faulker015

Following two weeks of relatively mild temperatures and intermittent rain, the next (and hopefully last) heat wave is building along the Colorado Front Range.  Once again, it is the product of a high pressure ridge, expanding northward from the Desert Southwest.  For the next week or so, afternoon highs are expected to reach the lower to mid 90s F, well above average for September. Fortunately, the recent rains have revived the vegetation and the longer nights, combined with our high elevation and thin, dry air, have allowed overnight temperatures to drop into the fifties.  In addition, rising hot air often ignites thunderstorms above the Front Range peaks, which then drift eastward to provide spotty relief from the heat. Our risk of these heat waves will continue until the jet stream becomes less stable in mid autumn, undulating across the country and dislodging warm atmospheric ridges with cool atmospheric troughs.  Snow usually dusts the higher peaks by late Septe...

On my regular flights between Colorado and Missouri, I am usually focused on the ground, studying the topography and rivers; should it be a night flight, I watch for city lights, observing the sequence of towns and cities that I have come to memorize from my numerous road trips. But tonight, as I fly from Denver to Columbia, Missouri, I will be watching the sky.  This is the annual peak night for the Perseid Meteor Shower, produced by remnant debris from the Swift-Tuttle Comet.  As the Earth crosses the comet's path around the sun, the dust particles collide with and ignite in our atmosphere, producing numerous meteors.  The Perseids are often abundant and are expected to increase in coming decades as the comet's path more closely aligns with the orbit of our planet. As I write this blog from Denver International Airport, sunset and our takeoff are still two hours away but the radar shows that precipitation is minimal between here and Columbia, suggesting that high clouds...

As hordes of humans head for the beach this summer, rip currents will take a deadly toll.  Unfortunately, they often develop when conditions at the shore appear to be ideal, catching many swimmers off guard. Rip currents evolve due to a steady onshore flow of seawater; this may result from counterclockwise winds around an offshore storm or from clockwise winds around a dome of high pressure.  In either case, water builds up along the beach and that pressure leads to breaks within the offshore sandbar; as the retreating flow funnels through those breaks, strong rip currents (not always evident on the surface) develop, sweeping bathers away from shore.  Those caught in a rip current are advised to swim parallel to the shore until they are safely out of the channelized stream; unfortunately, panic often sets in and such advice is fatally ignored. Today, as Tropical Storm Chris churns 200 miles off Wilmington, North Carolina, rip current warnings have been posted for most of ...

While the Trump Administration believes that our northern neighbors are a security threat, I certainly appreciate the cool, dry air that they sent this way (no tariffs attached).  This morning, it felt more like late September than late June along the Colorado Front Range. This welcome change was the product of high pressure over the Pacific Northwest and low pressure over the Northern Plains.  Between these atmospheric pumps, the pleasant Canadian air was driven southward, displacing the heat that has plagued us for the past week or so.  Colliding with that heat, the cool air may spawn thunderstorms later today. Unfortunately, our respite will be brief and the southwestern atmospheric ridge will reclaim the Front Range by Monday.  In the meantime, we'll enjoy highs in the upper seventies and low eighties and overnight lows in the upper fifties (F).  My personal thanks to Canada for the refreshing air, however short it's visit.

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 (s...