WMOD00527

• Title: Quantitative Precipitation Forecasting for Improving Reservoir Operations
• Date: 4/1/1995
• Weather Modification - Doc Type: Report

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Grid Point Column Numbers

Figure 1. - American River Basin topography (500-ft intervals) and Rhea orographic precipitation model5-km grid points
used in study.

entirely in the ARB (Reynolds and Dennis, 1986). One of the products of the SCPP was a
good meteorological data base from the ARB. Consequently, this QPF study was based upon
SCPP precipitation and rawinsonde (upper-air soundings of pressure, temperature, moisture,
and winds) data; NWS rawinsonde data from Oakland; CDWR data used in the HED71
hydrologic model; and Reclamation precipitation and Folsom Reservoir inflow data.

2.4.1 Precipitation Data

This study concentrated on heavy precipitation episodes that occurred during the SCPP
winter field seasons (November through April). Heavy precipitation episodes were defined
as storms where observed cumulative precipitation totals exceeded 60 mm (2.34 in.) of water
equivalent over a significant area (four or more gauge sites) of the ARB, and any breaks in
precipitation were less than 24 h. From mid-January 1980 to mid-March 1986, 42 such
periods were selected by examining precipitation data collected during Reclamation's SCPP.

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