On February 22, Denver City Council
will consider a proposal to partner with the National Oceanic and Atmospheric Administration
and install a weather observation station on the Sand Creek Uplands Open Space at the site of the former Stapleton Airport. This site will provide automated real-time and long-term data, but will not replace Denver International Airport
as the official weather observation site for Denver.
Yes, for the umpteen-billionth time, DIA sucks as a weather-observation location for Denver proper. But you know what? It doesn’t matter.
There are a lot of places in the United States where 23 miles doesn’t make much difference in what the weather is doing over days, weeks, months or years. That’s not the case with Denver. There's a world of difference between the weather downtown and 23 miles away at DIA because of the complex terrain we have around here. Here’s just a short list of what changes the weather between the airport and central Denver:
• Different wind patterns. Sometimes It’s windy at the airport when it’s not windy in other places, and vice versa. Wind really affects temperature and precipitation around here.
• DIA lies right in the core of the “Denver Cyclone,” which is a localized wind pattern that is a strong catalyst for severe thunderstorms.
• Snow dynamics are very different at DIA, which gets a lot less snow than much of the rest of Denver.
• Summer afternoon clouds and storms take longer to get to DIA, so the airport is warmer than much of Denver because, on average, it stays sunnier longer. This greatly affects the arbitrary “90-degree day” count that obsesses so many people.
• Our coldest days in the winter happen when frigid air from the Midwest backs “uphill” toward the Front Range. DIA is closer to those cold fronts, so it gets colder — and stays colder longer — there than in the rest of town.
Awesome, right? DIA is hotter and stormier in the summer…colder and drier in the winter. I could go on, but you get the idea.
Now, here’s why it doesn't matter:
Federally funded weather observation started with the U.S. Army Signal Corps in 1870, which used telegraph wires to carry information from military forts and other available locations to be used for the “Benefit of Commerce
,” to warn of impending storms.
• Besides being put in military facilities, telegraph stations were placed on railway lines, which were the principal means of conducting cross-country commerce at the time. Being a big rail hub in the West, Denver was chosen as an observation site. In 1871, the first observation site was placed at 16th and Larimer streets. In 1916, it moved to 19th and Stout streets, in the U.S. Post Office building. From 1931 to 1949, observations were taken at both the downtown post office and Stapleton Airport; in 1950, Stapleton became the official weather station.
Why the airport? Commerce, remember? Air travel was growing fast and is very weather-dependent — and the feds' mission is to support commerce. That’s why the official site moved to DIA in 1995.
Over the years, the instruments used to observe weather changed. Alcohol and mercury thermometers were less precise and required the liquid to rise to the exact tick mark on the thermometer to register a temperature. By contrast, modern electronic temperature-measuring equipment has three thermometers that measure in degrees Celsius, which is then converted to Fahrenheit (we’re the only place in the world that still does this...don’t get me started), and the readings are rounded and averaged to obtain the “official” temperature.
Over the years, the city has changed, too. Even if the weather station had stayed at 16th and Larimer, local conditions now are vastly different from those in the 1870s because of development. The thermal mass of buildings and pavement have altered downtown so that it can't be compared to the Denver of the late-nineteenth century.
So the landscape has changed, the locations have changed and the instruments have changed, making long-term weather record-keeping a “nice to have” bunch of data — but geez, it’s not clean or consistent data by any measure.
Back when I was doing TV weather, I stopped reporting DIA temps somewhere around 2006. I mean, who cares? In the world of IBM's WeatherUnderground
, you have access to hundreds of weather stations along the Front Range so you can see what the weather is right next to you.
“Official” is, well, officially irrelevant.