Tools used in the U.S. Seasonal Drought Outlook (SDO) include the Climate Prediction Center (CPC) temperature and precipitation outlooks for December and December-January-February (DJF), 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 DJF, and initial conditions such as soil moisture. The U.S. Drought Monitor valid on November 19, 2024 was used for initial drought conditions. La Nina conditions are likely to emerge by the end of December 2024 and persist through March 2025 and is a factor in this outlook.

The Western region has experienced a combination of both degradation and improvement of abnormal dryness (D0) and drought (D1-D4), as depicted in the U.S. Drought Monitor (USDM) since mid-October. The degradation of abnormal dryness and drought was predominantly limited to parts of the southwestern contiguous U.S. (CONUS) and central to eastern Montana, where many locations experienced less than 50 percent of their average precipitation over the last 30 days. Conversely, parts of the Pacific Northwest and northern Rockies experienced improving conditions, associated with an active storm track. This has resulted in above average snowpack for this time of year, stream flows running near to above normal, and improvements to soil moisture. Looking ahead through the DJF season, precipitation and temperature outlooks favor a continuation of the active, wet pattern and cooler than average temperatures, respectively, which will likely lead to additional improvements to, and removal of, drought conditions in the Pacific Northwest and northern Rockies. In the southwestern CONUS and the central Rockies, however, drought persistence is predominantly favored. This broad persistence is due to offsetting signals associated with La Nina and the climatological winter rainy season for these regions, in addition to very dry soils. Some drought development is favored in portions of southern Arizona where warmer and drier than average conditions are more strongly favored in the Climate Prediction Center’s (CPC) seasonal temperature and precipitation outlooks.

Forecast confidence is moderate to high for the Western region.

Drought has been slow to develop or intensify across much of the Northern Plains since mid-October, associated with warmer than average temperatures (widespread 5 to 10 degrees Fahrenheit above normal) and below normal precipitation for many locations. Conditions were similar for much of the Central Plains as well until recent weeks, when a shift to a wetter pattern allowed for several low pressure systems to develop downstream of the Rockies and provide some much needed relief, improving drought conditions. The DJF season is typically a dry time of year for the High Plains region, favoring widespread drought persistence. However, do not rule out the possibility for improvements or even removal through the end of 2024 across portions of the Central Plains, associated with very heavy precipitation in recent weeks (widespread 30-day precipitation totals of 3 to 5 inches across Kansas and southeastern Nebraska). Some improvements are also favored in northwestern Wyoming, associated with La Nina and the favored northward-displaced storm track.

Forecast confidence is moderate for the High Plains region.

Many locations across portions of Oklahoma, northern Texas, and the Lower Mississippi and Tennessee Valleys experienced improvements to, and removal of, drought and abnormal dryness, associated with a wet pattern in recent weeks. Oklahoma, northern Texas, and the Ozarks received well over 4 inches of rainfall, with some locations picking up in excess of 8 inches of rainfall. Parts of central and southern Texas, Mississippi, and eastern Tennessee were not so lucky, as above normal temperatures and below normal precipitation resulted in 1 to 2 category degradations in the drought depiction over the last 30 days. Fortunately, some much needed rain fell across parts of the Lower Mississippi Valley in the weeks leading up to the DJF drought outlook release. Parts of central Louisiana picked up in excess of 15 inches of rain locally. In spite of La Nina, which typically favors warmer and drier conditions on average across the southern tier of the CONUS during DJF, the recent precipitation may be enough to result in additional improvements to the drought depiction across the central Gulf Coast states through the end of 2024. The same can be said for portions of north-central Oklahoma and northwestern Arkansas. However, La Nina may still act to offset improvements across the Gulf Coast states by the end of February, but the degree to which this occurs is uncertain, given the cooler time of year and lower evapotranspiration rates, hence why drought persistence is favored.

Forecast confidence is moderate for the Southern region.

