Monday, January 21, 2019

Tale of Two Wind Directions

For most of the day, a gusty SSW wind brought sunshine and mild temperatures to the Colorado Front Range.  Produced by high pressure to our northeast and low pressure to our west, this wind was downsloping from the Front Range and from the Palmer Divide to our south.  As air descends, it heats up and dries out, producing the mild, sunny conditions.

About 3:30 PM, the wind suddenly shifted from the northeast, reflecting the fact that a cold front had crossed the urban corridor.  From that point on, the wind was upsloping, pulling in moisture from the High Plains and cooling the air as it was forced to rise by the terrain.  The mountains and foothills to our west were soon hidden by clouds and haze and snow is expected to develop along the Front Range later this evening.  Continuing through the night and during the morning hours, up to 8 inches of accumulation are expected, especially in western and southern suburbs of Metro Denver.

Here along the Colorado Front Range, weather is all about wind direction and a sudden shift in the wind leads to a dramatic change in temperature and cloud cover.  Since I was outdoors this afternoon, that transition was immediately apparent; our avian residents took notice as well, suddenly flocking to the feeding area where a calorie source is readily available.