This Week's Drought Summary (1/30)

January 30, 2020

A series of Pacific weather systems continued to move across the contiguous U.S. (CONUS) in a fairly westerly jet stream flow during this U.S. Drought Monitor (USDM) week. The systems dropped copious amounts of precipitation along the Coastal and Cascade mountain ranges of Northern California and the Pacific Northwest, with above-normal precipitation continuing across most of the Pacific Northwest to the Rockies. The Pacific systems were dried out once they crossed the Rockies, but some picked up Gulf of Mexico moisture to provide above-normal precipitation from parts of New Mexico northeastward to the Great Lakes. Surface lows were generated by the upper-level Pacific systems, with some tracking to the Northeast and others moving along the Gulf Coast. The Gulf lows gave Texas to the Lower Mississippi Valley above-normal precipitation, while the others generated above-normal precipitation in the Middle Appalachian to Mid-Atlantic states. It was drier than normal from California to the Rio Grande Valley, across most of the northern Plains and Southeast, and parts of the central High Plains and Ohio Valley. With a westerly flow, most of the CONUS was warmer than normal, with only the Southeast having near to cooler-than-normal temperatures.


Half an inch to an inch of precipitation occurred across most of the Northeast this week, with locally 2 or more inches in southern portions and less than half an inch in parts of northern New England. According to the National Weather Service (NWS), the 2.54-inch total in Wilmington, Delaware, on January 25 was the third-wettest January day on record, behind a pair of 2.60-inch amounts (on January 3, 1936, and January 22, 1902). With an inch or more of precipitation falling over Maryland and Delaware, resulting in improving Standardized Precipitation Index (SPI) values, the western and northern portions of the D0 over this area were trimmed. Otherwise, no change was made to the Northeast.


Most of Florida to the coastal Carolinas had half an inch or less of precipitation this week. Otherwise, half an inch or more of precipitation was widespread across the Southeast from Alabama to Virginia, with an estimated (based on radar) 2 inches or more locally from northeast Georgia to northern Virginia. D0 spread further down the North Carolina coast into the South Carolina lowlands, and D0 expanded across parts of Florida and southern Georgia and further in southwest Alabama, based on mounting deficits over the last one to 3 months. In coastal North Carolina, groundwater levels and surface streamflows were starting to fall into the below-normal range. According to U.S. Department of Agriculture (USDA NASS) statistics, 38% of pasture and rangeland was in poor to very poor condition in Virginia, and there were reports that “hay supplies are tight due to poor hay production in the fall.” The poor conditions in the Southeast were due to autumn drought, followed by insufficient time for re-growth before winter. For this reason, and because substantial rain occurred this week, no new D0 was added to central Virginia where 6-month precipitation deficits were evident. The USDA statistics also noted that 19% of the North Carolina pasture and rangeland was in poor to very poor condition.


Eastern portions of the South region received widespread half inch or more of precipitation, while western Texas was dry, especially along the Rio Grande Valley. An inch or more of precipitation fell from eastern Texas and southeast Oklahoma to the Mississippi River, with embedded areas of 2+ inches along the Gulf Coast and from northern Louisiana to southern Arkansas. Half an inch or more also fell in the Oklahoma panhandle and northern portions of the Texas panhandle. Consequently, drought and abnormal dryness contracted in parts of Texas, Oklahoma, Louisiana, and Arkansas. But drought or abnormal dryness expanded or intensified in parts of western Texas, southern Louisiana, and southeast Mississippi. The USDA reported that 28% of Tennessee’s pasture and rangeland was in poor to very poor condition, but, as for the Southeast, this was due to autumn drought, followed by insufficient time for re-growth before winter.


Less than 0.25 inch of precipitation fell across most of Minnesota and parts of southeast Illinois to southwestern Indiana, while most of the Midwest received half an inch or more, and locally more than an inch. With most of the region experiencing wet conditions for the last 1 to 12 months, there was no drought or abnormal dryness in the Midwest this week.

High Plains

Much of the High Plains region had less than a tenth of an inch of precipitation this week. Half an inch or more fell across southeastern Nebraska to southern Kansas and in the mountains of Colorado and western Wyoming, with pockets of 0.25-0.50 inch elsewhere. Although 6-month precipitation deficits are still significant, D2 was deleted in western and southern Colorado where recent precipitation made 1 to 3-month precipitation deficits and drought indicators less severe and where mountain snowpack was near normal. D0-D2 were trimmed slightly in southwest Kansas where precipitation was above normal this