Abstract:
The results of a 2-year project to investigate the feasibility of automatically detecting precipitation type for highway hazard-reduction programs in the Cascade Mountains of Washington State are reported. The project investigated available technology for remote identification of precipitation type, selected a suitable sensor for testing, and compared field and laboratory tests with visual observations. Modifications of the hardware and software were conducted to optimize the use of precipitation identification (PID) sensors in operational hazard-reduction programs.A PID sensor was installed at the Washington State Department of Transportation (WSDOT) observation station at Snoqualmie Pass, and was connected to automatic data-logging equipment. Another PID was equipped for mobile use and tested at mountain sites in Alaska, other areas of Washington, and in Japan.Data from each sensor were compared against visual observations. The results of this analysis showed adequate performance from the PID. The analysis also showed that the PID data can be a valuable asset to the hazard mitigation programs along mountain highways, particularly when combined with data-loggers, totaling precipitation gages, and computer graphics.

Authors:
Ferguson,S. A.

Keywords:
precipitation identification, rain, snow, hazard, avalanche

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Abstract:
Hoarfrost formation in a maritime inversion climate has been studied via inferred snow/air interface temperatures, vertical temperature profiles of the interface, and application of dew point hygrometry. Two dominant growth situations have been discerned. The first involved highly saturated air near the interface and strong radiational cooling of the snow surface, producing a wide variety of crystal sizes (1-6mm). The second showed strong radiational cooling of the snow surface in an altered environment with secondary introduction of water vapour from the presence of supercooled clouds. The latter often showed accelerated growth, the formation of large dendritic crystals (8-15mm) in short time periods (less than four hours). Subsequent snowfalls of increasing water equivalent on surface hoar beds resulted in numerous direct action avalanches. Threshold crystal size for bed layer weakness varied widely (0.7-15mm) and was related to old snow surface roughness and new snow precipitation characteristics.

Authors:
Breyfogle,Steven R.

Keywords:
avalanche, environment, frost, hoarfrost, profile, roughness, snow, temperature

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Abstract:
The Central Avalanche Hazard Forecasting project has been funded by the Washington State Highway Commission since July 1975 in order to test the feasibility and effectiveness of central avalanche forecasting for the Cascade Mountain Passes and adjacent territory . Historically, avalanche forecasting in the Cascade Mountains has been done locally on an area-by-area basis by Highway Department personnel and by Forest Rangers and professional ski patrolmen at individual ski areas. This project explored the possibilities of improving both mountain weather and related avalanche forecasts for use by WSDOT during winter operations in the mountain passes and, secondarily, explored the usefulness of anarea-wide forecasting service to other, cooperating agencies. The aim of this work has been to establish the technical and administrative framework for an operational, on-going mountain weather and avalanche forecasting service for Western Washington under the joint support of interested public agencies. This aim has been achieved in autumn 1978 by the operation of an avalanche forecasting office administered by the US Forest Service, housed by the National Weather Service, and supported by WSDT, with additional peripheral support from both the public and private sectors. Previous reports published by the project include: Interim Report, June 1976 (Report No. 23.2); Final Report, June 1977 (Report No. 23.3)Implementation Report, December 1978, which will be published in Spring 1979If you would like to obtain copies of any of these reports, contact WSDOT Public Transportation and Planning Division in Olympia (SCAN 234-61 49) or the Avalanche Research Office on SCAN 323-7180 or Write Avalanche Research,Department of Atmospheric Sciences AK-40, University of Washington, Seattle,Phil Taylor, Research Engineer, has done an outstanding job of developing much of this equipment and devising methods of operation. He is, unfortunately, no longer with the University. He will be working in Autumn 1978 with the US Forest Service as a consultant in addition to his continuing work with the US Geological Survey. This Operating Manual is intended to be an informational document with limited distribution and its format reflects that informality.

Authors:
University of Washington

Keywords:
agencies, avalanche, avalanche forecasting, developed, effectiveness, equipment, forecasting, framework, hazard, highway, Interim, ITS, manual, methods, Operating, planning, project, public, research, survey, transportation, Washington, Washington state, winter

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Abstract:
The Central Avalanche Hazard Forecasting project had had two principal aims : The design and establishment of an avalanche data network and central avalanche and mountain weather forecasting facility to serve the highway passes and other hazard areas of the Cascade Mountains in Washington. Improvements in the practices of conventional avalanche forecasting and the introduction of new techniques in statistical analysis and pattern recognition. Achievement of the first aim has been described in previous Reports 23.2 and 23.3. This present Report 23.4 gives the results of fundamental research into avalanche forecasting theory and discusses the application of these results is to central avalanche forecasting for the Cascade Mountains of Western Washington .

