All Weather News

Quiet Day – Drought May Be Accelerating Fall Foliage, Leaves “Leaving” Earlier?


“…The urban heat island in large cities has been shown to delay fall color by 1-2 weeks, compared to surrounding areas, and that effect is thought to be due to warmer nights..” – Lee Frelich, Director of the University of Minnesota Center for Forest Ecology; his full comments below.

Matthew Nisbet, an associate professor in the School of Communication at American University, and colleagues have found that people who are indifferent, or even hostile, to climate change are more receptive to the issue when it’s talked about as a health issue.” – from an article focused on the health implications of a warming climate at NPR.

The whole issue of climate change is now so intensely politicized and so intensely fought over, if you put a foot wrong in any regards, if you make a claim that can’t stand up, it then becomes ammunition in this intense culture battle that we have.” – George Marshall, Climate Outreach Information Network, from an NPR story below.

“…Or an iced area larger than Alaska, Texas and California combined melted away in 31 days last month while you and I carried on our usual business. And it’s still melting. Should we be concerned? What do you think?” – from Doug Craig’s eye-opening Climate of Change post at; details below.


First Flakes? No need to hyperventilate, panic or call your mother just yet, but the GFS is hinting at temperatures in the lowest 4,000 feet cold enough to support the first flurries of the season over North Dakota by Tuesday morning of next week. Something to look forward to.


The Edge of Dampness. Will it actually rain? I’m having my doubts. The high-resolution, 12-kilometer RPM model from WSI shows a smear of light rain over southern Minnesota at 3 pm, the best chance of puddles south of the metro area.


Today’s Weather Map. NOAA’s WRF model, valid 4 pm today, shows a streak of light rain from Denver to Sioux City to Eau Claire, showers along the leading edge of cooler air. More heavy T-storms are predicted for Florida, a surge of Gulf moisture pushing rain into Houston, more showers and T-storms over the four-corners region of the southwest. Otherwise dry weather prevails.

Will Dry Weather Impact Minnesota’s Fall Foliage? The answer is a qualified yes, at least for unwatered trees in the metro area. I posed this question to Lee Frelich, Director of the University of Minnesota Center for Forest Ecology. Here is his e-mail response:

For most species of trees, droughts, and cool late summer/early fall temperatures bring on fall color, whereas wet weather and warmer late summer/fall temperatures delay fall color. For a few species of trees, early versus late spring also plays a role, since their leaves only last a certain length of time, so that an early spring causes leaves to fall off earlier.

I think we are seeing the effects of the developing drought on trees right now in the Twin Cities area. I don’t think the August cool spell was cool enough to affect trees here, but it probably was in northern MN. 8-10 days of temperatures at night in the 40s are needed to trigger fall color development. The urban heat island in large cities has been shown to delay fall color by 1-2 weeks, compared to surrounding areas, and that effect is thought to be due to warmer nights.

It’s interesting that we have hardly any fall color development on campus in St. Paul – the lawns here are watered and trees are not under drought stress, but just off campus, unwatered trees are shedding leaves.”

* photo credit above: Flickr.


Rainfall Departure From Normal Since July 31. The north metro is running a 4-5″ rainfall deficit since August 1, most of Minnesota trending (much) drier than average. Details and more maps explaining the evolving drought from The Minnesota Climatology Working Group: “The abnormally dry conditions in central and east central Minnesota developed rapidly during the month of August and during early September with many locations reporting less than one and one-half inch of rainfall.”

Airplane Contrails And Their Effect On Temperatures. In light of 9/11 I wanted to repost an article that highlighted research into the impact of jet contrails on surface temperatures. After planes nationwide were grounded by the FAA in the wake of the terrorist attack, meteorologists noticed something curious: air temperatures spiked by 1-2 F. The theory: no jets meant no jet contrails, high thin cirrus clouds at 25,000 feet, which can have a slight cooling effect during the day, a warming effect at night. Here’s an excerpt from The Christian Science Monitor: “…Then Sept. 11, 2001 presented a unique opportunity to study what the sky looked like without airplanes and contrails. In the wake of the 9-11 terrorist attacks, the FAA prohibited commercial aviation over the United States for three days. That’s when David Travis, an atmospheric scientist at the University of Wisconsin, Whitewater, thought to look at how temperatures might differ at temperature stations around the country. He found that [PDF], for those three days, the average range between highs and lows at more than 4,000 weather stations across the US was 1 degree C wider than normal. In other words, contrails seemed to raise nighttime temperatures and lower daytimes ones.”

Surge Warnings Went Out Before Hurricane Isaac Hit. There is still a huge amount of anger and indignation on the part of New Orleans residents who live in parishes outside of the immediate metro, unprotected from the new and improved levee system retrofitted in the wake of Katrina in 2005. More from “During the two days before Hurricane Isaac plodded across southeastern Louisiana, parish and state officials were given maps by federal weather forecasters and state and university surge experts that detailed the significant storm surge flooding that would occur in areas without levees, such as LaPlace, St. Tammany Parish and poorly protected locations on the east and west banks of Plaquemines Parish. Some of those maps and detailed written warnings of storm surge heights were issued directly to the public, but the public fixation on Isaac’s low Category 1 ranking under the outdated Saffir-Simpson system likely led many residents to forgo evacuating those areas.”

