Climatic Controls and Spatial Variations of Precipitation in the Western United States

Ecological types of the eastern slope of the Wind River Range, Shoshone National Forest, Wyoming

“…During the late winter and spring (March-May), the northwesterly flows begin to weaken due to the northward expansion of tropical airstreams and the southward expansion of arctic air masses (Mock 1996). Moisture from the Gulf of Mexico is carried northward to the high plains of Wind River Range, Shoshone National Forest…”

“…In November, the northwesterly storm systems resume, and precipitation increases to between 50 and 70 mm along the eastern flank of the WRR, and 70 and 125 mm near the Continental Divide (Mock 1996).…”

“…As a result, large precipitation increases are evident in the eastern high plains of Wyoming and eastern Front Range of the Rocky Mountains (Mock 1996), and the eastern flank of the WRR receives its highest amounts of precipitation (60 to 80 mm/month) in the form of rain and snow. Precipitation near the Continental Divide begins to decrease during the late winter and spring, ranging between 70 and 110 mm/month.…”

A diatom record of late Holocene climate variation in the northern range of Yellowstone National Park, USA

“…The Rocky Mountain region has a spatially variable climate, which is the product of the topographic gradients and the resultant differential heating of mountain slopes, diversion or concentration of winds through mountain passes, precipitation rain shadows, amongst others. Mock (1996) suggests a complex of climatic controls that each modifies different spatial regimes within the mountainous terrain. As a result, sites that are relatively close to one another may not experience the same climate or show the same history, because each may be influenced by a synoptic climatology that is modified by the local topography (Williams et al, 1996).…”

Evidence for a relationship between spring snow cover in North America and summer rainfall in New Mexico

“…We first re-examine the ENSO signal [Douglas et al, 1993] and the abrupt climato-and find strong seasonal changes between coldlogical transition from dry conditions in May and season and warm-season precipitation anomalies June to relatively rainy conditions in July related to wintertime ENSO variability. We then throughout most of southern Arizona and western examine a different potential forcing mechanism New Mexico [Mock, 1996;Bowen, 1996]. for summer rainfall anomalies, related to land …”