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I reached the Salem exit on I-90 at 3:40pm and prepared for an intercept. |
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A large wall cloud developed. A period of disorganization followed, as the entire updraft lowered its base. A tornado warning was issued by NWS FSD, and they upped the storm motion to 45kts. With the 70-80kt mid-level speed max nosing into the area, it was possible the storm could accelerate even further. I took a chance and drove away from the storm... eastward, to the next I-90 exit. |
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Here is the first image I took from the next exit (4:02pm). The RFB was organizing nicely and sloping in toward the precip. I plotted the future track of the storm on a map and prepared to potentially play the when-will-the-warp-speed-storm-drop-a-tornado-and-will-I-be-in-position-to-see-it? game. (A game I usually lose). |
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Significant cloud-base rotation was underway, with rotating rain curtains near the center of this photo. |
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At 4:08pm, a nub funnel peeked out from the center of the dynamic merry-go-round meso. |
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During the next minute, the "Salem" tornado was born... with a single wild condensation vortex having swirled across the ground seconds before I snapped this photo. The rainy RFD cleared locally, offering strong contrast. |
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Tornado transitioned back to a truncated cone within pronounced low-level meso. |
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Condensation reached for the earth. The tornado kicked up a large amount of dust/debris over the next minute. |
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The tornado veered leftward on a more easterly course for several moments... then turned back to the northeast. |
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Tornado grew into a stovepipe. |
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Image of entire mesocyclone structure, framed by some local flora and the photographer's right foot. |
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Tornado approaches and rips through several stands of cottonwood trees. |
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Dramatic helical motions near ground. |
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The debris fan reminded me a lot of SLT's imagery of the Webb IA tornado. |
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Zoom. |
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At 4:16pm I snapped my final photograph of the Salem tornado, and abandoned my location for I-90 eastbound. From the onramp, I filmed the tornado as it began to cross the area in which I'd previously been standing. I then gathered some fairly remarkable footage as the strengthening tornado spread its debris fan across the interstate. The tornado passed into a field, growing into a stout stovepipe while clear-slotting colored it ghostly white. Debris began falling on my vehicle. The tornado continued northeastward, shrunk, bended into a 90-degree angle at its midsection, and roped out ~4:22pm a couple miles north of the interestate. |
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Post-tornadic large & wet RFD. |
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I stairstepped northeastward toward the town of Colton, SD and in time noted significant rotating/cascading motions. I stopped and observed these for a moment, beginning to think they were the sort of "hind-end" storm features I often stare at in awe while the primary meso is recycling/scooting away well ahead of me. I continued northward in an effort to retain/improve my position on the storm, when tornadogenesis did in fact occur with those features. The tornado began at 4:54pm as a narrow gray tube, then began to lean over as a dust cloud developed. A bright shower of debris followed; a farmstead had been struck. The tornado lasted two minutes. |
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I fought to keep up with the storm through Pipestone, MN. The updraft looked fairly sheared-over and disorganized at cloud base. Newly tornado-warned cells had developed back in southeastern SD. I moved back to the southwest side of town for an intercept along the MN border |
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This was the tail-end tornado-warned cell as it approached Dell Rapids, SD. It first sported a blocky wall cloud but quickly transitioned to a more highly-based P.O.S. The warning expired. |
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I headed east on the same highway with which I'd pursued the previous storm. Winds in the inflow sector were dead calm. About this time, it earned a severe thunderstorm warning again. |
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I bid the storm and its cute horseshoe RFD farewell ~7:15pm. |
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Departing convection viewed from I-90 at sundown. The ride home was pleasant until I encountered a wall of water south of Omaha. A five-hour drive took nearly eight as a result. |
