Author: United States. National Weather Service
Publisher:
Published: 1979-02
Total Pages: 212
ISBN-13:
DOWNLOAD EBOOK →Author: E. Marshall Hansen
Publisher:
Published: 1975
Total Pages: 68
ISBN-13:
DOWNLOAD EBOOK →Three cases of extreme local precipitation within the Intermountain summer season were studied to determine the source of moisture for these events. The rains occurred at Phoenix, Ariz. on June 22, 1972 (133 mm in 2 hours), at Elko, Nev. on August 27, 1970 (105 mm in about 2 hours), and at Morgan, Utah on August 16, 1958 (about 150 rnm in 1 hour). Synoptic data were used to analyze surface and upper levelmoisture changes in time and space. In each case the study showed that a tongue of high moisture at low levels approached the vicinity of or encompassed the storm area prior to onset of the rain. The tongue of moisture was very narrow in reaching toward the Elko and Morgan storms and could be traced, through continuity of changes in pattern with time, back to the Gulf of California. The moisture is believed to be conveyed through the natural channel provided by the Gulf and the paralleling ridges. The low-level moisture followed a path controlled to some extent by major mountain barriers. A general conclusion is that greater emphasis should be given to tropical Pacific moisture in evaluating extreme summer precipitation values for the Intermountain region.
Author: Harold J. Day
Publisher:
Published: 1976
Total Pages: 60
ISBN-13:
DOWNLOAD EBOOK →Flood plain management has been a subject of special concern in the United States for the past two decades. A river forecasting system is an integral part of a total flood plain management program. It is particularly important in those activities associated with temporary evacuation and/or floodproofing. The flood warning system associated with a river forecast system can be one of the most cost-effective alternatives for flood plain management. This study examines flood damage reduction in four carefully selected communities in the Connecticut River Basin. Using data from these communities a basin-wide extrapolation could proceed to other flood-prone communities in the basin. Properties on the flood plain were classified into residential, commercial, industrial and automobile categories. Stage damage assessments were made for those categories for four situations: no warning (NW), limited warning time (LWT), maximum practical evacuation (MPE), and floodproofing of one-story houses (FP(l)). The investigation found that approximately $750,000 of reducible damages can be expected on commercial and residential elements of the flood plain. Although reducible damages associated with industrial structures were not evaluated, elsewhere in the Nation such values often are of the same order of magnitude as residential and commercial. Total basin-wide reducible damages, therefore, undoubtedly exceed $1,500,000 per year. The present annual cost to the National Weather Service of providing river forecasts throughout the basin is approximately $75,000. A total of $200,000 per year would be adequate to provide forecast services associated with reducible damages.