894
FXUS63 KILX 270458
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1158 PM CDT Sun May 26 2024

.KEY MESSAGES...

- Another round of stronger storms are possible this evening for
  areas south of I-72. Discrete cells with the threat of large
  hail and isolated tornadoes are initially forecast before
  becoming a line of thunderstorms, with hail and damaging winds
  as the hazards.

- Localized heavy rain and flooding for areas near and south of
  I-70 as storms, bringing high precipitation amounts, pass
  through this evening.

- The weather calms down after tonight, providing us a benign week
  of weather. The next chance (30-40%) of showers and
  thunderstorms arrives Friday night into Saturday.

&&

.UPDATE...
Issued at 859 PM CDT Sun May 26 2024

A QLCS/linear thunderstorm system continues eastward along/south
of I-70 this evening, generating reports of wind damage and large
hail, but so far no confirmed tornadoes this far north. However,
a severe thunderstorm watch continues north of I-70 and a tornado
watch south of I-70. This feature should exit southeast IL into
Indiana by 10 PM. The cold front associated with this system
appears to be roughly along the Illinois River as of 830 PM,
however subsidence and increasing CIN behind the QLCS should
eliminate the severe weather threat. Overnight, the front will
continue to traverse the central IL forecast area, exiting the
area by around sunrise. Overnight, a few more showers and
thunderstorms could be triggered by the front, while winds will
switch to northwesterly and trigger some cooler temperatures with
lows in the mid 50s to lower 60s south of I-70. Updates have been
sent for trends in precipitation coverage this evening, and a
couple degrees off of lows for tonight.

37

&&

.DISCUSSION...
Issued at 233 PM CDT Sun May 26 2024

The next round of storms is possible this evening, mainly near and
south of I-72. There is some uncertainty whether this round will
make far enough north to be in the CWA or not but the newest HRRR
and ARW show it just south of I-72. These are likely to be supercell
structured with a large hail and tornado risk early in the event
(21z-00z). Then will merge into a more linear form as it exits
southeastern Illinois, posing more of a hail and damaging wind risk.
The HRRR 12z soundings show STP of 1, SHIP of 2.1, midlevel lapse
rates of ~8 C/km, and PWATs of 1.5-1.9 inches for this evening. We
kept the Flood Watch for south of I-70 because of the higher PWATs,
and the potential for training cells.

After this evening, the weather will clear out. Memorial Day will be
nice and dry with highs in the low to mid 70s. There could be some
breezy winds at times, particularly late in the day. From the 12z
HREF, there is a 50-60% chance of wind gusts greater than 30 mph
in the late afternoon into the evening hours, then calming down by
the overnight hours.

Temperatures through the extended forecast will gradually warm up by
next weekend. Low to mid 70s for highs through Thursday, then
reaching the upper 70s to low 80s. The next significant chance for
precipitation comes Friday night into Saturday, with 30-40% chance
of showers and thunderstorms.

Copple

&&

.AVIATION...  (For the 06z TAFs through 06z Monday Night)
Issued at 1158 PM CDT Sun May 26 2024

A cold front will continue to push through the central IL
terminals for the first few hours of the forecast period, with
little or no chance for any precipitation developing along the
front at this point. However, an area of MVFR cigs is poised just
upstream, and is expected to move over most of the area overnight.
Lifting and dissipation of this cloud cover should result in VFR
conditions by 13Z-16Z. Another shortwave will arrive in the
afternoon, resulting in widely scattered showers and thunderstorms
mainly near and north of the I-74 corridor until around 04Z. Winds
NW around 10 by 06Z-11Z, increasing to 12-16 kts with gusts 20-25
kts by 16Z. Winds decreasing after 01Z.

37

&&

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

$$