Compton, Illinois Weather Forecast Discussion

951
FXUS63 KLOT 010526
AFDLOT
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1226 AM CDT Wed Oct 1 2025
.KEY MESSAGES...
- Dry and unseasonably warm daytime conditions through the
  weekend.
&&
.UPDATE...
Issued at 856 PM CDT Tue Sep 30 2025
No significant updates to forecast through Wednesday morning.
Forecast area remains within the southwestern periphery of a
sprawling area of surface high pressure centered near James Bay
Ontario this evening. 00Z upper air analysis depicted a 5880
meter 500 mb mid-level high located right over the forecast
area, maintaining subsidence mild and quiet weather conditions.
Only question of note is with the potential for redevelopment
of patchy fog late tonight/early Wednesday, given surface dew
point temperatures in the lower 60s downwind of Lake Michigan
across northeast IL and northwest IN. However, model guidance
continues to indicate increasing easterly flow just above the
boundary layer (20+ kts around 975-950 mb) in response to a
mid-level short wave lifting across MN. This breezy flow just
off the surface should aid in mixing out moisture at the top of
the boundary layer, which along with some increasing high cirrus
clouds spilling into the ridge from the west should be less
supportive of any significant fog development overnight.
Advection of drier air from IN (mid-40s dew points there
currently) should also help to limit fog potential across our
southeast.
Did bump overnight lows up a degree or two in some spots and
made a few tweaks to our dew point trends, but otherwise the
going forecast appears to be in fine shape and no significant
changes are needed.
Ratzer
&&
.DISCUSSION...
Issued at 150 PM CDT Tue Sep 30 2025
An upper level ridge axis remains over the western Great Lakes
this afternoon. Southerly winds on the west side of the ridge
is pulling moisture from the Gulf northward for an impressive
cloud shield spanning the eastern Great Plains. A shortwave
trough over the Colorado front range will move northeastward
tonight and Wednesday. The trough will weaken and phase with the
longer wave pattern aloft, but it will help nudge the ridge axis
southeastward toward the Ohio River basin. Cloud cover is
expected to increase as the trough moves closer. Winds will
slowly become more southeasterly on Wednesday before switching
to the southwest into Thursday. Temperatures will remain in the
80s south of Interstate 80 tomorrow, but the southeasterly
winds are expected to keep far northeastern Illinois in the
70s.
Wide spread 80s return on Thursday. An upper level ridge will
try to build back over the area for high pressure to grow once
again. Temperatures on Friday and Saturday will increase back
into the mid to upper 80s and with southwest winds, even the
city of Chicago will be in the low to mid 80s. With finer fuels
being dry, there is a limited risk for fire weather concerns
toward the end of the week. Luckily the winds should be light
enough through the work week, but with the gradient flow
increasing over the weekend it is possible forecasted wind
gusts are being underrepresented in models which may increase
the fire danger, particularly for more interior locations away
from Chicago.
Models are still suggesting an upper level trough will move over
the Great Plains early next week which will send a cold front
toward the area increasing precip chances with it. However,
models are still not showing great agreement in the overall
pattern. For now, there was no need to change the PoPs that the
NBM provided knowing the lower confidence in timing. The set up
does not look conducive for severe weather and cool air
advection behind the front should knock temperatures back down
to more seasonable conditions by the middle of next week.
DK
&&
.AVIATION /06Z TAFS THROUGH 12Z THURSDAY/...
Issued at 1226 AM CDT Wed Oct 1 2025
There are no aviation weather concerns for the 06Z TAF period.
Easterlies 5 to occasionally near 10 kt overnight will pick up
closer to 10 kt by mid-morning Wednesday. Expect VFR through the
period.
Doom
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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NWS LOT Office Area Forecast Discussion