Thursday, September 16, 2010

Melting Glaciers Revealing Buried Artifacts 3,000+ Years Old

Monster Hail! For the record: quarter-size hail (1" in diameter) is considered severe. Then what do you call something like this? 7.75" in diameter - somewhere between softball and GRAPEFRUIT size hail that fell on the western suburbs of Wichita, Kansas Wednesday. Remarkable. It may have set a record for the largest hailstone ever observed in the state of Kansas. About a month ago VOLLEYBALL-size hail fell on central south Dakota. What the heck is going on? More from the local NWS office here.

Tornadic Storm Sweeps Across New York City. A wild squall line raced across metro NYC around the dinner hour Thursday, producing 70 mph. winds on Staten Island (where tornado warnings were issued) and gusts over 100 mph on Long Island. At least one death has been attributed to this freak severe storm - unusual for mid September in the northeast. An impressive YouTube time-lapse of the storm (taken with a Droid X) is here.

"This Don't Look Like Brooklyn" Winds stronger than hurricane-force swept across the New York City area, toppling hundreds of trees and powerlines - a typical storm for Kansas, not the Big Apple.

Ohio Tornado Outbreak. Another swarm of deadly tornadoes touched down on Ohio Thursday evening - there are reports of injuries and significant structural damage, especially near Athens (where this Twitter photo was taken), Wooster, Reedsville, and Rockport, just over the border in West Virginia.

Melting Glaciers = Ancient Artifacts. The slow-motion meltdown of glaciers from the Andes to the Alps and Himalyas has revealed a treasure-trove of ancient artifacts. In this story from Reuters, news of a shrinking ice field in Norway, the Juvfonna glacier, where 600 artifacts turned up on the rocks almost simultaneously, including old bows and arrows, even a 3,400 year old shoe! Many of these items will rot if not stored properly - scientists are racing the clock to collect and safely store as many of these historic items as possible. The front edge of the Juvfonna ice field has retreated 60 feet - just this year.

Anniversary of the Rogers Tornado. At 9:55 on September 16, 2006 an EF-2 rated tornado swept through Rogers, Minnesota, damaging scores of homes and leaving behind one tragic fatality. Severe thunderstorm warnings (and a tornado watch) were in effect at the time, but the tornado warning was issued after the twister had already touched down. In a subsequent study of the tornado outbreak the local NWS office admitted that it didn't have access to the FAA radar from MSP International (which updates every minute, and could have provided the necessary lead-time for a tornado warning to be issued in time). By comparison the NEXRAD Doppler at Chanhassen updates every 4 minutes, scanning an entire "volume" of the atmosphere, sampling the lowest levels - where tornadic signatures are most likely to show up. That "lag" in Doppler scans made all the difference. To be fair (to local forecasters) the tornado struck after dark, when it was far more difficult to tap the expertise of local SKYWARN weather spotters. The tornado also spun up quickly, with little warning - this "velocity" display shows the inbound and outbound wind patterns circulating around the rotating "supercell" storm that ultimately spawned the tornado. It's worth remembering that tornadoes are far too small to show up on Doppler - all we can do is track the parent thunderhead, and look for signs of extreme rotation. Fewer than 25% of all rotating storms ever go on to spawn a tornado, studies show. The late hour, coupled with the sudden intensification, factored into the equation. It was a painful learning curve for not only NWS forecasters and local media, but the public. The bottom line: technology is good - and getting better - but in spite of best efforts and the most sophisticated Doppler radar systems available, there will be (rare) situations where tornadoes form with little or no warning. In the end there's simply no substitute for common sense. Even if the sirens aren't sounding, if storms are moving in and the wind increases rapidly, err on the side of safety and head to the basement (increase your chances of survival by climbing under a table or workbench to lessen the risk of being crushed by falling debris). More from the NWS study of the Rogers tornado here.

Rogers Tornado Path. The National Weather Service Assessment of the September 16, 2006 EF-2 tornado showed an initial touchdown near Lake Sylvan, strengthening to EF-2 status as it swept across the northern/western sections of Rogers, crossing the Mississippi River before lifting again near Ramsey.

Aftermath. YouTube footage courtesy of KARE-11 shows the severe damage from the Rogers tornado, well-constructed homes literally flattened by winds estimated over 100 mph.

Ripening Leaves. Thanks to Rich Koivisto from the Duluth area for reminding us how spectacular autumn can be along the North Shore of Lake Superior. About 10-25% of the trees are peaking across parts of northern Minnesota - frost this weekend may accelerate peak color, which is probably 7-14 days away up north.

Fast-Forward Fall. Is sure feels more like early October out there, and if you have a hankering to check out some flaming fall foliage head north; roughly 25-50% of the leaves have peaked from near Moorhead and Fergus Falls to International Falls. Peak color here in the Twin Cities usually comes the last week of September into the first 10 days of October. See more from the Minnesota DNR here.

