Going Fast. As of 7 pm Monday there was only 6" snow on the ground at MSP International Airport. That's a loss of 5" in one day. Actually, it's probably a good thing we're losing some of this snow now, in mid February. It may alleviate some of the flood risk in late March.
February Data. On February 1 MSP had 14" of snow on the ground, with 11" reported Sunday evening, the 13th. I can't remember the last time we lost 5" in a 24 hour period. Data from the Minnesota State Climate Office.
Pothole Weather. Ah, the freeze-thaw cycle is upon us (1-2 weeks ahead of schedule I might add). Water has the unpleasant tendency to expand when it freezes. That means during the daylight hours water gets into tiny cracks in highway surfaces, and at night that liquid water expands as the mercury dips below 32 F. Over time this literally pulverizes, shreds the highway surface. Add a few thousand cars passing over this brittle surface and you can wind up with some crater-size potholes. Nothing quite this bad (I pray), but I can't remember seeing so many hubcab-eating potholes lurking out there. All you can realistically do is slow down (and try not to swerve into oncoming traffic).
Too Early To Retire The Shovel? Just when you thought it was safe to exhale. Nothing definitive yet - but the models are strongly hinting at accumulating snow early next week, one GFS model even suggesting a potential for a foot. That may be pushing it, but this will be a slow-moving, southern storm, tapping moisture from the Gulf of Mexico. it may also be a long-lasting snow event, possibly 36 hours of precipitation. The catch? A thin layer of warm air aloft may change snow over to rain (or an icy mix), especially south/east of the Twin Cities. There's no way to know (yet) where that rain/snow line will set up. We'll obviously keep an eye on this, see if there is continuity from one model run to the next, and if the models converge on a believable solution. Let me make this perfectly clear: I do NOT think we'll see a foot of snow early next week. A few slushy inches? Possibly. No cause for panic, loathing or mass evacuation.....not yet.
Snow Water Equivalent. NOAA's Hydrological Remote Sensing Center has an interactive tool that allows you to calculate how much water is locked up in the snow. My eyes are shot, but I think the metro is in the 4-6" of liquid water range, with a few small patches of 6-8" over southwestern Minnesota, south/west of Willmar. Again, the rate of melting will be determined by how fast we warm up in late February and March (gradual or sudden) and the presence of rain, which would accelerate snow-melt and heighten the risk of serious river flooding.
"For at least the second time this winter, following Atlanta's snowfall this week, snow was on the ground in every state of the Union except Florida. Clearly a most unusual winter. It's not that we have had extreme low temperatures, quite the contrary. It's just the persistence of below-normal temperatures on average and, until now, the lack of the mild spells Atlanta normally sees during the course of a winter. Also, like last winter, the frequency of snow or ice events and threats of them for a close call have been far more numerous than average. Since 1895 statewide December and January were the third coldest on record in Georgia just behind the winters of 1917-18 and 1976-1977. December was the coldest statewide in the Peach State in 116 years."
Record High Temperatures Far Outpace Record Lows Across U.S. A 2009 report from NCAR, the National Center for Atmospheric Research, showed a fairly pronounced trend in recent decades: twice as many record highs as record lows from 2000-2009. An excerpt: "BOULDER—Spurred by a warming climate, daily record high temperatures occurred twice as often as record lows over the last decade across the continental United States, new research shows. The ratio of record highs to lows is likely to increase dramatically in coming decades if emissions of greenhouse gases continue to climb. "Climate change is making itself felt in terms of day-to-day weather in the United States," says Gerald Meehl, the lead author and a senior scientist at the National Center for Atmospheric Research (NCAR). "The ways these records are being broken show how our climate is already shifting."...... If temperatures were not warming, the number of record daily highs and lows being set each year would be approximately even. Instead, for the period from January 1, 2000, to September 30, 2009, the continental United States set 291,237 record highs and 142,420 record lows, as the country experienced unusually mild winter weather and intense summer heat waves. A record daily high means that temperatures were warmer on a given day than on that same date throughout a weather station's history. The authors used a quality control process to ensure the reliability of data from thousands of weather stations across the country, while looking at data over the past six decades to capture longer-term trends. This decade's warming was more pronounced in the western United States, where the ratio was more than two to one, than in the eastern United States, where the ratio was about one-and-a-half to one."
Increasingly Variable Summer Rainfall In Southeast Linked To Climate Change. An article from Duke University on the shifting rainfall patterns across the southeastern USA: "DURHAM, N.C. – A new study by a Duke University-led team of climate scientists suggests that global warming is the main cause of a significant intensification in the North Atlantic Subtropical High (NASH) that in recent decades has more than doubled the frequency of abnormally wet or dry summer weather in the southeastern United States. The NASH, commonly referred to as the Bermuda High, is an area of high pressure that forms each summer near Bermuda, where its powerful surface center helps steer Atlantic hurricanes and plays a major role in shaping weather in the eastern United States, Western Europe and northwestern Africa."