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<br />convective condensation level (T CCL) and potential buoyancy (PB) at 500 mb, easily determined from
<br />morning National Weather Service sounding data, to forecast afternoon convection. Categories of
<br />maximum echo top heights were found to arrange according to TCCL and PB. The physical basis of
<br />TCCL and PB to implicitly represent a period of time for coalescence to produce supercooled drizzle and
<br />rain drops is discussed. The technique performed well at forecasting the occurrencl~ and height of
<br />afternoon convective clouds, and the accuracy of the occurrence forecast improved if precipitable water
<br />was used as an additional criteria Aircraft measurements of supercooled rain drop concentrations
<br />showed that a discriminator function, dependent only on TCCL and PB, gave a good indication of the
<br />presence or absence of supercooled drizzle and rain drops in the updrafts of clouds at the -10oC seeding
<br />level. Median concentrations of supercooled drizzle and rain drops (Nn > 3(0) in updraft regions at the
<br />-10oC level were found to be best approximated by a third order polynomial dependent on TcCL and PB,
<br />presenting a possible physical link between cloud scale, environment and in-cloud conditions.
<br />
<br />Scott, R W.. and R R Czys, 1990: An objective process to forecast convective precipitation and seedability of
<br />clouds in the Midwestern United States. XV General Assembly, April 23-27, 1990. European
<br />Geophysical Society, Copenhagen, Denmark.
<br />
<br />No abstract.
<br />
<br />Scott, R W., and R R Czys, 1990: Convection intensity and seeding suitability forecasts m a dynamic
<br />seeding experiment in Illinois. 12th Conference on Weather Analysis Forecasting, Monterey, CA,
<br />October 2-6, 1989. American Meteorological Society, Boston, MA, 107-110.
<br />
<br />No abstract.
<br />
<br />Scott, R W., 1989: Forecasting convection intensities in Illinois from rawinsonde signatures. Proceedings,
<br />5th WMO Scientific Conference on Weather Modification and Applied Cloud Physics, Beijing, China,
<br />May 8-12, 1989. World Meteorological Organization, Geneva, WMOf[D-No. 269, 1:221-224.
<br />
<br />No abstract.
<br />
<br />Scott. R W., and F. A. Huff, 1987: Forecasting with a contemporary forecasting/nowcasting system in a
<br />randomized dynamic seeding experiment. Proceedings, XIX General Assembly of the International
<br />Union of Geodesy and Geophysics, August 9-22, 1987. Vancouver, British Columbia, Canada, Vol. 3,
<br />852.
<br />
<br />No abstract.
<br />
<br />Secretary of Commerce, 1979: National Weather Modification Policies and Programs. A report to the President
<br />and the Congress. Supt. of Doc., US-GPO, Washington, DC (003-017-00470-8),93 pp.
<br />
<br />No abstract.
<br />
<br />Shang, R, 1989: A numerical study of aerosol scavenging by ice crystals. M.S. thesis, Department of
<br />Atmospheric Physics, University of Nevada, Reno, NY, 93 pp.
<br />
<br />Two theoretical models are presented which allow computing the efficiency with which aerosol particles
<br />are collected by simple ice crystal plates. The present models in,corporate gravitational, inertial,
<br />diffu~ive, and electrostatic effects. The effect of an internal charge distribution, due to differential
<br />incorporation of ionic substances into ice crystal lattice, on aerosol scavenging is also investigated.
<br />Some calculations were performed using a low density for ice particles, to simulate scavenging
<br />
<br />69
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