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Total episode duration, which varied from a low of three hours to a high of 80 hours, averaged 33 hours with a median of 26 hours (or slightly more than one day). SLW was observed for as few as three hours to as many as 61 hours during these episodes and averaged 23 hours (median about 20 hours or nearly one day). As a percent of the episode hours, on the average, SLW was observed 70 percent of the time and the median was even higher (about 80 percent). This indicates that in most of the storms some SLW is likely to be present most of the time. In 12 of the episodes, SLW first appeared as a major synoptic feature (usually a front but sometimes an upper trough or low) was approaching Arizona from the west or northwest. The maximum upwind distance was 360 nautical miles while both the median and average distances were close to 200 nautical miles. Exceptions were that in one episode the surface front was essentially overhead before the SLW was observed and in another episode which involved a synoptic feature SLW appeared when an upper low (which had formed east of the area and moved westward) got to within about 60-90 miles of Happy Jack. However, the usual pattern was for SLW to appear while an identifiable synoptic feature was still many miles upwind, which would afford several hours of potential seeding time if SLW was present. The trend of the SLW, in most of the episodes, followed an interesting and to a degree predictable pattern, It usually began with light hourly amounts or with an occasional moderate hourly value mixed in for a few hours, increasing to moderate and sometimes strong hourly values as the main synoptic feature approached the area. After passage of the synoptic feature, 3-17 I I I I I I I I I I I I I I I I I I I