155
FXUS63 KILX 011046
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
446 AM CST Sun Nov 1 2026

.KEY MESSAGES...

- Patchy drizzle late tonight into Monday morning may briefly
  reduce surface visibility to under 1 mile across central
  Illinois.

- Strong winds will ramp up midweek, with gusts reaching 20 to
  30 mph Monday and 30 to 40 mph Tuesday.

- A dynamic storm system brings a 50 to 70 percent chance of
  around 1.0 inch of widespread rainfall Tuesday evening, with
  localized amounts up to 2.75 inches.

&&

.DISCUSSION...
Issued at 209 AM CST Sun Nov 1 2026

/Near Term (Today and Tonight)/

Upper-air analysis depicts a split-flow regime over central
Illinois early this morning, with a pair of compact shortwave
troughs lifting across the Upper-Mississippi Valley and another
translating across the Lower Ohio River Valley. Sufficient
synoptic forcing--driven by both dCVA and gentle isentropic
ascent--supports scattered showers into early afternoon.
However, regional mesoscale soundings indicate persistent low-
level dry air. Despite saturation in the 850-700mb layer,
stubborn near- surface dryness will restrict coverage and
intensity. While most locations receive between a trace and a
few hundredths of an inch of precipitation, localized amounts up
to 0.25 inches are possible where low-level dry air is
overcome, consistent with 00z REFS LPMM QPF. Abundant cloud
cover will hold afternoon temperatures in the low- to mid-60s,
keeping forecasts 3-5 degF cooler than NBM guidance.

Showery activity should taper off this evening as subsidence
and weak ridging build in behind the departing shortwaves.
Nevertheless, the period from overnight into Monday remains
favorable for patchy, transient drizzle. This is primarily
driven by warm, moist isentropic ascent lifting poleward across
the Mid-Mississippi Valley Monday morning, augmented by an
embedded shortwave rippling ahead of a deepening low pressure
system over the Nebraska and South Dakota plains. Given the lack
of cloud ice nuclei, measurable rainfall will remain
negligible. The greater impact could be on surface visibility,
which could fall below 1 mile in spots if you believe REFS
guidance.

/Dynamic Midweek Storm System (Monday Night through Wednesday)/

Forecast uncertainty increases by Monday night as the jet
stream buckles over the central U.S., driving multiple mid-level
shortwave troughs southward through midweek. Minor model
discrepancies persist regarding trough phasing and precise
frontal timing, though guidance consensus has converged on a
Tuesday evening cold frontal passage across central Illinois.

As the synoptic low deepens and upper-level energy
consolidates, the surface pressure gradient tightens
significantly. EPS and GEFS mean wind gusts project peak speeds
of 20-30 mph on Monday, increasing to 30-40 mph on Tuesday near
the cold front. This dynamic system will draw mid-70s
temperatures and a rich plume of Gulf moisture northward,
pushing atmospheric precipitable water (PWAT) values near 1.75
inches--approaching the 99th percentile for early November
climatology. NBM Mean 48-hour QPF supports widespread rainfall
totals around 1.0 inch through 6 AM Thursday (50-70% chance),
with high-end 90th percentile forecasts indicating localized
totals between 2.0 and 2.75 inches.

A few severe storms cannot be ruled out Tuesday evening.
Kinematic fields will be robust, characterized by 40-50 kts of
bulk shear. Although model-derived thermodynamics remain modest
(MLCAPE < 150 J/kg), a narrow tongue of 60+ sfc dewpoints is
forecast to surge ahead of the front. Sporadic damaging wind
gusts present the main threat; however, low-level hodographs
exhibit an elongated loop, suggesting a conditional tornado
threat if sufficient low-level instability materializes to
promote stretching.

/Late Week (Thursday through Next Weekend)/

Uncertainty remains regarding how the primary upper low evolves
late in the week. Ensemble guidance (GEFS and EPS) suggests the
low may meander over the Great Lakes through Thursday before
departing Friday. Should this materialize, daily shower chances
will persist through Thursday along the systems slow-moving
deformation axis. Following an abbreviated break in
precipitation on Friday, another frontal system approaches next
weekend, bringing additional rain chances and potentially frosty
temperatures.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 423 AM CST Sun Nov 1 2026

A dry sub-cloud layer will promote continued VFR ceilings
through much of the afternoon while also limiting shower
coverage and intensity. We are therefore only carrying a
mention of VCSH in our TAFs today.

Ceilings will gradually lower throughout the TAF period, with
MVFR conditions spreading from south to north between 20z-01z.
Then, as warm/moist air continues to pile into the region from
the south this evening, patchy drizzle is forecast to develop,
prompting ceilings into the IFR/LIFR range overnight.

Winds will maintain a SE component today, occasionally gusting
near 20 kts this afternoon.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

KEY MESSAGES...MJA
DISCUSSION...MJA
AVIATION...MJA