The Pacific weather systems have brought precipitation to coastal Oregon, Washington, and northern California this week, with 2 to locally over 5 inches measured in favored upslope areas. But this is the wet season and precipitation normals are high, so only a few parts of southwest Oregon, northwest California, and northwest Washington were wetter than normal for the week. The rain soaks the coastal soils and makes it wet in the short term, but the bigger hydrological picture is dry. Precipitation in the Pacific Northwest is below to much below normal for the water year to date (beginning October 1, 2019), and mountain snowpack is below normal in many areas. The Pacific fronts move quickly across the region, drying out as they cross the coastal ranges and leaving below-normal precipitation in interior Washington and Oregon. Streams are near to above normal along the coast, but below normal east of the coastal ranges. Other indicators reveal dryness east of the coastal ranges, including soil moisture, SPI, and SPEI, especially for the 1 to 9 month time scales. As a result, the 3 D1 areas in interior Washington and Oregon were joined, and D0 expanded in northeast Washington. D0-D1 expanded in southeast Idaho and D0 expanded in southwest Montana, where 3-month precipitation deficits were notable. But above-normal precipitation over the last 30 days prompted contraction of D0 in the Idaho panhandle and adjacent Montana, and in parts of eastern Idaho. The impacts indicator in the Pacific Northwest was changed from S to SL to indicate both short-term and long-term precipitation deficits.
Precipitation in California ranged from over 2 inches in the northwest to an inch or more in favored upslope areas of the coastal and Sierra Nevada ranges. Half an inch or less fell in the central valleys. Parts of northeast Nevada and the Rockies had half an inch or more of precipitation, but much of the rest of the West was dry with a tenth of an inch or less precipitation falling. In New Mexico, impacts from ranchers in the southeast related poor grass growth due to hot, dry, windy conditions, with no grass for grazing in some areas. The poor grasslands can be traced to lack of rain from spring 2019 and the failure of the summer and fall monsoon rains. D0 was expanded into southeast New Mexico and adjacent Texas based on a combination of 1-6 month precipitation deficits, 1-month SPI, 1-9 month SPEI, soil moisture, and groundwater indicators. These indicators also justified the introduction of a spot of D1 in Guadalupe, DeBaca, and Torrance Counties.