Thursday, July 31, 2014

Triple Play Upslope

Three days ago, as I headed west across Kansas, high pressure over the Southern Plains swept heat and humidity northward.  In concert, a low pressure system was moving eastward along the Colorado-New Mexico border, intensifying this southerly flow and directing the stream of warm, moist air toward the Front Range.  By the following afternoon, Metro Denver had temperatures in the upper 80s (F) with dew points in the 60s, reflecting humidity well above normal for this semi-arid region.

Ahead of a cold front, which was dropping south across the Great Plains, thunderstorms began to ignite, producing scattered heavy downpours along the Front Range urban corridor.  Then, overnight Tuesday into Wednesday, the front passed through Denver and a steady, easterly wind pushed the entrenched, humid air up against the foothills.  The enduring upslope kept temperatures in the 50s for the next 36 hours, unleashing bands of moderate rain and light drizzle.

Today, as the upslope dynamics break down, partly sunny skies should develop.  Nevertheless, residual moisture will feed afternoon thunderstorms, ignited by the intense Colorado sun.  Similar conditions are forecast for tomorrow but, by the weekend, the monsoon moisture will be cut off by high pressure over the region and dry, sunny weather is expected; then again, weather forecasts beyond 24 hours are of dubious value.