July 19 Clayton County Iowa Severe Weather

An Enhanced Risk for severe weather for northeast Iowa was posted by the Storm Prediction Center on Wednesday, July 19, 2017. Sustained severe weather moved east from South Dakota in the morning into southern Minnesota and northern Iowa, reaching Clayton County by 5:50 pm. Before its arrival, I selected an open spotting location on Highway 13 at the top of a hill about one mile north of the town of Strawberry Point. Above, I await the approaching storm at 6:04 pm in this panoramic image facing northwest. Note its wind-driven "cake layered" appearance.

6:08 pm. The leading edge of the storm, now about 7 miles distant, has taken on a shelf cloud look.

6:11 pm. A dramatic capture of the leading edge of the shelf cloud in the NNE sky.

Also 6:11 pm. Turbulent leading edge of the shelf cloud in the SW sky. Storm movement was right-to-left in image.

Vertical capture of the same view a few seconds later. The leading edge of the shelf cloud has generated small and very brief funnels.

6:12 pm. The shelf cloud has created an sun-illuminated arch as it moves toward the back right of this panoramic image (southeast). Nikon D7200 DSLR camera.

Radar capture of the area for 6:05 pm. Note the red tornado-warned box in NE Clayton County.

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July 21 Johnson County Tornado Warning

Still located at the Interstate 380 rest area just south of Cedar Rapids, Iowa and just north of the Swisher exit, the severe storm cell in Johnson County on Friday, July 21, 2017 was progressing.
This image, captured at 4:46 pm CDT, shows an extensive shelf cloud stretching west from the intense center of the cell.

Meanwhile, toward the center of the cell one minute later, things were getting interesting. This image shows a lowering with an intense rain-wrapped area where I was sure a tornado might form.

4:48 pm. Panorama looking south toward Johnson County as seen from the rest area.

4:49 pm. Zoomed-in version of the image above this one. Note the turbulent low hanging clouds along the southern horizon in the background. This was captured right as, or just before a tornado warning was issued for Johnson County, with the towns of Kalona and Hills later being effected. Nikon D7200 DSLR camera.

4:50 pm. Radarscope Pro capture of the moment, showing my position (blue target) and the tornado-warned box in red.

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July 21 Generation Gap

While the atmosphere was generating this severe storm in Johnson County, Iowa on Friday, July 21, 2017, a large gap appeared between the wall cloud--located more to the east--and a shelf cloud--spread out to the west. Above is a panoramic view of the storm at 4:40 pm CDT, as seen from the Interstate 380 rest area just south of Cedar Rapids, Iowa and just north of the Swisher, Iowa exit. The gap exhibited a dynamic churning motion, sort of a battle between the rotating and the straight line areas of wind.

4:42 pm. A slightly closer panoramic view of the area, with the strong updraft area inside the gap more visually prominent.

4:43 pm. A vertical and closeup of the finely textured gap, with the wall cloud residing at lower left.

Also at 4:43 pm, with a wider field of view of the "battleground."

4:44 pm. Just below the gap area. Nikon D7200 DSLR video frame capture. With a ragged funnel and a lowering here, a tornado seemed imminent, but failed to happen. Tornado warnings were issued further south for the towns of Kalona and Hills in Johnson County less than ten minutes later.

Radar capture for 4:45 pm. My position at the I-380 rest area is indicated by the target icon, with the arrow pointing to the more intense area of the severe storm. The white circle indicates the approximate location of the gap.

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July 21 Storm: The Beat Goes On

More images of the Johnson County Iowa storm on Friday afternoon/evening, July 21, 2017.
Above, a classic wall cloud continued to wow me at 4:34 pm CDT. This image looks southwest from the rear of the Interstate 380 rest area, just south of Cedar Rapids and just north of the Swisher, Iowa exit.

4:36 pm. Resembling a tall-whipped ice cream cone, this vertical image captures the storm's aggressive updraft (top) and its wall cloud (bottom).

This video frame capture shows the turbulent top of the severe cell at 4:39 pm. Nikon D7200 DSLR camera.

Radar frame capture for 4:35 pm. The most intense area of the storm is indicated by the arrow, and my location at the rest area, the target icon. Storm movement was generally to the east.

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July 21 Classic Wall Cloud

Pulling into the Interstate 380 rest area just north of the Swisher, Iowa exit around 4:22 pm CDT on Friday, July 21, 2017, the beautifully shaped base and wall cloud had grown immense in the SW sky. Though not exhibiting a rapid rotation, it still merited a spotter's report by me to the NWS in the Quad Cities at 4:24 pm.

4:27 pm. Looking SW from the back of the rest area. Wispy thin white clouds were orbiting the lowering counter-clockwise and can be seen at the top of the image above, and below (4:28 pm).

4:33 pm. The wall cloud has now taken on a more smooth appearance (above). Nikon D7200 DSLR camera.

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July 21 Beautiful Storm Structure In Johnson County Iowa

A revised Storm Prediction Center Enhanced Risk was posted from central to eastern Iowa on Friday afternoon, July 21, 2017, followed soon thereafter by Severe Thunderstorm Watch 429 (above). Almost unnoticed by me, a small cell began to form southwest of Williamsburg, Iowa in Iowa County around 3:35 pm. I had been expecting storms to initiate further north, more inside the Enhanced Risk and Watch 429 boxes. 20 minutes later--to my surprise--the cell had grown considerably and went severe-warned. It was time to head out and catch it!

Shown above is my position at 4:10 pm at the Cedar Rapids Blairsferry Road Interstate 380 overpass, with the arrow pointing toward the severe-warned cell. Below is the camera's view of the storm at the same moment. Note the strong updraft of the cell, evident even at just under 30 miles distant.

Now southbound on I-380 in southern Cedar Rapids at 4:18 pm (above). The storm cell is exhibiting a strong cauliflower-like updraft appearance with a wall cloud on its western (right in image) flank.

4:20 pm and just north of the Eastern Iowa Airport exit (Exit 13). Drawing closer to it with each mile. The wall cloud has become much more obvious now under the updraft. The most intense part of this storm was located about 14 miles to the SW, near Middle Amana, Iowa.

Two minutes later and just north of my eventual spotting position--the rest area just north of the Swisher, Iowa exit. The wall cloud now dominates the scene. Nikon D7200 DSLR camera.

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Under Severe Limits

A line of storms, stretching from central to northeast Iowa on Wednesday evening, July 12, 2017, produced two severe-warned areas around 5:30 pm CDT. The southern and westernmost was near Marshalltown, and the northern and easternmost near Oelwein. I chose the southwest option, and drove to it from Cedar Rapids via interstates 380 and 80. Above, a roll-type shelf cloud with scud is seen on the horizon at 6:34 pm while I was westbound on I-80, just about 1.5 miles east of the Amana exit (US Highway 151). Despite its ominous appearance, the storm had lost its severe tag by 5:45 pm.

Pulling off the US Highway 151 exit, I chose a widened part of the road about a quarter-mile north of I-80. This view looks NW at the approaching shelf cloud at 6:37 pm. The gust front was now about 5 miles distant.

Panorama of the same scene a minute later.

Northwest view of the shelf cloud from across the road at the same location at 6:39 pm. Nikon D7200 DSLR camera.

The atmospheric ingredients on this day were such to create heavy rain situations, and I ran into this in downtown Cedar Rapids on my way home--at one point nearly being unable to see the lane stripes on Interstate 380 ( a few minutes after the above GoPro Hero 4 video, in which this still was made).

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