Map credit: Times Picayune.

Researchers Devise More Accurate Method For Predicting Hurricane Activity. Here’s an excerpt of a fascinating article from NC State University: “Researchers from North Carolina State University have developed a new method for forecasting seasonal hurricane activity that is 15 percent more accurate than previous techniques. “This approach should give policymakers more reliable information than current state-of-the-art methods,” says Dr. Nagiza Samatova, an associate professor of computer science at NC State and co-author of a paper describing the work. “This will hopefully give them more confidence in planning for the hurricane season.” Conventional models used to predict seasonal hurricane activity rely on classical statistical methods using historical data. Hurricane predictions are challenging, in part, because there are an enormous number of variables in play – such as temperature and humidity – which need to be entered for different places and different times. This means there are hundreds of thousands of factors to be considered.”

Photo credit: “The researchers, including Dr. Fredrick Semazzi (pictured), hope to use their new method to improve our understanding of hurricane behavior.”

Curiosities: How Are Hurricane Named And Who Names Them? I get this question a fair amount; has a timely article that provides some answers; here’s an excerpt:

Q: How are hurricanes named and who names them?

A: The first known scientific use of hurricane naming arose in the Pacific during World War II. It was an easy and effective way to distinguish one tropical cyclone from another on the weather maps, said Steve Ackerman, a UW-Madison professor of atmospheric and oceanic sciences and director of the Cooperative Institute for Meteorological Satellite Studies. The system was simple and alphabetical: The name of the first storm of the season would begin with A; the second, B; the third, C; and so on.

Naming hurricanes, he added, also gave homesick soldiers a way to recall loved ones. Thus began the practice by predominantly male meteorologists of giving female names to hurricanes. This practice persisted at the National Hurricane Center in Miami until the late 1970s.

Is Earth In Danger Of Solar Flares? Great. One more thing to worry about. But solar activity is forecast to peak in 2013, and there is a small, but not insignificant risk of a solar flare large enough to impact communications and even power grids here on Earth. Here’s an excerpt from a not-so-comforting story at My Fox Phoenix: “…But scientists warn a solar storm, if it’s big enough, can knock out power anytime, anywhere. “Once the magnetic field of the Earth starts to change, that affects things on the day side and night side of the planet, so the effects are global,” said Penn. And the damage could be a life changing event.  Severe solar damage to SRP’s power grid could take more than a year to fix.
“In a time of less strong demand, it might be as little as 10 to 12 months.  In a time when electrical demand is expanding quickly, it might be as much as 18 months or more,” said Hunt. 18 months or more?

Explosion On Jupiter. Details from; here’s an excerpt: “Apparently, something hit Jupiter during the early hours of Sept. 10th (11:35 UT), igniting a ferocious fireball in the giant planet’s cloudtops. Amateur astronomer Dan Peterson Racine, Wisconsin, saw it first through his Meade 12″ LX200 telescope. “It was a bright white flash that lasted only 1.5 – 2 seconds,” he reports. Another amateur astronomer, George Hall of Dallas, Texas, was video-recording Jupiter at the time, and he confirmed the fireball with this video screenshot (above).

The Onion Weather Center: “We Dumb It Down The Best We Can For Our Viewers In The Deep South”. Mildly offensive? You bet. Funny? You be the judge. More from The Onion: “The Onion Weather Center delivers a very special weather report for all of our very special viewers in the Deep South, who require a little extra attention to help them understand that really big numbers mean hot temperatures.”



The Leaves are Leaving

It’s dry out there; yesterday’s Fire Warnings more typical of Montana than Minnesota. Will a deepening drought have an impact on the blaze of color on area trees in the coming weeks? I posed that question to Lee Frelich, Director of the University of Minnesota’s Center for Forest Ecology.

“For most species of trees, droughts, and cool late summer/early fall temperatures bring on fall color, whereas wet weather and warmer late summer/fall temperatures delay fall color.” Frelich told me that 8-10 nights in the 40s are needed to trigger fall color.

We haven’t seen that yet, but dry weather may be having an impact. “I think we are seeing the effects of the developing drought on trees right now in the Twin Cities area”. Frelich added that irrigated trees in St. Paul are fine; off-campus (unwatered) trees are shedding leaves.

We cool off today, 20 degrees cooler than yesterday – a shower possible later; not nearly enough rain to put a real dent in the drought. Skies clear and warm into the weekend; more 70s likely; 80 possible by Sunday.

It’s almost time to drag your favorite jacket out of cold storage – highs hold in the 50s by the middle of next week; a vague, windblown hint of brisk days to come.


