The U.S. Government’s Amazingly Wrong Forecast for This Winter
It predicted “above-normal” temperatures. Oops.
Surprised by how tough this winter has been? You’re in good company: Last fall the Climate Prediction Center of the National Oceanic and Atmospheric Administration predicted that temperatures would be above normal from November through January across much of the Lower 48 states. This graphic shows just how wrong the official forecast of the U.S. government was:
The big red blotch in the top map represents parts of the country in which the Climate Prediction Center forecast above-average temperatures. The frigid-looking blue blotch in the bottom “verification” map shows areas where temperatures turned out to be below average.
“Not one of our better forecasts,” admits Mike Halpert, the Climate Prediction Center’s acting director. The center grades itself on what it calls the Heidke skill score, which ranges from 100 (perfection) to -50 (monkeys throwing darts would have done better). October’s forecast for the three-month period of November through January came in at -22. Truth be told, the September prediction for October-December was slightly worse, at -23. The main cause in both cases was the same: Underestimating the mammoth December cold wave, which brought snow to Dallas and chilled partiers in Times Square on New Year’s Eve.
The cause of the tough winter, as is well known by now, is the polar vortex, which has been distorted by a strong and persistent ridge of high pressure over the eastern Pacific and the west coast of the United States. First, it’s causing California’s drought. Second, polar winds are flowing northward around the high-pressure ridge and then plunging down along the ridge’s backside.
What the Climate Prediction Center hasn’t been able to figure out is why that ridge has maintained its position so persistently. “Sometimes trying to figure out why something happened is as hard as making the forecast of what will happen,” Halpert said in a Feb. 14 interview.