Southeast this week. A vast majority of Mississippi, Alabama, Georgia, the Carolinas and Virginia receiving less than one-quarter inch of total rainfall for the week. Exceptional drought (D4) was introduced in western North Carolina, while extreme drought (D3) expanded across parts of Virginia, eastern North Carolina and central South Carolina. Severe drought (D2) was also expanded in northeastern portions of North Carolina.
Significant rainfall was strictly confined to the southern peripheries of the Southeast. Localized thunderstorms delivered 2.0 to 3.5 inches of rain along the eastern Georgia-Florida border and across southern Florida. Exceptional drought (D4) improved in portions of southern Georgia and within the Florida Panhandle. Improvement to extreme drought (D3) occurred in central and southern Georgia, southern Alabama and in northern and eastern parts of Florida.
Northeast
The majority of the Northeast experienced near to above normal temperatures last week, while there was a sharp divide in precipitation. The heaviest rainfall occurred across northern New York, Vermont, New Hampshire and western Maine, where totals reached 2.0 to 3.5 inches. Conversely, a vast swath covering much of West Virginia, Maryland, Delaware, Pennsylvania and parts of southern New York, southern New England and northern Maine received less than one-half inch of rain, with many areas seeing less than one-tenth inch.
Abnormal normal rainfall justified improvements to abnormal dryness (D0) and moderate to severe drought (D1-D2) in Maine, New Hampshire, Vermont and eastern New York. Abnormal dryness was also improved in central Pennsylvania.
In contrast, widespread precipitation deficits led to expansion of abnormally dry and drought conditions. Extreme drought (D3) was introduced in southern and eastern West Virginia, while severe drought (D2) expanded in central parts of the state. Moderate drought (D1) was also expanded in southern portions of New England and south-central Pennsylvania this week.
Looking Ahead
The U.S. is expected to experience a highly active and contrasting weather pattern through the end of the upcoming drought monitoring period.
An early-season heatwave will dominate much of the Central and Eastern U.S. to start the forecast period, with interior areas of the Mid-Atlantic and Carolinas reaching the lower to middle 90s. Some locations could challenge daily temperature records before a cold front arrives for the second half of the drought monitoring period, bringing cooler and more seasonable conditions. At the same time, the Intermountain West and Rockies will remain unusually cold, with late-season snow expected in the higher elevations of Colorado and Wyoming.
During the first half of the drought monitoring period, the strong cold front moving across the Plains and Midwest will also trigger widespread showers and severe thunderstorms. Heavy rainfall may lead to scattered flash flooding to start the forecast period, especially across Texas, Oklahoma, and Arkansas. The risk of excessive rainfall is forecast to expand from western Texas eastward into the central Appalachians by the middle of the period, increasing the potential for flooding and storm-related disruptions across a broad portion of the country.
For the second half of the period, the outlook also points toward a widespread wetter-than-normal pattern across most of the country. Increased precipitation chances extend from the Southwest to the East Coast, with the greatest likelihood of above-average rainfall focused on southern Texas. The West Coast, Pacific Northwest, northern Rockies and northern Midwest are projected to receive near-normal precipitation. Notably, no regions of the country are currently favored to experience below-normal rainfall.
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Source: U.S. Drought Monitor