Ever wonder where the temperature reading comes from when you're watching the news or looking at your phone?
That number, or at least where it comes from, is about to change in Denver, and it could affect the way your weather is both observed and recorded.
The Denver Museum of Nature & Science announced earlier this month that it was closing the eight-year-old City Park weather station due to the ongoing construction there. Almost every news channel in town cites the number from this weather station as its official temperature. Here's an example, from 7News in Denver last week:
DMNS spokeswoman Maura O'Neal says that it's expected to close by November 30, with no immediate downtown replacement once it does shutter. That means the only reliable weather station in Denver will be at Denver International Airport, a full eighteen miles from the city's center. A new station will open at some point in the future, but there is no timetable on when it'll open, leaving a gap in reliable and official weather records in central Denver.
Mike Nelson, chief meteorologist at 7News, the National Weather Service and others banded together to push the City of Denver to purchase and install high-end weather instrumentation in 2009 in City Park.
"I'm a little sad, because this was kind of my baby," says Nelson. "It's a valuable part of the data stream."
Most cities' official climate data is kept and maintained at an airport site, so Denver isn't bucking the national trend by relying on a reading from DIA. But there are considerable differences between the DIA observation site and most others that could impact the way weather temperatures are recorded.
First, DIA is uniquely far from the center of the city. Some cities, such as New York City, San Francisco and Los Angeles, have introduced official climate sites in their respective downtowns for a more accurate view of weather conditions, as opposed to outlying airport sites.
Second, and more important, Denver is a city full of microclimates, or big weather differences in small distances, mostly because of elevation and close proximity to the mountains.
For example, Denver's average high temperature in 2017 at City Park has been 69.6 degrees, with an average low of 43.8 degrees, according to statistics from Colorado's state climatologist. DIA's official high was almost identical, with a reading of 69.3 degrees, but its average low was 40.5 degrees, more than three degrees cooler than the observation site.
Moreover, City Park has had 12.88 inches of precipitation so far this year, compared to just 11.46 inches at DIA. Last winter's snowfall came out to 28.7 inches at City Park compared to just 21.8 inches at the airport.
An inch or two of precipitation and a few degrees' difference may not seem important, but it does matter, particularly when analyzing long-term climate trends. With no reliable downtown interim climate site, tracking things such as climate change and Denver's urban heat island effect will be more difficult, simply because of the fact that there won't be a fully reliable weather station downtown.
Channel 7's Nelson pointed out in a 2012 blog post some of the differences he'd found between DIA and the City Park site, notably that summer high temperatures were warmer at DIA and winter low temperatures were colder.
A list of potential downtown weather-station replacement sites has been drawn up, but bringing it back to City Park isn't in the plans, according to O'Neal.
"None that are far enough along that I’d be comfortable saying out loud," O'Neal says when asked about where a new station might go. She adds that the station will be required to be within five miles of the old Stapleton Airport.
The National Weather Service office in Boulder is trying to secure funding for an official climate site in central Denver as well.
"We would like to place an official NWS observation site in metro Denver, within a location that will preserve the climatological record," says Nezette Rydel, the meteorologist-in-charge at NWS Boulder. "We have identified possible sites. We do not have funds for a new station at this time, although we continue to work with the NWS to identify and secure funding."
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