What the heck happened? This was uncomfortably close to being "out of the blue". The metro area was in a slight risk of severe storms from SPC, the Storm Prediction Center, but the general perception is that the local weather community was caught with its Doppler down. An upper-level disturbance, a counterclockwise-rotating swirl of unusually cold air 4-8 miles aloft sparked a widespread surge of rain, almost resembling an MCS, a meso-convective system, which tends to form at night, not during the day. Even though it was cool (upper 60s) there was enough instability, wind shear, and pure spin (vorticity) in the atmosphere to whip up brief, strong, "mesocyclones", rotating thunderstorms capable of hail and tornadoes. The cell that formed over South Minneapolis developed VERY quickly, by the time warnings were formally issued and the sirens were sounding the threat (from the S. Minneapolis tornado) was probably long gone. It was a signal that the atmosphere was explosively/dangerously unstable, minutes later there was another touchdown near Cottage Grove, then later more tornadoes near Canon Falls, Mankato and North Branch. In all there may have been as many as 4-5 separate tornado touch downs on Wednesday
What the...? The Minneapolis tornado is making a lot of people very, very uncomfortable. It's one thing if a tornado forms over fields with little/no warning, but within 1 mile of the MSP International Airport and 1-2 miles from downtown Minneapolis? That's an entirely different scenario, the definition of an "OH CRAP" moment. No watches or warnings were in effect at the time of the apparent touchdown. To the best of my knowledge no local TV station was on the air warning of dangerous conditions bearing down on the Minneapolis skyline. Worst case? No, the IDS would not have tipped over. But outer glass walls could have been stripped, shattered - raining deadly debris on pedestrians below, severing the Skyway system, turning cars (and buses) on the Nicollet Mall into projectiles. A few years ago a study focused on Chicago, what might happen if a major, F3-F5 tornado struck during rush hour. The projections sounded like something out of a horror movie: 3,000 to 5,000 people dead, 20,000-50,000 locals injured, damage running into the BILLIONS of dollars. The report shook a lot of people up, myself included. A major tornado hitting a major city, especially at rush hour, with hundreds of thousands of commuters trapped in their cars, would be a catastrophe that would make Hurricane Katrina look like a proverbial walk in the park...
Major Urban Tornadoes. A recent study in the Dallas - Fort Worth area predicted that a major (EF3-EF5) tornado, hitting during rush hour, could claim thousands of lives, injuries running into the tens of thousands with a damage toll topping 2-3 billion. The report echoed a similar study focusing on Chicago, underscoring two things: a). in spite of a handful of tornadoes hitting downtowns in recent years we've been relatively lucky, and b). a worst-case, long-lasting, violent tornado would leave behind a trail of damage and death that could dwarf the aftermath of a major hurricane.__________________________________________
So yesterday, as my good friend and meteorological colleague Kristin Clark called into WeatherNation for a blow-by-blow account of what she was seeing in the sky above South Minneapolis, I held my breath, said a quick prayer, hoping it wouldn't strengthen into something truly life-threatening on a massive scale. To be fair, the expression "small tornado" is an oxymoron. ANY tornado is a pretty big deal, even a "small" EF0 or EF1, with winds under 100 or 110 mph, strong enough to take down big trees and cause significant roof damage. That's probably what hit S. Minneapolis (and later, the Cottage Grove area).
But the event, this surprise urban tornado, underscores the obvious: technology isn't perfect. Never will be. Doppler will NOT pick up every single tornado, especially the small, brief tornadoes. Local authorities, Civil Defense, National Weather Service, local media, favorite meteorologists, in spite of best intentions, will NEVER be able to catch all the threats in real time.
It's sobering to hear, but it's the truth: to some degree all of us are on our own. We are responsible for our own safety. If you see the cloud base rotating and lowering to the ground, in front of your eyes (accompanied by your ears popping and a growing roar, like thunder that won't go away) do yourself, and future generations, a big favor and get your butt to a safe spot, preferably below ground, below grade. Remember, the threat isn't being lofted into the sky like Dorothy in the Wizard of Oz. It's standing up and being hit on the head by a tiny pebble traveling at 150 mph. Blunt head trauma. Flying debris. That's how most people become tornado victims. In light of yesterday's scare vow to maintain control over situational awareness, rely on your own wits (in addition to the NWS and local media) and realize that, in the end, YOU are responsible for keeping yourself out of trouble.
Thumbprint of an Urban Tornado. From the Chanhassen, National Weather Service Doppler, this is an SRV (Storm Relative Velocity) image from the Twin Cities, MPX Doppler Radar from 2 pm yesterday, when WeatherNation meteorologist Kristin Clark was taking video of a developing tornado over South Minneapolis. Note the vivid "couplet" just east of St. Louis Park, over south Minneapolis. The bright green is air moving toward the radar site (in Chanhassen), while the bright red air is moving away from the site, suggesting very strong rotation in this particular T-storm cell. The Doppler signature is a strong hint that this was, in fact, a small tornado, and not straight-line winds.
