summerrules

Actually wasn’t too far off the mark here with widespread 90s across the region. Just a tad too hot in some places. Meanwhile, the GFS had temps in the 70s and 80s for much of the region (even 60s in Wisconsin LOL) at the same forecast range and, ironically, had parts of South Dakota in the upper 100s. So no, this was not a “win” for the GFS. Sorry.

5th consecutive day with temps in the 90s in Chicago today, despite the smoke, showers, lake breezes, etc. It's been over four years since ORD has seen a stretch this long, and in a Nino summer, no less LOL. Not too shabby if you ask me.

Both models handled it poorly, just in different ways, so not really. That said, if you live in the central US and don't enjoy the heat, you'd better hope the 18z GFS is way off in the long range.

Had an AQI over 800 earlier, and it's still terrible. The moment I stepped outside, I could feel it in my eyes and lungs. Lake breezes are usually a good thing this time of year, but today they just pulled more smoke into the area, leading to the worst AQI the Chicago metro has ever recorded. Still managed lower 90s despite the smoke and onshore wind tho.

HRRR already has ORD at 97 by 18z Tuesday, so 100 is definitely in play. Not sure why LOT is only going with 94, that seems way too low. With warmer thermals and lower DPs promoting better mixing, I'd be shocked if we don't beat the early July heatwave. TWC's 99° forecast for ORD seems much closer to reality.

or not

AIFS-ENS has had an excellent performance this summer and is much more in line with the EPS. Just saying.

The GFS is a clear outlier for that time period compared to every other model. Toss it.

The ridge has been trending significantly farther east over the past several runs, (just like the previous one which set records in the East). If that trend continues, it could prolong the heat in this region. I'd also be surprised to see a ridge that strong get squashed that easily if the 600 dm heights verify.

one member gets it to near 4.5 c. Again, what is this going to do to our baseline climate? This is legit concerning imo.

The 1930s summers were notably hotter overall than the 1950s or (any individual year before or after) in Des Moines (and The Plains) from what I'm seeing. Des Moines' all-time record high of 110°F was set during the Dust Bowl, and many of its most extreme heat records also date from that period. You can argue that the drought alone would have produced a hot summer, but it's difficult to refute the evidence that land degradation intensified the heat. Removing native grasslands and exposing dry, bare soil reduced evapotranspiration and soil moisture, allowing much more incoming solar energy to go directly into heating the surface and lower atmosphere instead of evaporating water. That creates a positive feedback where hotter temperatures dry the soil even further, leading to even more heating. Modern climate modeling studies have shown this feedback substantially amplified the Dust Bowl heat beyond what drought alone would have produced. We also haven't seen anything approaching the persistence and spatial extent of the 1930s heat in the central U.S. since then. Even 2012, despite being an exceptional heat and drought year, wasn't on the same level over the 30s summers as a whole, let alone just July. As for the bolded, not sure if that's true. The 2020s thus far has averaged hotter for max temps compared to the 50s in The Heartland during summer.

Seems to be trending east too, just like this latest ridge…

I understand the argument you're making, and I agree latitude was certainly a factor and it wasn’t just the eastward trend. I should have been more specific, so I’ll just say that the eastward trend AND the slight weakening/flattening of the ridge itself played a major role in our outcome. If the ridge had verified closer to 597 dm like some of the models were showing earlier and remained farther west, as several earlier runs depicted, I think we almost certainly would have squeezed out a few more days in the 90s at least. Maybe we don't end up with the 10–11 day stretch of 95°+ that some guidance was hinting at, but at minimum week-long run of 90s with a couple shots at 100° seems entirely plausible in that specific scenario. Boston isn’t super comparable in this case tbh. Despite having a significantly cooler climatology than we do, they still managed a couple of 100° days and challenged records without even sitting beneath the core of the 594 dm ridge, which arguably makes what they experienced even more impressive. To me, that highlights just how important the ridge's placement and strength were. Had the ridge axis ended up even 100–200 miles farther west we likely would have remained capped and hotter for longer, with stronger subsidence and warmer low-level thicknesses sticking around for longer, resulting in a longer stretch of 90s and a much better chance of reaching 100° (assuming the same 594 dm strength, if it were like 600 dm who knows what would’ve happened). Either way, I'm not going to argue it any further, it was a respectable stretch of heat and humidity around here, but in the end it wasn't especially memorable. Weather can get extremely fickle at times, and even just slight changes in the upper levels can have huge impacts on our sensible weather. We may even see a more noteworthy heat event around mid-month if the Euro is onto something, but that's way out there.

The removal of native grasslands combined with poor farming practices directly influenced the circulation pattern of the entire Northern Hemisphere, and as a result intensified the extreme heat during the 1930s by reducing soil moisture and increasing surface heating, leading to the formation of The Dust Bowl. Going to take a long time to beat some of those records set back in that era, even as the climate warms. https://news.ucar.edu/132872/1930s-dust-bowl-affected-extreme-heat-around-northern-hemisphere