Climate Stories…

Canaries Of Climate Change (1). One of the things I’m trying to do, in addition to sharing stories and posts that catch my eye from day to day, is provide some perspective. Not only what is it, but what does it MEAN, and why should I care? Doug Craig does a remarkable job of putting Arctic ice melt into perspective in his Climate of Change posts at; here’s an excerpt of a must-read entry: “…And get this. In 2007, the melt rate for August was 66,000 square kilometers (25,400 square miles) per day. Each day in August of 2007 an area of ice the size of West Virginia melted into the ocean. Every day. That means 31 West Virginias of ice melted away that month. The following year it got worse. “In August of 2008, the year with the previous highest August ice loss, the rate was 80,600 square kilometers (31,100 square miles) per day.” That means that each day, an area of ice close to the size of South Carolina vanished. The whole month. 31 South Carolinas. Melted away. And this year it got worse yet. This year, “the rate of ice loss for August was 91,700 square kilometers (35,400 square miles) per day, the fastest observed for the month of August over the period of satellite observations.” An area of ice the size of Maine disappeared every day. 31 Maines of ice went bye-bye last month.”

When Heat Kills: Global Warming As Public Health Threat. I was living in Chicago in 1995, when a “heat storm”, a deadly spike in heat arrived, with very little advance warning. The Executive Producer at the local station I was working at wanted to do a schtick piece for the newscast, a back and forth with a meteorologist in Phoenix. “Which city is hotter?” Hahahaha. I told her that people were going to die, to position reporters at Chicago hospitals. We wound up getting into a shouting match in the newsroom. “You don’t get it!” she screamed. “You don’t get television!” That may be true, but in this specific case she should have listened to her meteorologist. The next day: wall-to-wall coverage of the 700+ heat deaths and a city-wide Chicago heat emergency. Researchers discovered it wasn’t so much the daytime heat as it was the nighttime warmth; temperatures stayed above 84 F for 3 nights. There was no relief, no chance for people to recover. NPR has the story; here’s a clip: “The current poster child for global warming is a polar bear, sitting on a melting iceberg. Some health officials argue the symbol should, instead, be a child. That’s because emerging science shows that people respond more favorably to warnings about climate change when it’s portrayed as a health issue rather than as an environmental problem. Epidemiologist George Luber at the Centers for Disease Control and Prevention says the most obvious risk from a warming world is killer heat. A deadly heat wave that struck Chicago in 1995 made many people aware of how disastrous sustained high temperatures can be. About 750 people died from the heat in Chicago, “and that was amplified by the European heat wave of 2003, where we had over 70,000 excess deaths attributable to the heat wave,” he says. Today, Luber’s job at the CDC is to deal with health issues related to climate change. And heat waves are just part of his portfolio.”

Photo credit above: Mike Fisher/AP. “Cook County morgue workers walk between a row of refrigerated trucks outside the morgue in July 1995, when a deadly heat wave struck Chicago.”

How Climate Change Could Make Summer Crime Waves Worse. There is a correlation between heat and crime. It’s that simple. The Atlantic looks at recent trends and research and connects the dots into the future; here’s an excerpt: “Chicago has suffered over the past few months from a particularly bad case of the twin maladies of summer in the city: heat and crime waves. In the last week of August alone, 82 people were shot in Chicago, including as many as 19 over a single mid-week night. As a depressing indicator of just how common this news had become, the local media was reduced to reporting the shootings in bullet-point form. The Chicago spree, as unusually severe as it has been, mimics a pattern that researchers (and police officials and, heck, just about all of us) have long observed. When temperatures go up, crime often does, too (last summer’s startling London riots were partly blamed on the weather).”

Forest Mortality And Climate Change: The Big Picture. Warm weather isn’t killing trees (directly). But it’s allowing pests to live yearround, bark beetles capable of weakening and destroying millions of acres of vibrant forestland. Here’s a clip from an article at “Over the past two decades, extensive forest death triggered by hot and dry climatic conditions has been documented on every continent except Antarctica. Forest mortality due to drought and heat stress is expected to increase due to climate change. Although research has focused on isolated incidents of forest mortality, little is known about the potential effects of widespread forest die-offs. A new analysis of the current literature on this topic by Carnegie’s William and Leander Anderegg is published September 9 in Nature Climate Chang.”

“TruthMarket”. A Wikipedia for the truth? Crowd-sourcing complex issues to find out what is based on rumor vs. fact? An intriguing concept; more details at “Wouldn’t it be nice if there were a way to make American politics just a little more rational, just a little more evidence based? Wouldn’t it be even nicer if there was a website, or an app, that helped that process along? Maybe, just maybe, a promising innovation called TruthMarket can help with the problem. It’s a site where people who care about the truth crowd-fund campaigns dedicated to either proving the veracity of true claims, or the falsity of wrong ones… where, in essence, you make money by showing definitively that you’re right. The goal, of course, is to use market forces to vanquish truthiness… and, well, here’s hoping that it works.”



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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

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