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“Cold” vs. “Warm” Snowstorms; Why Air Temperature Determines Severity of Icing and Traffic Problems

12 Dec 2012, 6:25 am

Temperature Matters

So how was your commute yesterday? Amazing how nasty the roads are, more than 48 hours after The Big Dump. We’re all fixated on how many inches will fall, when we should be more focused on the air temperature.

Wet snow falling at 25-30F is radically different than powdery snow, with an air temperature of 10-15F. MnDOT’s de-icing chemicals work quickly and efficiently – unless – temperatures drop below 15 F. or so. And repeated traffic on cold, freshly-fallen snow can compress all that fresh fluff into a concrete-like sheet of glare ice. Accumulation is important, but air temperature (at the tail-end of a storm) is a better tip-off of how bad travel conditions will be. Cold snows are much more problematic.

With that long, wheezy preamble – let me reassure you that the drive will get easier today, with highs near 32F. Yes, the ice may finally budge, even melt on dark, asphalt pavement.

ECMWF model guidance is hinting at a few inches of (wet) snow Saturday into Sunday morning. A plowable amount is possible, but with temperatures closer to freezing I expect less havoc on the highways.

We may top 32 F late next week – before cooling down to the 20s for a very white Christmas.


* Photo above from Sunday’s snow blitz in Minneapolis: Brennan Jontz Photography.


Saturday Snow? Another southern storm will make a pass at Minnesota on Saturday. Although I don’t expect anything as severe as last Sunday, accumulating (plowable) snowfall amounts are quite possible. The big difference? High temperatures Saturday should be close to freezing, meaning a wet, slushy snow – and a better chance that MnDOT de-icing equipment will be able to keep most roads ice-free this time. In theory. ECMWF map above valid 18z Saturday, courtesy of WSI.


How Much? It’s still early to be throwing around inch-accumulation amounts for Saturday, but the ECMWF model is printing out .51″ liquid on Saturday, which could translate into a period of moderate to heavy wet snow, a few inches of slush. Sunday looks drier with some sun and highs in the low 20s.

Water Waning Into Winter. Here’s an update on the nagging drought from NOAA’s ClimateWatch: “…Farmers are feeling the pinch from all of this lack of water. We’ve already seen damage to corn and soybeans. Now we’re beginning to see a diminished winter wheat crop. Wheat is a staple grain, but in the winter it often doubles as cattle forage. So it’s not just measured in loaves of bread, but also in pounds of cow! As of November 27, the US Department of Agriculture estimated that 65% of the winter wheat grown in the United States was being affected by the drought. Nearly a quarter of the winter wheat crop is categorized either in poor or very poor condition. Across the Plains, winter wheat yields are below average, especially in Nebraska and South Dakota, the epicenter of drought conditions. The drought has also caused a serious water shortage in two of the nation’s great rivers: the Missouri and the Mississippi. Reservoir managers along the Missouri are holding water back to ensure local supply. But less water from the Missouri means less water in the Mississippi. If Mississippi water levels drop further, barge traffic will be shut down. This would slow the delivery of commodities, including fuel, and drive up prices for consumers…”

National Hurricane Center To Adopt New Storm Surge Map, Warning System Over The Next Three Years. New Orlean’s has a very interesting story – here’s a clip: “During the next three years, the National Hurricane Center will roll out two new ways of warning the public of the risk of hurricane storm surges. Forecasters hope the new warnings will revolutionize the public’s understanding and response to storm surge flooding, while also quieting the growing chorus of coastal residents who are concerned that traditional hurricane strength warnings don’t go far enough to protect them. National Hurricane Center Director Rick Knabb and Storm Surge Team Lead Jamie Rhome explained the plans to upgrade storm surge warnings and public information during a Wednesday meeting at the center that they requested in response to | The Times-Picayune editorials urging the speedy adoption of new surge warnings…”

Photo credit above: “(Gallery by Ted Jackson, | The Times-Picayune)