Authors:
LaChapplle,E. R., Furguson,S. A., Marriott,R. T., Moore,M. B., Reanier,F. W., Sackett,E. M., Taylor,P. L.

Keywords:
analysis, avalanche, avalanche forecasting, snow, weather, data, design, facilities, forecasting, hazard, highway, project, research, Washington

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Abstract:
The Alternate Methods of Avalanche control project has been funded by the Washington State Highway Commission since August 1974 in order to develop simple, reliable and repeatable methods of triggering avalanche release which are free from the storage, handling and availability problems of explosives and artillery shells and which can be readily applied to avalanche paths typical to many smaller ones causing hazards for highways.The Alternate Methods of Avalanche Control project has been funded by the Washington State Highway Commission since August 1974 in order to develop simple, reliable and repeatable methods of triggering avalanche release which are free from the storage, and availability problems of explosives and artillery and which can readily be applied to avalanche paths typical of the many ones causing frequent hazards for highways. The research involved tests in both Washington and Colorado to permit evaluation of the control methods in diverse climates and snow conditions, leading to more generally applicable results than could be obtained at a single site. The technical and scientific aspects of the work in Colorado were coordinated by the San Juan Avalanche Project of the University of Colorado. Field work in Washington state and the general supervision of the program and the engineering design were carried out by the University of Washington Geophysics Program. The U.S. Forest Service at Utah, also joined in a cooperative test of our methods and equipment. This Final Report describes the tests and the results of the entire project.

Authors:
LaChapplle,E. R., Bell,D. B., Johnson,J. B., Lindsay,R. W., Sackett,E. M.

Keywords:
availability, avalanche, snow, weather, stress waves, condition, control, design, equipment, evaluation, hazard, highway, Highways, program, research, tests, Washington, Washington state

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Abstract:
This report reviews the second year of work on the Washington State Highway Commission Department of Highways project Central Avalanche Hazard Forecasting (WSDH Agreement Y-1700) to test the feasibility and effectiveness of central avalanche forecasting for the Cascade Mountain passes and adjacent area. The possibilities and techniques for improving both mountain weather and related avalanche forecasts for use by WSDH during winter operation in the mountain passes were further explored, and, secondarily, the usefulness of an area wide forecasting service to other cooperating agencies. This report defines and significant changes from the first year of operation in collection, assimilation or transmission of snow, weather and avalanche data by the Forecasting Office, and details modifications of the data network itself, especially new instrumentation and telemetry equipment . Weather and avalanche forecasting accuracy and reliability are assessed by comparing daily weather and avalanche forecasts with file d data. The conceptual framework and analytical methods used by forecasters to deduce current and probable future avalanche activity from the available data network input and current and extrapolated meteorological data are presented. A general preliminary guide to forecasting methodology for the Washington Cascades is defined and discussed.

Authors:
LaChapplle,E. R., Moore,M. B., Reanier,F. W., Sackett,E. M.

Keywords:
agencies, avalanche, avalanche forecasting, snow, weather, data, effectiveness, equipment, forecasting, framework, hazard, highway, Highways, methodology, methods, project, reliability, review, Washington, Washington state, winter

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Abstract:
This report summarizes the first year of activity under Washington State Department of Highways project Central Avalanche Hazard Forecasting (Agreement Y-1700) to test the feasibility and effectiveness of central avalanche forecasting for the Cascade Mountain Passes and adjacent territory . This project explores thepossibilities of improving both mountain weather and related avalanche forecasts for use by the WSDH during winter operations in the mountain passes, and, secondarily, explores the usefulness of an area-wide forecasting service to other, cooperating agencies. The eventual aim of this work is to establish thetechnical and administrative framework for an operational, on-going mountain weather and avalanche forecasting service for Western Washington under the joint support of interested public agencies.

Authors:
LaChapplle,E. R., Moore,M. B., Reanier,F. W.

Keywords:
agencies, avalanche, avalanche forecasting, snow, weather, effectiveness, forecasting, framework, hazard, highway, highways, Interim, project, public, Washington, Washington state, winter

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Abstract:
A collection of reports resulting from the second year's study. Reports are entitled:1. Air Bag System by E.R. LaChapelle, C.R. Morig and P.L. Taylor 2. Gas Exploder System by E.R. LaChapelle, C.R. Morig, and P.L. Taylor 3. Vibrator Tests by E.R. LaChapelle, C.R. Morig and P.L. Taylor 4. Mechanical Resonance of Snow by J.B. Johnson 5. Interface Modification Field Tests by E. R. LaChapelle 6. Approximate Solutions for the Interruption of the Creep and Glide of a snowpack by Rigid Structures by J.A. Langdon

Authors:
LaChapplle,E. R., Johnson,J. B., Langdon,J. A., Morig,C. R.

