WMOD00218

• Contract/Permit #: #97-3
• Applicant: Western Kansas Groundwater
• Project Name: Kansas Weather Modification
• Date: 1/1/1997
• Weather Modification - Doc Type: Report

The importance of the above statistic is important. It means
that on about half of the.seeding days, we could use most aircraft
to seed exclusively in one area or the other. In effect, on those
days when the ratio of aircraft to target-area-size can be lowered
significantly, the probability of dramatically reducing crop-
damaging hail should increase dramatically. As mentioned in the
previou~ section, out of the hail-days with the most damage, only
one day had relatively high damage in both areas. Checking further
into that operational day revealed there were 'dead' periods in both
target areas that same day and one target area could employ a
greater number of planes than what was assigned to its target area.
It may be a hopeless wish that we will always be'as fortunate as we
were this year, however, this scenario may occur more frequently
than we think and is something that needs to be followed up on in
future years. That is, if there is a physical basis for this effect,
it could be of great value to program operations and it could work
to our advantage . The questions becomes, "Is it likely there is a
general tendency for a large severe storm cluster, or a large
complex of very severe storms to overwhelm any tendency for other
very severe storms to develop within a certain distance from it?" To
hypothesize the effect: The region of non-severe storm development
would depend upon certain characteristics of the large, developing
severe storm complex itself. The larger and more severe the storm,
the greater might be the distance of non-severe storm development
from that storm. The 51% number of days in which flights were common
to both target areas this season, may be reflecting the answer to
that question in a practical manner.

Last year in this report we described how 1996 was a way-off-
the-scale type of year in terms of storm numbers and severity.
Interestingly, our total number cf seeding days this season was 74,
compared to 76 in 1996, an indication of just how extreme it wa~ in
1996 with much less target area to cover. Because of the increased
number of'aircraft now on the program, our 1997 seeding totals all
exceeded those of 1996, except at cloud top. however, more
interesting comparisons to last season are seen when aircraft-to-
aircraft comparisons are made between years, in which case 1997 is
well below the effort expended in 1996. For instance:

Total seeding flights in 1997 and 1996 were 651 vs. 516,
respectively, or 26% more than last year and respective flight hours
were 1952.6 vs, 1427.2---almost 37% more in 1997. However, on a per
aircraft basis, the average number of flights in 1997 were 21% less
than last year and the average number of seeding flight hours were
14.5% less than last year. Observation flights were 213 in 1997 vs.
117 in 1996---82% more in 1997; respective flight hours were 271.8
vs 115, or 136% more than last year. "Other" flights---maintenance,
shuttling from one airport to another to standby, etc., numbered 333
in 1997 vs. 211 in 1996 and respective flight hours were 265.2 vs
144.5, or almost 84% more flight hours this season. Combined, the
observation and other flights totaled 546 in 1997 vs. 328 in 1996
and the observation and 'other' flight time was 547.0 hours vs.

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