Thursday, August 19, 2010

1 Year Anniversary of the Minneapolis Tornado (nice summerlike weekend)

Update: 3:20 pm. Severe Threat Eases. SPC has issued a severe storm watch east of Eau Claire - severe thunderstorms are bubbling up across central Wisconsin, the greatest threat is 50-150 miles east of the Twin Cities. We still can't rule out an isolated T-storm this evening, best chance east of the St. Croix River - but most towns and neighborhoods should experience a dry (quiet) Friday evening.



1 Year Anniversary - Minneapolis Tornado
. On August 19, 2009 a small (EF-0) tornado touched down on South Minneapolis, tracking over 1/2 mile, lifting up into the parent thunderhead near the Minneapolis Convention Center. Damage was minor, but the tornado struck with no warning (no watches or warnings were in effect at the time). A line of showers was sweeping through the metro area (only 1 or 2 lightning strikes reported - no hail). There was just enough low-level wind shear in the lowest 2 miles of the atmosphere to spin up a weak tornado. WeatherNation meteorologist Kristin Clark was home, in South Minneapolis. Her father (Tom, a TV meteorologist in Pennsylvania) was installing a weather instrument on the wall, noticed that the barometer was falling before his eyes - looked out window and saw a wall cloud lowering toward the ground. Seconds later a funnel descended from the wall cloud, the entire episode captured on Kristin's iPhone). Central Lutheran Church was damaged, more damage reported near the intersection of I-94 and I-35 W. The Electric Fetus store at 4th and Franklin had roof and window damage. This is the only video of the S. Minneapolis tornado (that I'm aware of) - a blunt reminder that tornadoes CAN hit large metropolitan areas, sometimes with little or no warning. Bottom line: there's still no substitute for common sense. If you see rotating, lowering clouds and the winds pick up suddenly, head for safety - even if the sirens aren't sounding! More on this (surprise) tornado from the MN State Climatology Office here. (tornado footage courtesy of Conservation Minnesota and WeatherNation).






Tucson Light Show. Russel Barker, who lives outside Tucson, Arizona, described a wild Wednesday night of violent electrical storms, even a few rare funnel clouds over the mountains. Photos courtesy of KOA-TV.

Thursday Gloom. Yes, it was a gray day across central and southern Minnesota (the sun stayed out over northern MN much of the day). Highs ranged from 65 at Grand Marais to 74 in St. Cloud, 80 in the Twin Cities and a muggy 84 in Rochester, where dew points held in the low 70s.

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

Today: Showers and T-storms likely, locally heavy rain early may produce minor flooding of streets in some areas. Skies brighten midday and afternoon - another round of strong/severe storms possible late afternoon/evening. Winds: S/SW 10-20. High: 83

Friday night: Storms taper - partial clearing late. Low: 67

Saturday: Plenty of sun, warm and dry. Winds: N 10-15. High: 87

Saturday night: Clear and dry - comfortably mild. Low: 71

Sunday: Hazy sun, windy and hot. Winds: SE 10-20. High: 91

Monday: Sun fades, still hot. PM storms rumble into town. High: near 90

Tuesday: Partly sunny, breezy and less humid. High: 79

Wednesday: Mostly sunny and pleasant, very comfortable. High: 77

Thursday: Sunshine lingers - still pleasant. High: 78

Another day - another severe storm risk. It's like June never ended. As the summer goes on (in theory) the lower atmosphere should be cooling, while temperatures several miles aloft trend warmer, resulting in a more STABLE atmosphere, a sky that's less conducive to severe thunderstorms blossoming to life every afternoon. Severe season (in theory) peaks in late May and the first half of June, when the airmass draped over Minnesota tends to be most unstable, irritable and capable of spawning spinning "supercell" thunderstorms, large hail and rare tornadoes (which are nothing more than extreme T-storm updrafts which are pulled down to the ground by an "RFD", a rear-flank downdraft, a downward rush of warmer, drier, buoyant air).

Tornado Swarm - A New Record? The MPX (Twin Cities) office of the National Weather Service just released a comprehensive report about the June 17 mega-outbreak, a total of 25 separate tornadoes touching down in the MPX area. Factoring in data from Duluth, and La Crosse, it appears that there were a total of 27 tornadoes, tying the old record of 27 set on June 16, 1992. The Grand Forks office has yet to release their final tally, but 1 to 2 DOZEN additional tornadoes were reported (including the monstrous, 1/2 mile wide EF-4 that swept into Wadena), so it would appear that the final count for June 17, 2010 will be SOMEWHERE IN THE 40s - meaning a new all-time record for Minnesota! All the details are here.

During a typical summer the severe risk diminishes as we sail into July and August, the weather dominated by hazy sunshine, lingering humidity, and a touch of morning fog as we enter late August and early September. That's how it's SUPPOSED to work, at least on paper, during an "average" summer. Of course this year has been anything but average: a potentially record-breaking final tornado tally of 40-50 tornadoes on a single day, June 17, around the state, volleyball-size hail in central South Dakota, monsoon-like rains swamping huge portions of Iowa, and the real kicker: a preliminary subtotal of 123 tornadoes reported in Minnesota since June 17, leading the nation in tornado touchdowns. Remarkable.

