Precipitation shadows in the Hudson Valley

The classic topographically—induced precipitation shadow is often associated with the large mountain ranges of the western United States. Here, we present three cases of such rain shadows in and around the Hudson Valley of New York State, where the valley walls range from 200 – 800 m. These events occurred during the intensive field campaign (IFC; September – October 2003) of the Hudson Valley Ambient Meteorology Study (“HVAMS”). The HVAMS IFC deployment featured a dense network of high quality high temporal resolution surface stations and remote sensing platforms, including periodic and continuous measurements of vertical profiles of winds, temperature, and humidity. As such, previously anecdotal evidence of downsloping—induced precipitation shadows in the Hudson Valley can now be quantitatively documented. We will show that these rain shadow zones are directly related to the overlying wind field and underlying topography, as well as the vertical temperature/humidity profiles. Finally, we show how the long-term (less dense) observation network does not depict these rain shadows.