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Owen P. Cramer

Abstract

Potential temperature (θ) analysis supplies needed information that is not obtainable by other methods of graphical analysis. Terrain surface θ maps and large-scale θ cross sections are constructed by using data from weather stations, raobs, and aircraft soundings. Interpretation of the isentropes gives a fairly detailed picture of temperature, stability, and potential wind conditions at and above the surface in mountainous terrain. Applications include weather analyses for fire and pest control and studies of smoke dispersion.

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OWEN P. CRAMER

Abstract

Three kinds of mesosystems—two squall mesosystems, an instability line, and a strong marine push—were all observed in Oregon on the same day. Each system produced sudden changes in temperature and gale-force winds, yet none was identified on routine synoptic analyses. The development and progress of each mesosystem is reconstructed in a series of detailed sea-level analyses. Effects on local winds and temperature of a pseudo cold front associated with a squall mesosystem in mountainous terrain were documented as the system passed through a mesonet in the Cascade Range. The impact of these mesosystems emphasizes the need for greater attention to mesoscale systems for identification and warning of important summer weather events. The mesosystems appear to be closely related to the approach of a minor short-wave trough, with maximum development at the 250-mb level.

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Owen P. Cramer and Robert E. Lynott

The application of atmospheric cross sections to a relatively small area is explored as a tool in the study of surface winds in mountainous terrain. Covering a distance of only 50 mi through the Oregon Coast Range, these charts help in tracing airflow over local obstacles and portray changes in stability and stratification. Evidence is presented that vertical patterns of potential temperature must be considered in the detailed analysis of wind structure in mountain areas.

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Owen P. Cramer and Robert E. Lynott

Abstract

A combination of subsidence, east winds and advection of warm air produced a summer heat wave that raised maximum temperatures 35F in four days. This meteorological event was analyzed at the mesoscale, from data in reports from 15 lower elevation stations and from 90 fire-weather stations in mountainous western Oregon. The temperature analyses show the influences of major physiographic features and a stratified marine airmass. The complex temperature patterns, illustrated in cross sections and terrain surface potential temperature analyses, are related to both pressure and wind-flow patterns.

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ROBERT E. LYNOTT and OWEN P. CRAMER

Abstract

The most destructive windstorm of recorded history in the Pacific Northwest occurred on October 12, 1962. With a method between that of mesoanalysis and ordinary synoptic analysis, detailed reanalysis was made of the structure of the storm over Oregon and Washington, including isobaric patterns and frontal positions at I-hr. intervals. The significant features of the storm are described. Comparison is made with other notable windstorms in the region. The pressure pattern is used to determine location and magnitude of maximum winds.

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Mark J. Schroeder, Michael A. Fosberg, Owen P. Cramer, and Clyde A. O'Dell

This paper reviews the literature on the main aspects of marine air invasion on the Pacific coast. In particular, it considers the sea breeze, Pacific coast monsoon, and airflow over coastal mountains. The major problems associated with marine air invasion are: 1) the relationship of microscale convection, waves, and banded convection- waves to the sea-breeze energetics and sea-breeze front, 2) the interaction of energy forming and dissipating processes from the general circulation down to the micrometeorological scale, 3) the climatology and dynamics of the monsoon, and 4) the mechanism of the lee waves observed in the lee of the heated coastal mountains. Lee waves often form in a statically unstable atmosphere.

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