84 F. high on Tuesday in the Twin Cities.

78 F. average high for August 28.

78 F. high on August 28, 2011.

Mid-90s possible today, again Thursday.

Excessive Heat Watch (MSP metro) & Fire Weather Watch (southern Minnesota) posted for tomorrow


Katrina struck New Orleans 7 years ago today as a Category 4 hurricane. Within weeks the death toll would rise over 1,800, an estimated $81 billion in damage. It was the deadliest storm since 1928 for the USA. Wikipedia has a good recap here.


Excessive Heat Watch for Thursday. Hennepin and Ramsey counties are under an Excessive Heat Watch tomorrow; a Fire Weather Watch also posted for much of southern Minnesota; the combination of upper 90s, bright sun, strong winds and low humidity may cause brushfires to spread rapidly. Source: Ham Weather and NOAA.

"There is unequivocal evidence that Earth’s lower atmosphere, ocean, and land surface are warming; sea level is rising; and snow cover, mountain glaciers, and Arctic sea ice are shrinking. The dominant cause of the warming since the 1950s is human activities. This scientific finding is based on a large and persuasive body of research.” - from the latest AMS (American Meteorological Society) statement on climate change.




Isaac Stalls. Just like the models were hinting yesterday, Isaac has come to a screeching halt near Houma, Louisiana. Most of the storm's circulation is still over warm Gulf of Mexico water, allowing Isaac to maintain it's intensity. It's a giant, watery vacuum cleaner, hoovering up moisture from the Gulf, squeezing it out over the parishes of Louisiana and southern Mississippi. NWS Doppler from New Orleans at 8:38 am.

Peak Wind Gusts So Far Today (courtesy of WeatherBug):

PYDRS - - Gust 97 mph at 1:39 a.m. CDT - - WeatherBug unit at SBPG Port Ship Service in Poydras, LA  (10 miles SE of New Orleans)

MTRJG - - Gust 81 mph at 3:42 a.m. CDT - - WeatherBug unit at East Jefferson General Hospital in Metairie, Louisiana.

KNBG - - Gust 79 mph at 3:31 a.m. CDT - - Airport site at Naval Air Station in Belle Chasse, LA (just SE of New Orleans)

KBVE - - Gust 78 mph at 2:24 a.m. CDT - - NWS site at Boothville, LA  (near the mouth of the Mississippi River)

KNEW - - Gust 76 mph at 3:35 a.m. CDT - - NWS airport site at Lakefront Airport in New Orleans, Louisiana, USA  


Wind Gusts. Some of the oil platforms 10-30 miles south/east of the mouth of the Mississippi River reported wind gusts over 100 mph overnight. Info: Earth Networks.


A Remarkable Sight. The view of Isaac from NASA's Modis satellite Tuesday was amazing. Dry air wrapping into the circulation kept Isaac sputtering along for much of Sunday and Monday, but the concentric shape Tuesday afternoon was a tangible sign that Isaac was (finally) getting its act together, and intensifying.


Rising Waters. Professional storm chaser Reed Timmer snapped this photo of the Bea Rivage Casino in Biloxi Tuesday morning as Isaac's storm surge pushed tides up 2-4 feet out ahead of the storm.


Comparing Isaac To Katrina. In reality there is no comparison. Katrina was a Category 5 super-hurricane before weakening slightly, to a Category 4, as it came ashore 7 years ago today. The Wall Street Journal has a very effective interactive tool to compare the two storms, back to back: "While Tropical Storm Isaac is far less powerful than Hurricane Katrina, which was a Category 3 hurricane when it made landfall along the Gulf Coast on Aug. 29, 2005, NHC forecasters said Isaac could push a substantial amount of water into low-lying areas, with a storm surge of up to 12 feet in coastal Mississippi and Louisiana."


Eyewall Regeneration. One of the more fascinating elements of hurricane science is the ability for a hurricane to shed its eyewall, the donut-shaped ring where the strongest winds blow. Like a snake shedding its skin a hurricane's eyewall goes through cycles, a smaller eyewall forming within the main eye (upper right), followed by rapid disintegration of the original eyewall. We're still learning more about how hurricanes evolve over time - I grabbed these frame shots from the NWS Doppler in New Orleans Tuesday evening. I know, what a geek.


Uncharted (Warming) Waters. I can't recall ever seeing anything like this in late August (or any other summer/autumn month). Sea surface temperatures (SST) are running as much as 5-8 F. warmer than average from the North Atlantic into the Arctic and the northern Pacific Ocean. Map courtesy of NOAA.


Study Tracks Relationship Between Storms, Cities. We know that large metro areas can "seed" clouds, pollutants increasing the potential for flooding and hail downwind. Here's an excerpt of an interesting story at phys.org: "We're trying to quantify something that has had anecdotal evidence through the years but has not been approached in a systematic way," said Geoff Henebry, a professor and senior scientist at the Geographic INformation Science Center of Excellence at South Dakota State University...."Our research will explore how city size and shape - both horizontal and vertical - can influence storm track, direction, and intensity," Henebry said."


