WMOD00274

• Title: Western Kansas Weather Modification Program 2006 - Final Report
• Prepared By: Walter E. Geiger III
• Date: 10/30/2006
• State: KS
• Weather Modification - Doc Type: Report

can be highly productive over large areas using wing generators. Its likely under these conditions
that dynamic effects is markedly reduced, whereas, a static seeding effect is being achieved
causing the cloud's micro-physical characteristics to be altered by seeding.

There is another form of cloud system which has occasional important seeding potential
for producing precipitation in Kansas: the multiple~celled-convective system (MCCS).

MCCS cloud usually form as a cluster of small, wispy, weak air-mass type of cloud
bubbles within a fairly small area---typically 10 - 30 miles in diameter. If one, or more, clouds
grow sufficiently and can merge with another, the resulting cloud often tends to enlarge and
continue growing. In chain reaction fashion this promotes more mergers of nearby clouds, thus
continuing to increase both cloud volume and intensity, etc. Such cloud systems eventually are
capable of producing heavy precipitation over large areas and persist much longer than otherwise
be the case under normal conditions. Initially, upd~afts found within such a system often are
embedded and difficult to locate, however, once this cloud system grows to a certain size,
updrafts generally organize better and the resulting bloud becomes easier to continue seeding if
surrounding cloud and visibility conditions remain safe for flying. Under the unseeded natural
condition, MCCS regions often become a "first echo" seen on radar. First echoes have a high
correlation to being the day's first severe storm. .

Most of the important research on the dynamics of the multiple-celled-convective system
was done in the 1980s in West-Central Texas. Rad~ studies of Northwest Kansas clouds from
1972 to 1974 by Dr. Dean Bark found this area was .likely to be a fertile breeding ground for
MCCS cloud development. Data comparisons to Western Kansas suggest Western Kansas may
be an even better area for similar clouds developing:than was the research area in Texas. In
earlier years of the WKWMP scant attention was paid to those weak-appearing multiple-celled
cloud clusters until one had grown fairly large. If thqse cloud systems had been inspected and
treated in their early stages instead of waiting to see ,whether they would grow to become larger,
most likely greater success in rain stimulation and/or hail suppression would have occurred in
them. Today, however, we anticipate these smaller dloud clusters can develop into larger cloud
systems and will provide targets of opportunity to produce increased rainfall over large areas, or
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that these could become regions of initial daily severe storm development. Flights are launched
early when such conditions arise. Spectacular results in rain enhancement appear to have
occurred when seeding similar cloud systems in the past.

We've identified one type of problem cloud on the WKWMP formed by elevated
convection. It has been with us forever, but until relatively recently it has not been identified as
such, nor widely recognized and considered as a type of "new-growth" cloud to be dealt with,
different from a pre-collapse new-growth feeder cloud. It is very likely there are different
varieties of elevated convection-generated clouds as well. The following hypothesis is from
personal observation, pilot reports and radar data---definitely needing further study and
refinement:

New growth clouds initially are produced around severe storms mostly by below-cloud
base updrafts; our elevated convection type of cloud, however, masks the difference between it
and the below-cloud-base cloud in that they both appear similar-looking with the exception of
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