High Pressure Keeps Us Dry Ahead of Tomorrow's Rain

We started off our Thursday morning with some cloud cover, which held our temperatures in the 60s for most of the night. Once those pesky clouds moved out, temperatures underwent a progress we call rapid cooling. Temperatures then rapidly rapidly down into the upper 40s - low 50s this morning making for a chilly start to our Thursday. One where grabbing a light jacket before heading out the door wouldn't have been a bad idea. In fact, temperatures this morning were 10-15 degrees cooler in most spots than how we were 24 hours ago.

As the day progresses, high pressure will continue to build into the region, keeping the weather quiet for the rest of our Thursday. Highs will slowly climb into the upper 60s for some and lower 70s for others. Regardless of where highs top out for the afternoon, most of the day will feature VERY fall-like conditions with temperatures in the upper 60s. Our highest wind gust at the Chicago-Rockford International Airport was 30 mph. Winds today will still be a bit breezy at times but a little lighter in strength. Winds will blow out of the west and could occasionally gust to around 20 mph.

Overnight, winds will become more southerly as a warm front quickly pushes through the Stateline and heads northward. This will play a key part in how Friday’s forecast unfolds. Most of the night will stay dry, but clouds will be on the increase ahead of an approaching cold front. Most of us should remain dry up until scattered showers begin to develop around sunrise. Winds will also pick up in intensity as the night progresses. The first round of showers and storms will likely move through just in time for the morning commute.  Having the rain gear ready to go before you head out the door would be a good call. There won't be much of a severe threat with the first round, but heavy rain is possible.

As the cold front pushes east through the afternoon, a line of strong storms look to develop across Iowa. The Storm Prediction Center has placed the western portion of the Stateline in a Slight (level 2 out of 5) Risk for severe storms. As isolated thunderstorms develop tomorrow afternoon, the primary concerns will be for gusty large hail and an isolated tornado. Then once these storms begin to congeal and form a more linear complex, that threat transitions to mostly high wind gusts. Just make sure that your weather radios are working properly so that you can receive any watches and warnings that are issued by the National Weather Service. 

Storms could not only impact the evening commute, but also Friday Night Football games and the last City Market of the season. Heavy rainfall could also pose a concern. Models have hinted at the heaviest of the rain staying off to our south and southwest. It all really depends on where the strongest storms form along the cold front as it pushes through Friday evening.

Rockford has had a very wet month of September. So far, we have seen about 8.5″ of rainfall, so the ground is currently pretty saturated. Atmospheric moisture will be high during the late afternoon and evening tomorrow. So as said above, depending on where these storms move along the cold front, most spots could see 1-2" of rain with higher amounts in localized areas. This means flash flooding could become a concern as we head into the weekend. A few spotty showers or storms could even linger through the early hours of Friday night before drier air moves in behind the passing cold front into Saturday.