Tools used in the U.S. Seasonal Drought Outlook (SDO) included the Climate Prediction Center (CPC) temperature and precipitation outlooks for November 2018 through January 2019 (NDJ), 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), the Week 3-4 outlooks and tools from CPC, dynamical models at the monthly and seasonal time scales, the 384-hour total precipitation forecasts from several runs of the GFS, climatology for the NDJ season, and initial conditions. The oceanic and atmospheric conditions currently reflect ENSO-neutral but with recent trends indicating a developing El Niņo. El Niņo is favored to form duirng the next two months with a 70 to 75 percent chance of it continuing through the Northern Hemisphere winter season.
Drought expanded and intensified this summer across the Pacific Northwest due to below-normal rainfall and above-normal temperatures. Recent rainfall and cooler temperatures resulted in improving conditions across coastal Washington during the past month. Despite a slight tilt in the odds for below normal precipitation during NDJ, the coastal Pacific Northwest typically receive 40 to 67 percent of their annual precipitation during this three month period. Based on the increasingly wet time of year, removal and improvement of drought is forecast for the coastal Pacific Northwest. Drought persistence is most likely across parts of the northern Rockies where 90-day precipitation deficits are more than 2 to 6 inches (based on AHPS), low 7-day streamflows, and the seasonal outlook indicating enhanced odds for below normal precipitation. 7-day streamflows across the upper Colorado River Basin that includes Utah are in the lowest 10th percentile. Due to these initial conditions and long-term nature of the drought, broad scale persistence is forecast for southern California, the interior Pacific Northwest, Great Basin, Central Rockies and the adjacent high Plains. Prospects for improvement and removal of drought are slightly higher across the Southwest, including parts of southern Utah and southern Colorado due to predicted above normal short-term and long-term precipitation.
Forecast confidence is high for the coastal Pacific Northwest and moderate for the remainder of the Western Region.
Below-normal precipitation was observed across south-central Colorado during the past 30 days. 7-day streamflows are in the lowest 25th percentile across central and western Colorado. Due to these dry initial conditions and lack of a strong wet signal among precipitation tools, persistence is forecast from the central to northern Rockies. Persistence is also most likely across the Dakotas where climatology becomes increasingly dry during NDJ. During the past month, heavy rainfall resulted in major improvements in drought status across the central Great Plains. Based on the Week-2 outlook calling for increased chance of above-normal precipitaiton and a favorable time of year for soil moisture recharge, removal is likely for any lingering drought areas in eastern Kansas.
Forecast confidence is moderate for the High Plains Region.
Recent heavy rainfall resulted in 1 to 3 class improvements in drought status across much of Texas, Oklahoma, and northern Louisiana. A wet pattern is likely during the remainder of October with widespread rainfall amounts of 1 to 5 inches forecast across much of these areas. Based on these factors along with above normal precipitation favored during NDJ and a favorable time of year for soil moisture recharge, continued improvement and removal of drought are expected across the Southern Region.
Forecast confidence for the Southern Region is high for Oklahoma and Texas but moderate for Mississippi and Tennessee.
Heavy to excessive rainfall occurred throughout parts of the Midwest during the past week with drought coverage and intensity continuing to decline. Based on the lack of a dry signal among the precipitation tools, additional removal of drought across Missouri is likely.
Forecast confidence is high for the Midwest Region.
Hurricane Michael made landfall near Mexico Beach, Florida on Oct 10. Michael and its remnant low brought widespread flooding rainfall and reduced drought in Georgia and South Carolina. Due to the short-term to seasonal precipitation outlooks indicating a slight tilt in the odds for above normal precipitation, drought removal is likely in the area.
Forecast confidence is moderate for the Southeast Region.
A relatively small area of drought exists across northern parts of New York and Vermont. Based on a favorable time of year for soil moisture recharge and without a dry signal at any time scale, improvement (D2) and removal (D1) of drought is expected by the end of January.
Forecast confidence is moderate for the Northeast Region.
Moderate drought continues along the southern Alaska Panhandle. Short-term and the seasonal outlook favor above normal precipitation in this region. One class improvement (D1 removal and D2 improvement) is likely due to typically high precipitation amounts during NDJ. There is no drought in Hawaii and Puerto Rico, and no drought development is expected.
Forecast confidence is high for Alaska.
Forecaster: Yun Fan
Next Seasonal Drought Outlook issued: November 15, 2018 at 8:30 AM EST