237
FXUS63 KDVN 081144
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
644 AM CDT Mon Jun 8 2026

.KEY MESSAGES...

- Rounds of nocturnal and diurnal convection through tonight
  will bring a risk of locally heavy rainfall due to weak winds
  aloft. If storms stall or repeat over the same areas, flash
  flooding is possible.

- Heat and humidity will return around mid-week with
  temperatures in the 90s and heat indices pushing 100 or
  higher. The probability of heat headlines around mid-week is
  33-40 percent.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 137 AM CDT Mon Jun 8 2026

The heavy rain yesterday focused around a weak boundary located near
I-80. Said boundary is still present and runs from near KC75 to near
KGGI. A secondary but much more subtle boundary runs from near KAAA
to near KIKV.

Through sunrise and through Monday, PWATs are progged to be 1.5 to
near 2 inches and winds aloft are still weak. Warm rain processes
should dominate creating very efficient rainfall rates. Storm scale
processes will produce additional boundaries thus raising the
probability that storms may repeat over the same areas and cause
flash flooding.

The 00z REFS LPMM is suggesting the potential for 2.5 to 3+ inches
of rain near the boundary in southeast Iowa and more localized areas
north of I-80. More disturbing and much higher numbers from the REFS
LPMM are showing up this afternoon in northwest Illinois.

Based on this the flash flood watch is being expanded to the entire
area. If storms stall or repeat over the same areas, rainfall rates
of 2 to 3 inches an hour for two or more hours are very possible.

By evening, the upper level low will exit the area and rain will
quickly end from west to east. However, with a weak high building
into the area, winds will turn light overnight. The light winds and
wet ground raises the prospects of fog development. Right now HREF
probabilities for visibilities under 1 mile are 20-30%. The fog
potential will need to be re-evaluated to see if probabilities
increase over the next 12-18 hours.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 137 AM CDT Mon Jun 8 2026

Tuesday through Monday
Assessment...high (>80%) confidence of temperatures well above
normal. Low (20-25%) confidence for rain.

If fog develops Monday night, that will play significantly into how
warm it will get on Tuesday. The model trend of above normal
temperatures through Friday remains solid.

As mentioned yesterday, the highest heat indices are
Tuesday/Wednesday. A strong front is forecast to move through the
area Wednesday night or Thursday that will bring cooler temperatures
for next weekend.

Heat indices Tuesday continue to indicate 95 to 100 but areas south
of I-80 have a 30-40% probability of exceeding 100. On Wednesday the
probability of seeing heat indices of 100+ is now at 50-60%.
Depending upon how rain chances play out, heat headlines may be
needed in the Tuesday/Wednesday time frame.

The model consensus currently has 20-40 percent rain chances mainly
north of I-80 Tuesday night. These chances may push further north if
the heat dome builds quicker into the area. The storms running
around the edge of the heat dome would have the potential to be
severe. The primary severe risk would be damaging winds. SPC does
have a marginal risk for the area, but mainly for Tuesday night.

Wednesday night into Thursday looks interesting.

A stronger front is progged to move through the area that will be
associated with a strong upper level disturbance. Winds in the mid-
levels of the atmosphere are progged to be around 50 knots
indicating organized storms with the potential for severe storms.
CSU ML progs and other ML analog sites have a 30-45% probability of
damaging winds occurring Wednesday/Wednesday night. However, large
hail and tornadoes cannot be fully ruled out. Depending upon the
timing of the front, strong to severe storms may persist into
Thursday.

Wednesday night has the best chances for rain. The current model
consensus has 60-90 percent chances for rain. Outside of Wednesday
night, the model consensus has daily 20-40 percent chances for rain
Friday through Monday.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 634 AM CDT Mon Jun 8 2026

Widespread showers and isolated thunderstorms continue to lift
northward across the area early this morning. Mainly IFR to LIFR
conditions are being reported with brief improvement to MVFR to
VFR in no precipitation. Used tempo groups in the first 4 hours
in areas of higher confidence where showers and storms will
occur and use prob30 after that. IFR conditions are expected
through the day with some improvement after 21 UTC. Widespread
showers and storms are expected through late morning before
showers and storms become more isolated during the afternoon.
Winds are forecast to become light and variable after 00 and
this may lad to fog development across the area with at least MVFR
visibilities possible.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Flood Watch through this evening for IAZ040>042-051>054-
     063>068-076>078-087>089-098-099.
IL...Flood Watch through this evening for ILZ001-002-007-009-
     015>018-024>026-034-035.
MO...Flood Watch through this evening for MOZ009-010.

&&

$$

SHORT TERM...08
LONG TERM...08
AVIATION...Cousins