Thursday, June 28, 2018

Front Range Heat Wave

The atmospheric ridge that has been building over the Desert Southwest this past week has spread northward to the Colorado Front Range.  We reached an afternoon high of 100 degrees F yesterday and expect to exceed that mark today.

Beneath this high pressure dome, air sinks and heats up.  In addition, cloud development is suppressed and Pacific cold fronts are shunted to the north of the dome, reducing any chance of precipitation.  Highs in the Desert Southwest have exceeded 110 degrees F at lower elevations (e.g. in Phoenix and Las Vegas) and overnight lows have barely dipped below 90 degrees F.  To the east, across the Southern Plains and lower Mississippi Valley, the heat is less intense but is exacerbated by humidity (with dew points in the mid seventies), producing a heat index near 100 degrees F.

Fortunately, the higher elevation and drier air along the Front Range enhances radiative cooling at night and our overnight lows are falling into the low-mid sixties (still almost ten degrees above normal).  Here in Colorado, the atmospheric ridge is expected to retreat by the weekend, bringing cooler temperatures and a chance for precipitation.