Onarga, Illinois Weather Forecast Discussion

799
FXUS63 KLOT 022328
AFDLOT
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
628 PM CDT Thu Oct 2 2025
.KEY MESSAGES...
- Dry and unseasonably warm daytime conditions to persist
  through the weekend.
- Monitoring an increased fire danger this weekend, but
  primarily on Sunday.
- A much cooler airmass arrives middle to end of next week.
&&
.DISCUSSION...
Issued at 222 PM CDT Thu Oct 2 2025
Our unseasonably mild and dry stretch continues through the
weekend before a cold front brings our next chance of
precipitation early next week, followed by a transition to a
period of more seasonable temperatures.
Summer-like (near record) temperatures are expected again on
Friday, with highs in the mid to upper 80s. For reference, record
high temperatures for Friday the 3rd are 91 and 90 at Chicago and
Rockford, respectively. The only difference from today`s weather
will be the likelihood of a bit more diurnal afternoon Cu
development as a slug of slightly better low-level moisture
shifts overhead. Accordingly, this is expected to set up a partly
cloudy afternoon. Also, still cannot rule out a couple of isolated
light sprinkles from any deeper CU in the afternoon. However,
with these looking to be few and far between we will forgo any
type of mention in the gridded forecast.
Deep mixing and subsidence warming aloft will lead to dry, and
breezy conditions with near record high temperatures in the 80s
through the weekend. The main focus this weekend remains on
dewpoint, RH, and wind trends. Latest guidance trends continue to
suggest that dewpoints will likely mix out more aggressively
compared to Friday, with Sunday currently looking like the driest
of the two days. Afternoon RH values in the 30-40 percent range on
Saturday and then 25-35 percent range on Sunday look pretty
reasonable at this range, with some potential for these to come
down a bit further depending on the degree of mixing. Southerly
wind gusts up to 25 mph are possible Saturday and then about 30 to
perhaps 35 mph on Sunday, strongest north and west of I-55 and
across northwest Illinois within a belt of stronger BL flow. Will
continue to highlight an elevated fire danger both days as a
result, but Sunday obviously is the greater concern at this time.
At this point, it looks like we`ll probably stay shy of Red Flag
conditions.
A strong cold front is still slatted to push through the region
during the Monday-Tuesday timeframe. An initial boundary/pre-
frontal trough/composite outflow will approach the region on
Monday, possibly with an initial batch of showers. Most guidance
indicates temperatures will warm back into the 80s across most of
the area Monday afternoon before the main frontal zone slips
through later on Tuesday. While mid-level lapse rates and
associated instability looks unimpressive ahead of the front
Tuesday afternoon, stronger deep-layer flow will arrive through
the day, and if some muted insolation is realized, it wouldn`t be
totally out of the question for a few stronger thunderstorms ahead
of the surging cold front. A faster FROPA would tend to diminish
this potential. Ascent will continue atop the frontal inversion
into Tuesday night, leading to a chance for lingering anafrontal
showers and perhaps a few thunderstorms before things dry out on
Wednesday.
A much cooler airmass will remain in place through the end of
next week. Low temperatures Thursday morning generally in the
40s are expected, with a chance for a few upper 30s in typical
cool/sheltered spots.
Carlaw/KJB
&&
.AVIATION /00Z TAFS THROUGH 06Z SATURDAY/...
Issued at 628 PM CDT Thu Oct 2 2025
There are no significant forecast concerns this period. A lake
breeze has moved west of ORD/MDW, shifting winds more to the
east/southeast with speeds to 10kt, which will diminish over the
next few hours. Directions will turn more southeasterly this
evening and then turn to the south/southwest overnight. By
mid/late Friday morning, directions should favor southwest with
speeds to 10kts possible. A lake breeze is expected Friday
afternoon but confidence is low for how far inland it may move,
but it may reach ORD/MDW by sunset. If it doesn`t, wind
directions will likely still turn southerly, possibly south/
southeasterly by early Friday evening.
There is a low chance, 10%, for a few showers Friday afternoon
into Friday evening, mainly south of the terminals. cms
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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NWS LOT Office Area Forecast Discussion