Tools used in the Monthly Drought Outlook (MDO) included the updated 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, La Niña composites, and initial conditions such as soil moisture. The U.S. Drought Monitor, valid on November 22, was used for initial drought conditions.
During the last 30 days, a pattern change brought increased Pacific moisture across the West, though amounts across the Northwest remained generally below-normal under a rapidly increasing climatology. Locally heavy early season moisture brought some drought relief to Southern California, though the drought depiction across the West remained largely unchanged over the last four weeks. During the first week of December, widespread heavy coastal rainfall and snows across the Cascades and Sierra Nevada ranges are forecast, which would bring additional much needed moisture to the West. A troughing pattern with continued wetness is also favored for Week-2, and dynamical model forecasts indicate a potential for the pattern to continue into late December as well. While this moisture would be beneficial, given the multiple poor wet seasons prior to this year that have resulted in severe to extreme drought impacts, it is unlikely for even above-average December moisture to generate widespread drought reductions across California. Drought improvements would be most likely across coastal areas of northern California, Oregon, and Washington. Additionally, heavy snowfall across the northern Intermountain West may bring some drought relief to central Idaho.
Forecast confidence is moderate for the Western Region.
Across the High Plains, storm systems brought some drought relief to North Dakota and eastern Kansas during November, but mostly dry conditions prevailed elsewhere, promoting slow degradation ahead of the winter freeze. December is a cold and dry month for much of the Plains, which limits the potential for substantive changes to the overall drought depiction. The updated CPC precipitation outlook for December favors below-normal precipitation or equal chances of below, near, or above-normal precipitation for the Plains, and the temperature outlook favors below-average temperatures with high probabilities along the Northern Tier. Below-average temperatures during December should hasten the freezing of soils and streams, and, coupled with seasonable dryness, persistence of existing drought areas is the most likely outcome.
Forecast confidence is high for the High Plains Region.
November closed on a very wet and stormy note for portions of the Southern Region, with abnormally heavy rainfall falling across central and eastern Texas and parts of Louisiana, and a second storm system bringing heavy rain and severe weather to Arkansas and Mississippi. As these recent rains work into the soils and streams, short term drought relief is likely. During early December, another storm system is favored to develop along the mid-Mississippi Valley, which would bring widespread heavy precipitation to portions of Arkansas and the Tennessee Valley. The updated CPC precipitation outlook for December also favors above-normal precipitation for the Tennessee Valley. Therefore, drought relief is also favored for Arkansas, Tennessee, and northern Mississippi.
Forecast confidence is moderate for the Southern Region.
A series of storm systems during November brought widespread precipitation to Missouri, eastern Iowa, and Wisconsin, resulting in fairly substantial drought reductions. Additional drought relief from recent precipitation may also occur across southeastern Missouri at the close of November. Following this wet pattern, the updated December precipitation outlook from CPC favors below-normal precipitation across these same areas. Therefore, persistence of the remaining drought areas is the favored outcome. Further east, a new storm system during the first week of December is forecast to bring widespread heavy precipitation to the Ohio River Valley, and above-normal precipitation is favored through December. Therefore, drought reduction is forecast for southern Illinois, Kentucky, southern Indiana, and southwestern Ohio.
Forecast confidence is moderate for the Midwestern Region.
Unseasonably warm and dry conditions promoted drought expansion across the Southeast during November, with locally heavy precipitation bringing some relief to the southern Appalachians. At the end of November, a strong frontal system brought widespread precipitation and severe weather to much of the Southeast, which will likely result in some short term relief of drought conditions across parts of Alabama and northern Georgia. This short term relief is not necessarily a departure from the drought development favored on the seasonal drought outlook, given the ongoing La Niña event which favors below-average precipitation on a broader time scale. Drought improvements are indicated on this outlook, however, due to the potential for the reduced impacts to last through the end of the month even if drier conditions return. In fact, drought development is favored for portions of the South Atlantic coastal plain, which largely missed out on recent heavy rainfall.
Forecast confidence is low to moderate for the Southeastern Region.
Periods of storminess continued to bring moisture recharge to the Northeast, gradually chipping away at the remaining areas of drought. Drought conditions continue to persist, however, where groundwater levels dropped the lowest during the peak of the summer drought. A storm system that brought severe weather to the Southeast is currently bringing additional moisture to the Northeast, and a second, wetter system is forecast to sweep through the region during the first week of December. These systems should continue the pattern of gradual drought reduction across the Northeast.
Forecast confidence is moderate to high for the Northeast.
No drought or abnormal dryness is currently in place across Alaska and Puerto Rico, and no drought is favored to develop in either region during December. Across Hawaii, a wetter pattern over the past few weeks has resulted in gradual drought reduction, particularly across the Big Island. This wetter pattern is favored to continue through December, which favors additional drought improvements.
Forecast confidence is moderate for Hawaii, and high for Alaska and Puerto Rico.
Forecaster: Adam Allgood
Next Monthly Outlook issued: December 31, 2022 at 3:00 PM EST