Keywords:
avalanche, snow, weather, creep, glide, control, field test, interim, structures, tests

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Abstract:
This report describes the results of a feasibility study comprising Phase I of a Central AvalancheHazard Forecasting Program for mountain passes in the State of Washington. The report describes existing weather and avalanche data sources, and suggests improvements and additions for improved input to and feedback from a centralized avalanche forecaster's office which will improve avalanche predictions for all passes within the State. WSDH and consultant efforts and results during FY 75 are described, and specific recommendations for PhaseII, implementation of avalanche hazard forecasting, are provided.

Authors:
Washington State Highway Commission Department of Highways

Keywords:
avalanche, avalanche hazard, weather, weather observations, wind, temperature, precipitation, data reporting, avalanche hazard forecasting, communications, data, data sources, forecasting, hazard, prediction, program, Washington

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Abstract:
Part 2 continues the Cascade Passes Avalanche Atlas; Part 1 was published in August 1974 and covers avalanche hazards on Chinook, Cayuse, White and Snoqualmie Passes. The documentation of hazards at Stevens Pass includes only those avalanche paths which directly or potentially affect the highway, U.S. 2. There are numerous other adjacent avalanche paths--Lichtenberg Mountain is a good example--which are prominent in the vicinity of the Pass but which do not present any real likelihood of reaching the highway under foreseeable avalanche conditions. These latter paths are not delineated on the maps or photos, although many do appear within the mapped areas. There is a long history of avalanche occurrences at Stevens Pass, stemming both from railroad and highway experience. Most of the earlier history is unrecorded. A considerable amount of anecdotal knowl- edge for recent years is available from Highway Department personnel with long experience in the area. The historical record has drawn heavily on this experience. The primary compilation of data for Part 2 of the Cascade Passes Atlas was done by Len Miller during his tenure as a contract avalanche consultant for the Highway Department. This compilation has subsequently been amended and extended through the cooperation of the Department avalanche crew at Stevens Pass under the leadership of Steve Reister.

Authors:
LaChapplle,E. R., Brown,C. B., Evans,R. J.

Keywords:
Atlas, avalanche, Cascade, condition, data, hazard, highway

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Abstract:
A collection of reports resulting from the first year's study Alternate Methods of Avalanche Control. The reports are entitled:1. Air Bag System by E. R. LaChappelle and P.L. Taylor2. Gas Exploder System by E. R. LaChappelle and P. L. Taylor3. Snow Behavior Behind a Continuous Avalanche Defense Structure by J.A. Langdon.4. Interface Modification Field Tests by E. R. LaChappelle5. Mechanical Resonance of Snow by J. B. Johnson and R. J. Evans6. The 1974-75 Winter by M. B. Moore

Authors:
Brown,C. B., Evans,R. J., Johnson,B., Langdon,A., Moore,B., Taylor,L.

Keywords:
alternative, avalanche, avalanche forecasting, snow, weather, creep, glide, behavior, control, field test, interim, tests, winter

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Abstract:
A collection of reports about avalanche conditions and avalanche prevention measures on Washington mountain highways in general and to the North Cascade Highway in particular involving various aspects of creep deformation and glide of the snow cover as they affect avalanche defense structure design; reconnaissance of a proposed new highway route through the Cascade Mountains and a continuing study of the relationship between synoptic winter weather patterns and the formation and distribution of snow avalanches in the Cascades.The reports are entitled:1. Effect o f Glide and Creep on Rigid Obstacles by C.B. Brown and R.J. Evans.2. Creep and the Snow-Earth Interface Condition in the Seasonal AlpineSnow-Pack by D. M. McClung.3. In- Situ Investigations o f the Temperature Dependence o f the Creep ofLow Density Snow by D.M. McClung4. Naches Tunnel Avalanche Reconnaissance by E. R. LaChapelle.5. Investigation of Synoptic and Surface Weather Situations Leadinq toAvalanche Cycles in the Washinqton Cascades for the 1973-74 winter by M. B. Moore.

Authors:
Moore,M. B., McClung,D. L., LaChapplle,E. R., Brown,C., Evans,R. J., LaChapplle,E. R.

Keywords:
avalanche, Avalanche Forecasting, Avalanches, Cascade, condition, creep, density, design, glide, highway, Highways, North, North Cascade, seasonal, snow, Study, temperature, Washington, weather hazards, winter

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Abstract:
A collection of reports on several different aspects of avalanche formation. The reports are entitled: 1. Some Considerations for Avalanche Defense Design for the Washington Cascades. 2. Incorporation of Glide and Creep Measurements into Snow Slab Mechanics. 3. Avalanches and Synoptic Weather Situations in the Cascades during the Winters of 1971-72 and 1972-73. 4. Indication of Snow Avalanche Periodicity Through Interpretation of Vegetation Patterns in the North Cascades, Washington. 5. A Visit to the Swiss Federal Institute for Snow and Avalanche Research. 6. Decision Methods

Authors:
LaChapplle,E. R., Brown,C. B., Evans,R. J., Fox,T., Smith,L., McClung,D. L.

