Wednesday, December 30, 2015

In Wild Winter, Warm North Pole Storm Chills U.S. Forecast as Flooding Threatens Levees

[New York Times] What a season it has been for demonstrating how severe weather in the United States is shaped by, and shapes, conditions elsewhere around the planet. Of course, the main event is the still-growing El Niño warmup of the tropical Pacific Ocean, which has worldwide impacts — particularly in poor countries. For a primer, see this helpful explanatory video and article from The Times, and a great update from Capital Weather Gang.
Below, I’ll discuss the growing prospect of record-breaking flooding along the Mississippi River, fueled in part by the Pacific Ocean pattern. Jeff Masters has a worrisome piece on his Wunderground blog noting that such flooding has never been experienced at this time of year. My focus will be on how vulnerable levees may raise the odds of disaster.
But first let’s look north.
Justin Gillis filed an excellent report tonight on factors behind severe weather around the world, stressing that El Niño is hardly the only player: “This winter, a climate pattern called the Arctic Oscillation is also keeping cold air bottled up in the high north, allowing heat and moisture to accumulate in the middle latitudes."
You almost assuredly saw at least one story about how the potent storm that triggered deadly tornado outbreaks and flooding across the South and Midwest in recent days carried so much warm air to the North Pole that temperatures over the sea ice, normally well below zero through the dark boreal winter, briefly hitting 33 degrees Fahrenheit today.*
(If you didn’t, click back to the Capital Weather Gang and Andrew Freedman’s coverage for starters.)
The storm system (named Storm Frank by British forecasters), inspired overheated headlines describing how the “North Pole [is] Set to Unfreeze as Temperature Soars” and the like. It’s not, as the WeatherBELL meteorologist Ryan Maue pointed out on Twitter today, writing, “Hope you enjoyed the North Pole heat wave — now back to normal programming down to -25°F … warm up next week.” Read More