Drought top story in southern Plains

An intense low-pressure system moved across the contiguous U.S., bringing heavy precipitation (greater than 2 inches) across much of the central Plains and Midwest this past week.

The most widespread improvements were made to northern Nebraska, eastern South Dakota, southern Minnesota, southern Wisconsin, northern Indiana and southern Texas where more well above normal precipitation was observed. Dry conditions continued across much of the Southern region, with widespread degradations occurring across the Tennessee Valley, central Mississippi Valley and northern parts of the southern Plains.

South

Dry conditions continue across much of the Southern region. Exceptional drought (D4) and extreme drought (D3) was expanded in central and northern Mississippi, while D3 was expanded into northern Louisiana.

Moderate drought (D1) to severe drought (D2) was expanded in southern Arkansas. Board 1-category degradation occurred over the states of Oklahoma and Tennessee. Plus parts of western, central and northern Texas, where dryness continues to degrade conditions.

Precipitation in these areas are around 1 to 2 inches below normal for the month. The drought expansion and intensification was based on short-term SPI/SPEI, NDMC’s short-term blend, streamflow and soil moisture data.

While heavy precipitation brought improvements to parts of southern and eastern Texas and in southern Mississippi, with some areas reporting over 2 inches of rainfall. The result was exceptional drought being removed from southern Mississippi and extreme drought was removed from southern Texas.

Midwest

A broad 1-category improvement was made to southern Minnesota, southern Wisconsin, northern Illinois and northern Indiana and in parts of Iowa and Ohio. More than an inch of precipitation occurred. Some areas receiving more than 5 inches of precipitation.

This excess precipitation, in these areas, alleviated longer-term precipitation deficits and improved soil moisture and streamflow impacts. This meant improvements to abnormal dryness (D0) and all drought categories. Exceptional drought (D4) was from the region, located in eastern Iowa, and extreme drought (D3) from parts of central and southwest Minnesota.

Meanwhile, dry conditions continue to affect the northern and southern parts of the region. Parts of northeastern Wisconsin continues to be dry, resulting in the expansion of moderate drought (D1) and severe drought (D2), while D0 and D1 was expanded into parts of northwest and southeast Missouri. Degradations were supported by precipitation deficits, short-term SPI/SPEI timescales, streamflow and soil moisture data.

High Plains

Heavy precipitation brought widespread improvements to the southeastern parts of the region, especially along the South Dakota and Nebraska border. Much of northern Nebraska received at least 2 inches of precipitation, with some areas reporting more than 7 inches.

Board 1-category improvements were made across northern Nebraska, while 2-category improvements were made where historic rainfall was reported. The heavy precipitation also improved abnormal dryness (D0) and moderate to severe drought (D1-D2) conditions in eastern South Dakota, as shown in short-term SPI/SPEI timescales and soil moisture data.

A small area in southwest Nebraska, Chase County, was degraded to D1 due to acute dryness over the past two months and justified by short-term SPI/SPEI data and soil moisture being consistently under the 20th percentile.

In Kansas, northern parts of the state received precipitation this past week but not enough to lead to large improvements. Precipitation did improve a small area of extreme drought (D3) in the central part of the state, in the counties of McPherson and Saline.

Status quo was maintained across much of the state with some degradation occurring along the eastern part of the state based on SPI/SPEI and soil moisture data.

West

Beneficial precipitation led to improvements in moderate drought to extreme drought (D0-D3) in portions of northwest Montana, as shown in SPI/SPEI, streamflow and soil moisture data. Status quo was maintained across the rest of the region.

Looking ahead

During the next five days, Oct. 19 to 24, a front extending from the upper Mississippi Valley to the southern High Plains will move eastward to the Lower Great Lakes/Mid-Atlantic to the Central Gulf Coast by Friday. The system will produce rain over parts of the Upper/Middle Mississippi Valley on Wednesday evening, moving into the Great Lakes/Ohio Valley by Thursday and continuing eastward into Friday.

On Oct. 21, guidance shows potential for significant rainfall over parts of the Northeast, while the West is forecasted to receive rain from the weekend into next week. Some of the precipitation over the West should fall as snow in the higher northern Rockies, with snow levels gradually declining with time.

The Climate Prediction Center’s six- to 10-day outlook, Oct. 23 to 27, favors near to above-normal precipitation throughout much of contiguous U.S. Increased probabilities for above-normal temperatures are forecast from the Plains to the East Coast. Below-normal temperatures are likely across much of the West.

Rocky Bilotta is with the National Oceanic Atmospheric Administration and National Centers for Environmental Information.