Tuesday, August 31, 2010

A Noted Climate Skeptic Changes His Tune

Close Encounter With a Category 4 Hurricane. Although Earl weakened (ever so slightly) on Tuesday it's still a very dangerous, category 4 storm, capable of inflicting massive damage on the Outer Banks of North Carolina, where a Hurricane Watch has been posted. Mandatory evacuations are now underway on North Carolina's barrier islands. The storm is still expected to take a jog to the north/northeast, sparing the east coast a direct hit. But it's going to be close, very close, and authorities want to err on the side of caution. Millions of people living right along the Atlantic coast may be impacted by heavy surf, coastal flooding, even beach erosion as Earl accelerates to the north - possibly staging a direct hit on Nova Scotia, Canada by late in the week. NOAA has a special page devoted to tracking Hurricane Earl here.

Double Trouble. Hurricane Earl weakened slightly Tuesday (central pressure rose a few millibars, the eye not as well defined). But the combination of warm ocean water (83-86 F) and relatively light steering winds aloft should mean favorable conditions for Earl to remain a very powerful category 3-4 storm into Thursday, when its forecast to approach the Carolina coast.

Predicted Track of Earl. The GFDL model brings Hurricane Earl directly over Cape Hatteras, North Carolina, possibly as a category 3 storm with sustained winds of 111-130 mph and a storm surge exceeding 20 feet in some areas, capable of inundating parts of the Outer Banks, which are heavily developed (most homes close to sea level, even the highest "hills" no more than 20-30 feet above sea level). Hundreds of thousands of people living from Ocean City, MD to Cape Fear, North Dakota may have to flee inland to escape the wrath of Earl. Notice how the GFDL model (one of the more reliable weather models for hurricane tracking) takes Earl farther west, hugging the east coast, with a first landfall over the Outer Banks, a second landfall near Providence, a potential path that would probably translate into tens of millions of dollars in damage. The majority of models keep the track (and strongest winds) 100-300 miles offshore. For another great hurricane tracking site click on Mike's Weather Page here.

Potential Trouble. This is a NOAA graphic showing predicted wave heights hitting the Outer Banks of North Carolina by Thursday at 8 pm. 20-24 foot waves are possible (!) which would create the potential for devastating beach erosion and coastal flooding. Hurricane watches are now posted for much of coastal North Carolina, from Surf City to Duck.

Hint of What's To Come. Hurricane Earl strengthened to category 4 status Monday, the eye of the storm passing 75-125 miles north of of Puerto Rico, whipping up 18-22 foot swells along the northern coastline. At least 10,000 people were without power, another 3,000 without running water. More on Hurricane Earl's romp through the Caribbean from the New York Times here, USA Today has another overview of the storm in this article.

A Very Close Call. The WRF model is predicting that Hurricane Earl's violent eye-wall may come within 100-200 miles of the Outer Banks of North Carolina - some evacuations may be necessary later today and Thursday as the storm approaches - a storm surge of 5-12 feet above normal high tide may inundate low-lying regions of the Carolinas and the Delmarva Peninsula.

Uh Oh. It's that time of year - when everyone tries to put the fear of God in you about the upcoming winter. Personally, I don't trust any forecast beyond 7-10 days - just too many factors in play. It's true that we've gone from an El Nino pattern (winter and early spring) into more of a full-blown La Nina cooling of Pacific ocean water. That could mean a higher probability of an "old fashioned" Minnesota winter, with more snow and temperatures trending colder than average. That goes against the trends we've witnessed in recent winters - warmer overall (especially at night) with fewer subzero outbreaks - and sporadic, unreliable snow conditions (just ask anyone with a snowmobile). Interesting to ponder, but I wouldn't get too worked up about the winter to come, at least not yet. For some good water-cooler chatter & gossip click here to get an eyeful from the folks at the Farmer's Almanac.

Weather Monster - From Space. The view from the ISS, the International Space Station, was pretty spectacular, Hurricane Earl's 30 mile-wide "eye" clearly visible from near-Earth orbit, a little more than 200 miles above the ground.

