HOW LOW DO WE GO...

The sun continues to drift lower in the sky, and daily, the shadows are lengthening. Like it or not, summer is fading and I have no doubt we have seen the worst 2025 has to offer. But don't take my word, all you have to do is look at the thermometer. Tuesday morning, the majority of the area will be in the 40s, some spots not far from record lows.

Before I get into that topic, let's talk highs Monday afternoon. All around the Midwest, readings held in the upper 60s to low 70s, a far cry from a week ago when it was 93 at the NWS in the Quad Cities with a heat index of 108. In fact, with a low there of 49 Monday morning, temperatures had cooled 44 degrees over that period. Figure in the heat index, and Monday felt 59 degrees cooler. That's what I call a change, a welcome one at that!

Here's a look at Monday's highs, showing the extent of the cool air mass.

In Dubuque, it never reached 70 with a high of 69. Going back 153 years, only 1.49% of August days per year have fallen below the threshold of 70 degrees. The day most likely to see a sub-70 high over that 153-year period is August 27th with 15 occurrences.

Overnight, clear skies, dry air, and light winds beneath a sprawling high pressure, allowed stout radiational cooling. Around daybreak, readings well into the 40s should be widespread. The 3k NAM shows lows of 44 to 49. Notice how the high resolution aspect of the model shows the density of the cold air by depicting the coldest readings (in light blue), where it drains into the valleys with minimal wind to mix it out. It's quite possible that some of the typical cold spots in valley locations may dip as low as 42 thanks to this process.

The 12K NAM, the little cousin of the 3K NAM, shows a similar solution, but with less definition due to its lower resolution.

At this point, there is strong evidence Tuesday's lows will give existing records a run for their money. However, current thinking is that most areas should be a notch above what's needed to reach record-breaking thresholds.

Here are the benchmarks necessary for records Tuesday morning.

Burlington........46, 1910

Cedar Rapids...41, 1934

Dubuque...........44, 1964

Moline...............45, 1934

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STEADY AS SHE GOES...

Following the frisky start to Tuesday, abundant sunshine and dry air is expected to produce a nice temperature recovery. Highs in the upper 60s to low 70s are anticipated, with less in the way of wind. It's going to be a fine afternoon.

Tuesday night temperatures will take a quick downward turn after sunset. However, some late night clouds ahead of a weak front may save us from a similar fate as Monday night. Upper 40s to low 50s seem a more likely solution. Still, that's quite crisp, even for late August.

Wednesday, an upper air disturbance will approach from the NW. It will be starved for moisture, but there could be enough forcing and warm air advection for a few showers or isolated thundershowers in the afternoon or evening. The potential seems to be focused on the area north of I-80, especially HWY 30 north. Much like a winter clipper, a narrow band of heavier rain could fall where the most concentrated lift occurs. Up to 1/4 inch of rain is possible where this sets up. Otherwise, amounts will taper off significant on either side of the rain swath. Here's what models are currently suggesting for potential rain totals.

The EURO

The GF

The 3K NAM

Temperatures Wednesday will be warmer but will be hindered some by clouds, particularly in the north where readings may struggle to reach 70. The south without the rain threat and less in the way of clouds could pop back into the upper 70s.

Thursday, a cold front associated with the system sweeps southward. There appears to be enough forcing along the front to generate at least widely scattered showers and periods of clouds. The north could even get into some post frontal showers late in the day, due largely to instability driven by cooler air aloft in northeasterly flow. This will likely be the warmest day of the week and upcoming weekend, with highs of 75 to 80.

After that, Great Lakes ridging takes over with a strong high pressure parked over Wisconsin Saturday. That will reinforce the cool air with E/NE winds delivering a new round of cool dry air. That keeps the weekend nice and comfortable. It also forces any respectable moisture well to the west and south, where the active storm track will reside. That keeps us high and dry through Sunday.

The EURO shows this for temperatures in the Quad Cities through the upcoming weekend.

For my money, that's the way to end the month of August and meteorological summer! Roll weather...TS

P.S. Thanks to so many of you who expressed your condolences at the passing of my mother. My family appreciates your thoughts and prayers! Also, a big thanks to Nick Stewart, who managed the posts here last week while I attended to the funeral.