A Plague of Hail

So let it be written. So let it be done. First of all, I wasn't expecting any thunderstorms at all for Cedar Rapids, Iowa on Tuesday, April 7, 2020. The Storm Prediction Center (SPC), had the city just barely inside the lightest outlook for thunderstorms, and had only a 5% chance for hail in an area stretching east of Davenport (top graphic). A day later the SPC posted a preliminary report for actual hail occurrences (bottom graphic, above).

Around 5:10 pm CDT, a small area formed some 28 miles west of Cedar Rapids, near the towns of Dysart and Garrison, and began to track east. At 5:27 pm it had intensified (radar capture, above left) but was not severe warned. By 5:35 pm it was (above right).

Of course now I began to take closer notice of the situation and set up my spotting observations from my backyard on the east edge of Bowman Woods Park in Cedar Rapids. Above is what the underside of the storm's anvil looked like facing west at 5:42 pm, as it stretched overhead toward the east.

A similar capture looking west at 5:48 pm, with the anvil beginning to block out the sun.

5:49 pm. Severe-warned storm cell is exhibiting a very vigorous updraft.

5:53 pm. Similar capture, wider view.

5:54 pm radar capture as the storm cell was over Cedar Rapids. Though severe warned, this storm did not affect much in my viewable area, and passed on leaving a feeling that the threat for anything further was over.

Not so! At 6:15 a new storm cell now materialized just west of Cedar Rapids, trailing the earlier one. Air temperature was 78 degrees F, 60 degree dew point with 54% relative humidity.

By 6:30 pm, ominous amateur and weather radio reports told of significant hail associated with the new storm cell to the west. Above, my view of the west sky overlooking Bowman Woods Park at 6:35 pm--a classic calm before the storm scenario--as the hail would come about three minutes later.

Radarscope capture closely corresponding to the photograph above it.

And hail it did! This image from 6:40 pm shows hail pelting down in our backyard. Falling hail started as pea size, grew to penny size, then golf ball, then a few with maximum sizes of 2.5 inches!

Radar capture for 6:40 pm.

Backyard hail at 6:44 pm, near the end of the event.

6:45 pm. A handful of harvested golf ball size hail. Note the conglomerate dimpled appearance of these stones.

6:52 pm. The hail storm finally over and a safe view of the leftovers.

6:54 pm. The trailing edge of this potent storm, looking west. The trailing edge slid east to my south and caused no further mayhem here.

Aftermath: Hail stones with various shapes and compositions, at 7:05 pm (above, top), and two of the largest stones gathered at 7:15 pm (above, bottom).

7:10 pm. A view of the departing storm system to my east, seen over our house roof.

7:24 pm. Departing severe-warned storm cell looking more dramatic as it created distance. At this moment the cell was some 20 miles distant to the southeast, just north of Mechanicsville, Iowa in Cedar County.

Corresponding radar capture to the images above and below.

7:31 pm. Panorama captured from Bowman Woods Park, looking east. The area at right is part of the southern edge of the system which missed this location.

7:32 pm. Panoramic view of the trailing edge of the storm system as it departed east, looking south from Bowman Woods Park.

Curiously, an eerie and dense ground fog enveloped the area following the storm's departure. This image looks east along Boyson Road at Brentwood Drive NE in Cedar Rapids, near the border with the neighboring community of Marion, Iowa at 7:43 pm. Weather conditions at this moment: 66 degrees F, 58 degree dew point and 84% relative humidity. Nikon D7200 DSLR camera.

POSTSCRIPT: The largest discovered hailstone from our backyard is compared to an old tennis ball.

The one and only hail damage casualty from home. Superficial dents to the roof of my car excluded, it was to the wind vane arrow of my Davis Instruments Vantage Vue weather station, which was broken off. What make this truly amazing is the fact that the wind vane shaft is such a small target, a mere 1/4 inch-wide and protrudes only two inches out from under the main unit. (Surprisingly the main unit and the fragile anemometer cups survived intact). My first thought was that the wind vane suffered a wild chance hit, but now as I ponder the volume of hail that was falling at the time, I guess I should not be surprised. Storms have not been kind to my roof-mounted weather stations. My former weather station, an Oregon Scientific WMR968 unit, was damaged beyond repair by a falling tree branch on June 29, 2012. The largest hailstones from the April 7, 2020 storm may be the largest I've ever witnessed! iPhone 6 Plus camera.

7:35 pm CDT, Tuesday, April 7, 2020. My weather station with the backdrop of the departing storm system whose hail damaged its wind vane. Nikon D7200 DSLR camera.