Tuesday Numbers. In spite of considerable cloudiness the mercury reached 86 in the Twin Cities Tuesday, 81 in St. Cloud (just over 1" of rain), but a cool, comfortable 74 at Alexandria, where 1.27" of rain fell.

* 3.26" of rain fell just west of Granite Falls, in Yellow Medicine County, late Monday night. That's roughly a month's worth of rain in less than 6 hours.
Paul's Conservation Minnesota Outlook For The Twin Cities and all of Minnesota

Today: Plenty of sun, breezy and less humid - a dry (quiet) day. Winds: E/NE 10-15. High: 78

Wednesday night: Clear evening, then increasing clouds overnight. Low: 63

Thursday: Periods of rain, possibly heavy at times. Heavy thunderstorms possible (probably not severe though). High: 73

Friday: Windy and even cooler with patchy clouds giving way to slow clearing. High: 68

Saturday: Probably the nicest day of the holiday weekend. Lot's of comfortable sun, low humidity. Winds: NW 10-20. High: 73

Sunday: Sun fades behind increasing clouds - still dry. Winds: E 7-12. High: 76

Labor Day: Mostly cloudy, very slight chance of a passing shower or sprinkle (but most of the day looks dry right now). Winds: SE 10-20. High: 77

Tuesday: Showers and T-storms, then windy, turning cooler. High: near 80 (falling by afternoon).

The end is near....to our swampy, hair-curling, sauna-like weather, that is. No more raging thunderstorms, dripping dew points or near-record, 90-degree plus high temperatures. We're due for a break in the pattern, and it's here. Winds have shifted around, blowing from the north/northeast, allowing much cooler, cleaner, less humid air to surge southward out of Canada. You'll notice a welcome dip in humidity levels today, and by the end of the week it will truly start to feel like mid or even late September out there. August is history - and so is the WORST of the heat & whine-worthy dew points. There is, in fact, a light at the end of our muggy, stormy tunnel. It's been a wild, jungle-like summer across Minnesota, significantly warmer and more humid than average, a possible record for not only individual tornado touch-downs (145 at last report), but a potentially record-smashing number of tornado and severe storm watches and warnings.

Monday night was a true head-scratcher. Shortly before midnight SPC (the Storm Prediction Center) issued a tornado watch for much of central and southern MN, until 7 am Tuesday morning! No, that doesn't happen very often. There were no tornado reports (that I could find), but after the crazy summer Minnesota has experienced everyone wanted to err on the side of caution.

We get a break today - enough cool, clean air surging southward out of Canada for highs in the 70s with a welcome dip in humidity, dew points dropping into the low 50s by evening. But a second wave of low pressure, a wrinkle of cold air aloft, will irritate the front lurking just to our south, sparking another surge of showers and possible T-storms Thursday. The models are printing out some .5 to 1" rainfall amounts, even a few heavy embedded T-storms, but instability and moisture will probably be lacking for a widespread severe outbreak. That said, the way this summer season is going - I wouldn't be shocked to see a few marginally severe storms over far southern MN tomorrow afternoon.

A reinforcing cool front whips up strong northwest winds Friday, patchy, wrap-around "backlash" clouds lingering much of the day up north, but some breaks in the clouds from St. Cloud to the Twin Cities - highs holding in the 60s. If there's any doubt in your mind that it's really September, those doubts will be quickly erased on Friday.

Saturday still appears to be the nicest day of the holiday weekend, a weak ridge of high pressure treating us to generous amounts of sun (and a bit less wind), highs in the low to mid 70s. Lake water temperatures may be nearly as warm as the air temperature Saturday, especially if you're planning a dip in the morning. Winds swing around to the east Sunday, then the southeast Labor Day, allowing warmer air to (try) to surge northward. This tug-of-war between opposing airmasses may spark an increase in high and mid clouds Sunday (still dry), and right now I'm wagering on more clouds than sun Monday, with only a slight chance of a passing shower or sprinkle. MOST of the holiday weekend - by far - should be dry, and comfortable, highs mostly in the 70s, with some 60-degree highs over far northern MN.