Keywords:
avalanche, snow, decisions, weather, vegetation, creep, glide, dendrochronology, avalanches, Cascade, design, methods, North, North Cascade, research, Study, Washington, winter

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Abstract:
This Summary Report synthesizes the work on avalanche control carried out at the University of Washington from 1970 through 1974. Five problem areas are addressed: 1. Identification of avalanche paths. 2. Description of historical frequency and size of avalanches. 3 Prediction of avalanche. 4. Identification of control methods. 5. Inclusion of control and prediction schemes in highway design and operation.

Authors:
LaChapplle,E. R., Brown,C. B., Evans,R. J.

Keywords:
avalanche, snow, decisions, weather, vegetation, creep, glide, avalanche forecasting, control, design, highway, highway design, methods, prediction, Washington

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Abstract:
This present compilation of avalanche paths affecting Washington State highways extends in the same format the information published in 1971 as the North Cascades Highway Avalanche Atlas. Part 11, in preparation, will cover Stevens Pass and Tumwater Canyon.The North Cascades Highway Atlas was prepared on the basis of extensive aerial and ground reconnaissance in a hitherto inaccessible wilderness area where no previous record of avalanche occurrence was available. Compilation for the Cascades Passes has proceeded on the same basis, with the added advantage that all of the areas in question have long been traversed by highways for which considerable historical records exist . It is necessary, though, to note that such a record has proven to be less advantageous than might be expected. In the case of the North Cascades Highway, identification of avalanche paths was based on objective appraisal of terrain and vegetation patterns, leading to an accurate and highly consistent compilation. In the present Cascade Passes Atlas, there are many instances where objective evidence and historical accounts fail to agree. Moreover, the nomenclature, rather than being assigned consistently, has developed -- ad hoc over the years and varies with individuals and agencies . These conflicts have been resolved in the final editing of this Atlas according to the best available evidence, but in some cases necessarily in an arbitrary fashion. The Snoqualmie Pass section of this Atlas includes reproductions of sketches prepared by the Department of Highways for use in recording avalanche occurrences. These sketches are included here to illustrate this mode of avalanche recording, since it is a valuable method for systematically accumulating an historical record of avalanche frequency and behavior.

Authors:
LaChapplle,E. R., Brown,C. B., Evans,R. J.

Keywords:
account, agencies, Atlas, avalanche, behavior, Cascade, developed, highway, Highways, North, North Cascade, Washington, Washington state

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Abstract:
An interim report of the second year of a three-year study of avalanche hazards along Washington mountain highways is presented. Applicable snow, avalanche and weather data for 1971-72 are given. Also included is a theoretical treatment o f the stress analysis of slab avalanches and a bibliography of snow clearing technology.

Authors:
LaChapplle,E. R., Brown,C. B., Evans,R. J.

Keywords:
analysis, Annual, avalanche, Avalanche control, Washington mountain highways, Snow and weather data, Snow clearing technology, Avalanches, control, data, hazard, highway, Highways, Interim, methods, snow, stresses, Study, technology, Washington, Washington state

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Abstract:
This report covers activities for the eighteen months ending September 1971 under a Washington State Highway Department Contract for Research Project No. Y1301 with the University of Washington. Snow and avalanche climate varies widely across the parts of the Cascade Mountains spanned by SR-20. Little information is presently available about temperatures and weather patterns over the passes, but a limited amount of snow depth data are available from snow courses. These snow data are presented and analyed.

Authors:
LaChapplle,E. R.

Keywords:
avalanche, Avalanches, data, highway, Highway SR 520, North Cascade, project, research, snow, temperature, Washington, Washington state

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Abstract:
This Avalanche Atlas catalogs details of snow avalanche activity along the North Cascades Highway, SR-20, between Newhalem on the west side of the Cascade Mountains and Mazama on the east side. Data contained herein have been collected during summer and winter reconnaissances in 1970 and 1971 under contract between the Washington State Highway Department and the University of Washington. Compilation of this Atlas completes the first phase of a planned three-year study of avalanche problems and control methods on the highways of the State of Washington.

Authors:
LaChapplle,E. R.

Keywords:
Atlas, avalanche, Cascade, control, data, highway, Highways, methods, North, North Cascade, snow, SR 20, Study, Washington, Washington state, winter

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