Doppler Evidence of a Tornado. Close-up of the SRV Doppler display, showing a developing tornado over south Minneapolis around 2 pm Wednesday afternoon. Check on the complete weather video at Conservation Minnesota to see the tornado that hit south Minneapolis.I hope you were able to check out Wednesday's tornado footage over at Conservation Minnesota's excellent weather center: (www.mnweathercenter.org). Wednesday at 2 pm WeatherNation meteorologist Kristin Clark was on her 7th floor Uptown balcony, with a sweeping view of downtown Minneapolis, with her parents, Tom and Noreen Clark (who I went to college with). Tom is a dear friend, the best man at my wedding, and a phenomenal TV meteorologist up in the Twin Cities of northeastern PA, Wilkes/Barre - Scranton. So they're standing outside, admiring the view, no watches, no warnings, no sirens, just a steady, heavy rain. The rain tapes, skies begin to clear and brighten, but then Kristin notices a lowering, rotating cloud base.
"A wall cloud is forming less than half a mile away!" Seconds later she's on the phone with all of us at WeatherNation, narrating the tornado, "debris is being thrown up into the air. It IS a tornado." I can hear her father, Tom, in the background "We have debris. Yes, we have minor debris!" It reminded me a little of the movie, Twister. I was just happy he didn't say "cows....we have COWS!" Remember that scene? Yes, that would be odd to hear coming from South Mpls, come to think of it.
WeatherNation meteorologist Kristin Clark, who captured the tornado that formed over South Minneapolis around 2 pm Wednesday afternoon. The video can be seen at mnweathercenter.org.So the tornado lasts maybe 2-3 minutes before getting completely wrapped in rain. It probably "occluded", the warm updraft literally choking to death by rain and hail-cooled air. My friend, Doug Williams, who works as a patent litigator at Fulbright Partners in downtown Minneapolis, reported seeing flying debris from his high-rise office building around 2:20! What the tornado sucked up over S. Minneapolis it probably dropped right on the downtown. I can't help but mention that the tornado circulation appeared to have passed directly over WCCO-TV's studios downtown.
What does this prove? Well, it's good to be lucky, and Kristin was in the right place at the right time. In her words "I'm no longer a tornado virgin." Amen to that. It also underscores the fact that tornadoes can and do hit major cities. Just because you live in a metropolitan area does not mean you're immune from a tornado risk. A few high rise buildings, more asphalt and concrete is NOT a tornado deterrent.
Wednesday's freak-downtown-tornado also underscores the fact that Doppler radar isn't perfect. It works best on the big (EF2 to EF5) tornadoes. Many times the smaller twisters, the EF0s and EF1s will get "lost in the sauce"; it's very difficult trying to catch every tornado of this size in advance. The bottom line: there's still no substitute for common sense. Even if the sirens aren't sounding, if you see clouds rotating, lowering to the ground, if you're witnessing debris being tossed up into the air, do the right thing and head for safety!
And in Kristin's defense, she's a smart gal: she could see - instantly - the tornado was moving away from her, racing north toward the downtown skyline at close to 30 mph. As much as we all liked watching her video, nothing is worth putting your life at risk, no more how dramatic the visuals.
Drought-denting Rains. Check out the accumulated rainfall from yesterday's storm, raw data courtesy of the Twin Cities (MPX) National Weather Service. The north metro saw the heaviest rains, over 1.5" for parts of Wright, northern Hennepin and Anoka counties. But much heavier (3-5") amounts, showing up as shades of red, soaked Princeton, Mora and Sandstone. Chisago and Isanti counties saw some of the heaviest rains, a blessing, considering that's where "extreme" drought conditions were reported before today. Another area of flooding rains was reported over west central MN, some 5-6" rainfall estimates between Appleton and Milan. That's almost 2 months worth of rain in one day.Other rainfall amounts
Twin Cities (MSP Aiport) 1.39"
Eden Prairie (Flying Cloud) 1.54"
Crystal 1.97"
St. Paul 1.04"
St. Cloud .98"
Duluth 2.34"
Brainerd .09"
Paul's Outlook for the greater St. Cloud area
Thursday: Mostly cloudy, windy and cooler - showers likely, especially PM hours. Winds: NW 15-25. High: 66
Thursday night: Cool, damp and breezy, a few more sprinkles. Low: 54
Friday: More clouds than sun, another PM shower or sprinkle - still breezy and autumnlike. High: 68
Saturday: A mix of clouds and sun, less wind - nicer day to be outside. High: 74
Sunday: Mostly sunny and warmer, extremely lake-worthy! High: near 80
Monday: Warm sun, few complaints. High: 84
Tuesday: Showers, possible thunderstorms. High: 78
Wednesday: Showers give way to clearing, a cooler breeze kicks in. High: 73
Preliminary Damage Reports from the NWS. Tornadoes show up as red, wind damage (undetermined) as orange, hail damage as green dots. Check in with the local NWS office today for updates on the tornado outbreak. The Chanhassen NWS office home page is here.Damage Reports from Wednesday
PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
921 PM CDT WED AUG 19 2009
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0220 PM TSTM WND DMG MINNEAPOLIS 44.96N 93.27W
08/19/2009 HENNEPIN MN AMATEUR RADIO
TREES DOWN ON HOUSES AT 37TH AND 5TH AVE SO. AND ALSO AT
38TH AND 4TH AVE. SO. AND AT PORTLAND AVE SO AND 35TH
0220 PM TSTM WND DMG MINNEAPOLIS 44.96N 93.27W
08/19/2009 HENNEPIN MN EMERGENCY MNGR
ROOF OFF HOUSE, LARGE TREE BLOCKING ROAD AND POWER POLES
DOWN AT PORTLAND AND 35TH AVE SOUTH.
