Tools used in the U.S. Monthly Drought Outlook (MDO) include the Climate Prediction Center (CPC) temperature and precipitation outlooks for December, 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 December, and initial conditions such as soil moisture. The U.S. Drought Monitor valid on November 28, 2023 was used for initial drought conditions.

During early December, Pacific flow is forecast to bring widespread heavy precipitation to the Pacific Northwest, with moisture working inland sufficiently to bring fairly heavy mountain snows to the northern and central Rockies. Drier conditions are favored to prevail across southern and central California, though favorable initial conditions preclude the potential for any widespread development of drought or abnormal dryness. Near to above-normal precipitation is favored to continue across the northern half of the Western Region during Week-2, and the updated CPC precipitation outlook for December favors above-normal precipitation for the Northwest, and below-normal precipitation for southern California. These wet outlooks favor continued drought reductions for the Pacific Northwest and Cascades region. Persistence is maintained further east, where climatological precipitation is less, and where precipitation primarily builds mountain snowpacks, which have begun the season below-average. Low climatological precipitation also favors persistence across the southern Four Corners region.

Forecast confidence for the Western Region is moderate to high.

Drought conditions slowly expanded across the central High Plains during November. Snowpack conditions early in the cold season are below-average for much of the High Plains region, although a storm system brought a swath of heavy snow to northwestern Oklahoma and northeastern Kansas. During December, a fairly dry climatology and increasingly cold temperatures favors drought persistence. Any precipitation that occurs will increasingly fall as snow, which is unlikely to significantly recharge the soils through the end of the month. Abnormal dryness may expand slightly across North Dakota before the soils and streams completely freeze, as the updated CPC monthly outlook favors below-average precipitation, but widespread drought development is not anticipated.

Forecast confidence for the High Plains Region is moderate to high.

A heavy precipitation event in early December is favored to bring some initial drought relief to eastern Texas and the central Gulf Coast, while lighter amounts further north should yield some beneficial recharge. Forecast tools at all time scales during December favor a wet pattern overall for much of the Southern Region, extending from eastern Texas and southeastern Oklahoma eastward. This pattern is consistent with El Nino conditions, which typically promote an active southern stream across the southern CONUS. Based on these outlooks, drought reduction is favored for southeastern Texas, Louisiana, Arkansas, Mississippi, and southern Tennessee. The wet signal becomes less clear across northern Tennessee, and given the somewhat longer term nature of the drought, persistence is the most likely outcome. Persistence is also forecast for western Texas, given the dry climatology and lack of a clear wet signal.

Forecast confidence for the Southern Region is moderate.

A drier than average November prevented widespread soil moisture recharge across the Midwest Region and prompted some expansion of drought conditions ahead of the winter months. During the first week of December, a swath of light to moderate precipitation is forecast to overspread Missouri northeastward to the southern Great Lakes region, which should yield some beneficial recharge. Although these accumulations may not promote widespread changes to the drought depiction, they should help prevent further degradations. The updated CPC monthly outlook favors below-average precipitation across the upper-Midwest and western Great Lakes, and above-normal precipitation for much of Missouri. The favored dryness may cause some expansion of abnormal dryness across the upper Midwest, but widespread drought development is not favored given the seasonably cold temperatures. Some drought relief is possible for southern Missouri.

Forecast confidence for the Midwestern Region is moderate.

The same system favored to bring heavy rainfall in early December across portions of the Southern Region will also overspread the Southeast, bringing some relief to the widespread drought conditions across the region. Forecast accumulations are expected to be highest along the Gulf Coast, extending northeastward into central Georgia, though most of the region is favored to receive at least moderate rainfall, except for the Florida Peninsula. The updated CPC monthly outlook favors above-normal precipitation for the Southeast Region, with some longer range forecasts depicting a highly active southern stream setting up during the latter half of the month. Therefore, drought reduction is favored for almost the entire Southeast Region. Persistence is maintained along and west of the Blue Ridge, where the wet signal is weaker and drought conditions are more entrenched.

Forecast confidence for the Southeast Region is moderate.

Only small portions of the Northeast Region are currently experiencing drought conditions, including much of Maryland, far southeastern Pennsylvania, and a region just south of Lake Ontario. A pattern change has brought wetter weather to the mid-Atlantic region, resulting in some recent drought improvements. The overall wetter pattern is favored to continue through December, and with soils and streams largely unfrozen in the region, the potential for widespread recharge is high. Therefore, drought reductions are favored for Maryland and Pennsylvania. South of Lake Ontario, drought persistence is favored in the absence of a clearer wet signal.

Forecast confidence for the Northeast Region is moderate to high.

No drought conditions are currently in place across Alaska, and no drought is expected to develop during the cold and dark month of December.

Forecast confidence for Alaska is high.

Across Hawaii, a Kona Low event is unfolding, with widespread heavy rainfall overspreading the entire island chain and favored to continue over the next day or so. These rains (and high elevation snow across the Big Island) have resulted in flood watches and warnings across the state, and the copious moisture should bring some temporary drought relief during December, despite a drier pattern remaining favored over the next few months. Climatological precipitation is fairly high during December, so this single event is unlikely to significantly alter the overall drought depiction.

Forecast confidence for Hawaii is low to moderate.

Although dynamical models favor an uptick in moisture during Week-2, December is favored to remain drier than average for much of the Caribbean region, including Puerto Rico. Therefore, drought persistence is the most likely outcome.

Forecast confidence for Puerto Rico is low to moderate.

Drought remains in place across portions of the US Virgin Islands. December is favored to remain drier than average across the Caribbean region, including the US Virgin Islands. Therefore, similar to Puerto Rico, drought persistence is forecast.

Forecast confidence for the US Virgin Islands is low to moderate.

Forecaster: Adam Allgood

Next Monthly Drought Outlook issued: December 31, 2023 at 3:00 PM EST