May 14, 2020 Severe Wx In SE Iowa

Sunday, May 17, 2020


This was the Storm Prediction Center (SPC) Convective Outlook posted on Thursday afternoon, May 14, 2020, with a Slight Risk for severe weather extending through a swath of southern Iowa.


A growing line of storms west of Des Moines became severe-warned at 3:40 pm CDT and were tracking east. On the heels of this development, the NWS SPC issued Severe Thunderstorm Watch 182 at 4:25 pm, which included portions of south-central Iowa (above).


As this line of storms progressed east, a tornado warning was issued at 4:50 pm for an area southeast of Indianola, Iowa (above) and it remained as such until about 5:15 pm. I had my spotting gear all ready in my vehicle, so shortly after the tornado warning was issued I headed south from Cedar Rapids on Interstate 380/US Highway 218 for an intercept location that would give me plenty of time to reach before its arrival.


5:52 pm CDT. This was my view of the western sky with its growing storm clouds while southbound on US Highway 218 just north of Hills, Iowa in Johnson County. Monitoring my radar at this time I determined the storm track was going to most likely move through the Washington, Iowa area to my south.


6:15 pm. I arrived at my spotting position, a longtime favorite of mine, located on Yucca Avenue, .1-mile south of Highway 92, about 1 mile east of US Highway 218 and about 1.8 miles east of the town of Ainsworth in Washington County. Temperatures in Cedar Rapids upon my departure were in the mid-sixties with similar dews, at my arrival here it had increased to 76 degrees F, also with a similar dew point. My spotting position was on a farm field drive-in area, allowing me off the road safety and a clear 360-degree view of the sky. A spent shotgun shell there (above), however, left me a little on the uneasy side...


6:17 pm. Panoramic view of the west sky, looking toward Ainsworth.


Radarscope frame capture corresponding to the photograph above it, with my stationary position indicated by the blue target icon. A severe thunderstorm watch was extended for the rest of southeast Iowa at 6:20 pm.


6:27 pm. My spotting position on Yucca Avenue, looking west.


Radar update for 6:39 pm.


7:27 pm. Looking northwest at an initial area of interest, which eventually moved out (toward the right), without any reportable criteria.


7:35 pm. A new area of interest--wall cloud--to my southwest. This I did report after checking into the Washington County ARES net (147.045 MHz) and net controller Lynn Reasor (N0XOB).


Radar image corresponding to 7:35 pm. My spotting area has now become severe-warned, with an obvious intense area of lightning and hail approaching to my west.


7:38 pm. Closeup of the ragged wall cloud to my southwest. The distance (about 30 miles) and its low contrast (due to fading daylight) made observing any rotation very difficult. The wall cloud was located near the town of Packwood in Jefferson County.


7:43 pm. Similar capture. The intense area was now 22 miles distant and located near the town of Fairfield in Jefferson County.


7:48 pm. Go Pro Hero 4 video frame capture of yours truly racing back to the car after shooting storm from other side of the road amid CG lightning.


7:49 pm. Storm now southwest of the town of Brighton in Washington County, 20 miles distant.


7:51 pm. Wall cloud exhibiting a funnel-like appendage.


Radar image corresponding to 7:50 pm. Note the lavender-colored areas of intense hail in this reflectivity image.


7:53 pm. Closeup of wall cloud and its ragged base.


7:55 pm. Similar closeup of the wall cloud.


7:56 pm. Most intense area of the storm now moving more to my south.


Radar image corresponding to the photograph above it.


7:57 pm. Wall cloud is reflecting the little sunlight that is still available.

Weather.us base velocity map for 8:00 pm. Arrow points to area of greatest intensity southwest of Brighton, Iowa in Washington County, in relation to my stationary spotting position.


8:00 pm. Storm area now contains an inflow cloud. Image looks SSW. The wall cloud is about 16 miles distant, southwest of the town of Brighton.


Radar image corresponding to 8:00 pm. The target icon is my spotting position, with the white arrows showing storm motion.


8:03 pm. Similar view looking down Yucca Avenue and facing SSW. Storm is about 14 miles distant, just west of the town of Wayland in Henry County.


8:05 pm. Growing dark, with fading contrasts. Nikon D7200 DSL camera.


Corresponding radar image. With growing darkness and the incoming threat of lightning, high wind, heavy rain and hail (outlined area), I decided my spotting time here was at end. I politely checked out of the Washington County ARES net and hightailed it back north on US Highway 218 and headed for home.


GoPro Hero 4 video frame captures (8:33 pm, top, 8:35 pm bottom) of lightning on the way home while northbound on Highway 218 south of Hills, Iowa. I evaded the hail and most of the heavy rain by leaving when I did and experienced some beautiful and vivid lightning displays. Finally back home after 9:00 pm.

1 comments:

Unknown May 21, 2020 at 12:07 PM  

Great coverage Gregg. As we talked about. I think the more severe weather may happen a little later than usual. Excellent blog you got going on here

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