December 7, 2021 National Drought Summary

The discussion in the Looking Ahead section is simply a description of what the official national guidance from the National Weather Service (NWS) National Centers for Environmental Prediction is depicting for current areas of dryness and drought. The NWS forecast products utilizedinclude the HPC 5-day QPF and 5-day Mean Temperature progs, the 6-10 Day Outlooks of Temperature and Precipitation Probability, and the 8-14Day Outlooks of Temperature and Precipitation Probability, valid as of late Wednesday afternoon of the USDM release week. The NWS forecast webpage used for this section is: http://www.cpc.ncep.noaa.gov/products/forecasts/.

Weather Summary: This U.S. Drought Monitor (USDM) week saw continued deterioration in conditions across areas of the Mid-Atlantic (Virginia, North Carolina) and the Southeast (South Carolina, Georgia) in response to below-normal precipitation (past 30- to 90-day period), declining soil moisture and streamflow levels. Likewise, drought-affected areas expanded and intensified on the map in areas of the South including Louisiana, Arkansas, and Texas as well as in the Southern Plains of Oklahoma, where overall warm and dry conditions have prevailed during the past 30- to 120-day period. Across areas of the Northern Plains, Upper Midwest, and the Northeast, light-to-heavy snowfall accumulations were observed during the past week. The heaviest accumulations (8-18 inches) were centered on northern portions of Minnesota, Wisconsin, and Michigan, while lake-effect snowfall (2 to 8 inches) impacted areas downwind of Lake Erie and Lake Ontario in New York, according to snowfall analysis from the National Weather Service (NWS) National Operational Hydrologic Remote Sensing Center (NOHRSC). Out West, some areas including the North Cascades, Sierra Nevada, and the Northern and Central Rockies, received much-needed snowfall this past week. However, basin-level snowpack conditions remained below normal across the entire western United States. In Hawaii, a Kona Low delivered very heavy rainfall accumulations (highest totals exceeding 16+ inches) leading to widespread flooding, power outages, and damage to infrastructure in areas across the Hawaiian Island this week. Impacts from the multi-day event led Hawaii Governor Ige to declare a state of emergency on December 6. With the meteorological autumn (September-November) coming to a close, the Lower 48 experienced its third warmest fall on record with the largest mean temperature departures from average observed across areas of the Northern and Central Plains, according to NOAA’s National Centers for Environmental Information (NCEI). In terms of fall precipitation, the driest conditions were observed across parts of the Southwest, Texas, Montana, Wisconsin, and the Carolinas.

Northeast: In the region, only minor changes were made on this week’s map including expansion of areas of Abnormally Dry (D0) in eastern Maryland, Delaware, and West Virginia in response to shorter-term dryness (past 30- to 90-day period) and declining streamflow levels. For the week, the region was generally dry with exception to snowfall in Upstate New York as well as in northern Maine. Average temperatures for the week were cooler than normal across northern parts of the region, including northern portions of Maine, New Hampshire, and Vermont, where departures ranged from 2 to 6 degrees below normal. Elsewhere in the region, average temperatures were 2 to 8 degrees above normal. According to NOAA NCEI, the last 4-month and 6-month periods were the warmest on record for the Northeast Climate Region.