We had record setting calendar rainfall amounts at O'Hare Airport with 6.97 inches down since midnight last night. We had a 24 hour total of 8.20 inches of rain since 7 AM yesterday at that same location, with most locations in the city on north receiving 3 to 8 inches. The culprit last night was a stalled frontal boundary on top of the ridge of heat that has been baking much of the nation over the last month. A line of storms basically formed along that boundary across the northern half of the city, stalled, then slowly moved south, and then combining with the reminants of a bow echo that was coming in from the west that had formed in Iowa.
Now, the same thing is happening again at about the exact same time tonight, just maybe about 15 or so miles to my south! No MCS activity in Iowa yet, but there is development along the I-88 cooridor from eastern Iowa all the way into Indiana. Also a second MCS is developing just south of Minneapolis that might come into play tomorrow morning. The lead MCS that moved through Wisconsin earlier this evening and prompted a severe thunderstorm watch north of Milwaukee has weakened. The second one may turn south and effect our western suburbs according to the models. Models are kicking out 5 to 6 inches just west of the immediate Chicago area, with much lower amounts near the lake due to an earlier lake breeze front! In other words, the north shore areas of Chicago that "only" received about 3 to 4 inches of rain last night (versus the 7 inches just 15 miles west) may be saved again. But the models don't normally do a good job predicting this nocturnal storm complexes, so I'm not really trusting them. If we duplicate last night's "feat", this could lead to some catastrophic flooding in some areas. But while I don't wish ill will on anyone, hopefully a different area will get the brunt majority of the rain than the areas that got hit hard last night. Lots of flooded areas near me, so hopefully this stays just a bit south and west of my area tonight.
