Lockport, Illinois Weather Forecast Discussion

219
FXUS63 KLOT 232041
AFDLOT
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
Issued by National Weather Service Lincoln IL
341 PM CDT Tue Sep 23 2025
.KEY MESSAGES...
- There is a chance for showers and a few embedded storms mainly
  south of I-80 this evening and overnight, but the greatest
  potential for rain is anticipated to focus mainly south of the
  forecast area.
- Intermittent showers may linger across the region Wednesday
  with a chance of lake effect showers Thursday, but a trend
  towards drier conditions is expected through the end of the
  week and upcoming weekend.
&&
.DISCUSSION...
Issued at 341 PM CDT Tue Sep 23 2025
Through Tonight:
Showers and storms continue to generate along a boundary from
Iroquois County IL into Benton County IN. The western extent of
this activity has not been well handled by CAMs, having begun
along a gravity wave this morning. Storm motion is roughly
parallel to the boundary, and with multiple strong cells having
repeatedly moved over the same areas MRMS is estimating
precipitation in the 1-2 inch range from eastern Iroquois
County into Benton County IN.
Given the persistent convection and that some at least local
stabilization has likely taken place, some uncertainty remains
as to how intense and how long these storms continue. With a
short wave trough moving in from the east this evening, it`s
anticipated that the greatest coverage of showers and storms
will be to the south of the forecast area. However, those
to the south of I-80 stand the best chance of seeing additional
rainfall with perhaps some embedded thunderstorms this evening
and overnight.
Meanwhile, a cold front will push through the forecast area this
evening and overnight, bringing north-northeasterly winds
with perhaps some gustiness overnight. These enhanced north
winds may increase wave heights along the lake shore.
NWS ILX
Wednesday through Tuesday:
The upper-low over the Great Lakes is expected to begin to
phase with the shortwave trough ejecting out of the south-
central Plains Wednesday morning. With the associated cold front
forecast to be draped across north-central IL and IN, suspect
any lingering precipitation with these features should be
focused south of I-80 for Wednesday afternoon. Therefore, it
appears that most of the area should start to see drier
conditions but with some continued cloud cover. That said,
breezy northeast winds are expected to persist through Wednesday
with gusts peaking in the 20-25 mph range during the afternoon
hours. These onshore winds will help to build waves at area
beaches resulting in dangerous swimming conditions that look to
persist into Thursday.
The phased trough is expected to begin to move east Wednesday
night into Thursday which will allow drier conditions to fully
return to the area. However, a shortwave disturbance will pivot
around the backside of the trough Thursday morning and interact
with some lingering low-level moisture and convergence near the
lake. Couple this with a few hundred joules of lake induced
CAPE and conditions appear favorable for a period of lake effect
showers and perhaps thunderstorms Thursday morning into the
early afternoon hours. As winds turn more northwesterly Thursday
afternoon the lake effect showers are expected to push east
into northern IN and thus bring an end to rain in our forecast
area. Outside of these showers, temperatures on Wednesday and
Thursday will be the coolest of the week due to aforementioned
north winds. So expect highs these days to only top out in the
lower to mid-70s with overnight lows in the lower 50s.
Heading into Friday, upper ridging will return to the Great
Lakes Friday into early next week which will result in another
period of dry and seasonably warm conditions. While guidance
continues to show a cold front trying to move through late
Saturday into Sunday, the cold air and moisture with this front
look very lacking and thus should allow the dry and warm weather
to prevail. Therefore, expect highs during this period to be in
the upper 70s to lower 80s each afternoon with overnight lows in
the mid-50s. Though, potential for daily lake breezes will
likely keep temperatures cooler along the lakeshore each day.
Yack
&&
.AVIATION /18Z TAFS THROUGH 00Z THURSDAY/...
Issued at 1221 PM CDT Tue Sep 23 2025
Key Aviation Messages for the current TAF period:
- Another round of showers possible this evening overnight
  though better coverage expected to the south in central
  Illinois
- MVFR, and potentially even IFR, cigs expected tonight
Winds turned northeast with a cold front moving south out of
Wisconsin and is being reinforced by a lake breeze. There is a
chance for occasional gusts this afternoon and evening between
15 to 25 knots, but being more isolated in nature it was
left out of the TAF for now. Stratus will move southward
behind the front, increasing the chance for MVFR cigs into
Tuesday evening. Guidance is starting to lean toward IFR cigs
being possible, but confidence is still too low to add it in
the TAF. MVFR cigs and northeast winds are expected to remain
into Wednesday morning. PROB30 for showers later this afternoon
and evening for all sites but KRFD has been included, but best
chances remain south of the forecast areas.
As the front moves southward overnight, models are suggesting
that there will be renewed chances of showers, and maybe
isolated storms, along a convergent axis that develops. The
better chances remain in central Illinois. However, there was
enough model agreement to keep a PROB30 in for KGYY.
NWS Lincoln
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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NWS LOT Office Area Forecast Discussion