Tools used in the U.S. Monthly Drought Outlook (MDO) include the Climate Prediction Center (CPC) temperature and precipitation outlooks for August, 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 August, and initial conditions such as soil moisture. The U.S. Drought Monitor valid on July 23, 2024 was used for initial drought conditions.

A relatively dry climatology and increased chances of below-normal precipitation and above-normal temperatures in the updated August outlook support persistence for the Pacific Northwest, northern Intermountain West, and northern Rockies. Development is forecast for areas with the driest initial conditions. Although the week-2 and updated August outlooks favor above-normal precipitation for parts of Arizona and New Mexico, broad-scale persistence is forecast given the lack of heavy precipitation forecast during the first week of August and widespread improvement is not anticipated in the long-term drought areas.

Forecast confidence is moderate for the West Region.

The monthly drought outlook for the High Plains Region is complicated by a predicted pattern change from late July/early August to mid-August. Except for pockets of above-normal precipitation confined to eastern Colorado, southwestern Kansas, and central Nebraska, 30-day precipitation generally averaged below-normal across the Northern to Central Great Plains. A heat wave is ongoing at the end of July and these above-normal temperatures are forecast to continue into the beginning of August, which will lead to a rapid drying of topsoil. However, during the second week of August, the GEFS and ECMWF ensemble means depict an amplifying 500-hPa trough over central North America which is likely to result in much cooler temperatures and an increased chance of above-normal precipitation throughout the Northern to Central Great Plains. Based on the recent and ongoing heat along with little to no precipitation during the first week of August, persistence and targeted areas of development, coinciding with the driest initial conditions, are forecast. The predicted pattern change by the second week of August precludes a larger area of development being forecast.

Forecast confidence is low for the High Plains Region.

The rapid onset and intensification of drought earlier this summer affected much of Tennessee and northern Mississippi. Since the updated August precipitation outlook calls for increased below-normal precipitation and above-normal temperature probabilities, persistence is forecast for the ongoing drought areas of central Tennessee and northern Mississippi. For the remainder of the Lower Mississippi Valley and central to southern Texas, 30-day precipitation surpluses and moist topsoil preclude any development being forecast. Farther to the west across the Southern Great Plains and Rio Grande Valley, broad-scale persistence is forecast given the likelihood of above-normal temperatures during August and lack of a strong wet signal. Development is most likely across parts of central to southwestern Oklahoma and northwestern Texas where the final week of July was mostly dry and soil moisture is declining. The Southern Great Plains will be monitored closely for the rapid onset of drought which is included in CPC’s week-2 hazards.

Forecast confidence is high for the South Region.

A majority of the Midwest remains drought-free but short-term drought developed across parts of Ohio and Kentucky during late June and July. More than 1 inch of rainfall is forecast for these drought areas at the beginning of August, but the updated August precipitation outlook calls for equal chances of below, near, or above-normal precipitation. Based on the 2-week total precipitation forecasts from the GEFS and ECMWF ensemble means, improvement and removal are more likely across Ohio than Kentucky. Based on initial conditions and the updated August precipitation outlook, development is not anticipated across the Corn Belt, Ohio Valley, and Middle to Upper Mississippi Valley.

Forecast confidence is moderate for the Midwest Region.

Following the rapid onset and intensification of drought across the Carolinas, Georgia, and northern Alabama earlier this summer, a major pattern change brought beneficial rainfall to these areas during the latter half of July. From July 16 to 29, widespread rainfall amounts of more than 5 inches were observed throughout much of northern Alabama, Georgia, and the Carolinas. Based on this recent heavier rainfall and the updated August outlook leaning towards above-normal precipitation, drought removal or improvement is forecast for much of the Southeast. This improvement/removal extends north through Virginia but forecast confidence is lower especially for northern and central Virginia where rainfall amounts were much lower during mid to late July.

Forecast confidence is moderate for the Southeast Region.

Drought rapidly developed and intensified throughout the Mid-Atlantic and Central Appalachians during June and early July. This summer drought may be peaking in coverage and intensity. The WPC 7-day precipitation outlook depicts widespread rainfall amounts of 1 to 2 inches (locally more) across much of the ongoing drought areas and the updated August outlook slightly favors above-normal precipitation. Therefore, removal or improvement is forecast. Forecast confidence is lowest across the severe (D2) to extreme (D3) drought areas of West Virginia and western Maryland where impacts may linger and a slower recovery is expected.

Forecast confidence is low for the Northeast Region.

Alaska is mostly drought-free with only a small moderate drought area designated for southeastern Alaska. As a 500-hPa ridge builds over that part of the state early in August, persistence is the most likely outcome.

Forecast confidence is moderate for Alaska.

Hawaii

Persistence is forecast for ongoing drought areas of Hawaii since the GEFS and ECMWF ensemble means generally depict near to below-normal precipitation during early to mid-August. Development is not designated due to uncertainty on where it would most likely occur on the monthly time scale.

Forecast confidence is high for Hawaii.

Puerto Rico has remained drought-free since late April. Given the antecedent wetness, wet climatology, and increased chances of above-normal precipitation during August, development is unlikely.

Forecast confidence is high for Puerto Rico.

Similar to neighboring Puerto Rico and for the same reasons, the U.S. Virgin Islands are likely to remain drought-free through the end of August.

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

Forecaster: Brad Pugh

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