US Drought Monitor and Summary, Dec. 20, 2019

Source: droughtmonitor.unl.edu
This Week’s Drought Summary: A series of Pacific fronts brought welcome moisture to the Northwest (from northern California northward into Washington), but even with this precipitation, the Water Year to Date (WYTD; since Oct. 1) basin average precipitation and Snow Water Content (SWC) were still well below normal (30-70%). Farther east, frigid Arctic air (weekly average temperatures up to 15 degree F below normal) was bottled up in the northern Plains and upper Midwest (and central Canada), while the West, South, and East observed above-normal readings (weekly temperature anomalies + 3 to 6 degree F). As the fronts progressed eastward, they slowed and waves of low pressure developed along the fronts, generating widespread rains (1-4 inches, locally to 8 inches) in the Southeast, mid-Atlantic, and along coastal New England. In the colder air to the north, the precipitation fell as snow, blanketing parts of the lower Missouri and Ohio Valleys, northern Appalachians, eastern Great Lakes region, and interior New England with light to moderate totals (2-6 inches). In contrast, the Southwest, Plains, and western Corn Belt were mainly dry. In Alaska, above-normal temperatures prevailed across the state, with decent precipitation observed along the southern coast. Shower activity increased across the eastern Hawaiian Islands, allowing for some improvements on the Big Island.

South: While western sections were dry (Oklahoma, western two-thirds of Texas), precipitation gradually increased across eastern sections, with scattered lines of showers and thunderstorms dropping light to moderate totals (1 to 3 inches) on parts of Louisiana, Mississippi, and Tennessee. The rains were enough to provide some slight improvement in northern and central Louisiana (D0 and D1 shrunken), but much lighter amounts in southwestern Arkansas and eastern Texas, along with slightly above-normal temperatures, somewhat increased the area of D0-D2 in those 2 areas. In western Oklahoma, conditions were maintained as November and December precipitation is normally quite low this time of year (each month contributes to 1-2% of the annual total), and seasonable temperatures helped.

Looking Ahead: During the next 5 days (Dec. 19-23), most of the lower 48 States will be tranquil (dry), except for heavy precipitation (more than 4 inches) in the Pacific Northwest (from northern California northward), and in the southeastern quarter of the Nation (2-5 inches in the central and eastern Gulf and southern Atlantic Coasts). If this rain occurs, parts of Florida may close in or break their record high December amount, effectively wiping away any existing drought. The upper and eastern Great Lakes region should see snow showers along favored locations. 5-day temperatures should average above-normal for much of the contiguous U.S.
The CPC 6-10 day outlook (Dec. 24-28) favors above-normal precipitation across the Southwest, Plains, and upper Midwest, and in southern and eastern Alaska. Subnormal precipitation is likely along the Atlantic Coast and Montana. Temperatures are expected to average below-normal in the Far West and Alaska, with good odds for unseasonably mild readings in the eastern half of the Nation.