Last Wednesday morning at 4:54 a.m. the National Weather Service reported Lincoln’s temperature, as it does every hour, from readings collected on equipment housed at the Lincoln Airport.
It announced to the world that our town was super-record-breaking cold — minus 17 cold. At 7:54 a.m., it was still minus 16. At 8:54 a.m., it’d warmed to 13 below. And yet on one Journal Star employee's phone, at 8:31 a.m., the Weather Channel app said it was a balmy minus 6 in Lincoln.
Perhaps you possess similar screenshots.
Asked about the discrepancy on a record-setting day, Melissa Medori, a spokeswoman with the Weather Co., asked for the specific zip code where the weather app was pulling its info.
The NWS official temp reading in Lincoln is recorded at the airport, a METAR — or Meteorological Terminal Aviation Routine — station. That’s where the minus 16, minus 13 and the low-low of minus 17 all originated Wednesday.
Weather apps don’t always draw current conditions from public data provided by METAR stations; they pull data for forecasts and temp readings from an array of sources dotting the country. So does the National Weather Service, but most of the observing platforms it cites for current conditions meet federal standards for aviation.
“We use a different paradigm from gathering observations from fixed sensors only (like those only at airports, etc.),” Medori wrote in an email. “We've tested, designed and built a platform that, through syntheses of several other sources of data, can produce a very high-resolution current conditions report. On top of those data sources and weather models analyzed with machine learning within a cloud-based infrastructure, we also have a high-resolution climatology grid to ‘spread’ the data.
“So instead of using only observations at airports, our platform ‘fills in’ the gaps between to create a forecast grid for the entire globe. So we're able to provide current conditions and forecasts down to a city block, as opposed to miles away at an airport.”
Collecting information recorded by large, high-quality gear, as well as smaller, personal weather stations to amass weather data is the way the wind is blowing, said Michael Moritz, a meteorologist with the National Weather Service who is based in Hastings, where he sometimes spots personal weather stations west of town, installed atop pivot irrigation systems.
“They’re important for production, assessing their crops,” he said. “Sometimes, they just want to know what it is outside their house, and not 20 miles away. All weather is local.”
And many who have installed them share the data through vast networks such as Weather Underground, the Weather Channel’s personal station system (and hyperlocal weather app), or with others such as WeatherBug, Dark Sky and on and on.
Medori said her company draws information for forecasts and current conditions from a combination of traditional METAR stations, as well as 275,000 personal weather stations, satellite, radar and additional sources, processing 400 terabytes of data daily.
So perhaps when you’re hearing about record lows, but your Weather Channel app is telling you it’s merely minus 6, that temperature was pulled from a reading transmitted by a personal weather station located nearer the phone. Medori said last week she couldn’t be sure of that until speaking with some developers who were on vacation through the new year.
There’s likely to be more sub-zero temperatures this weekend to draw a comparison.
The Weather Channel’s forecast for Lincoln calls for a high of minus 1 on New Year’s Eve, and a low of minus 15. For comparison’s sake, the National Weather Service at the same time calls for a Sunday high of 0 and a low of minus 19.
But who’s counting?