806
FXUS63 KILX 041050
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
550 AM CDT Fri Jul 4 2025

.KEY MESSAGES...

- Mostly dry conditions will prevail through Saturday morning
  across central and southeast IL. Isolated showers and
  thunderstorms are possible west of the IL river during mid and
  late Saturday afternoon.

- Hot and humid conditions are expected during this 4th of July
  holiday weekend, with highs in the lower 90s and afternoon heat
  indices in the mid 90s to near 100 degrees.

- A better chance of showers and thunderstorms returns Saturday
  night through Monday (30-50% chance) as a cold front slowly
  moves through later this weekend. Locally heavy rainfall,
  lightning and  a few strong wind gusts are possible.

&&

.DISCUSSION...
Issued at 345 AM CDT Fri Jul 4 2025

Radar mosaic shows convection over southern and western portions
of WI into far northeast IL north of Chicago and tracking
southeast, associated with a warm frontal boundary. Clouds
associated with this convective system are along and north of I-80
while patches of mid/high clouds were over from I-72 south.
Patchy fog over southern IL with a pocket of dense fog at Mt
Vernon. Added patchy fog to southeast IL until around 8 am. Weak
1018-1020 mb high pressure was over the eastern Great Lakes and
eastern Ohio river valley and ridging back into the mid MS river
valley. A cold front was over central MT into far nw ND. Aloft a
590-592 dm 500 mb high was over the Eastern Plains and is
projected to build over IL during today as 500 mb heights rise
above 591 dm.

Subtropical ridge to bring hot and humid conditions to the area
today with highs in the lower 90s and dewpoints in the mid 60s to
near 70F, with heat indices (feels like temperatures) reaching
mid to upper 90s this afternoon. Partly to mostly sunny skies
today with some passing high clouds along with scattered cumulus
clouds developing late morning and afternoon. Fairly light winds
again today with nearby high pressure ridge to our east, with
south winds generally less than 10 mph. Fair wx continues tonight
and should be a good viewing of fireworks though on the warm and
muggy side with 9 pm temps in the lower 80s and upper 70s by 10
pm.

A 591-592 dm 500 mb ridge still over central and southeast IL on
Saturday to bring another hot and humid day, and keeping much of
CWA dry. Though a cold front moving se into central parts of WI
and Iowa by late Sat afternoon to have isolated convection
possible during mid/late Sat afternoon west of the IL river in
more unstable airmass. Highs Sat in the lower 90s with afternoon
heat indices in the mid 90s to near 100F. Cold front projected to
track se into nw IL by dawn Sunday and slowly move into heart of
central IL Sunday night and into southeast IL Monday. Will see
increasing chances of convection over nw half of CWA during Sat
night and into rest of CWA by Sunday afternoon/Sunday night.
SPC does not have CWA in any severe wx outlooks through Monday
though can not rule out a few stronger cells with gusty winds and
heavy rains and lightning over IL river valley late Sat afternoon
and evening and over rest of area Sunday afternoon/evening. PW
values could top 2 inches with tropical air mass in place this
weekend into Monday. WPC has marginal risk of excessive rainfall
Sunday afternoon/Sunday night over much of area and over southeast
IL on Monday. Flash flood guidance values are running fairly high,
with 1.75-2.25 inches/1 hr, 2-3 inches/3 hr and 3-4 inches/6 hr.
Highs Sunday in the mid to upper 80s central IL and lower 90s in
southeast IL. Heat indices Sunday afternoon in the mid to upper
90s with southeast IL near 100F. Highs Monday in the mid to upper
80s and heat indices 90-95F Mon afternoon. Consensus of models
show drier wx returning Monday night into Tue morning, though
could be isolated convection southeast IL Mon evening which is
closer to front moving over southern IL and northern KY.

Strong mid/upper level ridge builds over the Rockies during next
week with weak upper level trof over the Eastern States. More
unsettled wx pattern to return to the area during mid and later
part of next work week with daily chances of showers and
thunderstorms from Tue afternoon on especially on Wed as another
front moves southward into IL. Heavy rains again will be a threat
in tropical air mass in place. Very warm and humid Tue with highs
in the upper 80s to near 90F and afternoon heat indices in the
mid 90s. Seasonable highs in the mid to upper 80s Wed-Friday with
humid conditions lingering with dewpoints in the mid 60s to lower
70s.

07

&&

.AVIATION...  (For the 12z TAFs through 12z Saturday Morning)
Issued at 550 AM CDT Fri Jul 4 2025

VFR conditions expected through tonight, with mainly high clouds
from convective debris, though a few clouds near 5000 feet begin
to develop before midday. South winds will increase a bit,
windiest west of KBMI-KSPI, though remaining below 10 knots.

Geelhart

&&

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

$$