HR: 1340h
AN: U53A-0714 [Abstracts]
TI: Mountain Snowpack, Lowland Winter Precipitation, and Variability in Three Western US Mountain
Ranges
AU: * Losleben, M V
EM: markl@culter.colorado.edu
AF: INSTAAR, University of Colorado, 818 County Road 116, Nederland, CO 80466
United States
AU: Pepin, N
EM: nicholas.pepin@port.ac.uk
AF: University of Portsmouth, Buckingham Bldg, Lion Terrace, Portsmouth, Hants, POI3HE
United Kingdom
AB:
Demands on mountain snowpack in the Western United States are increasing explosively and the margin between water supply and
demand is disappearing. Since snowpack is the primary water source in most regions, this paper examines high elevation
snowpack in localized regions of three mountain ranges of the western United States and contrasts this to cumulative winter
precipitation in their abutting lowlands. The three regions are the Rockies, Cascades, and the Sierra Nevada. Through
examination of inter-annual variability, extremes, and trends we found that snowpack variability is greatest in the Cascades
and least in the Rockies. Analysis of extreme snowpack shows strong relationships with circulation in the Cascades and
Sierra, but not in the Rockies. Extreme occurrences of widespread low snowpack (i.e. in all three ranges) are common, whereas
those of widespread high snowpack are rare.
Further, the relationship between high elevation snowpack and adjacent lowland precipitation (LWP) is de-coupled, suggesting
that LWP should not be used as a proxy for upland snowpack conditions. At a finer spatial scale, two sites six km apart on
the east slope of the Colorado Front Range show similarly significant contrasts in snowpack. Differences at this fine scale
can also be resolved into different atmospheric circulation patterns.
In conclusion, our analyses suggest that the snowpack in the Cascades may be the most sensitive to future climate change,
while that in the Rockies the least.
DE: 9350 North America
DE: 1863 Snow and ice (1827)
DE: 1655 Water cycles (1836)
SC: Union [U]
MN: 2004 AGU Fall Meeting