WMOD00313

• Title: Cloud Physics Studies in Utah During 1978
• Date: 9/1/1978
• State: UT
• Weather Modification - Doc Type: Report

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Figure 4.1.9 contains the flight track of the KIA during this
mission, and observed ice nuclei as detected by the NCAR counter are noted
on the flight track. It may be noted that no ice nuclei were detected
during this mission. None should have been detected because no seeding
occurred.

SUMMARY - FZight #1~ 12 March
The first flight over the Uinta Range was made in the early afternoon
of 12 March. The atmosphere was convectively unstable below the mountain-
top level, but since the winds were from the west and west northwest, the
instability was not released. High concentrations of natural ice crystals
were present over the Uinta crest, but no significant supercooled water
was present. Because a number of tha crystals over the Uinta crest were
so large and unrimed, most of the precipitation on the Uinta Range appears
to have originated over the Wasatch Range and reached the Uinta Range as
fallout. No seeding was conducted or warranted over the Uinta Range and
no ice nuclei were detected.

4.1.2 Wasatch FZight
The flight track for the first and only research mission flown over
the Wasatch Range during this storm is shown in Figure 4.1.10. The fl ight
departed from Salt Lake City at about 1635, and an approach to Provo Air-
port was made near 1745. During ,the approach to Provo, the airspeed indi-
cator was determined to be malfunctioning due to ice in the pitot pressure
lines. A missed approach was executed and we proceeded directly to
Laramie to repair the system.
The sounding during the climb-out of. Salt Lake City is shown in
Figure 4.1.11. Convective instability was present below 750 mb. The air-
craft entered cloud shortly after takeoff and remained in cloud.
The hodograph (not shown) i nd icated that the surface ltJinds .
were from the south at about 4 m s-l, and changed to the west and north-
west through the cloud layer. Above 2 km the winds remained from the
northwest, and at approximately 5 to 10 m s-l throughout the sounding.
From this sounding and hodograph and other synoptic data not shown, it
was apparent that the frontal system and low pressure center had passed
over Salt Lake City and that the convective instability occurred behind
the front and behind the low pressure center.