WMOD00234

• Contract/Permit #: #93-5
• Applicant: Western Kansas Groundwater
• Project Name: Kansas Weather Modification
• Date: 1/1/1993
• Weather Modification - Doc Type: Report

\ .

\
I

year average. Significant hail-days occurred on April 30th
(84 claims), just before the program began, and September 18th
(345 claims), three days after it ended. The long-term
average number of hail-days since 1975 was 49.1 days. So, 1993
ended with about 21 days more than average, or 42.6% above.
Last year we counted 63 hail-days, also well above normal,
making two years of back-to-back abnormally high-day ac"Civity.
It needs to be pointed out our hail-day data comes from
insurance adjuster reports which have been known to have
occasional da~e discrepancies of hail damage occurrence.
Such errors will cause inaccuracy in terms of numbers of hail-
day occurrence, whereas, numbers of claims filed remain the
same. For instance, in 1993 there were 19 days in which one to
three claims were generally reported with no seeding being
performed. Our seeding of all potential hail-bearing storms
aren't completely perfect, however, it is doubtful there were
so many hail-days occurring without a seeding flight or even
an observation flight. We have noticed this same problem
other years and have tried to correct for it. Many hail-day
dates, when in error, usually need to be amended to a day
before or after the erroneous reported date. WeeKend storm
days and night storms usually cause more reporting problems
than on weekdays during daylight.

Last year's final report suggested reasons to
relatively high number of hail-days in Western Kansas
lack of hail claims in comparison to Eastern Kansas.

explain. the
and relative
They were:

1. More night s~orrn activity and timing of occurrence

2. Generally lower a~ternoon surface temperatures

3. High atmospheric moisture

4. The WKWM Program and adding a 5th seeding aircraft

In the 1993 season three of the four above factors were
present yet hail claims were very high, the primary difference was
that 1993 summer surface temperatures were more normal (higher)
than in 1992. Combined with . an upper air pattern making it
conduci ve to the regular passages of fronts and troughs, the
prolonged high moisture and high temperatures occuring in Western
Kansas in 1993 presented textbook cases in demonstrating the
importance of the basic elements needed to produce severe storms.

I
II
I

In summary, excellent crop prospects early in the 1993 growing
season, undoubtedly led to much more of the total wheat crop was
insured when compared to a long-term average. Numbers to support
that thesis will be available next year. Also, two very important
ingredients needed for convective storm development were pervasive
throughout the summer.. .heat and moisture...a dangerous combination
for producing favorable to producing high numbers of hail-days.

22