Troy Grove, Illinois Weather Forecast Discussion

791
FXUS63 KLOT 241050
AFDLOT
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
550 AM CDT Wed Sep 24 2025
.KEY MESSAGES...
- Intermittent showers mainly well south of I-80 lingers
  through Wednesday evening.
- Chances for lake effect showers overnight and into Thursday
  morning closer to the lake.
- Drier conditions to end the week as temperatures inch back
  into the 80s over the weekend.
&&
.DISCUSSION...
Issued at 242 AM CDT Wed Sep 24 2025
Water vapor satellite imagery this morning shows a pair for vort
lobes spinning over Michigan`s Upper Peninsula and southern
Wisconsin, while an upper level short wave sinks down the Great
Plains. Scattered showers continue near and south of US-24
closer to the better forcing under a broad upper level jet
streak. Meanwhile, isolated showers have developed from
Princeton to Joliet along a mid level convergence axis. With
instability being so shallow (and capped) thunder is not
expected and these showers should gradually peter out over the
next couple hours. Broad upper level clouds will remain over the
area through day break keeping minimum temperatures in the low
60s south of I-88. However, breaks in the cloud cover are
forming over Wisconsin that are creeping into northern Illinois
as that vort lobe slinks southward which may help the northern
part of the forecast area start Wednesday out in the upper 50s.
The previously mentioned short wave will continue to phase with
the upper level low over the Great Lakes and swing eastward
through the day. As it does, an upper level jet streak will
intensify to around 100 knots over southeast Missouri to
northwest Ohio. Mid 60s dew points should remain through the
day southeast of I-55. As localized vort maxes pass over the
area, isolated to scattered showers are possible through the day
Wednesday. However, the better forcing is expected to be south
and east of the forecast area. Poor lapse rates will probably
keep the thunder threat to a minimum, so it was currently left
out of the forecast.
Winds will be out of the northeast and become more northerly
through the day. Winds will be breezy closer to the lakeshore
where gusts around 20 mph are expected this morning and into the
afternoon. Winds will diminish and become more northerly this
evening, if not slightly northwesterly. An additional slug of
mid level moisture will move down the lake this evening, with a
cooler air mass near 10C at 850 mb. Temperatures over the lake
are solidly in the 60s and with good fetch and decent sfc-850 mb
temperature gradient, there is a chance for lake effect showers
to develop along the lake shore, particularly Wednesday night
into Thursday morning.
The upper level trough finally starts to move east Thursday and
Friday and settling over the southeast. Meanwhile, an upper
level ridge is expected to build over the Plains and shift into
the Western Great Lakes. Surface high pressure and a drier air
mass will slowly spread over the area to end the week to
finally remove precipitation mentions from the forecast.
Temperatures will slowly creep up into the weekend. Low 80s are
possible for the western portion of the forecast area on
Friday, with better chances for widespread 80s over the weekend.
Current ensemble models are suggesting that that the ridge may
develop into an upper level high over the Great Lakes. And with
a low over the southeast, that could develop yet another pseudo-
Rex block pattern over the area - which would keep warmer temps
and drier conditions through early next week.
DK
&&
.AVIATION /12Z TAFS THROUGH 18Z THURSDAY/...
Issued at 550 AM CDT Wed Sep 24 2025
MVFR cigs will occur at the terminals this morning, but bases
will gradually lift to VFR this afternoon (except at GYY),
although the exact timing remains uncertain. Additional MVFR
cigs are possible tonight, but mainly INVOF GYY and the lake--
confidence at ORD/MDW was too low to introduce another mention
at this time. At RFD and DPA: A period of IFR cigs will occur
this morning before cigs also gradually lift.
Can`t entirely rule out the potential for a few lake effect
showers towards midday into the afternoon, but chances are too
low for a mention at this time.
North to northeast winds will prevail today with intermittent
gusts increasing to around 15 to 20 kts later this morning and
afternoon. Winds will then ease and should become north to
northwesterly this evening and overnight. Weakening low-level
flow near and west of the Fox Valley tonight could support
patchy BR/FG development at DPA and RFD.
Carlaw
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Beach Hazards Statement through Thursday morning for ILZ006-
     ILZ103-ILZ104.
IN...Beach Hazards Statement through Thursday afternoon for INZ001-
     INZ002.
LM...Small Craft Advisory until 7 AM CDT Thursday for the IL
     nearshore waters.
Small Craft Advisory from 7 PM this evening to 7 AM CDT
     Thursday for the IN nearshore waters.
&&
$$
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NWS LOT Office Area Forecast Discussion