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<br />passage. The cutoff systems had a gradual easterly progression that was usually <br />less than 15 ms-1. <br /> <br />, This category also included larg~ amplitud~ shortwaves. The observed wind <br />shifts in the large amplitude shortwaves were very similar to the cutoff cir- <br />culations. However, the speed of the large amplitude shortwaves was much more <br />rapid than the movement of cutoff circulations, resulting in shorter storm <br />periods over the Sierra Nevada. <br /> <br />2) Large amplitude long wave patt~rn producing cold northerly storms <br /> <br />This group of storms represented the coldest storms encountered in the <br />Sierra Nevada. A schematic representation of these storms is shown in Fig. 3e. <br />This category included rapidly moving storms that were forced over a large <br />amplitude ridge to the west and then dug from north to south over the project <br />area. Winds were westerly near the time of the trough passage, providing the <br />greatest mountain normal wind component. After the trough passed, winds shifted <br />to northerly and often northeasterly, which eliminated a mountain normal wind <br />component. .-- <br /> <br />The variations in this storm type depended on the storm trajectory. An <br />inland trajectory took the shortwave over Idaho, and down through Utah. The <br />more inland the trajectory, the war'mer the storm was over California. Very <br />little frontal structure and little precipitation was observed in storms with <br />inland trajectories. Storms with trajectories directly over the west coast had <br />colder temperatures with more precipitation. The precipitation associated with <br />the storms was usuall; short lived~ occurring over a period of 2-6 hours. <br />Surface fronts were either weak or not evident. Systems with offshore trajec- <br />tories had temperatures that were extremely cold. Snow often occurred near sea <br /> <br />9 <br /> <br />-J <br />