367
FXUS63 KDVN 160949 CCA
AFDDVN

Area Forecast Discussion...CORRECTED
National Weather Service Quad Cities IA IL
449 AM CDT Thu Jul 16 2026

.KEY MESSAGES...

- Hot and humid conditions through Saturday, with afternoon
  heat indices in the mid 90s to around 100F.

- Isolated to scattered showers and storms through Saturday
  largely diurnally driven with Friday PM favored for the better
  coverage (30-50%), although Saturday coverage may rival in the
  late afternoon/evening along a cool front.

- Wildfire smoke will be found in our skies into the weekend.
  This looks to be mostly aloft resulting in hazy skies at
  times, however thicker concentrations near surface and
  unhealthy air quality is possible across parts of northern
  Illinois through tonight.

- Pattern change next week will bring periodic storm chances and
  cooler temperatures.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 300 AM CDT Thu Jul 16 2026

Light winds, abundant low level moisture and radiational cooling
will bring the potential for some fog again early this morning,
mainly in the river valleys and nearby areas. This should
dissipate by around 8 AM.

There are signs of change in this dry and hot pattern, and
initially this begins with the return of shower and storm
chances today. These chances are low (15-30%) and a result of
weak forcing with a lake enhanced front possibly washing out
near the U.S. Hwy 20 to Hwy 30 corridor in IL today. While
a moisture-rich environment (PWAT values 1.8 to 2 inches) and
weak forcing from a remnant upper low encroach from the south.

The weak backdoor front could aid in getting the wildfire smoke
closer to the surface into parts of northern Illinois, which
could contribute to unhealthy air quality and an Air Quality
Alert remains in effect for Jo Daviess and Stephenson counties
through this evening. The HRRR shows high near surface smoke
concentrations meandering into NW Illinois at times today and
again later tonight through Friday. With this in mind, folks
in N Illinois and nearby areas of eastern Iowa are encouraged to
monitor air quality, particularly if you`re sensitive to air
pollution and plan to be outdoors. Monitor for any changes to
Air Quality Alerts.

Otherwise, today is another day of similar heat and humidity
with highs mainly around 90 to the lower 90s and PM peak
heat index readings from the mid 90s to around 100F. Some
localized higher readings over 100F will be possible.

Tonight, any isolated shower or storms should dissipate with the
loss of heating leaving behind another warm, muggy night with
lows around 70 to the lower 70s.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 300 AM CDT Thu Jul 16 2026

Shower and storm chances will increase a bit (20-50%) on Friday
as the moisture-rich airmass (PWATs 1.8 to 2 inches) overspreads
the area while weak forcing lingers attendant to the remnant
upper low. The peak coverage is expected in the afternoon with
the activity gradually waning with the loss of heating Friday
night. Modest instability could support a couple of stronger
storms with potential for gusty winds with precip loading or
cell collapse, but limited vertical wind shear should keep the
threat for severe very low. Slow storm motions and large warm
cloud layer depths supporting high rainfall rates of 1-2"/hr will
lead to the potential for localized heavy rain. The scattered
convection could alleviate the heat for some, otherwise it will
be another day of highs around 90 or lower 90s and with some
higher dew points the potential could exist for more widespread
heat index readings around 100 or possibly a little higher,
although clouds and convection will play a factor for just how
hot it gets.

Saturday, the signal is increasing for a cold front arriving in
the late afternoon and evening accompanied by storm chances.
PoPs are currently 20-30%, greatest in our eastern counties, but
given the signal for a bit more frontal convergence and the
lingering very moist airmass, I believe the PoPs may need to get
pushed up more (30-50%) coverage area-wide. Stronger deep layer
shear aided by a strengthening Great Lakes jet may foster the
potential for at least isolated severe storms with damaging winds
the primary threat. Currently the stronger shear is east of the
Mississippi and that is the area where the Storm Prediction Center
has placed a Level 1 out of 5, or Marginal risk for severe weather
Saturday PM. Similar to Friday, with the high moisture content
heat index readings could be more widespread around 100 or a bit
higher.

The front will pass through Saturday night and high pressure will
bring some slight cooling for Sunday with highs mainly in the
mid to upper 80s, with a few areas southwest still around 90.

The pattern is set to undergo a change toward broad eastern
troughing and western ridging over the weekend into next week.
A series of shortwaves or ridge riders on the edge of the
"ring of fire" out west should result in periodic storm chances.
Can`t rule out some severe threat at times in the northwest
flow aloft, but plenty of uncertainties in timing/strength/
location of these waves at this range. What is of higher
confidence is a return to cooler/seasonable temperatures
next week with the Climate Prediction Center (CPC) latest 6-10 day
outlook showing some signal (30-40%) for leaning below normal
July 21-25.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1210 AM CDT Thu Jul 16 2026

Predominantly VFR conditions expected through the period with
light and variable winds. Patchy to areas of valley fog will
be possible once again around sunrise, with variable visibility
from LIFR to MVFR possible. Confidence is low on the potential
and coverage. I have trimmed back fog mention at CID and MLI
based on lack of fog last night and dew point depressions still
around 4-5 degrees, and left MVFR visibility mention at DBQ and
BRL where spreads are lower. Diurnal cumulus development with
scattered to perhaps a few broken periods is expected Thursday
PM. Can`t rule out isolated PM convection, particularly near
DBQ being in closer proximity to a weak backdoor cool front and
BRL being closer to a high PWAT airmass and weak forcing from a
weakening low, but probabilities (<20%) are too low for mention.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...Air Quality Alert until midnight CDT tonight for ILZ001-002.
MO...None.

&&

$$

SHORT TERM...05
LONG TERM...05
AVIATION...05