Tools used in the U.S. Seasonal Drought Outlook (SDO) include the Climate Prediction Center (CPC) temperature and precipitation outlooks for October and October-November-December (OND), various short- and medium-range forecasts and models such as the 7-day quantitative precipitation forecast (QPF) totals from the Weather Prediction Center (WPC), the 6-10 day and 8-14 day CPC extended-range forecasts (ERFs), dynamical models at the monthly and seasonal time scale, climatology for OND, and initial conditions such as soil moisture. The U.S. Drought Monitor valid on September 17, 2024 was used for initial drought conditions.

An increasingly wet climatology (30 to 40 percent of the annual precipitation typically occurs during OND) along with increased above-normal precipitation probabilities support drought improvement and removal from the Pacific Northwest to Northern Rockies. Persistence is more likely for ongoing drought across the Great Basin and Southwest. The OND outlook depicts elevated below-normal precipitation probabilities across southern parts of Nevada and Utah along with Arizona. Despite the favored dryness on a seasonal time scale, large-scale development is not anticipated across the Southwest by the end of December. If La Niña becomes well-established this fall, then development would become more likely for this region later in the 2024-2025 winter. This may be reflected in subsequent seasonal drought outlooks.

Forecast confidence is moderate for the West Region.

An increasingly dry climatology (only 10 to 15 percent of the annual precipitation typically occurs during OND) and EC of below, near, or above-normal precipitation support drought persistence across the Dakotas, Nebraska, and Wyoming. In addition to climatology and the seasonal forecast guidance, below-normal precipitation is favored during late September for the Northern Great Plains. Farther to the south where the OND outlook favors below-normal precipitation and consistent with La Niña precipitation composites, development is most likely across portions of Kansas and southeastern Colorado.

Forecast confidence is high for the High Plains Region.

Heavy rainfall, associated with Hurricane Francine, resulted in drought improvement or removal to parts of the Lower Mississippi Valley and Tennessee Valley. However, moderate to extreme drought continues for much of Tennessee and Mississippi. Drought coverage and intensity varies farther to the west across Arkansas, northern Louisiana, Oklahoma, and Texas. Based on the OND outlook with elevated below-normal precipitation probabilities and La Niña precipitation composites, ongoing drought is forecast to persist. Development is most likely for western Arkansas, Oklahoma, and portions of Texas where 30 to 90-day precipitation deficits exist. Recent heavy precipitation and track uncertainty with any potential tropical cyclone emerging from the Gulf of Mexico preclude forecasting development across the Lower Mississippi Valley. If La Niña develops this fall, then more widespread development throughout the Southern Great Plains and Lower Mississippi Valley would become likely later into the 2024-2025 winter.

Forecast confidence is high for the Southern Great Plains and low for the Lower Mississippi Valley of the South Region.

Drought expanded and intensified across the Ohio Valley this past summer. Much of Ohio is designated with severe to exceptional drought according to the U.S. Drought Monitor. Many of the 28-day average streamflows and soil moisture are well below the 10th percentile throughout eastern and southern Ohio. The severe drought extends westward along and to the south of the Ohio River. Since mid to late September is expected to be mostly dry and unseasonably warm, drought may worsen across the Upper Ohio Valley during the next few weeks. Later in the fall and into the early winter when seasonal temperatures cool, drought intensity across the Ohio Valley may begin to stabilize and chances for soil moisture recharge would begin to increase. However, through the end of December, broad-scale persistence is the most likely outcome for much of the Ohio Valley and Middle Mississippi Valley given the lack of a wet signal at any time scale. Farther to the north across northeastern Indiana and northern Ohio where 90-day precipitation deficits are lower and the OND outlook slightly favors above-normal precipitation, drought improvement or removal is forecast. Short-term drought recently developed across parts of northern Illinois, Wisconsin, and the Upper Peninsula of Michigan. Based on the OND precipitation outlook, removal is forecast for these areas.

Forecast confidence is moderate for the Midwest Region.

The major Ohio Valley and Central Appalachians drought extends east into western Virginia. Based on near to above-normal precipitation favored from mid to late September through the beginning of October and EC of below, near, or above-normal precipitation forecast in the OND outlook, improvement or removal is favored for western Virginia. Broad-scale persistence is more likely across the Southern Appalachians and inland areas of Georgia and Alabama where the development of La Niña could lead to drier conditions by November or December. Forecast confidence for persistence is low due to high uncertainty in the track of potential tropical cyclones that may emerge from the Gulf of Mexico. The GEFS and ECMWF models are in good agreement and consistent that a tropical cyclone (TC) likely develops in the northwestern Caribbean Sea or southern Gulf of Mexico during late September. However, the predicted track varies widely among model solutions, ranging from the western Gulf of Mexico, northern Gulf Coast including the Florida Panhandle, Florida Peninsula, or offshore of the East Coast. Drought improvement or removal is slightly favored for portions of Alabama, Georgia, South Carolina, and the Florida Panhandle where the October outlook tilts wet.

Forecast confidence is low for the Southeast Region.

According to the U.S. Drought Monitor, severe to exceptional drought continues throughout much of West Virginia with moderate to severe drought designated for western Maryland and southwestern Pennsylvania. Based on large precipitation deficits (more than 5 inches) dating back to 90 and 180 days, 28-day average streamflows in the lowest 10th percentile, and equal chances (EC) for below, near, or above-normal precipitation in the OND outlook, persistence is forecast for West Virginia. Farther to the north and east across parts of southwestern Pennsylvania and western Maryland, precipitation deficits are smaller and there is a better chance for drought improvement or removal by the end of December. Removal is forecast for the short-term drought areas in Delaware, New Jersey, and northeastern Maryland due to climatology and the lack of a dry signal at any time scale. Although coastal New England has dried out recently, drought is not expected to develop and continue through the end of December for this region.

Forecast confidence is high for the Northeast Region.

Alaska became drought-free on September 17, according to the U.S. Drought Monitor. Since the OND outlook only slightly favors below-normal precipitation for parts of southeastern Alaska and given the time of year, drought is unlikely to develop.

Forecast confidence is high for Alaska.

Drought coverage and amelioration continued across much of Hawaii during the late summer. A relatively wet climatology and the likely development of La Niña favors additional improvement and removal of remaining drought for the Hawaiian Islands by the end of December.

Forecast confidence is high for Hawaii.

Puerto Rico is likely to remain drought-free due to wet initial conditions (90-day precipitation averaged more than 150% of normal and 28-day average streamflow in the upper tercile). Also, the North American Multi-Model Ensemble (NMME) favors above-normal precipitation during OND.

Forecast confidence is high for Puerto Rico.

The U.S. Virgin Islands are drought-free and given the NMME depicting increased above-normal precipitation probabilities during OND, no development is forecast.

Forecast confidence is high for the U.S. Virgin Islands.

Forecaster: Brad Pugh

Next Seasonal Drought Outlook issued: October 17, 2024 at 8:30 AM EDT