Lows ran 67-73 this morning, making it one of, if not, the warmest October overnight on record.
Most of the records are back to near 1895. Greater Lafayette records go back to 1879 (Purdue University 1879-1953 & Purdue Ag Farm 1954-present).
Highs today ran 79-88. The hottest weather was pushed just south of here. Highs still reached 93 with peak heat index of 100 just 35 miles to the southwest at the Edgar County Airport near Chrisman, Illinois.
Peak heat index here today was 95 at Covington with Frankfort at a close second with 93.
Surge of cooler air begins to move in tomorrow with highs 69-77 dropping to 62-70 in the late afternoon from north to south (with lots of clouds & breezy conditions from the northeast).
Note how tenacious hot upper ridge hangs on deep in the Southeast as well cool.
What will usher in the cooler regime is a secondary cold front Thursday morning-midday.
A wave of some showers & a few storms will pass with it tonight-Thursday morning. Best potential for rainfall is over the north. Elsewhere, any rainfall will be hit or miss.
A narrow corridor of 1" of rainfall may occur on our far northern fringe.
After 44-48 Thursday night & 59-65 Friday with lots of clouds (& breezy conditions from the northeast), lows Friday night of 39-46 are possible. Low clouds may initially completely clear, but high & mid clouds will increase.
With east to east-southeast wind Saturday, a wave of scattered showers with isolated thunder should pass in the afternoon-evening with 45% coverage (with skies mostly cloudy).
Highs of 62-67 are likely.
A few showers are possible Sunday morning with 47-53, followed by partly to mostly cloudy skies (more sun north) with a north to northeast breeze.
A few showers are possible Monday morning, followed by partly to mostly cloudy skies, northwest winds & highs 58-64.
After 36-42 Monday night, highs on Tuesday (with partly cloudy skies) should run 59-64 with 36-42 Tuesday night.
With sun Wednesday, highs of 65-70 are likely.
So, temperatures will be below normal early next week.
Another cold front & upper trough should approach & pass next Thursday.
It may bring a few spotty showers/storms with strong north winds to 35 mph Thursday night-Friday morning behind it.
Note how strong the Canadian surface high is behind the front.
Pretty widespread frost to freezing is possible next Friday night-Saturday morning & Saturday night-Sunday morning (October 12-13) with lows 31-35.
Front & upper trough look to keep Hurricane in the Bay of Campeche or far southern Gulf away from the U.S. Mexico may see a landfall with lots of rainfall along the Texas to Florida Gulf Coasts from a PRE episode (heavy rainfall that is focused on stalled front ahead or well in advance of a hurricane......the flow around the hurricane will not allow the front to slip southward despite getting a continual push from the north).
After that frost & freezing, a burst of warmth with temperatures to 80s is possible for a bit mid-October.
Storm system may bring heavy snowfall from New Mexico, through Denver, CO & Cheyenne, WY with possible severe weather Iowa to Texas (severe extent/intensity dependent on how much moisture is pulled up into the Plains & Corn Belt, which is tied to how much moisture that hurricane will take away.........................................or if the hurricane remnant moisture gets pulled northeastward into that zone.)
Risk could extend to Missouri & Arkansas.
We will monitor to see if we can get in on some of the severe risk near October 20. Right now, best potential is to our west & southwest. We looks to get weakening band of rain & storms at the moment.
Much cooler weather should follow with a 26-32 freeze & widespread frost shortly after.
Note how upper level winds depict a significant upper ridge in late, late October to early November.
This continues to point to unseasonably warm weather here after that cold spell.
Massive upper ridge flattens by around November 4 with screaming upper jet west to east at +100 mph.
So, looks mostly dry & warm here in the October 28-November 4 period...........until around November 5-6.
At that point, it appears upper trough should dig into the Plains with strong +110 mph upper jet streak.
On a side note, thoughts are that overall Fall color will peak a bit later than normal (more like Halloween time).
I would tend to be around October 24 in the north & November 1 in the far south & more like around October 30 in Tippecanoe County.
Fall color (in some form) may linger later than normal to as late as mid-November given the mildness.
Looks warm enough for surface CAPE to 500 J/kg to southern Canada & Minnesota!
We should get some surface CAPE pooling here & then some deeper moisture from a Pacific hurricane.
This would tend to pool ahead of deepening upper trough.
We may be talking not only heavier rainfall, but also severe risk near November 5-6 & perhaps again November 9-12 period.
We will monitor.
Exact days are hard to impossible, but a general trend between analog data & model ensembles can be laid out.
There still looks like a high probability for below to much-below normal temperatures in the latter half of November.
Single digit & teens lows & minor snows are possible.