632
FXUS63 KILX 031114
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
614 AM CDT Sun May 3 2026

.KEY MESSAGES...

- A couple thunderstorms are forecast over parts of central and
  southeast Illinois this evening into tonight, with the highest
  chances (30-50%) south of a Jacksonville to Robinson line.
  More numerous storms are forecast tomorrow evening into early
  Tuesday morning.

- Each round of storms will carry a level 1 of 5 (marginal)
  risk for severe weather, with locally large hail and damaging
  wind gusts the primary hazards.

&&

.DISCUSSION...
Issued at 150 AM CDT Sun May 3 2026

*** AM SHOWERS, TURNING BREEZY, FEW STORMS LATE TODAY ***

At 145am, RAP mesoanalysis reveals a positively-tilted mid-level
trough extending from the Upper Midwest southwestward into the
Central High Plains. Cloud cover and a few light showers are
accompanying this feature upstream across Minnesota and Wisconsin,
and CAMs suggest these will shift over the local area by mid
morning. The 00z raob is quite dry (PW of 0.29"), so we suspect most
of this rain won`t reach the surface; nonetheless, with CAMs
suggesting the heaviest showers will drop a couple hundredths of
rainfall we felt 15-30% PoPs were warranted. Shortly after this
activity will be a period of gusty southwest winds as the gradient
tightens between the approaching surface low and departing high
pressure. Bufkit soundings suggest sustained speeds and gusts may
briefly approach 25 and 40 mph, respectively, especially between the
IL River Valley and I-57 during the 1-4pm timeframe.

This push of warm air advection (WAA) will bring afternoon
temperatures into the low 70s west of roughly I-55, while afternoon
highs run a bit cooler (mid to upper 60s) east of the I-57 corridor.
During the evening, a mid level disturbance will cool temperatures
aloft and result in 500-1000 J/kg elevated MUCAPE rooted around the
800mb level while providing lift to trigger a couple thunderstorms.
Sustained with a steady supply of moisture via a 40-50 kt LLJ, and
given 45-55 kt deep-layer shear, these storms may become strong
enough to support locally severe hail with a lower but nonzero wind
risk as well. Models haven`t fully agreed on where they`ll set up,
but neighborhood probabilities for >40 dBZ reflectivity from the
High Resolution Ensemble Forecast (HREF) system suggest the highest
confidence (30-50%) will be across areas near and south of a roughly
Jacksonville to Robinson line from 7pm to 1am.

*** CONTINUED STORM CHANCES MONDAY THROUGH TUESDAY NIGHT ***

Though it won`t be quite as breezy as today, WAA will continue
tomorrow, and since the day will start about 10 degrees warmer we
suspect the HRRR and RAP are reasonable in depicting afternoon highs
in the upper 70s to low 80s. Instability is forecast to build during
the day with HREF and REFS (Rapid Ensemble Forecast System) mean
showing over 1000 J/kg SBCAPE by late afternoon. Lack of forcing and
a weak capping inversion should foster dry conditions until moisture
convergence on the nose of the LLJ sparks scattered showers and
storms during the evening. Gusty to locally severe (58+ mph) winds
may accompany the strongest storms, particularly in any bowing
linear segments, though we can`t fully rule out an instance of
severe (1"+) hail. The risk would appear highest north of roughly I-
72/Danville during the 7pm to midnight timeframe, though some risk
may extend as far south as I-70 - roughly the southern bound of
SPC`s level 1 of 5 (marginal) risk.

A cold front will sink southward across the area tomorrow night,
stalling over southern Illinois and serving as a focus for
additional waves of showers and a few thunderstorms through at least
Tuesday night. In fact, Tuesday is setting up to be quite the damp
and gloomy day with cloud cover, nearly continuous showers, and
temperatures in the 50s. The National Blend of Models (NBM) even
suggests there will be a 40-60% (5-15%) chance for more than an inch
(2 inches) of rainfall south of roughly the I-72 corridor. In theory
this shouldn`t fall fast enough to result in hydrological issues,
but given how much rain (up to 5 inches) some of these areas
received last week we will need to keep one eye on this.

*** STAYING COOL WITH LOW PRECIP CHANCES LATE WEEK ***

The parent upper level trough will linger over Ontario late week,
with shortwaves orbiting it and offering the local area with
periodic, low (15-30%) shower chances and shots of chilly Canadian
air through the early part of the weekend. While global models and
their respective ensembles differ in how long it will take for this
upper level trough to retreat to the northeast, NBM`s
probabilistic distribution for daily high temperatures shifts
up each day Thursday through Saturday. For example, the 10th
percentile (90% chance of warmer temperatures) in Lincoln
increases from 56 Thursday to 61 Friday to 66 Saturday.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 615 AM CDT Sun May 3 2026

VFR conditions will prevail at all TAF sites next 24hrs.
Scattered mid clouds with broken high cirrus will move over the
sites this morning, but then lower during the day as an upper
wave moves over the area. Precip is also possible with cigs
around 8kft, so have a PROB30 group for each site for 1-3hrs. A
break will be seen in the afternoon before more showers and
possible storms develop in the south, only affecting SPI and
DEC. This will occur starting at 00z and lasting through the
evening. Cigs with these storms will be around 6kft. Precip will
end around 4z at SPI and DEC and then clouds will scatter out. Winds
will be southwest to westerly through the period. Wind speeds
will be less than 10kts to start, but increase during the day
with gusts pushing 30kts. Gusts will diminish during the
evening.

&&

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

&&

$$

KEY MESSAGES...Bumgardner
DISCUSSION...Bumgardner
AVIATION...Auten