396
FXUS63 KDVN 231104
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
604 AM CDT Thu Jul 23 2026

...12z Aviation Update...

.KEY MESSAGES...

- Heat and humidity returns for the weekend and into next week.
  Heat indices may approach or exceed 100 Sunday into Monday.

- Outside of low chances for rain Friday morning, mainly dry
  conditions should be seen. Possible exceptions are where the
  ring of fire develops once the heat dome builds into the area.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 148 AM CDT Thu Jul 23 2026

Continued cooler than normal with low humidity through sunset.

The question late tonight are the rain chances. Progged soundings
show a considerable amount of dry air in the low levels; which makes
sense given dew points in the 50s during the day.

Thus it appears that most of the forcing will go into cloud
development late tonight. While some models develop precipitation,
more are dry or mainly dry. Interestingly, the RRFS 18z and 00z runs
were dry as was the 18z REFS.

The better rain chances are south of the IA/MO border but will go
with some 20-40% rain chances generally south of an Ottumwa, IA to
Galesburg, IL line. As we get closer to the event, the rain chances
will probably lower and get pushed further south. Sprinkles are
definitely in play given the deep layer of moisture above 700 mb.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 148 AM CDT Thu Jul 23 2026

Friday/Friday night
Assessment...low (<20%) confidence on rain

Progged soundings of the atmosphere continue to show dry air in the
low levels through Friday morning. Thus rain is questionable but
with moisture in the mid-levels, sprinkles are on the table.

Like late Thursday night the rain chances generally look to be south
of an Ottumwa, IA to Galesburg, IL line. Thus will keep 20-40%
chances going for that area with slightly higher chances south of
the IA/MO border.

Friday night the models show rain chances on the warm advection
associated with the expanding heat dome. Again, the rain chances are
not high; 20-40 percent south of an Ottumwa, IA to Galesburg, IL
line with most of the area remaining dry.

Saturday through Sunday
Assessment...very high (>95%) confidence of heat and humidity
returning

The southerly flow that develops Friday night will continue through
the weekend allowing heat and humidity to return. While the humidity
will be noticeable Saturday, Sunday will be downright uncomfortable
with dew points generally 70 to 75. Heat indices on Sunday look to
approach 100 and may exceed 100 in some areas.

Sunday night through Tuesday
Assessment...high (>80%) confidence on heat and humidity continuing

The heat and humidity will continue into the first part of the work
week. Heat indices may again approach or exceed 100 on Monday which
raising the question of potential heat headlines Sunday through
Monday evening.

The wild card is where the ring of fire sets up. Organized storm
complexes should move across Minnesota in Wisconsin before turning
south and potentially moving into northern Illinois. The various
models suggest the far northeast and eastern area could get side-
swiped by a storm complex late Sunday night into Monday morning and
again late Monday night into Tuesday. If this scenario does occur,
it could affect any heat headlines for Monday.

The key will be where do the storm complexes Saturday night into
Sunday develop and go. This will impact where the storm complex
Sunday night into Monday forms and goes and likewise the Monday
night into Tuesday complex.

Tuesday night/Wednesday
Assessment...a certainty (>95%) of continued warm and humid
conditions

By Tuesday night the tropical connection with the Gulf weakens which
will allow dew points to generally drop back into the 65 to 70
range; humid but not oppressive. The heat dome ridge partially de-
amplifies and turns the mid-level flow more west to east across the
Midwest. As a result, the organized storm complexes should remain
across Minnesota and Wisconsin.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 600 AM CDT Thu Jul 23 2026

High pressure maintaining acrs the mid and upper MS RVR Valley
will make for another day of light sfc winds and mainly VFR
conditions. There will be patches of 5-7K FT AGL stratocu, as
well as some diurnal development of ambient CU of SCT-BKN
coverage by afternoon, but again at VFR levels. Sfc winds today, when
not light and variable, will be from the south to southeast at
5-10 KTs. Light and variable sfc winds return tonight after
sunset.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.

&&

$$

SHORT TERM...08
LONG TERM...08
AVIATION...12