We've seen worse. Not perfect, but all things considered, better than average for the last major holiday weekend of summer.

Good News! The dreaded dew point is about to go into free-fall, one cool front arriving Wednesday, a second (reinforcing) surge of Canadian air dropping the dew point into the 40s from Friday into Sunday, meaning less than half as much water floating above our heads as Tuesday. By Labor Day the dew point returns to 60, humid - but tolerable.

"Eye-wall Regeneration." The more we study hurricanes the more mysterious they turn out to be. It turns out hurricanes go through complex cycles which researchers are just now beginning to grasp. Sometimes called "concentric eye-wall cycles" or "eye-wall replacement cycles" - the process is amazing. As hurricanes strengthen the diameter of the calm "eye" drops, sometimes to a radius of 10-15 miles. When that happens the outer spiral bands often reform a second (larger) eye-wall, surrounding the inner eye, robbing it of some of it's moisture and energy. This second, larger, donut-size swirl of raging wind and water eventually contracts until it entirely replaces the original eye - hours or days later the entire process starts again. During this eye-wall replacement cycle the hurricane may temporarily weaken, only to intensify dramatically as the newer, larger eye-wall begins to contract again. It makes forecasting hurricane intensity extra-difficult for the forecasters at NHC, the National Hurricane Center in Miami. To get a better idea of how they make their forecasts check out the latest "discussion" from the meteorologists trying to get a handle on the track & intensity of Earl. Warning: geek alert - these discussions are highly technical, but the true weather enthusiasts may appreciate the logic that goes into these forecasts. More on eye-wall replacement cycles here and here.

Full Circle. One (hearty, tenacious) couple - a daydream to walk around the entire shoreline of Lake Superior (in one summer). 675+ miles - on foot! Talk about a mega-expedition: 5 months, 3 states and a Canadian province. They found the greatest lake to be in pretty good shape (overall) - clean enough to drink out of in a number of bays. It's a fascinating story - learn more on the Full Circle web site here.

Just How Environmentally Friendly Are Electrical Vehicles? It turns out all hybrids are not created equal - some are easier on the environment than others, especially factoring in the eventual recycling of batteries into the mix. Gizmag has an interesting read here.

The Man Behind the "F-Scale." Dr. Theodore Fujita was a true genius - he's the guy that came up with the "F-scale" to rate the destructive power of tornadoes. He was a true legend at the University of Chicago, quiet, unassuming, but brilliant, pushing the boundaries on tornado research. A good YouTube video summarizing his life and achievements can be found here.

Bjorn Lomborg, Former Skeptic, Now Believes in Climate Change. The world's most high-profile climate skeptic is now saying that "global warming is undoubtedly one of the chief concerns facing the world today" and "undoubtedly one of the chief concerns facing the world today." For a long time Lomborg thought of himself as more of a pragmatists than an actual outright skeptic or climate denier, he always seemed to believe that climate change was a real problem, but thought it was all greatly exaggerated. But in a new book to be published next month he argues that upwards of $100 billion/year may need to be invested "to essentially resolve the climate change issue by the end of this century." But calls for "climate engineering" - seeding clouds to reflect sunlight, dumping chemicals into oceans to reduce acidification, will be sure to prolong the controversy over how best to mitigate climate change in the years and decades ahead. An article in the U.K.'s Guardian newspaper is here.

Review Finds Flaws in U.N. Climate Panel Structure. The New York Times has a story about the embattled IPCC, the Intergovernmental Panel on Climate Change, which is under pressure to change some of its operational practices in light of the leaked (hacked) e-mails last December. Specifically, a review panel set up to investigate has come back with a report telling the IPCC to modify and improve the way it manages its assessments of climate change, with scientists more open to alternative (and potentially conflicting) views, more transparency about potential conflicts of interest and a need to tread more carefully when making full-blown policy prescriptions.

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