FROM MOISTURE FEAST TO FAMINE

The main weather story continues to be the very comfortable weather across the Midwest this weekend into the work week with the combination of cooler temperatures and very low humidity levels. I want to take some time to discuss the incredibly dry air that's coming in from northern Canada, By early this week precipitable water values will continue to plummet well below normal for this time of year. Tuesday morning will likely be the bottom in terms of temperatures and moisture values with a precipitable water value near 0.5".

Saturday evening's weather balloon from Davenport, Iowa shows a measured precipitable water value of just 0.69". More shocking is the incredibly dry midlevels of the atmosphere with mid-RH at just 22%. Dry as a bone! For some context, 0.65" is the 10th percentile for PWAT values, so we are near the bottom all-time. Tuesday morning the record low for the date is 0.47", and based on model guidance we will be quite close to that.

Looking at the surface moisture values, we have had quite a run of above-normal daily max dewpoint values. Aside for that dip in late July/early August, we have been running close to the 75th percentile frequently since mid-June. We started the transition Saturday and this will likely fall off a cliff by Monday and Tuesday.

Last weekend we were way ahead of this cooldown, discussing the return of cooler temperatures. I also discussed the potential of wildfire smoke moving in with the northwest flow but thankfully that has not been the case. Looking at visible satellite imagery from Saturday evening there is very limited smoke coming from our friends to the north. Additionally, that northwest flow is keeping smoke from active fires in Idaho and Montana to our southwest. It's becoming quite rare to get this push of cool air in late summer and not have to deal with smoke issues and for that I am very thankful.

The limited moisture will keep the rain chances in check as well. Looking at the raw readout from all 50 members of the European Ensemble there is a major lack of rain chances over the next week. Longer term we are starting to see some potential returning around the Sept. 4/5 time frame, which is around the time I discussed the past few posts that the above-normal temperatures may return.

The American ensemble, the GEFS, also indicates slowly increasing rain chances around that time. So in terms of weather to watch, that is likely the next storm systems to monitor but we have a rather long ride to go before we get to that point. The forecast is on somewhat easy mode for a while.

Forecast temperatures going forward for the Quad Cities region shows the comfortable air taking over this week with a slow, gradual warming back into the low-80s by next weekend. This is some of the best weather the Midwest offers this time of year. The first (true) week of college football is looking quite pleasant across the region for tailgating and play on the field!

One more quick note before we wrap this up, I am closely watching trends for the upcoming winter and if you like cold and snow, we are seeing a bit of a signal that might be the case for the Great Lakes region. La Nina is starting to look increasingly likely to take back over and that would favor a wetter-than-normal winter with a more active storm track. Other teleconnections such as the strongly negative PDO would favor an active winter as well. We are early in the seasonal forecasting time frame, but I am getting rather interested in what winter 2025-2026 may have to offer.

Have a great Sunday everyone!

-Meteorologist Nick Stewart