Drought Outlook: Improvements for the Plains, Further Deterioration in Southeast

Although development and intensification of drought becomes less likely as temperatures cool this fall, persistence is favored across the long-term drought areas of the Northeast. Prospects for drought removal improve to the west across northern Ohio, northeast Indiana, and lower Michigan where drought is more short-term in duration.

Drought persistence is forecast across the interior Southeast, and parts of Alabama, Georgia, Tennessee, and the upstate of South Carolina are the most likely areas for development through the end of November.

Improvement or removal of drought is favored across the Great Plains along with southeast Arizona and New Mexico. Persistence is forecast across the protracted drought areas of the West, while removal is favored along coastal Oregon where it becomes wetter earlier during the fall season.

The small remaining drought area across Puerto Rico is likely to be removed by the end of November. Drought removal is also forecast across Hawaii.

Forecast confidence is high for California and moderate for the remainder of the West.

• During the past month, drought coverage and intensity remained nearly steady across the West with development or intensification limited to parts of the Great Basin, northern Rockies, and eastern Oregon.
• Outside of the wetter monsoon areas of Arizona and New Mexico, persistence is most likely throughout most of the West given the long-term duration of the drought and the drier climatology through October.
• Removal is forecast for the small drought area along coastal Oregon as this area typically becomes wetter earlier in the fall season.

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Forecast confidence for southeast Arizona and western New Mexico is low.

• Although the AHPS indicates that most of southeast Arizona and western New Mexico received above-normal rainfall during the past 30 days, only minor improvements were made to the USDM depiction.
• Rainfall expected during the next week along with a relatively wet climatology through September favors improvement or removal of drought across southeast Arizona and western New Mexico. However, forecast confidence is low considering that monsoon rainfall in these areas is typically convective and scattered.

Forecast confidence for the northern and central Great Plains is low.

• Parts of the northern and central Great Plains are currently designated with moderate (D1) to extreme (D3) drought, with the most widespread drought centered across the northern high Plains. An amplifying upper-level trough is expected to bring 0.5 to 2.0 inches of rainfall during the next few days to most these drought areas.
• The CPC seasonal precipitation outlook features a tilt in the odds for above-median precipitation across the northern Great Plains. Based this seasonal precipitation outlook and short-term rainfall, improvement or removal is forecast. However, forecast confidence is tempered since the next three months are an increasingly dry time of year.

Forecast confidence for the southern Great Plains is moderate.

• Small areas of moderate to severe drought are currently depicted on the U.S. Drought Monitor across parts of Oklahoma, Texas, and southeast New Mexico.
• A forecast for improvement and removal of these drought areas is mostly based on rainfall expected during the remainder of August.
• The WPC indicates a broad area of more than 3 inches of rainfall, from southeast Oklahoma extending to the middle Rio Grande Valley, during the next week. The GFS model favors a continuation of above-median rainfall during the Week-2 period.
• Due to the increased rainfall and cloud cover forecasted, below-normal temperatures are also favored during the remainder of August.

Forecast confidence for the Southeast is moderate.

• Abnormal heat (temperatures averaging 1 to 3 degrees F above-normal) coupled with insufficient rainfall this summer also led to drought development and intensification across the Southeast. Soil moisture ranks in the lowest 10th percentile across much of the northern third of Georgia, prompting the U.S. Drought Monitor (USDM) to designate this area with D2 (severe) to D3 (extreme) drought.
• The CPC seasonal outlook for SON favors below-median precipitation for the interior Southeast. Given the continued worsening of drought, a dry signal in the seasonal precipitation tools, and a relatively dry climatology (15 to 20 percent of annual precipitation occurs during SON), drought persistence and development is forecast for parts of Alabama, Georgia, Tennessee, and the western Carolinas.
• During early to mid-August, an upper-level low tracked west along the Gulf Coast and resulted in major flooding across Louisiana. The heaviest rainfall associated with this upper-level low missed most of the ongoing drought areas of northeast Mississippi.
• The enhanced odds for below-median precipitation during SON favors persistence for the ongoing drought across Mississippi, but additional development is not expected due to rainfall forecast during the next two weeks.

Forecast confidence is low for the Northeast and moderate across Ohio, northeast Indiana, and lower Michigan.

• Inadequate rainfall and above-average temperatures (1 to 3 degrees F above-normal) resulted in drought expansion and intensification across parts of the Northeast along with Ohio, northeast Indiana, and lower Michigan this summer.
• The Advanced Hydrologic Prediction Service (AHPS) indicates that 180-day precipitation deficits are locally more than 8 inches across parts of the Northeast. As examples, the precipitation deficit is nearly 8 inches at both Boston and Buffalo since January 1.
• Due to these long term precipitation deficits and without a wet signal among the precipitation tools, persistence is most likely for the ongoing drought areas of New England along with parts of New York and Pennsylvania.
• By the end of November, drought is more likely to be removed (in current areas of D1) across northern Ohio, northeast Indiana, and lower Michigan due to the shorter duration of the drought in these areas.
• Short-term drought development remains a concern during the next month across the upper Ohio Valley. It should be noted that as temperatures cool this fall and evapotranspiration rates decrease, drought expansion and further intensification of drought across the Northeast becomes less likely.
• Forecast confidence is low across the Northeast due to varying factors such as the decreasing evapotranspiration rates, weak signals among precipitation tools, and the long-term precipitation deficits.

Forecast confidence for Hawaii is moderate.

• During the past El Niño, drought coverage peaked at nearly 80 percent of the Hawaiian Islands in early April. Since that time, that coverage decreased and is currently less than 15 percent.
• The enhanced odds for above-median precipitation forecast during SON favors continued removal of drought.

Forecast confidence for Puerto Rico is high.

• Only a small area of moderate drought (less than 7 percent coverage) persists across Puerto Rico.
• Based on a relatively wet climatology and the potential for La Niña conditions to develop, removal of this drought area is likely.