Observational and Numerical Investigations of the Interaction of Synoptic Scale Weather Systems with the Orography of the Western United States

9634191 Steenburgh众所周知，落基山脉在穿越山脉时对气旋天气系统有重大影响。然而，造成这种影响的确切性质和原因尚不清楚。该项目的主要目标是：(1)描述温带气旋和锋面与美国西部复杂地形的相互作用；(2)记录沿犹他州北部瓦萨奇山脉形成的对流雪带的演变和动态。这些地形影响和特征主导了美国西部的气象，并对危及生命和破坏经济的暴风雪、风暴和山洪负责。调查的一个组成部分将检查气旋和锋面等天气系统如何因与落基山脉的相互作用而改变。该项目将开发这种相互作用的区域气候学，并利用各种中尺度数据集进行一系列观察性案例研究。利用先进的中尺度数值模式的数值模拟将被广泛用于补充观测分析和研究地形过程如何改变这些系统的结构演变和动态平衡。调查的第二部分将描述沿犹他州北部瓦萨奇山脉形成的后锋对流雪带的结构和动力学。这些特征在盐湖城大都市区产生了大雪，似乎是天气气流与包括大盐湖在内的当地地形特征相互作用的结果。来自当地中尺度网络和WSR-88D多普勒雷达的观测，加上数值模拟，将被用来记录这些雪带的演变和动力学。为了改进局地预报，还将发展沿瓦萨奇锋线的锋后暴风雪的气候学。该项目将促进对美国西部地形诱发现象的理解和预测。它将描述气旋和锋面与该区域复杂地形的相互作用，并评估数值模式模拟这种相互作用产生的中尺度特征的能力。***

9634191 Steenburgh It is well known that the Rocky Mountains have significant effects on cyclonic weather systems as they cross the mountains. The exact nature and reason for this impact, however, is not well understood. The primary objectives of this project are (1) to describe the interaction of extratropical cyclones and fronts with the complex orography of the western United States and (2) to document the evolution and dynamics of convective snowbands that form along the Wasatch Mountains of northern Utah. These orographic effects and features dominate the meteorology of the western United States and are responsible for life threatening and economically disruptive snowstorms, windstorms, and flash floods One component of the investigation will examine how synoptic systems, such as cyclones and fronts, are modified by their interaction with the Rocky Mountains. The project will develop regional climatologies of such interaction and perform a series of observational case studies utilizing a variety of mesoscale data sets. Numerical simulations utilizing an advanced mesoscale numerical model will be used extensively to supplement observational analyses and examine how orographic processes alter the structural evolution and dynamical balances of these systems. The second part of the investigation will describe the structure and dynamics of post-frontal convective snowbands that form along the Wasatch Mountains of Northern Utah. These features produce heavy snowfall in the Salt Lake City metropolitan area and appear to form as a result of the interaction of the synoptic flow with local orographic features, including the Great Salt Lake. Observations from a local mesoscale network and WSR-88D Doppler radar, coupled with numeri- cal simulations, will be used to document the evolution and dynamics of these snow- bands. In order to improve local forecasting, a climatology of post-frontal snowstorms along the Wasatch Front will also be devel oped. This project will advance the understanding and forecasting of terrain induced phenomena of the western United States. It will describe the interaction of cyclones and fronts with the complex orography of the region and evaluate the ability of numerical models to simulate mesoscale features produced by such interaction. ***