Clouds of the Day - Sunday, May 24, 2020

A large area of showers and thunderstorms moved out of Nebraska into western and central Iowa overnight and this morning. As the storms moved toward eastern Iowa they began to weaken. As the “leftovers” moved into the Cedar Falls area the activity was weakening. What remained is depicted in the photos below. A weak outflow boundary and showers crossed the area. The first two photos were along and under the outflow and the next two photos were looking east after the showers passed.

Approaching outflow boundary with low level arcus (squall) cloud.

Under the arcus (squall) cloud looking southeast in direction the cloud is moving.

Here is the pressure trace. May 24th begins at the vertical line marked May 24, 2020. Notice the pressure jump at 9:00 a.m.; just past the 8:00 a.m. mark. As cooler outflow from the weakening thunderstorms to the west reached Cedar Falls the pressure increased. Notice the wind direction changed from easterly (100 degrees) to northwesterly (333 degrees) between 9:00 and 10:10 a.m.

Light rain showers with thunder fell after the pressure jump and the wind shifted. Rain was light, totaling only .06 inches. The two photos below show clouds to the east as the rain departed.

Cumulus, cumulus mediocris, and cumulus congestus in foreground. Dark cloud band appearing to reach the ground just above the trees center-left is a rain shaft. Photo looking east northeast.

Sun visible upper left through altostratus layer with ragged cumulus and cumulus congestus lower half of photo.

The photo above shows altostratus over the entire sky in two layers. The higher layer covers all but the very bottom of the photo where a lower and darker mid-level deck of altostratus is visible between the trees. There is small patch of altocumulus just left of the trees. The photo is looking slightly east of south.

Compare the photo with the radar image below. Cedar Falls, Iowa, where the photos are taken, is located just northwest of Waterloo, Iowa. Waterloo is on the map in the northeast quadrant of the map. The photo above is looking southerly toward the large area of showers and thunderstorms spreading north in Iowa. Looking at the photo it would be expected to see lowering cloud decks looking in the direction of the precipitation.