February 26, 2024

Soggy Autumn in the Pacific Northwest – Saturated Soil Across Western Washington and Southern British Columbia

These maps represent the moisture in the leading 2 centimeters (0.8 inches) of soil. Moisture in this layer– and somewhat much deeper in the root zone– can vary significantly over brief amount of times. Unlike deep groundwater aquifers, surface layer soils are quickly renewed by rainfall. Notification the large area of wetter-than-usual (dark blue) soils on November 15, the 3rd day of a potent storm. The narrow bands of wetness missed some locations, specifically inland locations, where surface area soils remained drier than usual (orange and red) throughout the month.
Surface area layer soils are also the first to dry. Notification that by November 22, parts of western Washington and southern British Columbia do not look rather as wet. But the parade of storms kept coming, with three climatic rivers pouring into the region within a week in late November.
Soils generally remained soaked throughout the record-wet season. Ground-based observers in Seattle recorded about 48 centimeters (19 inches) of rain from September through November– the largest amount because records started in 1945. Just over 25 centimeters (10 inches) fell in November alone, drizzling on all but 5 days of the month.
When soils are currently filled, extra rains can position an even greater risk for flooding and mudslides. Due to the ongoing antecedent moisture and heavy rainfall (3 to 5 inches) anticipated during the next week, a flooding possible hazard is published for northwest Washington.
NASA Earth Observatory image by Lauren Dauphin, using GRACE information from the National Drought Mitigation Center.

November 1– December 6, 2021
Soils throughout western Washington and southern British Columbia were saturated for much of the season.
As meteorological fall came to an end in 2021, parts of western Washington and southern British Columbia were still saturated from the barrage of rainstorms that repeatedly soaked the area. The wetness is specifically obvious in the areas soils, which had little time to dry in between storms.
These maps reveal a weekly “photo” of surface area soil wetness from November 1 to December 6, 2021, as determined by the Gravity Recovery and Climate Experiment Follow-On ( GRACE-FO) satellites. The colors portray the moisture percentile; that is, how the soil moisture on those days compared to long-term records (1948-2012). Blue locations have more abundant water than normal, and orange and red locations have less.

The colors depict the wetness percentile; that is, how the soil moisture on those days compared to long-lasting records (1948-2012). These maps represent the wetness in the top 2 centimeters (0.8 inches) of soil. Notice the large area of wetter-than-usual (dark blue) soils on November 15, the 3rd day of a potent storm. The narrow bands of wetness missed out on some locations, specifically inland locations, where surface area soils stayed drier than typical (red and orange) throughout the month.