Figure 6. Animation illustrating the modeled spatial distribution of SWE throughout the study period. Hourly model output was sampled every six hours to create the animation. The simulation begins by depicting the gradual ablation in the southern margins of the snow pack from March 26 through April 3. Warm air temperatures and rainfall beginning on April 4 resulted in rapid, widespread ablation of the snowpack, but as the rain turned to snow, accumulation begins again, especially in the northwest part of the study area (central North Dakota primarily). Additional snow accumulation occurs in the southern study area (central South Dakota and southern Minnesota) on April 11, but the accumulation is shallow and melts off within a few days.  From April 14 until the end of the study period on April 22, widespread snowmelt and ablation of the snow pack occurred.  The large "spike" of SWE that remains in the northwest part of the study area (near Lake Winnibigoshish, MN) is an artifact of the estimation of initial SWE conditions used to cold-start the snow model. Two sites in that vicinity reported snow depth on the ground on March 26 that was substantially greater than surrounding sites. While the model indicates rapid snowmelt was occurring throughout this area, it was unable to melt off the estimated snow pack in the Lake Winnibigoshish vicinity.

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