April 8, 2023 - Snow Western United States

Snow
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After a series of at least a dozen atmospheric rivers lashed the
Western United States between November 2022 and March 2023, mountain
snowpack reached record or near-record levels.

On April 5, 2023, the Moderate Resolution Imaging Spectroradiometer
(MODIS) on board NASA’s Terra satellite acquired a false-color image
centered on the state of Wyoming. In this type of image, snow appears
bright blue, grass is green, open land looks brown, and clouds may
appear either white or, if the clouds are high and very cold, may be
tinted with bright blue.

A blanket of heavy snow covers almost all of the high mountains in this
image, with the exception of an area in northern Idaho, where
vegetation predominates. Snow also stretches over part of the Midwest,
including South Dakota and North Dakota, and extends northward into
Canada. The deep blue waters of the Great Salt Lake, Utah, illustrate
the effect of this winter’s exuberant precipitation, even in the lower
elevations. In November 2022, the Great Salt Lake hit a new record low,
with the water level measured at 4,188.5 feet. By April 6, the level
had risen to 4,191.5 feet—a full 3-foot rise—even before the onset of
spring runoff.

Early April is the typical peak of snow water equivalent (SWE) in the
West. Because SWE estimates the amount of water held in the winter
snowpack, the SWE measured on April 1 is used as one of the initial
indicators of potential spring and summer water supply. According to
the National Integrated Drought Information System (NIDIS), California,
Nevada, Utah, and western Colorado all registered record-high SWE. In
northwestern Utah, the SWE is 300 percent above the 1991-2020 median.
In parts of the eastern Sierra Nevada along the border of California
and Utah, SWE peaked at 303 percent of median. In addition, along the
northwestern border of Arizona and southeast Nevada, SWE was estimated
at 408 percent, while central Arizona reached a full 600 percent of
median.

The high snowpack is welcome to drought-plagued portions of the West,
but the robust snowpack may trigger spring and summer floods,
especially if runoff is rapid. The NIDIS notes that serious drought
concerns remain in the parts of the Pacific Northwest, in part due to
lack of snow. They also expect Lake Powell to rise significantly by
summer, but Lake Mead may continue to fall. Both of those reservoirs
will remain at critically low levels, despite the anticipated runoff,
due to more than 20 years of drought.

Image Facts
Satellite: Terra
Date Acquired: 4/6/2023
Resolutions: 1km (800.6 KB), 500m (2.7 MB), 250m ( B)
Bands Used: 7,2,1
Image Credit: MODIS Land Rapid Response Team, NASA GSFC



https://modis.gsfc.nasa.gov/gallery/individual.php?db_date=2023-04-08

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