On the last day of September, we are getting our first true taste of what impact El Nino will have on the US. A tropical storm made landfall in Baja California and is being whisked eastward by an unusually powerful subtropical jet. This has brought flooding rains to the desert SW and will absolutely inundate Texas this week. This is a hallmark characteristic of El Nino.

Up here in Chicago, we will also get soaked as that active jet stream jogs northward around a Southeastern US High pressure system. The rain today will mostly be moderate, continuing through sunset. Temps will be cool but humid - 60s. 

The heaviest rain is likely tomorrow afternoon and evening as the main bulk of the storm pushes through the region. Expect local flash flooding as 1-2” is expected. Temps during the day tomorrow will be quite mild - around 70F- and, again, humid. 

We should dry out this week and into next week but temps will remain somewhat warm for this time of year (again a HALLMARK characteristic of El Nino).

I also do truly hate to be the bearer of bad news for those running the Chicago Marathon, but both models are forecasting highs in the mid-70s on October 11. It is still many days away so that could and likely will change, but it does not look like it’s going to be one of those characteristically cool fall days :/ 

Tl;dr - Tropical-fueled rain today and tomorrow, heavy at times. 60s to near 70. Drier Sat into nxt week. Warmer than normal.

Every Weather Text since Jan 10, 2024 is archived at this link