Paul's Conservation MN Outlook for the Twin Cities and all of Minnesota

Today: Showers early, then partial clearing with some afternoon sun. Winds: W/NW 10-15. High: 65

* Dry for evening football games, temperatures falling into the upper 50s - take a sweatshirt or light jacket.

Friday night: Patchy clouds - probably dry. Low: 46

Saturday: More clouds than sun, a morning sprinkle possible, few hours of sun possible mid/late afternoon. High: 59

Sunday: Nicer day of the weekend as high pressure drifts overhead. More sun, less wind. High: 65

Monday: Cloudy with light rain developing. High: near 70

Tuesday: Showers, possible thunder - tapering during the morning, then slow PM clearing. High: 68

Wednesday: A mix of clouds and sunshine, seasonably cool. High: 68

Thursday: Mostly cloudy with showers and T-storms , turning milder. High: 74

"Sept-ober". The calendar says September, but Thursday it looked and felt more like October out there. You know it's a chilly (highly unusual) day when Grand Marais is warmer than MSP! The sun broke through in St. Cloud and Alexandria, where at least the mercury was able to reach 60, but a "high" of 56 in the Twin Cities? That's the average high for October 25! 15 degrees cooler than our average high of 71 for September 16. Rainfall ranged from .16" at St. Cloud to .39" in the Twin Cities to a sopping 1.78" at Rochester.

Look at the bright side: today has to be a little better (at least a little bit milder) than yesterday. 56 for a "high" in the Twin Cities - that's the average high for October 25. We had a WeatherNation company picnic (scheduled to be outside), but in spite of a portable fire-pit we had to move the party indoors. Odd to be talking about wind chill in mid September. We WILL bounce back from this - we WILL see more 70s, maybe a couple more 80s before the weather turns for good. Don't get too down, unusual cool-downs like this are almost always followed by warming trends.

A clipper-like system whips up a few rain showers this morning (most of the rain passing north of MSP), but a drying west/northwest wind kicking in behind this trough of low pressure should provide partial clearing this afternoon, highs about 5-10 degrees warmer than yesterday. Evening football games should be dry, temperatures falling into the mid to upper 50s - take along a sweatshirt or jacket, you'll be glad you did.

A lingering disturbance aloft will keep pasty clouds overhead much of Saturday, models are even printing out a few light showers/sprinkles, especially morning and midday hours. I don't think we're facing an all-day rain, but a few light showers can't be ruled out, highs stuck in the 50s across most of Minnesota - not a great day, I fear.

Sunday will be the nicer day as the center of a fair weather high pressure bubble passes right over Minnesota, less wind, a bluer sky, highs topping 60 - it won't feel bad at all out there by Sunday afternoon. It still looks like another period of rain from Monday into Tuesday as winds swing around to the south/southeast and temperatures begin to moderate a bit.

BREAKING NEWS: The GFS model has us in the 70s, possibly the 80s, the last week of September and the first few days of October. You WILL have a chance to wiggle into your shorts and t-shirts a few more times. I promise.

Trust me. I'm a weatherman.

Huge Windstorm Spawns New Classification: "Super Derecho". The storm that swept across Kansas into Missouri and Illinois on May 8, 2009 was no ordinary wind storm. Spawning 18 tornadoes and straight-line winds from 90-100 mph, the damage swath was nearly 100 miles wide and 300-500 miles long, a derecho so massive it has the distinction of being the first documented "super derecho", according to NOAA. An intense vortex, the circulation had an eye-like structure (it almost looked like a "land hurricane"). More from here.

Dangerous "Boomerang". When you see a horse-shoe shaped wedge of bright colors on Doppler it's a sign that a storm is producing powerful, potentially dangerous straight-line winds. On rare occasions derechos can spark winds in excess of 100-120 mph, capable of extreme damage similar to that of a tornado.

"Land Hurricane". These super-derechos can cover as many as 4-8 states, simultaneously - they tend to develop during the overnight hours, by the time they dissipate, as much as 1,000 miles downwind of where they started, they will have traveled for as long as 18-24 hours! More on this remarkable, and little understood, weather phenomenon, in this article from UCAR in Boulder, Colorado.

Getting Real About a Warmer, Wetter Minnesota. In case you missed it, Star Tribune writer Bill McAuliffe wrote a timely story about the need for Minnesota to start planning on how to adapt to a warmer, stormier climate. A two-day conference at the Minnesota Landscape Arboretum wraps up today - more information from that report will be released to the public shortly. Personally, I think we'll probably have not choice but to focus on adaptation: some level of warming is already baked into our future. The question now is, how much, and how will a warmer, wetter atmosphere impact the frequency and intensity of our most extreme weather events: hail, flooding, tornadoes, winter icing, etc?

Coral Disease Outbreaks Linked To Winter Temperatures, Not Just Warm Summers. Recent studies suggest that unusually warm ocean water temperatures during the winter months can be just as damaging to coral reefs as summer warmth. The world's coral reefs provide an estimated $375 billion worth of value and services every year - increasingly warm, acidic water is damaging many of these reefs over time. More from NOAA here.

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