Saunemin, Illinois Weather Forecast Discussion

121
FXUS63 KLOT 050735
AFDLOT
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
235 AM CDT Fri Sep 5 2025
.KEY MESSAGES...
- Gusty southwest winds early this morning will turn westerly
  after sunrise, with sporadic gusts to 40 mph possible through
  the morning.
- A series of storm systems moving through the northern Great
  Lakes will reinforce fall-like conditions through the
  weekend.
- Generally dry and gradually warming weather is expected next
  week.
&&
.DISCUSSION...
Issued at 235 AM CDT Fri Sep 5 2025
Through Saturday:
The southern extent of a mid-level trough axis extending from a
low over far northern Wisconsin will exit to the south and east
by sunrise. WAA within a dry low to mid-level profile greatly
limited precip coverage early this morning, with isolated
sprinkles already shifting eastward over Lake Michigan.
A 50+ knot LLJ ahead of an incoming cold front is currently
crossing northern Illinois per recent KLOT VWP data. Sporadic
associated surface gusts up to around 20 knots have been
observed so far. Would anticipate that stronger gusts will
remain subdued with the nocturnal inversion through sunrise, but
strong CAA and ensuing daytime heating after sunrise as well as
a period of 2-4mb/3hr pressure rises should yield a quick
increase in surface gusts shortly after sunrise. WNW gusts up to
40 mph are possible this morning before the low-level gradient
flow weakens with time this afternoon. The strong WNW winds will
also promote building waves and resultant dangerous swim
conditions for the Porter County shore through this afternoon.
The mid-level trough crossing the area early this morning will
ultimately shear out across central Illinois by this afternoon
as a 90 knot mid-level jet exits to the east. While there is
some forcing present today by way of the right entrance of the
jet, modest mid-level moisture advection from the WSW may
arrive too late to interact with the better forcing. With
decently dry sub-cloud layer below 10kft today, would expect any
precip across far southern portions of the CWA to be limited to
some sprinkles at most.
Otherwise, expect an unseasonably cool period to persist into
the weekend with daytime highs in the mid 60s today and upper
60s on Saturday, and nighttime lows tonight in the low 40s for
interior northern Illinois to around 50 near Lake Michigan.
Kluber
Saturday Night through Thursday:
Upper level low pressure spinning over Hudson bay and northern
Quebec is progged to gradually fill and drift northeast late
this weekend into early next week, with the larger scale long-
wave trough axis shifting east of the forecast area. This will
allow surface high pressure to spread east across the forecast
area Sunday into Monday, maintaining dry weather characterized
by cool nights (lows in the 40s both Saturday and Sunday night)
and gradually warming daytime temperatures in the upper 60s and
the low-mid 70s Sunday into Monday.
Farther to our west, ensembles continue to depict a cut-off low
slowly drifting from the eastern Pacific into the West Coast
and downstream ridging and warm advection gradually spreading
toward the central CONUS into mid-week. Downstream of the ridge
axis, ensemble guidance does depict a mid-level short wave
tracking across the upper Midwest/northern Great Lakes region
Tuesday into early Wednesday, with a corresponding axis of warm
advection and modest moisture return mainly north and northwest
of the immediate forecast area from IA into MN/WI. Blended NBM
guidance does swipe far northwest and northern IL with some
slight (

NWS LOT Office Area Forecast Discussion