WMOD00574

• Title: Studies of Wintertime Storms Over the Tushar Mountains in Utah
• Date: 3/1/1986
• State: UT
• Country: United States
• Weather Modification - Doc Type: Report

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mb thick) stable layer capping the instability~ this stable layer

defined the top of convective clouds and progressed from low, warm

altitudes to higher, colder altitudes. The cross section also shows

that before the STORM period, there was a low altitude, stable cold air

drainage flow which was present at the Adamsville site in the Beaver

basin after sunset and lasting until about sunrise on February 8. Winds

in this drainage flow were from the southeast, with southwesterlies

above. The drainage flow was about 25mb thick (250 m). another low

level stable cold layer was present on the following night. It had

winds from the southwest and was probably not a simple drainage flow.

Throughout the STORM, the rawinsonde observations indicated that in

the Beaver Valley, airflow was from the southwest to west at all

altitudes except in the cold airmass, where it backed to northerlies.

Typical wind speeds at 700 mb were 10 to 15 m/s and at 500 mb, 15 to 20
m/s.

C. STORM Description
Precipitation amounts were averaged for the eight project gauges

(Swart, 1985) during each of the four STORM periods, and the values are

plotted in Figure 8. The figure also shows gauge altitude for reference.

Recall from Figure 1 that gauge #1 is at a valley site about 30 km west

of the Tushar Mountains, and the others cross the mountain range, Gauge

#8 is on the lee side of the Tushars for westerly flow, and gauges #6

and #7 are at high altitude locations. Figure 8 shows that most of the

STORM precipitation occurred during phase III. Furthermore, the spatial

distribution of snowfall was not "orographic'" during this phase, as

the amounts do not follow the terrain profile. In contrast, phases I and