311
FXUS63 KDVN 270539
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1239 AM CDT Sun Jul 27 2025

...Updated for 06z Aviation...

.KEY MESSAGES...

- Fog tonight, possibly dense along and north of I-80.

- Heat builds back in Sunday through Tuesday, potentially
  dangerous, but there will also be episodes of storms making
  for a challenging temperature forecast and low confidence on
  the spatial extent and magnitude of the heat (day to day
  evaluation needed).

- Pattern change late week to usher in cooler, more seasonable
  and drier conditions.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 212 PM CDT Sat Jul 26 2025

Following early day activity, coverage of showers and storms
has decreased with isolated to widely scattered activity
possible into this evening. No severe weather or new flooding is
expected.

For tonight, a 15-20% chance for showers and non-severe storms
will remain mainly along the Highway 34 corridor. Look for Fog
to develop across much of the area due to surface moisture from
recent rainfall and clearing skies. Models are hitting areas
along and north of I-80 for the greatest coverage and potential
for dense fog. A Dense Fog Advisory may be needed.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 212 PM CDT Sat Jul 26 2025

A ridge builds into the central U.S. Sunday into Tuesday, with
the CWA being on the northeastern periphery, which will allow
for potential for excessive heat and MCS activity.

Sunday looks dry for the most part, with 15-20% chances for
convection along and south of the Highway 34 corridor. With
highs around 90 and dew points in the mid 70s to around 80
(highest south), heat index values are expected to be 100-105
south of I-80. A Heat Advisory has been issued for these
southern areas.

Sunday night into Tuesday will see the greatest heat and MCS
potential. These two hazards may counter each other since any
thunderstorm activity may keep daytime temperatures cooler,
depending on track, timing, and coverage of convection which is
highly uncertain at this time. Any MCS activity, which would
most likely fall in the late night into morning hours both
Sunday night and Monday night, would bring potential for severe
thunderstorm winds and flooding. If convective activity does
not interfere with daytime temperatures, look for highs in the
low to mid 90s. Temperatures combined with dewpoints in the mid
70s to around 80, due in part to transpiration, heat index
values may be oppressive in the 105-110+ range both days. Heat
headlines may be needed as factors become more certain. Again,
confidence in these hazards is low a this time, so check back
for updates.

A pattern change then occurs mid to late week with chances for
showers and cooler conditions Wednesday, followed by cooler and
drier conditions late week. Highs in the 70s to around 80 are
currently expected.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1229 AM CDT Sun Jul 27 2025

Moist ground from recent rainfall, clearing skies and light
winds will lead to fog through 14z Sunday with periods
of LIFR/VLIFR likely at CID and DBQ. Confidence on dense fog
is a bit lower at MLI and BRL due to some patchy cloud cover,
but have periods of LIFR to MVFR. Any fog should dissipate
by mid morning, leaving behind diurnal sct-bkn cumulus with
initial MVFR CIGs lifting to VFR by 18z. An isolated shra/tsra
cannot be ruled out at times, especially south of I-80, but
coverage and confidence on occurrence at a terminal is too low
for any mention.

&&

.HYDROLOGY...
Issued at 200 PM CDT Sat Jul 26 2025

Some local tributary rivers are experiencing flooding from
rainfall that fell last night and this morning, especially in our
southern forecast area. Specifically, we are expecting rapid rises
along the Fox River in Wayland Missouri, where Moderate Flood
Stage is forecast. Rises into Minor Flood Stage are also being
seen along the Des Moines River in St. Francisville Missouri.
These crests are expected to last about 24 to 36 hours before
going back down below flood stage. Isolated-scattered storms can
be seen this afternoon and evening, but are not expected to have
too much more of an impact on the current forecasts out. If this
is to change, we will update accordingly.

Please see the latest Flood Statements and Flood Warnings for
details.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Heat Advisory from 1 PM this afternoon to 9 PM CDT this
     evening for IAZ076>078-087>089-098-099.
IL...Heat Advisory from 1 PM this afternoon to 9 PM CDT this
     evening for ILZ024>026-034-035.
MO...Heat Advisory from 1 PM this afternoon to 9 PM CDT this
     evening for MOZ009-010.

&&

$$

SHORT TERM...NWS
LONG TERM...NWS
AVIATION...McClure
HYDROLOGY...Gunkel