After brief, potent chill at the end of September with 30s Saturday morning in our northwestern areas with patchy frost, we are now working toward near record warmth as two Pacific hurricanes & two Pacific Coast storms (with Pacific tropical storm/hurricane origins) force chilly trough in the West & hot ridge in the East.
In the meantime, after 80s & sun today, it will be a warm, rather humid night with lows of 65-70. Some storms are possible in the north this evening-overnight.
There is a MARGINAL Risk of severe weather along the Kankakee River for this time period, per the Storm Prediction Center.
I think an isolated severe storm could occur north of U.S. 24, given that fact that we will be on the far southern edge of stronger wind fields & cooler temperatures aloft in that zone.
A few more storms could pop morning to midday a little farther southward in the heart of the area (Greater Lafayette) as the front is forced back south by an upper trough swinging through the Great Lakes area.
By this time, the stronger wind fields & cold temperatures aloft skimming by will move into Ohio, Pennsylvania & Ontario.
Highs Tuesday will vary from 72 in the far north to 84 in the south & around 80 in the Greater Lafayette area.
A few more spotty storms may still pop on the front in the area in the afternoon with heating. Note how the front then moves back northeastward Wednesday night, bathing us in warm, muggy, summery conditions.
This is in response to the Hurricane Rosa remnants & California system digging into the western U.S., but also the persistent southeastern U.S. subtropical ridge spread out from Texas to the Carolinas. The Phase of the MJO (from the Indian Ocean) is only enhancing this pattern of burst of southeastern/eastern U.S. heat & ridging northward.
This all works like a teeter totter. Upper troughiness on one side of the country means upper ridging on the other side (here).
With sunshine & gusty south-southwest winds, highs will run 84-87 Wednesday. The record high in Greater Lafayette data set is 90 set in 1922. The projected high of 86 would make it the warmest October 3 since 2005.
Here are the remnants of Rosa bringing flooding rainfall from Baja to Arizona to Utah, Colorado, even Nevada, while California storms will bring heavy rainfall & storms to southern California, all the way to Nevada, Idaho, Utah & Oregon.
You can see the associated teeter-totter trough/ridge scenario they bring with southeastern ridge a dominant feature, too!
It all spells warmth & wind here with very active weather with flooding rains in many areas of the West, then transferring to the Plains & Upper Midwest. Severe weather will become an issue in the Plains & western Corn Belt Wednesday with all of that warmth.
Look how incredibly active it is in the West, Plains & parts of the Corn Belt Wednesday-Sunday night!
Multiple rounds of severe weather are likely Texas to Wisconsin to as far southeast as our area. An all-out early-season snowstorm to blizzard will develop in the Rockies & then High Plains. Flooding will be widespread from the West to the Plains & parts of the Midwest.
As for our area........
We see the remnants of severe weather pass through Wednesday night with showers/storms lingering in our southern counties Thursday. At this point, no severe weather is expected Wednesday night or Thursday.
Additional rounds of showers/storms are likely Thursday night, Friday, Saturday & Sunday off & on with dry hours in-between as we are bathed in mugginess & warmth.
Severe weather indices show that the bulk of the risk will line up northwest & west of our area (yellow & orange).
However, you can see that some at least MARGINAL Risk creeps in from time to time Thursday night to Sunday night.
Colder weather should follow after 2-5" rainfall October 2-13.