From Mike Smith @ Meteorological Musings
A central Oklahoma microburst descends from the parent cloud to the ground. Photo from National Severe Storms Lab
At 6:46pm yesterday (Sunday) evening, a strong microburst (likely strong enough to bring down a commercial airliner, had it been at the end of a runway) occurred in northwest Wichita a few miles northeast of Mid-Continent Airport. Since these are fairly rare, I thought it might be of interest to view the microburst in several different ways:
First, here it is in the radar reflectivity data (the type you usually see on TV weathercasts). The center of the microburst is near the deepest red pixel. The time is 6:45pm.
A second view of the microburst comes from the Wichita Terminal Doppler Weather Radar (TDWR), an instrument designed specifically to detect microbursts, installed in the wake of Delta 191 and the series of downburst-related crashes in the 70’s and 80’s. Compare the location of “Wichita” on the two radar images and the freeway (Interstate 235, not labeled, but wraps around the west side of the city) on both maps to orient yourself.
This radar senses the wind in great detail. The radar at 6:46pm is showing a 46 knot (53 mph, deep brown pixel) wind blowing toward the north on the north side of the microburst and a winds blowing toward the south at 39 mph (light green) on the south side of the microburst. This represents 92 mph of wind shear, likely enough to bring down an aircraft!
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Also, for anyone wanting to track storms on radar in near real time, inexpensively on your PC, with no data fees, I have an app for that, StormPredator. – Anthony
You’re probably inadvertantly comparing oranges and apples: I’m not sure where the Doppler radar is for Wichita, but it is probably surprisingly distant from Wichita and the storm. Because the earth curves more than the radar beam, even if this is the bottom reflectively slice, the strong echo is probably centered quite far above the ground. If this is a composite reflectivity, a sum of all the slices pertaining to that storm, that strong return is probably quite high in altitude. Storms are not only 8 km deep or more, but they are not vertical, especially violent thunderstorms, because they thrive on wind shear through the entire troposphere. Your TDWR image, of strongest velocity, is probably quite distant from the WS Doppler radar and quite close to the storm outflow. So that peak velocity could be close to the ground.
There is another point about downbursts: If a relatively low slice is being used, the darkest reflectivity may be close to where the strongest downdraft is; this is because the weight of hail and the rapid cooling of that area by heavy and evaporating rain is bringing the air down the fastest. When the downburt approaches the ground, it spreads out. There might be very little wind directly under the core of the downdraft, with a vaguely doughnut shaped zone of high winds pushing out in every direction. If the thunderstorm is moving, possibly as fast or faster than a car travelling on an interstate, the strongest winds would be away from the downdraft, and located beyond the downdraft in the direction toward where the storm is moving.
Much literature by Fujita and others clearly explain common downburst dynamics.
Roger Knights says:
July 28, 2010 at 8:55 am
“How is this year’s tornado season shaping up? I think it was predicted to be heavy, but it hasn’t been so far, IIRC.”
Just wait till August. Things could warm up a bit on the tornado front then.
I know I have shared this before, but for those of you who have not seen it (I have watched it again and again)….check out this powerful wet microburst outside of Brisbane, Australia in Nov. 2008.
Ignore the “cyclone” title. It was not, but it sure looked like one.
Amazing….the maximum winds here were calculated to have hit 111 MPH.
Does anyone know of a paper or abstract analyzing this event? I would love to read it.
Chris
Norfolk, VA, USA
In the last “cold phase” of the ’60s and ’70s there were a lot of microbursts and a lot of crashes. The PDO shifted to warm. .. Then in the ’80s the crashes faded and in the ’90s we even had a year or two with NO airline fatalities. Then the PDO shifted to cold…
And we promptly had something like 3 airline crashes with fatalities (one or two with the loss of all on board. I think it was an Airbus near Mautius? Mauritania? with ‘weather related’ complications.).
So any one keep records of weather related airline crashes and / or micrburst activity such that a correlation coefficient could be calculated? Yeah, lots of confounders (like technology change…), but if it’s a strong signal…
If we’re getting a lot more and a lot more violent downdrafts of very cold air, and that’s not ‘expected’, well, it would point to a very interesting question or three about how well we understand climate dynamics…
Darrin, it was a tornado. I was there, or at least about 1 mile as the crow flies from that tornado. Took out the entire inside of a warehouse and broke the windows, but left the outer walls standing. It lifted the debris and spread it around, instead of smashing it to the ground underfoot. Tornado. But relatively speaking, not a strong one and didn’t last but a few seconds on the ground.
FYI, I was born and raised in NE Oregon, then moved to Corvallis and Albany for 30 years to attend college, get married, raise kids, and attend more college. VERY glad to be back in NE Oregon.
Thanks Ric Werme for those helpful links (see top of this thread). Everyone who is just like me (not a climeatoligist/scientist) – but obsessed and passionate about this whole CO2 warming hoax – should save them on their favourites as a simple, but general weather reference.
As you know, here in the UK, we rarely see the intense variety of weather events that you guys frequently experience in North America. As I look out of my window, the sun’s up now, it’s 7.40am, it might be overcast and it might rain again and I’ll probably say the obligatory British “Good morning, bit overcast” to the newsagent later on. But just for a change, I’d love to capture the occasional ‘twister’ or severe microburst. As you’ve all just gone to bed, when you guys wake up tomorrow, could you please send us some of your wonderful dramatic weather – then we would really have something exiting to complain about. “Morning, looks like the whole sky actually fell on Tom’s house last night”.
Keep up the good work Anthony.
Here’s the link to the NWS Full-Resolution Radar mosaic, folks.
http://radar.weather.gov/Conus/full_loop.php
It’s interactive. Find your local area and double-click — it’ll send you to the nearest radar site. It’s real time, but you can loop it to see trends.
Sorry, Mizz Pamela, but it can’t reach down into the valleys — however, a violent T-storm building in your area will show up on the scope as the core updrafts carry water vapor above the condensation level.
That “central Oklahoma microburst” actually happened in KANSAS. Even Toto knows Wichita ain’t in Oklahoma. The highway layout in the screen shots confirms, Wichita, KS.