WMOD00313

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

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4.2.1 unita Flights
The first flight over the Uinta Range during this storm series
occurred during the late afternoon of 21 March (Figure 4.2.4). During this
flight only thin clouds were observed above the mountain peaks and there-
fore, these flight data should be considered as a pre-storm situation. The
research flight by the King Air began just downwind (north side) of the
Uinta Range at 1645 and the KIA was west-bound for landing at Salt Lake
City 2 hrs later.
The sounding taken over My ton on the south side of the Uinta Range
at 1810 is shown in Figure 4.2.5. The sounding shows that there was some
convective instability present, but not enough moisture and lifting was
present to produce any significant clouds. The hodograph indicated light
southwesterly winds below mountain top level at typically < 5 m s-l. The
winds increased to 7 to 8 m s-l from above mountain top level to the 500 mb
level.

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Figures 4.2.6a, b, and c, contain streamlines at 4.8, 3.7 and 2.7 km,
respectively. At 4.8 km the winds were from the southwest with ee decreas-
ing a few degrees in the lee of the Uinta Range implying subsidence. At
3.7 km, the winds were much lighter and were displaying significant difflu-
ence around the Uinta Range with the e field indicative of ascending
. e
motion over and upwind of the Uinta Range. Descending motion was indicated
in the lee of the Uinta Mountains. At the lower levels, that is 2.7 km,
the winds were still light at < 5 m s-l and from the southwest. The winds
at this level were being deflected around the southern side of the Uinta
Range. Isotherms of ee indicate that there was some ascending motion on
the southern side of the Uinta Range, but it was not sufficient to produce
clouds.

Since no significant clouds were present for penetration during this
mission, no analog traces or microphysics data are presented. Figure 4.2.2
and 4.2.3 show there were no ground generators or airborne seeding occurring
over the Uinta Range at this time, and it may be seen from Figure 4.2.7
that no ice nuclei were detected during this flight.

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