Bloomberg News: Keep Satellites Aloft To Track Bad Weather Below. Here’s an excerpt of an Op-Ed from Bloomberg and “…Instead, in a few years, weather predictions in the U.S. are in danger of becoming less accurate. Why? Because the federal government is unprepared, at least temporarily, to operate a full complement of satellites. The gap could begin in October 2016, when a satellite put in orbit a year ago reaches the end of its expected five-year life. A replacement won’t be ready to launch until at least March 2017, and then it will take another year for its instruments to be checked out and ready to operate. That would leave a 17-month gap, during which three-to-five-day weather forecasts will be fuzzier...” Image above: NOAA

State Report Warned Of Storms As Big As Sandy. Meteorologically, Sandy was a 2×4 across the head, at least for coastal residents living in the Northeast. But scientists and city planners have been warning of such a storm for many decades now. AP and WABC-TV in New York has more: “More than three decades before Superstorm Sandy, a state law and a series of legislative reports began warning New York politicians to prepare for a storm of historic proportions, spelling out scenarios eerily similar to what actually happened: a towering storm surge; overwhelming flooding; swamped subway lines; widespread power outages. The Rockaway peninsula was deemed among the “most at risk.” But most of the warnings and a requirement in a 1978 law to create a regularly updated plan for the restoration of “vital services” after a storm went mostly unheeded, either because of tight budgets or the lack of political will to prepare for a hypothetical storm that may never hit...” Image above: NOAA.

An American Life, Made Better Through Big Data. Here’s a clip of a fascinating article from The Atlantic: “Imagine being told the storm of the century was going to hit in three days–anywhere between New York City and Richmond, Virginia. That may have been the scenario when superstorm Sandy turned toward the East Coast last month. Thankfully, five years ago the National Hurricane Center (NHC) began utilizing the Hurricane Weather Research and Forecasting model that analyzes big data collected from satellites and airborne observations, producing high-resolution computer-modeled forecasts every six hours. As a result, the NHC was able to predict the storm’s landfall five days out within 30 miles of direct impact in New Jersey. (Twenty years ago, even 72-hour forecasts were only accurate up to about 350 miles of landfall.) Big data was more than just a buzz word during Hurricane Sandy; it saved lives. This is one clear example of the growing role of big data in the public sector…”

Minnesota: Twice As Many Tornadoes As Wisconsin? When did this happen? 20 year averages from NOAA NCDC show an average of 45 tornadoes/year in Minnesota vs. 24/year in Wisconsin. No, we don’t live in Tornado Alley, but we do live in Tornado Cul desac. Better to hang out in Rhode Island, which has an average of (0) tornadoes/year.

What Is The Weather Coalition? This caught my eye: “The aim of the Weather Coalition is to bring together industry, state and local governments, and academia in an organized effort to urge Congress and the Executive Branch to fund national initiatives to expand research collaborations between these groups and federal agencies in the area of mesoscale observations and predictions. This effort will improve the country’s weather prediction and warning capabilities and provide assessments of the nation’s socioeconomic vulnerability to weather. The results will be enhanced competitiveness for U.S. industry, improved support for national defense, and increased protection of life and property…”

Absence Of A Farm Bill Threatens Agriculture’s Resilience To Extreme Weather. Agri-Pulse has the story; here’s an excerpt: “…Congress’ inability to pass a farm bill this year, however, puts the future at risk. Crop insurance and risk management options moving into next year – a recovery year for food and feed stocks – are uncertain at best. Research programs for more resilient crops are left unfunded and incomplete. And conservation programs that implement scientifically based best practices for managing stressed cropland and water resources are unavailable to farmers and ranchers. Without the farm bill, program enrollment has been halted. Necessary resources are inaccessible. with the extreme, unpredictable weather we have been experiencing, we can’t afford not to have a farm bill. Much scientific evidence suggests that unstable weather may become the norm….”

1% Sledding. Way to work up a sweat on the ice! Reminds me of when I was 13, using my mini-bike to deliver newspapers. Everyone is looking for an easier way to get it done. Then again, using a Segway on what looks like fairly thin ice is one effective way to get Nearer My God To Thee. Be careful out there. Image: Reddit and

Best Weather In The USA? If you’re a snow lover the best weather is right here, in this zip code (cherish the moment). But if you like sun, warmth and gentle breezes might I suggest San Diego, which does have the distinction of having America’s best overall climate. Photographer Jim Grant agrees.

