575
FXUS63 KILX 180442
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1142 PM CDT Mon Jun 17 2024

.KEY MESSAGES...

- Seasonably hot and humid weather will prevail this week. Heat
  index values will peak in the upper 90s to around 100 degrees
  Tuesday afternoon through Saturday afternoon.

- Isolated thunderstorms will be possible from time to time over
  the next few days...with a better chance for thunderstorms
  arriving late Saturday into Sunday.

&&

.UPDATE...
Issued at 730 PM CDT Mon Jun 17 2024

Much of the lingering convection has faded away, with just a few
showers left that are approaching Flora. However, high-res models
continue to hint at some redevelopment after midnight over the
eastern CWA, with a weak upper disturbance lifting out of the
lower Mississippi Valley. The NAM Nest has been most bullish in
this regard, though the HRRR has had a bit of an uptick recently
as well. PoP`s have been refined a bit with timing, and to
increase them to around 30% near/east of I-57 after midnight. A
large part of the forecast area should be mostly cloudy as well,
with plenty of high clouds streaming northeast. Temperatures are
generally on track to drop into the mid 70s once again.

Geelhart

&&

.SHORT TERM...(Tonight through Tuesday Night)
Issued at 307 PM CDT Mon Jun 17 2024

19z/2pm radar imagery shows isolated convection across the KILX
CWA...particularly east of I-57 and west of the Illinois River.
The isolated storms will persist until sunset, followed by dry
conditions from mid-evening through much of the overnight period.
CAMs have consistently been showing renewed convective development
associated with a subtle short-wave trough pivoting northward
from the lower Mississippi River Valley late tonight into early
Tuesday morning. Based on model consensus, it appears most of the
activity will focus along/east of I-57 after 09z/3am. Have included
20-30 PoPs across this area accordingly. After the early morning
showers fade, disorganized diurnal convection will re-develop
within the highly unstable airmass Tuesday afternoon. Areal
coverage will remain quite low, so have only included 20 PoPs at
this time. Lows tonight will only drop into the lower to middle
70s while highs on Tuesday will climb into the lower 90s. Maximum
heat index values will peak in the upper 90s to around 100 degrees
Tuesday afternoon.

Barnes

.LONG TERM...(Wednesday through Next Monday)
Issued at 307 PM CDT Mon Jun 17 2024

Upper high currently centered over the Carolinas will build
southwestward over the next couple of days, cutting off the flow
of deep-layer moisture from the Gulf of Mexico. With this moisture
shunted into Texas and remaining well S/SW of central Illinois,
diurnal storm chances will decrease Wednesday through Friday. Will
need to keep an eye on a weak cold front that will try to drop
southward out of the Northern Plains, but think most of its associated
convection will remain N/NW of the area across Iowa/Wisconsin.
Have confined low chance PoPs to locations along/northwest of the
Illinois River during that period, but think most locations will
remain dry. Main story will be the hot weather as heat index
values routinely peak at around 100 degrees. Hottest days will
likely be Friday/Saturday when air temperatures climb into the
middle and perhaps upper 90s in a few spots and heat index values
reach 100-105 degrees.

As has been advertised by the models for the past several runs, a
significant short-wave trough is expected to traverse the country
and push a cold front into central Illinois this weekend. 12z Jun
17 GFS and ECMWF are in relatively good agreement, showing the
front arriving Saturday night. As a result, have included chance
PoPs (30-50%) Saturday night into Sunday. Once the front departs,
cooler and less humid weather is expected early next week as highs
drop back into the middle to upper 80s by Monday.

Barnes

&&

.AVIATION...  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1142 PM CDT Mon Jun 17 2024

Evening model suite has begun to hint at some potential MVFR
ceilings around KPIA toward sunrise. Upstream satellite imagery
does show some patches of ceilings 1000-2000 across southeast
Missouri advecting northward. Latest HREF guidance shows about a
40% probability of ceilings below 3,000 feet in the 10-15Z time
frame. However, coverage in Missouri doesn`t appear especially
solid quite yet, so will monitor for a couple more hours to see if
a low ceiling is needed. Elsewhere, ceilings may dip to around
5,000 feet for a period around sunrise into mid morning, before
rising once again.

South winds expected to remain fairly breezy through the period,
with frequent gusts 20-25 knots.

Geelhart

&&

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

$$