After wilting in central Missouri over the last two days, enveloped in tropical heat and humidity, I arrived along the Colorado Front Range late this afternoon under low clouds and scattered showers; the temperature was 45 degrees F. These two weather extremes were produced by the same Pacific storm system; ahead of the front, muggy air was pumped into the Midwest from the Gulf of Mexico while, behind it, a plume of moisture was swept westward through the cool air. Since this flow is counterclockwise around the storm's central low, the moisture arrived from the northeast, the classic upslope direction for Metro Denver. Cooling and condensing as it rose across the western landscape, the plume dumped its cargo of moisture across northeastern Colorado.
Over the past 24 hours, Metro Denver received a half inch of rain in most areas while higher elevations to the west and south collected .75 inch or more, a welcome respite from the recent drought. Checking the foothills as I arrived from the east, it was obvious that the upslope shroud was beginning to lift though jet traffic was still landing to the north and likely offering a bumpy descent through the showers and virga. Our Littleton farm clearly benefited from the moisture, having taken on the untidy overgrowth that promises plenty of yard work this week.
As the system continues to move eastward, the muggy air and thunderstorms will be confined to the Eastern Seaboard and high pressure will reclaim the Heartland, bestowing warmth and sunshine for the days ahead. Here along the Front Range, the wind will shift to the south-southwest, a downsloping direction for Metro Denver; we expect sunshine, mild temperatures and a chance to dry out.