The Shill Becomes A Journalist. I now have even more respect for Bob Costas. Check out this article (and video) from; here’s an excerpt: “…Sunday afternoon, in a 90-second editorial during the halftime of the Sunday night NFL game on NBC, Costas quoted from a column by Jason Whitlock: “Handguns do not enhance our safety. They exacerbate our flaws, tempt us to escalate arguments, and bait us into embracing confrontation rather than avoiding it.” Costas then paraphrased from earlier in Whitlock’s column: “If Jovan Belcher didn’t possess a gun, he and Kasandra Perkins would both be alive today….”

Twitter – Instagram Photo War Reveals New Business Realities Of Social Networks. takes a look at the new reality with social media. Consumer-first? No, now it’s monetization-first, making investors happy. Here’s an excerpt: “The photo-sharing turf war is escalating, with Twitter copying Instagram-like features and Instagram (owned by Facebook) no longer making its photos viewable within tweets. No matter which company wins, users will lose. It seems time to just accept that Facebook and Twitter’s forget-about-money-and-put-users-first startup phase is over. Both companies are pivoting hard toward monetization and market-share protection as their primary goals…The networks have shifted focus from creating value to capturing value. And to capture value, they each feel the need to lock users into their own platforms and reduce integration, thus limiting competition…”

TSA Fail. No idea what airport this is – seriously doubt it’s MSP. Thanks to for passing this one along.

Climate Stories…


Climate Change Consensus Is Virtually Unanimous. Are you researching peer-reviewed science, or just forwarding blog posts from deniers (often funded by fossil fuel companies?) Here’s an excerpt of a story from Huffington Post: “A recent analysis of papers appearing in peer-reviewed science journals shows published scientists to be virtually unanimous in their agreement that human-produced carbon dioxide emissions are a significant cause of global warming. You are free to disagree with my characterization of the consensus as “virtually unanimous,” if you feel 99.83 percent doesn’t qualify. There are, after all, almost two-tenths of one percent who dissent from the majority assessment. Oberlin College geologist Dr. James L. Powell reviewed 13,950 papers published between January, 1991 and early November, 2012, and found that a mere 24 of them dissented. That’s .17 percent. 1 out of every 581. Powell further makes the point that those 24 were, on average, the least cited of the papers, saying, “Of one thing we can be certain: had any of these articles presented the magic bullet that falsifies human-caused global warming, that article would be on its way to becoming one of the most-cited in the history of science…”

Wind And Solar Power Paired With Storage Could Power Grid 99.9% Of The Time. Forget plastics – consider investing in high capacity battery storage technologies that can “save” power generated by wind and solar, and release it onto the grid when needed over time. Science Daily has the story; here’s an excerpt: “Renewable energy could fully power a large electric grid 99.9 percent of the time by 2030 at costs comparable to today’s electrical expenses, accorduing to new research by the University of Delaware and Delaware Technical Community College…”



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Welcome to the WeatherNation blog. Every day I sift through hundreds of stories, maps, graphics and meteorological web sites, trying to capture some of the most interesting weather nuggets, the stories behind the forecast. I’ll link to stories and share some of the web sites I use. I’m still passionate about the weather, have been ever since Tropical Storm Agnes flooded my home in Lancaster, PA in 1972. I’ve started 5 weather-related companies. “EarthWatch” created the world’s first 3-D weather graphics for TV stations – Steven Spielberg used our software in “Jurassic Park” and “Twister”. My last company, “Digital Cyclone”, personalized weather for cell phones. “My-Cast” was launched in 2001 and is still going strong on iPhone, Android and Blackberry. I sold DCI to Garmin in 2007 so I could focus on my latest venture: WeatherNation. I also write a daily weather column for The Star Tribune And if you’re on Twitter, you’ll find me @pdouglasweather

One response to ““Cold” vs. “Warm” Snowstorms; Why Air Temperature Determines Severity of Icing and Traffic Problems

  1. I read with interest your comments about weather satellites and wonder…why is NOAA involved and not NASA? I know that money to fund NASA is shrinking but with the importance of weather, I would think that NASA could help with the satellite situation…..just thinking out loud!!

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