A very warm and dry start to the fall season resulted in widespread deterioration and expansion of abnormal dryness and drought across the Midwest region. Temperatures over the last 30 days have been running 6 to 9 degrees Fahrenheit above average for nearly the entire region. However, in recent weeks, portions of the central Corn Belt and Upper Midwest experienced relief from a few strong storm systems, with many locations picking up well over 150 percent of their average precipitation during this time. La Nina typically favors a more active pattern for portions of the Midwest and Great Lakes, and this is favored in the CPC’s DJF precipitation outlook. Additionally, an active pattern is favored through the middle of December. Therefore, drought improvement (for severe to extreme drought areas, D2 to D3, as depicted in the USDM) and removal (for moderate drought areas, D1) is favored for much of the Midwest region. However, the improvements in western portions of the Midwest region, if they were to occur, are likely the result of recent precipitation totals and the favored active pattern on average through early to mid December. Seasonal precipitation signals are lacking thereafter for these areas. The Great Lakes has the highest likelihood of experiencing above average precipitation during DJF, according to the CPC’s DJF precipitation outlook. Additionally, warmer than average water temperatures in the Great Lakes may extend the lake effect snow season further into DJF, thereby favoring drought removal for severe drought (D2) areas in and around the Great Lakes. Conversely, uncertainty among the forecast tools increases farther westward in the Midwest region, favoring drought persistence by the end of February across northwestern portions of the Upper Midwest.

Forecast confidence is moderate for the Midwestern region.

On the heels of Hurricane Helene’s devastating heavy rainfall across portions of Florida, Georgia, upstate South Carolina, and western portions of North Carolina and Virginia, one of the driest Octobers on record immediately followed, leading to expansion of abnormal dryness and drought across much of the region from the Florida Panhandle northward to the Mid-Atlantic. Fortunately, a recent coastal storm system brought heavy precipitation to portions of the coastal plain of South Carolina and Georgia, staving off any abnormal dryness across those areas. CPC temperature and precipitation outlooks favor a warmer and drier than average DJF for much of the Southeast, which favors broad drought persistence across the region with the potential for drought development across much of the Florida Peninsula and interior areas of Georgia and the Carolinas. However, there could be some short-term improvements across portions of Alabama and Georgia due to very heavy rainfall along a frontal boundary leading up to the release of the DJF SDO, which helped to usher in moisture from the remnants of Tropical Storm Sara in the Gulf of Mexico. However, warmer and drier conditions may slowly deteriorate conditions again in these same areas by the end of February, hence the favored drought persistence forecast.

Forecast confidence is low to moderate for the Southeastern region.

As was the case for much of the CONUS east of the Rockies, the Northeastern region experienced a very dry October with temperatures running well above average. Unfortunately, the dryness started several months earlier for much of the Northeast, with widespread 90-day precipitation deficits on the order of 8 to 12 inches for areas currently depicted in drought. Stream flows and soil moisture are running well below the 10th percentile of the historical distribution, increasing the risk of wildfire. The potential for water restrictions also exists if meaningful precipitation does not fall soon. Unfortunately, drought is favored to persist across the coastal areas of the Northeast, particularly along the I-95 corridor. A lot of uncertainty exists regarding precipitation signals and how progressive the average storm track is by the end of February. However, given the time of year and that La Nina is likely to be weak, it may open the door for more subseasonal variability and short periods of above average precipitation that will act to stave off any further drought development. Some improvement and removal is favored for parts of western West Virginia and southwestern Pennsylvania, where above average precipitation is more likely by the end of February.

Forecast confidence is low for the Northeastern region.

A pocket of abnormal dryness in south-central parts of the Alaska Panhandle has been slow to improve over the past few months. Given the time of year and DJF being a wetter time of year along the South Coast and Panhandle, the abnormal dryness in the Panhandle is likely not to degrade to drought. As such, Alaska is forecast to remain drought-free.

Forecast confidence is high for Alaska.

Drought improvements were observed across the western Hawaiian islands and much of the central and eastern Big Island over the last 30 days. Conversely, leeward portions of the Big Island, Molokai, and Maui and parts of Lanai and Kahoolawe have experienced some degradation in their drought depiction. Hawaii is entering into its wettest time of year and with the predicted La Nina, which typically leads to more rainfall throughout the islands, drought improvement and removal are forecast for areas depicted in extreme drought (D3, as depicted in the USDM) and moderate to severe drought (D1 to D2) drought.

Forecast confidence is high for Hawaii.

Puerto Rico is drought-free as of the release of the DJF SDO, and is forecast to remain drought-free by the end of February. Soil moisture and stream flows are near to above average and, despite high odds for above average temperatures, there are increased odds for above average precipitation in both the CPC’s December and DJF outlooks from the North American Multimodel Ensemble (NMME).

Forecast confidence is high for Puerto Rico.

Similar to Puerto Rico, the U.S. Virgin Islands (USVI) are likely to remain, as they are at the start of December, drought-free by the end of February, associated with favorable antecedent conditions and precipitation outlooks for December and DJF.

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

Forecaster: Adam Hartman

Next Seasonal Drought Outlook issued: December 19, 2024 at 8:30 AM EST