Summer Temperatures in the Twin Cities:

June: +.8 F
July: +3.1 F
August: +5.6 F

Days Above 90 F at MSP:

May: 2
June: 1
July: 5
August: 7

Cooling Degree Days: (cumulative number of degrees above a daily average of 65 F)

Average since June 1: 532
2010 (since June 1): 734

Translation: we've all spent about 38% more money cooling our homes/businesses than usual so far this summer season.

Bottom line: it's actually getting warmer (than normal) as the summer goes on. In June we only had 1 day above 90, but so far in August we've sweated through 7 90-degree days. I don't think we can sustain this trend; we've lost 104 minutes of daylight since June 21, at some point (soon) this reduction in sunlight and longer nights WILL begin to cool off North America. We're already seeing September-like airmasses north of the Canadian border - another surge of cool, clean, comfortable air arrives by Tuesday of next week. Free A/C is likely from Tuesday into Thursday of next week.

A wrinkle of colder air embedded in an unusually active jet stream pattern will spark heavy showers and storms today - the best chance of jumbo puddles: early this morning. The latest models print out over 1" of rain by late morning - could be a very slow drive into work or school this morning - probably a better drive home later today. The Storm Prediction Center has east central MN and a big chunk of Wisconsin in a slight risk of severe storms later today, the best chance of hail/damaging winds/isolated tornadoes should come south/east of the Twin Cities, but we can't rule out a few rough storms in the immediate metro area.

The GREAT news: a well-timed bubble of high pressure clears us out Saturday, enough sun for upper 80s (low to mid 80s up north) and there's still a better than 50-50 shot we'll top the 90 degree mark Sunday, for the 16th time this summer. If the sun stays out long enough we may nick the 90 mark again Monday, before the next eastbound cool front sparks another line of T-storms late Monday and Monday night.


SPC Shocker. Hard to believe - another day - another (slight) risk of severe storms, especially south/east of the Twin Cities. The best chance of storms today: early morning, again late afternoon and evening. The Year of the Tornado grinds on...

Touch of Smog. According to the EPA the Twin Cities metro area is experiencing moderate levels of air pollution and smog, specifically elevated levels of ozone pollutants. Conditions are considerably worse out in the New York City metro area and counties in and near Oklahoma City. The latest conditions are here.

More Records. The map above shows a week's worth of records (yellow dots mark the location of record warm nighttime lows, red dots show record afternoon highs, green dots show record 24-hour rainfall reports, blue dots show record (cool) high temperatures. The warmth gripping much of America is still impressive - although one day/month/year doesn't prove anything, it underscores the trends in the data: TWICE as many record highs as record lows (worldwide) since 2000. Click on an interactive map of USA records here, data courtesy of Ham Weather.

Risk of Smoke. Thursday's NASA "Terra" MODIS satellite image shows wisps of smoke from Canadian forest fires sweeping across the Upper Midwest. The result may be more spectacular sunsets in the days to come (although since the smoke is thousands of feet overhead you probably won't smell anything unusual). The latest MODIS image is here.

Flash Floods Swamp Tennessee. Parts of central Tennessee were inundated with 4-6" of rain in less than 5 hours, producing severe flooding that washed away roads, trapping motorists in their cars. More from USA Today here.

August Sunrise/Sunset Calendar. Interested in sunrise/sunset times? Bored out of your mind? This site is pretty cool - you can plug in any city and get the sunrise/sunset times for any month. So far we've lost about 104 minutes of daylight since the Summer Solstice on June 21. I know - not a statistic you really wanted to hear...

August Climate Data. Since we're on the subject of calendars, here are the normal highs/lows and precipitation amounts - as well as the records, day by day, for the month of August. To see climate data for any month click here, and click on the month you're interested in under "Twin Cities Climate Calendar."

Hot + Carolinas = Snakes. It's been so (consistently) hot across North Carolina that snakes of all shapes and sizes have been driven indoors - it would appear that even snakes crave air conditioning. More from WeatherNation meteorologist Susie Martin here.

* Scientists Report Undersea Oil Plume Stretching 21 Miles From The BP Spill Site. An update from the Washington Post. The reality: although there's little oil showing up on the surface of the Gulf of Mexico, scientists have no idea what's happening thousands of feet underwater.

* A Sea of Change: Ocean Acidification Threatening Coastal Waters. Every year 30% of all the carbon dioxide released into the atmosphere is absorbed by the world's oceans. The end result: the oceans are now more acidic than ever before - changing the chemistry of seawater has implications for marine organisms, large and small. More from NOAA here.

* Thank God Global Warming Is A Hoax. Not sure, but I think this is tongue-in-cheek. After a summer like this the deniers are having a tougher time making their case. And it's not sunspots either. The amount of solar radiation reaching the Earth has diminished in the last 20-30 years, at the same time global temperatures have trended upward.

* The Truth: Still There, Still Inconvenient. The latest on "Climate-Gate" and the scientists whose e-mails were hacked late last year, all exonerated by the facts. The story in the Star Tribune is here.

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