Tools used in the U.S. Monthly Drought Outlook (MDO) include the Climate Prediction Center (CPC) temperature and precipitation outlooks for October, 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 time scale, climatology for October, and initial conditions such as soil moisture. The U.S. Drought Monitor valid on September 17, 2024 was used for initial drought conditions.

October is a relatively dry month for the Southwest and California (post-Monsoon, a below-average East Pacific tropical cyclone season limiting recurving potential, and climatology that precipitation ramps up later in the fall and winter). This drier climatology supports persistence across ongoing drought areas of California and the Southwest. Farther to the north, persistence is also forecast for the Northern Rockies and Pacific Northwest with a dry start to October and no signs of any early season wetness. Although the updated October outlook depicts increased below-normal precipitation probabilities, no large-scale development is anticipated since drought development tends to be slower for this region. If La Nina develops, then development would become more likely beyond the end of October.

Forecast confidence is high for the West Region.

September was drier and warmer-than-normal for much of the Northern to Central Great Plains. The NASA SPoRT tool depicts soil moisture below the 10th percentile for this region. Based on this antecedent dryness along with increased chances of below-normal precipitation and above-normal temperatures during October, drought is likely to expand across the Northern to Central Great Plains. Development is forecast for portions of eastern Kansas, eastern Nebraska, and southeastern South Dakota where 90-day precipitation has average less than 50 percent of normal and 30 to 90-day precipitation deficits are more than 2 and 5 inches, respectively. Favored dryness during October supports persistence for ongoing drought across Colorado and Wyoming.

Forecast confidence is high for the High Plains Region.

Heavy to excessive rainfall, associated with Hurricane Helene and its remnants, leads to drought improvement or removal for nearly all of the ongoing drought across Tennessee. Increased below-normal precipitation probabilities in the updated monthly outlook support persistence for ongoing drought across the Lower Mississippi Valley and Southern Great Plains. The most likely areas to have drought development by the end of October include western Arkansas, eastern and central Oklahoma, as well as eastern and northern Texas. These development areas generally have 30-day precipitation deficits and declining soil moisture. In addition to the favored October dryness, periods of unseasonably warm temperatures are expected which would result in higher evapotranspiration rates.

Forecast confidence is high for the South Region.

Following heavy rainfall associated with the remnants of Helene at the end of September, drought improvement is expected for portions of the Ohio Valley. Please note that even though the updated October outlook tilts towards below-normal precipitation, improvement was warranted due to the recent heavy precipitation. Farther north from the Ohio River, rainfall amounts were lower than 2 inches and with October favored to be on the drier side, persistence is forecast for eastern to northern Ohio, northern Indiana, and Illinois. Short-term drought recently developed across parts of Michigan and Wisconsin and those drought areas are likely to persist with no signs of beneficial precipitation anytime soon. Development is forecast for portions of Iowa where 30 to 90-day precipitation deficits are more than 2 and 5 inches, respectively. Given this antecedent dryness, a dry start to October along with above-normal temperatures is expected to result in at least moderate drought (D1) for western Iowa.

Forecast confidence is moderate for the Midwest Region.

As Hurricane Helene tracked inland, widespread heavy to flooding rainfall affected a large portion of the western Carolinas, Georgia, Alabama, and the Florida Panhandle. Removal is forecast for moderate drought (D1) areas that received more than 2 inches or severe drought (D2) areas that had more than 5 inches. Improvement is more likely across the severe drought (D2) area of northeastern Alabama that received 2 to 3 inches of rainfall. Given the antecedent wetness heading into October and the updated monthly outlook favoring either above-normal precipitation or equal chances of below, near, or above, development is unlikely through the end of October.

Forecast confidence is high for the Southeast Region.

According to the U.S. Drought Monitor valid on September 24, severe to exceptional drought is designated for much of West Virginia along with portions of western Maryland and southwestern Pennsylvania. Improvement or removal is forecast for areas that received heavy rainfall (more than 2 inches) associated with the remnants of Hurricane Helene. For areas that received lower rainfall amounts during the final week of September, persistence is forecast for central to northern West Virginia, western Maryland, and southwestern Pennsylvania. Short-term moderate drought is ongoing for parts of the Mid-Atlantic and New England. Due to mostly dry weather likely during the first week of October and equal chances of below, near, or above-normal precipitation in the updated monthly outlook, persistence is forecast from northeastern Maryland and Delaware north to New England.

Forecast confidence is moderate for the Northeast Region.

Alaska became drought-free on September 17, according to the U.S. Drought Monitor. Due to a relatively wet climatology, Alaska is likely to remain drought-free through the end of October.

Forecast confidence is high for Alaska.

Since late August, drought coverage and intensity remained either steady or decreased. Based on the North American Multi-Model Ensemble with increased below-normal precipitation probabilities, persistence is forecast.

Forecast confidence is moderate for Hawaii.

Although southern Puerto Rico dried out recently with 30-day precipitation deficits, development is not expected with 28-day streamflows near average and the North American Multi-Model Ensemble (NMME) favoring above-normal precipitation. Antecedent wetness makes development highly unlikely for the remainder of Puerto Rico.

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 October, no development is forecast.

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

Forecaster: Brad Pugh

Next Monthly Drought Outlook issued: October 31, 2024 at 3:00 PM EDT