Humidity rises with more scattered storms Monday

 After a brief break from the worst of the humidity and scattered storms, much of the Stateline will see a return to both Monday. The outflow boundary from yesterday's storms was to thank for a brief cooler and drier stretch for many. It also created quite the temperature difference between Eastern and Western parts of the Stateline Sunday evening. It was still in the upper 80s in Sterling through 6PM, while it was in the mid-70s near Poplar Grove.

Along that boundary, a few isolated storms developed in Carroll, Whiteside, and SW Lee Counties. The outflow is helping to enhance mid-level rotation a little bit, so storms may be capable of producing 30-40 mph wind gusts and brief funnel clouds along with lightning and downpours. Isolated to scattered storms will remain possible through the evening, primarily West of Rockford and Rochelle.

Storms will weaken even more into the night as they slide closer, eventually bringing downpours toward the rest of the Stateline after 3-4AM. Severe storms are unlikely in this window, with the main threat being heavy rain for short periods of time.

By mid-morning, the first round of showers and storms will clear out, allowing temperature to quickly rise into mid and upper 80s while dew points will reach into the mid-70s. This will place the heat index near 100° at times through the mid to late afternoon. A heat advisory is unlikely to be issued, but it will be noticeably warmer for most than it was Sunday afternoon.

This heat and humidity will fuel the next round of storms that will arrive after 4PM from the West. These storms will be capable of isolated damaging wind gusts up to 60 mph along with heavy rainfall. Strongest storms will exit not long after midnight, with only isolated showers and a few storms possible into early Tuesday morning.

Monday evening's storms may be able to produce some heavy rainfall that could result in flash flooding. If storms end up moving slower than forecast or track over already saturated ground, the risk for flash flooding would be higher. The Weather Prediction Center has placed the entire Stateline under a slight risk for flash flooding Monday.