0220 PM TSTM WND DMG MINNEAPOLIS 44.96N 93.27W
08/19/2009 HENNEPIN MN TRAINED SPOTTER
2 HOMES DAMAGED, 3 GARAGES DESTROYED, AND 2 FT DIAMETER
TREES DOWN NEAR PORTLAND AVE AND 4TH AVE SOUTH. ALSO 2
GARAGES DAMAGED AT INTERSECTION OF PARK AVE AND 47TH...
AND 2 HOUSES DAMAGED AT 48TH AND PARK AVE.
0220 PM TSTM WND DMG MINNEAPOLIS 44.96N 93.27W
08/19/2009 HENNEPIN MN EMERGENCY MNGR
LOTS OF TREES REPORTED DAMAGED FROM 4TH FRANKLIN TO 4TH
AND PORTLAND. HEARD OF REPORTED DAMAGE AT 15TH AND
PORTLAND NEAR THE CONVENTION CENTER.
0227 PM TSTM WND DMG MINNEAPOLIS 44.96N 93.27W
08/19/2009 HENNEPIN MN AMATEUR RADIO
TIME IS RECEIVED TIME OF DAMAGE. TREES AND POLES DOWN AT
37TH AND 5TH AVE. SO. HEARD OF POSSIBLE DAMAGE TO
COMMERCIAL AND RESIDENTIAL ROOFS TOO.
0240 PM TSTM WND DMG 2 N HASTINGS 44.76N 92.85W
08/19/2009 WASHINGTON MN EMERGENCY MNGR
ONE ROOF OF A HOME DAMAGED AT 122ND ST COURT SOUTH.
DECK...GARAGE DOOR AND PLAYGROUND EQUIPMENT ALSO DAMAGED
IN VICINITY.
0243 PM TORNADO COTTAGE GROVE 44.82N 92.93W
08/19/2009 WASHINGTON MN EMERGENCY MNGR
TORNADO ON GROUND AT HIGHWAY 61 HIGHWAY 95/MANNING AVE.
REPORTED BY DAKOTA COUNTY EOC. TREE DAMAGE AT RIVER OAKS
GOLF COURSE. ALSO COTTAGE GROVE POLICE SAW FUNNEL HIT
GROUND AND REMAIN ON THE GROUND FOR 100 YARDS NEAR LOCK
RIDGE AVE AT 240 PM. TREES UP TO 3 FEET IN DIAMETER
DOWNED AND WINDOWS BROKEN IN THIS AREA.
0246 PM HEAVY RAIN BLOOMINGTON 44.83N 93.32W
08/19/2009 U0.00 INCH HENNEPIN MN TRAINED SPOTTER
NORMANDALE SERVICE ROAD FLOODED BETWEEN I494 AND WEST
84TH STR.
0250 PM TSTM WND DMG BROOKLYN PARK 45.11N 93.35W
08/19/2009 HENNEPIN MN AMATEUR RADIO
TREES DOWN AT HWY 252 AND 85TH STR.
0255 PM TSTM WND DMG MARINE ON ST CROIX 45.20N 92.77W
08/19/2009 WASHINGTON MN EMERGENCY MNGR
TREES DOWN AND TUNNEL BLOCKED ON OSTROM TRAIL NORTH/CO RD
4. TREES ALSO DOWN EAST OF TUNNEL. TIME ESTIMATED.
0255 PM HEAVY RAIN BLOOMINGTON 44.83N 93.32W
08/19/2009 U0.00 INCH HENNEPIN MN AMATEUR RADIO
ONE FOOT OF WATER ON I494 IN BOTH DIRECTIONS AT I494 AND
LYNDALE AVE. SO.
