831
FXUS63 KDVN 140504
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1204 AM CDT Thu Aug 14 2025

...06z Aviation Update...

.KEY MESSAGES...

- More seasonable and not as humid conditions through Thursday.

- Heat and humidity to build back Friday through the weekend
  with heat index readings near or exceeding 100 degrees.

- Shower/storm chances increase Sunday through early next week.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 210 PM CDT Wed Aug 13 2025

Surface high pressure will largely remain in control while
gradually shifting through the region.

An ideal radiational cooling setup tonight with mainly clear
skies and light winds will allow lows to slip back into the
upper 50s and lower 60s. Can`t rule out some patchy radiational
fog late tonight through daybreak with the steep, shallow low
level inversion. However, after a full day of solar insolation
and drying any fog may tend to be very transient and quite
shallow with limited if any impacts.

Thursday will feature one last seasonable and less humid day
compliments of easterly flow. Highs look to get back into
the lower to mid 80s. Later in the day Thursday and Thursday
night much of the deterministic guidance track a shortwave
from the Dakotas to Wisconsin by 12z Friday. There is a low
chance (<20%) for some decaying debris and/or spotty showers
north of Hwy 30 and especially along the Hwy 20 corridor in
E Iowa. However, lingering subsidence and a rather large dry
layer from the surface to above 700 hPa lends to a lot of
uncertainty for any measurable precipitation and as such have
kept late Thursday PM/night dry at this time. We should see
some increase of mid/high clouds, which could play a little
havoc with lows Thursday night. Areas that manage to stay
mainly clear with favorable low level easterly flow will
likely drop back into the 50s, while areas where skies are
at least partly cloudy should see lows mostly in the lower
to mid 60s.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 210 PM CDT Wed Aug 13 2025

Deterministic guidance and ensembles support an amplification of
an upper level ridge across the region through the weekend,
with an active wave train and quasi-stationary frontal zone
situated across the Upper Midwest supporting the more active
weather primarily to our north. With that said, we`ll need to be
on watch for some propagation of nocturnal convection into
parts of the area Saturday night into Sunday with any upscale
growth or MCS activity. This potential will be dependent upon
how the convection evolves Friday night into Saturday and the
subsequent position of the frontal zone. Conceptually this
potential for nocturnal convection looks possible deeper into
the weekend. What is more confident however, is the ramping
heat and humidity with 850 hPa temperatures climbing into the
range of 20C to 25C supporting highs in the upper 80s and lower
90s Friday through Sunday. Dew points look to climb back into
the 70s with corresponding heat index readings back near or
above 100 degrees Friday (far south) and areawide Saturday and
Sunday though Sunday has some uncertainty given the potential
for early day convection for parts of the area.

Early next week looks continued active/unsettled and very warm/
muggy as a slowly sagging boundary pools moisture and provides
the focus for showers and storms Monday through Tuesday.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1159 PM CDT Wed Aug 13 2025

Unless we can get some patchy fog development toward dawn, it
appears to be a VFR TAF cycle through Thu evening. Some of the
CAMs recent runs are producing some more fog now in the calm
wind-SKC environment especially south of I-80. But for now,
think if it does occur it will be more of the shallow ground fog
and valley fog type stuff and will keep VFR VSBY`s going
overnight for now, but will have the fog watch on through
sunrise Thu morning. Some southeast sfc wind development as
Thursday progresses, maybe to the 4-8 KT speed realm by
afternoon. More cellular CU possible again by Thu afternoon, but
should be at VFR heights by the time it get`s noticeable.

&&

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

&&

$$

SHORT TERM...McClure
LONG TERM...12/McClure
AVIATION...12