The prediction of precipitation phase and intensity in complex terrain is challenging when the surface temperature is near 0• C. In calm weather con- 2-moment bulk, and bin), which parameterize snow in different ways, all produced a valley flow reversal but at different rates. Experiments examining sensitivity to the initial prescribed snow mixing ratio aloft were conducted to study the threshold precipitation at which this change in the direction of the valley flow field can occur. All prescribed snow fields produced a change in the valley wind velocity but with different timings. Finally, the evolution of the rain-snow boundary with the different snowfields was also studied and compared with the evolution of the wind speed near the surface. It was found that the change in the direction of the valley flow occurs after the 0 • C isotherm reaches the base of the mountain. Overall this study showed the importance to account for the latent heat exchange from melting snow. This weak temperature feedback can impact, in some specific weather conditions, the valley flow field in mountainous area.

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