Much of High Plains keeps missing out on moisture

This week was defined by a significant precipitation divide, highlighted by a major deluge across parts of the South and Gulf Coast.

Persistent storm systems funneled heavy moisture into Louisiana, Mississippi, and Alabama, where total rainfall reached 4 to 6 inches—and in some coastal pockets even higher—representing departures of 3 to 5 inches above seasonal norms.

While an active frontal corridor brought a secondary band of moderate rain (1 to 3 inches) from Texas through the Ohio Valley and into the Northeast, the Western U.S. remained exceptionally dry, with most areas west of the Rockies receiving less than 0.1 inch of rain. This lack of moisture, paired with blustery winds, triggered extreme fire danger across the Upper Mississippi Valley, though the period concluded with a pattern shift as a significant Pacific low-pressure system finally moved onshore to deliver moisture to the Northwest.

Temperature patterns showed an equally sharp geographical split, with unseasonable warmth gripping the West and parts of the South while a late-spring chill lingered over the North. In the Southwest and South Texas, summer-like heat took a firm hold as Rio Grande Village, Texas, hit a national high of 105 degrees Fahrenheit and Death Valley consistently reached the triple digits; overall, the Western U.S. averaged 5 to 15 degrees above normal.

Conversely, a significant cool-down settled over the Northern Plains and Upper Midwest, where the Dakotas and Minnesota experienced temperatures 5 to 15 degrees below seasonal averages. This thermal contrast was further sharpened by winter-like conditions in high-elevation regions of the West, where stations in Utah recorded lows as cold as 10 degres, even as record-challenging warmth began to expand across the Pacific Northwest and the Southern Border states.

South

The Southern region experienced a stark contrast in both precipitation and temperature during the week, defined by torrential Gulf Coast rains and a significant late-spring chill across the interior.

Precipitation was most intense across the central Gulf Coast, particularly in Louisiana and southern Mississippi, where weekly totals reached 7 to over 9 inches. These amounts represent exceptional departures of 6 to 7.5 inches above normal. Moderate to exceptional drought was reduced in southern and eastern portions of Texas.

Abnormal dryness was improved in parts of Texas. Conversely, drier conditions prevailed in west Texas and Oklahoma. Exceptional drought was introduced in southwest Oklahoma and from the Texas Panhandle into northwest Oklahoma, and expanded in parts of Arkansas.

Extreme drought expanded in northern portions of Texas and western Oklahoma. Heat persisted in southern Texas, where average temperatures reached the 80s and 90s, representing departures of up to 5°F above normal. However, a powerful cold anomaly gripped the northern, eastern, and central portions of the region. In these areas, temperatures were broadly 5 to 10 degrees below normal for the week.

Midwest

The Midwest region experienced a widespread late-spring chill and a stark contrast in moisture levels between the north and south. Temperatures were broadly below average across the entire region, with the vast majority of the Midwest observing departures of 5 to 10 degrees below normal.

Average temperatures ranged from a cool 30 to 40 degrees along the northern border of Minnesota and Wisconsin to the more seasonable 60 to 70 degrees in the southern reaches of Missouri and Kentucky. Precipitation was notably sparse across the northern half of the region, including Minnesota and Iowa, where totals remained under 0.1 inches, resulting in departures of 0.5 to 1.5 inches below normal.

In contrast, the southern tier—particularly across southern Missouri—saw more active weather with precipitation totals ranging from 1.5 to over 3 inches. Abnormal dryness was also expanded in parts of Minnesota, western Iowa and southern Missouri.

High Plains

Anomalous warmth dominated most of the High Plains, while precipitation was defined by a significant east-west gradient. The eastern portions of the region, remained under a persistent late-spring chill with average temperatures falling 4 to 10 degrees below seasonal norms. This area was also exceptionally dry, receiving less than 0.05 inches of rain, which resulted in precipitation deficits of 0.6 to 1.2 inches.

Persistent dryness resulted in the expansion of exceptional drought in Nebraska, while and moderate to extreme drought were expanded in northeastern Wyoming, South Dakota, Nebraska, and Kansas.

In contrast, the western High Plains across Wyoming, much of Colorado, and western portions of South Dakota and Nebraska, experienced unseasonable warmth, with departures ranging from 2 to 6 degrees above normal.

This warmth was accompanied by an active moisture corridor through the southern High Plains; while northern and eastern reaches were dry, portions of Colorado and adjacent areas of Wyoming and Kansas recorded 0.7 to 1.6 inches of precipitation, ranging from 0.3 to 0.9 inches above normal.

This above-normal precipitation resulted in the removal of exceptional drought and reduction of extreme drought in Wyoming, and improvements to severe drought to exceptional drought in Colorado and severe to extreme drought in western Kansas.

West

The West was characterized by unseasonable warmth and widespread dryness across the Pacific Coast and Great Basin, contrasted by cooler, more active conditions in the Rocky Mountains.

The eastern portion of the region—specifically eastern portions of Montana and New Mexico—remained notably cooler, with departures ranging 3 to 6 degrees below normal.

Extreme drought was expanded in Montana. Severe and moderate drought was expanded in Montana.

Looking ahead

Over the next five days (May 12 to 16), weather patterns across the United States will feature a stark contrast between record-challenging heat in the West and unsettled, cooler conditions in the East.

A building atmospheric ridge will maintain well-above-normal temperatures across the western U.S., with several high-temperature records likely to be tied or broken as this warmth spreads into the central Plains by mid-week.

Conversely, the eastern half of the country can expect near to below-normal temperatures as a series of frontal systems bring frequent rounds of showers and thunderstorms from the Midwest to the Atlantic Coast. Meanwhile, an incoming Pacific low-pressure system is forecast to deliver light to moderate precipitation to the Pacific Northwest and northern Rockies, while gusty winds may accompany the passage of these weather systems across the Rockies and Great Plains.

Further out, the Climate Prediction Center’s 6– to 10-day outlook (valid May 17 to 21) favors above-normal temperatures most of the contiguous U.S.

Probabilities for above-normal precipitation are increased across the vast majority of the lower 48 states.

Rocky Bilotta is with NOAA and NCEI.