WMOD00286 ‎(3)‎

• Project Name: Colorado River Basin Pilot Project
• Title: Comprehensive Atmospheric Data Report 1974-75 Season - Volume I
• Date: 8/31/1975
• Weather Modification - Doc Type: Report

3.2 EXPERIMENTAL DAY CRITERIA e
An experimental day constitutes a 24-hour period from 1100
MST to 1100 MST. Any 3-hour portion, or intermittent 3-hour or
greater portions, within the originally established 24-hour period
with a forecast potential for beneficial modification is designated by
the same experimental period. A declaration of an experimental day
is based primarily on the 0900 MST forecast. Further refinements
in the forecast are made from later data when an experimental period
is expected late in the 24- hour period. The final declaration of an
experimental period that occurs late in the 24-hour period generally
precedes the operational period by at least 3 hours.

An experimental day is declared when the following conditions
occur simultaneously within a time period of 3 hours or greater:

1) Precipitation of 0.01 inch or greater is forecast for one
or more of the following gages in the project target areas during the
1100 MST to 1100 MST period when condition 2 and 3 (below) are met:

a) NP-3' - Castle Creek
b) KO-3 - Wolf Creek West
c) KH-1 - Lemon Park
d) JK-l - Northfork Sand Creek
e) MO-l - Nipple Mountain 2W

e

2) 500 mb temperature of 230 C or warmer is forecast to
exist over the proj ect target areas.

3) The representative wind flow, usually 700 mb, is fore-
cast to be toward the mountain slopes of the project target areas (1700
through 3000).

The only change in this season's procedure in declaring
experimental decisions was that no declaration of an experimental day
will be made after 2300 MST each day. (This change was effective on
October 29, 1974.)

3.3 SEEDING OPERATIONS
Storm systems meeting experimental day criteria were
randomly seeded by selected ground-based silver iodide generators,

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