0305 PM TSTM WND DMG 1 N HUDSON 44.98N 92.74W
08/19/2009 ST. CROIX WI AMATEUR RADIO
LINE OF POWER POLES LEANING ONTO ROAD - ALMOST TOUCHING
ROAD AT COUNTY RD. A AND DORWIN RD. EVENT TIME IS
ESTIMATED.
0305 PM TSTM WND DMG HUDSON 44.97N 92.74W
08/19/2009 ST. CROIX WI AMATEUR RADIO
TREES DOWN AT COUNTY RD. UU AND LARSON LANE. TIME OF
EVENT IS ESTIMATED.
0330 PM TSTM WND DMG 1 E HUDSON 44.97N 92.72W
08/19/2009 ST. CROIX WI AMATEUR RADIO
4 INCH BRANCHES IN ROAD AND WHOLE TREES DOWN ON HWY 12
ONE HALF TO ONE MILE EAST OF HUDSON.
0343 PM HEAVY RAIN 8 WNW ISANTI 45.53N 93.41W
08/19/2009 M5.50 INCH ISANTI MN TRAINED SPOTTER
5.5 INCHES OF RAIN REPORTED BY SPOTTER IN SPENCER BROOK.
0345 PM HEAVY RAIN 5 S BRUNSWICK 45.72N 93.29W
08/19/2009 M4.40 INCH ISANTI MN TRAINED SPOTTER
RAINFALL TOTAL SINCE 330 AM.
0400 PM TSTM WND DMG NORTH BRANCH 45.51N 92.98W
08/19/2009 CHISAGO MN EMERGENCY MNGR
DAMAGE TO MIDDLE SCHOOL ROOF. BLEACHERS ALSO DRAGGED AND
OVERTURNED AT SCHOOL. TELEPHONE POLES DOWNED ALONG
HIGHWAY 95. ON EAST SIDE OF TOWN BY HWY 95...TREES UP TO
2 INCHES IN DIAMETER DOWNED AND SCATTERED SHEETS OF METAL
LAYING AROUND. TIME ESTIMATED.
0405 PM HEAVY RAIN 3 WNW BRAHAM 45.74N 93.24W
08/19/2009 M6.00 INCH KANABEC MN TRAINED SPOTTER
12 HOUR RAINFALL TOTAL
0411 PM TORNADO FOREST 45.14N 92.26W
08/19/2009 ST. CROIX WI TRAINED SPOTTER
TORNADO ON GROUND AT HWY 64 AT HWY 63 INTERSECTION.
0415 PM TORNADO 2 N FOREST 45.17N 92.26W
08/19/2009 ST. CROIX WI TRAINED SPOTTER
TORNADO STILL ON GROUND AT INTERSECTION OF 270TH STR. AND
20TH AVE.
0420 PM HEAVY RAIN 3 SSE QUAMBA 45.87N 93.15W
08/19/2009 M4.40 INCH KANABEC MN TRAINED SPOTTER
RAINFALL TOTAL IN 12 HOURS. MUD CREEK IS OUT OF ITS
BANKS.
0435 PM TSTM WND DMG 3 NW ESDAILE 44.65N 92.48W
08/19/2009 PIERCE WI TRAINED SPOTTER
DAMAGE TO CROPS AND TREES AT THE INTERSECTION OF V AND D
0454 PM HEAVY RAIN 5 SSW CAMBRIDGE 45.49N 93.25W
08/19/2009 M3.50 INCH ISANTI MN TRAINED SPOTTER
RAINFALL OCCURED OVER THE PAST 12 HOURS.
0515 PM HEAVY RAIN 5 SSW CAMBRIDGE 45.49N 93.25W
08/19/2009 M3.50 INCH ISANTI MN TRAINED SPOTTER
RAINFALL OCCURED OVER THE PAST 12 HOURS.
0628 PM TORNADO 3 E SPRINGFIELD 44.24N 94.92W
08/19/2009 BROWN MN TRAINED SPOTTER
SEVERAL TRAINED SPOTTERS REPORTED SEEING FUNNEL CLOUDS
AND OCCASIONAL TORNADO TOUCHDOWNS BETWEEN SPRINGFIELD AND
LEVANWORTH. REPORTS RECEIVED BETWEEN 628 AND 643 PM.
0759 PM FUNNEL CLOUD 2 N GOOD THUNDER 44.04N 94.07W
08/19/2009 BLUE EARTH MN AMATEUR RADIO
SPOTTER LOOKING NORTH FROM COUNTY ROAD 66 ESTIMATING
FUNNEL CLOUD IS 2 MILES NORTH OF GOOD THUNDER.
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