Unseasonable amounts of moisture and instability were present in the state of Iowa on Tuesday, October 9, 2018. It felt more like May than October. This, and other factors prompted the
Storm Prediction Center to post the convective (left) and tornado outlooks at 12:25 pm CDT.
An SPC Mesoscale Discussion (
1550) at 12:59 pm further added the 80% probability of a tornado watch issuance, and indeed it was posted at 1:45 pm (
Tornado Watch 404, above). Storm clusters began forming in south-central and south-east Iowa shortly thereafter, moving in a less normal NNE track. The first tornado-warned storm cell appeared in southern Marion and Mahaska counties at 2:20 pm, which prompted me to leave work a half-hour early to get ready for a possible intercept.
After quickly securing my photography and communication equipment, it was time to set out for the intercept. The image above, captured at 3:27 pm CDT while southbound on the Interstate 380 S-curve in downtown Cedar Rapids, Iowa, looks southwest toward a new tornado-warned cell, located about 25 miles distant, in northern Iowa County and southern Benton County.
Radar screen capture and our location for 3:30 pm.
3:38 pm CDT. Westbound on US Highway 30, just west of Fairfax, Iowa. The first of several wall clouds is beginning to come into view at our 10 o'clock position.
3:45 pm. Approaching the wall cloud with inflow tail cloud, about a half-mile east of 28th Avenue, and south of the town of Newhall, in Benton County. Wall cloud is about six miles to the southwest.
Radar screen capture and our location for 3:48 pm.
3:49 pm. We are stationary now, located on 27th Avenue at US Highway 30, south of Newhall in Benton County. This classic low-hanging wall cloud sported a rapidly rising right side. A confirmed EF0 tornado touchdown occurred southeast of the nearby town of Blairstown at 3:48 pm. I made a spotter report to the
National Weather Service in the Quad Cities (DVN) at 3:50 pm.
3:54 pm. Same wall cloud looking due west from US Highway 30. This storm was moving left-to-right in the image. The wall cloud exhibited dynamic movement.
3:55 pm. A panoramic capture of the wall cloud with much of the storm structure included, from 27th Avenue at US Highway 30. A laminar shelf cloud can be seen at left.
3:57 pm. A zoomed-in shot of the wall cloud, which is quickly moving north (right). At this time we made the decision to return to our vehicle and follow its track.
Radar reflectivity (left) and velocity captures corresponding to 3:55 pm. The white target icons indicate our position.
4:01 pm. Northbound on 1st Avenue (W14), just south of the town of Newhall. Panorama image of wall cloud and shelf cloud, located about 1.8 miles to the northwest.
4:01 pm. Closeup of the wall cloud.
4:05 pm. Northbound on 27th Avenue north of Newhall. The wall cloud now has a tighter appearance and includes a inflow tail cloud. Weather conditions at this time was: 82 degrees F, 75 degree dew point, 79% humidity, wind at SE at 5 mph.
4:09 pm. Stationary again and on 27th Avenue (W14), about 3.1 miles north of Newhall. Looking northwest at the wall cloud and tail cloud.
Video frame capture from 27th Avenue (W14), about 3.1 miles north of Newhall and about .6-mile south of 67th Street in Benton County. Top image from 4:11 pm, bottom at 4:14 pm. The storm was moving toward the upper right of the images (NNE). The bottom image includes an apparent horizontal vortex, rotating around the storm. A slight grazing of rain briefly fell on us here as the storm moved away.
4:10 pm radar screen capture, showing our stationary position (target icon). Black arrow indicates most intense area of the tornadic storm, white arrows show storm movement.
4:15 pm. Lowering in northeast sky on the eastern flank of the storm, over 67th Street. The sun was beginning to emerge from behind the camera, providing excellent photographic contrast.
4:18 pm. Billy Gant photographs the storm in this panoramic view looking north-northeast from 27th Avenue (W14), about .6-mile south of 67th Street in Benton County. At extreme lower left of this image is the hood of a watchful Benton County Sheriff.
4:19 pm. Black and white version of the storm. B&W conversion created by
Nik Collection/Silver Efex Pro 2.
4:58 pm. Stationary at
Van Horn Chevrolet car dealership along US Highway 30 in Benton County. The image looks south beyond 28th Avenue toward a funnel cloud.
5:03 pm. Backlit rotation from same location. A steady rain was falling.
Radar screen capture and our location (upper left) for 5:08 pm.
5:12 pm. The storm cell has now passed to the east of the car dealership. The wall cloud is exhibiting a laminar structure, and is moving right-to-left in image.
5:22 pm. Stationary and looking northeast from 72nd Street at 28th Avenue, about one mile southeast of Newhall. Funnel in background was located about 9 miles distant. Sirens were sounding at this moment, probably due to another tornado-warned cell located near Fairfax, Iowa, 6.5 miles to the southeast (see 5:08 pm radar image above).
5:47 pm. Northbound on I-380 near H Avenue, following another wall cloud to the north. I would make a ham radio report of this wall cloud minutes later.
5:55 pm. Looking northeast from County Home Road just east of I-380. The wall cloud has a tight, bell-shaped appearance.
6:01 pm. Looking north from County Home Road, toward the town of Alburnett, in Linn County. Though the storm was significantly weakening at this time, a classic wall cloud persisted. Filtered setting sunlight created this beautifully colorful look. Despite the dynamic nature of this day's tornadic event, we experienced minimal amounts of lightning and wind and zero amounts of hail. Nikon D7200 DSLR camera.
Read more...
Posts