"Blurricane". I think this was a typo. Here was the hourly observation from New Orleans at 5:53 pm yesterday: overcast, 79 F, dew point 73 F, winds gusting to 60 with "light snow". Huh? That would be quite a trick. Thanks to Miranda Hilgers for passing this along.


Gray Start, Fine Finish. A dying band of showers dropped about a tenth of an inch of rain on Alexandria, more at Eau Claire, but the sun came out by afternoon, boosting the mercury into the 80s statewide, 5-10 degrees above average.


Tangerine Dusk. WeatherNation TV meteorologist Todd Nelson took this photo last week up in St. Michael. Yes, the sky really was that color.


Paul's Star Tribune Outlook for the Twin Cities and all of Minnesota:

TODAY: Hot sun. Dew point: 61. Winds: SE 10-15. High: 94


WEDNESDAY NIGHT: Clear and sultry. Low: 72


THURSDAY: Excessive Heat Watch. Fire Weather Watch. Sizzling sun. Dew point: 55. Winds: SW 10. High: 95


FRIDAY: Still Steamy and unusually warm. Dew point: 56. Low: 71. High: 92


SATURDAY: Get to the lake! Hazy sun. Dew point: 60. Low: 72. High: near 90


SUNDAY: Sticky sun. Few T-storms north? Low: 70. High: 89


MONDAY: Slightly cooler, less humid. Dew point: 54. Low: 67. High: 87


TUESDAY: Muggy, few T-storms possible. Low: 69. High: 88



Another Heat Spike

We don't know as much as we think we know. Hyper-local models and Doppler eye-candy give the illusion that we have Mother Nature totally figured out. Note to self: we don't.

The atmosphere is a fluid. We have math (nasty calculus) that describes how this airy fluid SHOULD move over time, but our knowledge of how the atmosphere works is incomplete. Think stock market picks or fantasy football, on a global scale.

Hurricanes are especially humbling. With satellites it's doubtful we'll ever be totally surprised, but predicting precise tracks and intensity is still perilous.

If Isaac hugs the coast, the core of the hurricane over warm water, further strengthening is possible this morning - before pushing inland. Flash floods are possible as far north as St. Louis, even Chicago.

While we obsess over Isaac, desert heat is rushing toward Minnesota; 90+ today & upper 90s possible tomorrow. An Excessive Heat Watch is posted for Thursday along with a Fire Weather Watch, for a risk of fast-moving blazes. Heat lingers into early next week, hints of September by late next week. Whew.

Today's blog includes a new record for least Arctic ice ever observed. A troubling trend up north.


Climate Stories...


Arctic Sea Ice: Record Territory. We have surpassed the previous record ice loss in 2007, with another 2-3 weeks of melting left in the season...truly in uncharted waters. Graphic credit here.


Arctic Sea Ice Reaches Lowest Extent Ever Recorded. The story from Science Daily; here's an excerpt: "The blanket of sea ice floating on the Arctic Ocean melted to its lowest extent ever recorded since satellites began measuring it in 1979, according to the University of Colorado Boulder's National Snow and Ice Data Center. On Aug. 26, the Arctic sea ice extent fell to 1.58 million square miles, or 4.10 million square kilometers. The number is 27,000 square miles, or 70,000 square kilometers below the record low daily sea ice extent set Sept. 18, 2007. Since the summer Arctic sea ice minimum normally does not occur until the melt season ends in mid- to late September, the CU-Boulder research team expects the sea ice extent to continue to dwindle for the next two or three weeks, said Walt Meier, an NSID scientist."

Graphic credit above: "The extent of Arctic sea ice reached a record low in the satellite record on Aug. 26 and is expected to continue dropping for the next several weeks, according to a University of Colorado Boulder research team." (Credit: NSIDC, University of Colorado Boulder)


Cryogenic Treatment Could Cut Coal-Fired Power Plant Emissions by 90% Here's an excerpt of a gizmag.com story that caught my eye: freeze CO2 into submission? "A team of physicists from the University of Oregon (UO) has calculated that cooling the emissions from coal-fired power plants would result in a reduction of the levels of dangerous chemicals entering the atmosphere, including CO2, by 90 percent. While cryogenic treatment would also see a 25 percent drop in efficiency, and therefore result in electricity costs increasing around a quarter, the researchers believe these would be offset by benefits to society, such as reductions in health-care and climate-change costs."

Photo credit above: "Cooling the emissions from coal-fired power plants would significantly reduce the levels of dangerous chemicals entering the atmosphere." (Photo: Shutterstock)

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100 F. by Thursday? (Category 1 "Isaac" may keep strengthening into tonight)

Newer Post

95 F. Thursday Sizzler (19+" rains from Isaac; flooding rains push toward Little Rock & St. Louis)