Tuesday, May 19, 2009

Evening Light Shows

Our Littleton, Colorado, farm sits on the west wall of the South Platte Valley and commands a broad view to the southeast. On almost every warm day, from May through August, we are treated to an evening light show, as thunderstorms move above the Palmer Divide and adjacent High Plains.

Through the night, cool air descends from the Front Range, pooling along the valley floors of the South Platte River (north of the Palmer Divide) and Fountain Creek (to its south). By late morning, as the sun begins to warm this air, it flows upward across the terrain, picking up moisture from Piedmont lakes and mountain forests. Cooling and condensing as it rises, this flow ignites afternoon thunderstorms above the Front Range that drift eastward as they build into the prevailing, westerly winds.

Since the South Platte and Fountain Creek Valleys point toward the west end of the Palmer Divide and adjacent foothills, the Tarryall and Platte River Mountains are often a focal point for thunderstorm generation and the late-day parade of storms is generally most abundant along and near the broad ridge of the Divide. Our view is thus perfect for watching the evening displays of lightening as these storms drift eastward into Elbert and Lincoln Counties.