958
FXUS63 KILX 222324
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
624 PM CDT Sun Sep 22 2024

.KEY MESSAGES...

- Off and on showers will continue through Tuesday. Storm total
  rainfall will be greatest along and south of the I-72 corridor
  where 1 to 2 inches will occur.

&&

.SHORT TERM...(Tonight through Monday)
Issued at 314 PM CDT Sun Sep 22 2024

19z/2pm surface analysis shows a cold front between the Illinois
River and the I-55 corridor. Scattered showers are beginning to
re-develop ahead of the boundary...particularly east of I-55.
Think areal coverage will continue to increase over the next
couple of hours, resulting in 60-70 PoPs across the E/SE KILX CWA
through the remainder of the afternoon and into the early evening.
The front will settle southeastward tonight, eventually stalling
just north of the Ohio River overnight. With forcing shifting to
the south and slightly drier air advecting into the region behind
the departing cold front, think early evening showers will come
to an end and mostly dry weather can be anticipated overnight.
Low temperatures will range from the middle 50s northwest of the
Illinois River...to the middle 60s south of I-70.

The front will remain stalled across the Ohio River Valley on
Monday as a short-wave trough evident on latest water vapor
imagery over Colorado approaches from the west. Showers and a few
thunderstorms will develop in the vicinity of the boundary...with
the best rain chances during the day remaining focused south of
I-70. As the wave gets closer and a weak surface low develops and
tracks along the front, increased synoptic lift will bring another
round of light to moderate rain to much of central Illinois Monday
night.

Barnes

.LONG TERM...(Tuesday through Next Sunday)
Issued at 314 PM CDT Sun Sep 22 2024

Showers will be ongoing Tuesday morning, but will shift eastward
and come to an end from west to east during the afternoon. Storm
total rainfall from yesterday through Tuesday will be greatest
along/south of I-72 where amounts of 1 to 2 inches will be common.

After a period of dry weather Tuesday night into Wednesday, the
forecast for later in the period becomes a bit more complex as a
short-wave trough currently over northern Alberta digs southeastward
and cuts off over the Mississippi River Valley by mid to late
week. The exact evolution of this process remains unclear as
synoptic model solutions vary. Another complicating factor will be
the presence of a potential tropical system most models are
forecasting to track northward through the Gulf of Mexico by
Thursday/Friday. This system will likely shunt the upper low N/NW
as it approaches the Gulf Coast...potentially bringing an extended
period of scattered showers to portions of the Midwest Thursday
through the upcoming weekend. Some solutions even suggest tropical
moisture may be entrained by the upper low, although this does not
seem particularly plausible. End result is a low confidence
forecast featuring low chance PoPs for the end of the week into
next weekend.

Barnes

&&

.AVIATION...  (For the 00z TAFs through 00z Monday Evening)
Issued at 624 PM CDT Sun Sep 22 2024

Cold front has reached KCMI, and threat of any thunder appears to
have ended at the TAF sites. Northwest winds up to 10 knots will
become more northerly this evening, then northeast Monday morning.

Area of MVFR ceilings impacting KPIA/KBMI at 23Z will push
southeast behind the front, though the southwest flank of it will
be more scattered. As winds become more northerly, 18Z HREF
ensembles suggest areas near KBMI/KCMI will see a period of IFR
ceilings between about 03-07Z (40-60% chance). Overall, a more
widespread expansion of ceilings just above 1,000 feet will occur
late in the night, likely persisting a good portion of Monday.
However, some improvement to VFR is anticipated at KPIA
potentially as early as 16-18Z.

Geelhart

&&

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

$$