Wednesday was a day of feast or famine around much of my area. As expected showers and thunderstorm danced around the region with mixed results. Some places were soaked while others didn't even see a drop. Here in the Cedar Rapids area, in Marion (where I live), 3.17" of rain came down in 2 separate downpours. However, In Waterloo no rain fell and amounts in the Quad Cites and Dubuque were around 1/10th of an inch or less.
You can see how varied the amounts were over small areas with 3" of rain on the north side of the city while in downtown Cedar Rapids amounts were closer to 1/2".
I've noticed over the past 2 weeks vigorous troughs (like the one we experienced Wednesday) have been passing through the central Midwes creating bands of heavy rain, especially north of I-80. These trough passages were each associated with a negative dip in the EPO (Eastern Pacific Oscillation). These negative phases (or dips) have resulted in swaths of significant rain, particularly heavy for mid-August.
Below you can see in Cedar Rapids one trough passage dumped 1.74" around August 7th. Another the 14th-15th just recently produced an additional 2.30. That's not far from what we would typically see over the entire month.
You can also see another significant drop in the EPO is expected around August 20th. If recent history holds it goes to reason that another healthy rain event looms on the horizon. Interestingly enough, that's what both of our major mid-range models are showing.
Before we even get to that, another disturbance will roll through Thursday afternoon and evening. Once again, showers and storms will be scattered but with plenty of moisture, where they do form locally heavy rain is possible. Hopefully we can get some of that further south where drought exists and Wednesday's rains were essentially a no show. Here's what the NAM NEST shows with Thursday's system.
Getting back to the disturbance the EPO is advertising Monday, all signs point towards a well organized system and a healthy surface low by August standards.
Even though it's several days away the ingredients are showing for heavy rain over parts of the central Midwest. The EURO indicates this.
The GFS has this.
As always, time will tell but it sure looks like an interesting late summer storm. Until then, roll weather...TS