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Desert Research Institute: "Initial forecasting of mesoscale atmospheric phenomena in the Truckee Meadows Basin"

Final Report

This Partners Project used a 3-D numerical model (Regional Atmospheric Modeling system, RAMS) to simulate atmospheric processes in the Truckee Meadows Basin for two synoptically different case studies during the intensive atmospheric field program conducted in the Reno Basin in November 1994.

The first case was characterized by relatively high atmospheric stability and a developed thermal inversion. The model was set up with two grids: a coarse grid with 41x41 horizontal points and resolution of 5 km and a nested grid with 62x62 points and 1-km resolution. The model was initialized by both NWS and additional slow-ascent soundings taken during the case study, and the results indicate the model was able to predict the thermal inversion and appearance of gravity waves.

The second case was a windstorm event. The numerical model was able to reproduce high winds, shear instabilities and associated turbulence, as well as waves in the main basin and surrounding valleys and basins. Simulation results agreed with radiosonde and wind profiler measurements. According to the model results, there was a significant flow reversal and two stratified maximums of turbulence kinetic energy. One of the maximums was related to surface shear and the larger one was due to elevated shear near the mountain ridges.