Sure, it’s been hot for most of Colorado lately. But one city in particular has been exceptionally warm.
In Denver, the mercury soared all the way up to 85 degrees last Friday, more than 20 degrees above average for this time of the year. Colorado Springs set a new daily record high last Friday (86 degrees), and Pueblo set one last Thursday (94 degrees).
But in Alamosa, located in the heart of southern Colorado’s San Luis Valley, they’ve had eight straight days of daily record highs. That streak was (barely) snapped on Monday, but not before more than a week’s worth of new daily records.
— NWS Pueblo (@NWSPueblo) May 4, 2020
According to Klint Skelly, a meteorologist at the National Weather Service office in Pueblo, the consecutive record high temperatures have been mainly due to a persistently warm wind pattern.
“If you get the right setup, in this case it’s southwesterly winds off the San Juan Mountains, it just heats up. It was a pretty persistent pattern over the eight days,” Skelly said of Alamosa’s eight-day heat wave. “It was uncommon for eight days in a row. But if the pattern is right, it’s going to be warm and dry.”
When wind flows down off of a mountain range, it accelerates as it hurdles down toward a flatter surface, similar to a kid on a playground slide. When that air accelerates, it also compresses and warms. If that weather pattern takes place over a prolonged period, it’ll often lead to extra warm and windy temperatures over that time frame.
In Alamosa, located in the heart of the notoriously dry San Luis Valley, that often means warmer and drier weather than the rest of Colorado. Alamosa is located just east of the San Juan mountains of southwest Colorado and just west of the Wet Mountains of south-central Colorado, meaning that downsloping winds are relatively common there.
But the prolonged southerly component to those downsloping winds ticked up those temperatures even higher than usual. That, simply and generally, led to the lengthy heat wave of daily record highs.
Gusts in Alamosa have been regularly gusting to 30 to 40 mph, including a peak 33 mph wind gust on Monday afternoon at the San Luis Valley Regional Airport in Alamosa.
It should be noted that Alamosa’s official climatological record only dates back to 1943, which is substantially shorter than other Colorado cities such as Denver (records date back to 1872) or Colorado Springs (1894). That increases the likelihood of setting a daily record.
Even with that in mind, eight straight days of daily record highs is impressive, and Alamosa accomplished the feat this week.
“It’s just the pattern that’s set up,” Skelly said. “Pueblo and Colorado Springs, we set records here two or three days in a row. But not nearly as long as the San Luis Valley.”
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