207
FXUS63 KDVN 300754
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
254 AM CDT Sat Aug 30 2025

.KEY MESSAGES...

- Seasonable late summer temperatures continue this weekend
  into early next week, with mostly dry conditions expected.

- A cold front during the middle of next week brings a better
  chance of rain and much cooler temperatures.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 254 AM CDT Sat Aug 30 2025

Surface high pressure over the western Great Lakes continues to
feed a cool, dry easterly low level flow across our region
today. Widespread low clouds and fog have been noted across much
of Wisconsin, while mid and high level clouds stream southeast
from the Dakotas to Illinois. Northern portions of our forecast
area have the greatest potential for fog this morning, right in
between the low level clouds in Wisconsin and the higher level
clouds further southwest. This fog should burn off by mid
morning giving way to a mostly sunny sky with temperatures
reaching the 70s to low 80s with the coolest temperatures in the
northeast and warmest in the southwest.

Just as with yesterday, there remains an area of greater
moisture mainly across central and southeast Iowa that will lead
to an area of maximized instability this afternoon. While
there`s not much in the way of forcing for widespread
convection, isolated showers and thunderstorms are possible in
this axis of instability from mid afternoon through early
evening. Both CAMs and lower resolution guidance are less
aggressive with afternoon convection today compared to
yesterday, so it is likely that total coverage will be a bit
less today.

The persistent easterly flow pushes the greater moisture further
west on Sunday, thus pushing the focus for showers and
thunderstorms westward as well. The main focus will be over
Nebraska and western Iowa near a slow moving upper trough, but
we do see the NBM keeps at least some minor PoP in our far
western forecast area Sunday afternoon.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 254 AM CDT Sat Aug 30 2025

Surface high pressure gradually weakens and spreads eastward
through the Great Lakes early next week, loosening its grip on
our area. Meanwhile, the persistent trough to our west finally
drops southward opening us up to some subtle height rises
aloft. So we may see the temperature warm a few degrees, up to
near or slightly above normal levels near 80 degrees Monday into
Tuesday.

This all changes midweek, though. A much stronger trough is
headed our way. Currently it`s tracking east across the North
Slopes of Alaska, but as it moves east across the Canadian
Arctic a compact and intense lobe of energy is expected to push
southward, arriving and intensifying over the Upper Midwest
Wednesday into Thursday. This pushes a strong cold front through
our region on Wednesday, with a stiff NNW wind, clouds, and some
rain behind it. This period represents our best chance of rain
this week, at least in terms of widespread synoptically
generated rainfall. Among the long range guidance, 80 to 100
percent of ensemble members produce measurable rainfall across
our forecast area in the 24 hours ending Wednesday evening.
Current NBM PoP is lower than that owing primarily to timing
uncertainty with respect to which period this will fall in.
However, latest trends in guidance have improved on timing
consistency and I`d expect NBM PoP to increase in coming runs.
There`s not a strong moisture connection with this front, so
rain amounts will remain light (< 0.3 inch) but more widespread
than we`ve seen in recent days.

While there remains some variance in guidance with respect to
the intensity and track of the upcoming closed low dropping into
the Upper Midwest, there has been improvement over the last
several model runs with a greater portion favoring the cooler
solutions. For example, among the 12Z long range ensemble
guidance 850MB temperatures Thursday afternoon, there was only
a 3C difference between the 25th and 75th percentiles
(interquartile range or IQR). Just 24 hours earlier, that spread
was 5C and 24 hours prior it was 7C. This shows increasing
confidence in these post frontal temperatures. Similarly, the
ensemble mean 850MB temperature at the same time frame has
decreased by about 2C with each of those model runs, indicating
greater confidence in the colder temperatures. Similarly, NBM
forecast highs Thursday continue to gradually decrease, although
in situations with increasing model consensus NBM will often
lag a little bit in making adjustments. So there`s still a
potential for temperatures to be even colder than the current
going forecast especially if the long range guidance trend
continues and solidifies.

The surface high associated with this air mass moves through
Saturday into Sunday, with upper ridging nudging back in at
least briefly behind it. That should spell a decent warm up next
weekend into early next week, at least back closer to normal.
The uncertainty here is primarily on how quickly this warm up
commences.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1228 AM CDT Sat Aug 30 2025

Light winds and VFR conditions will predominate. The main
concern is the potential for fog early this morning and the
potential for showers or thunderstorms again Saturday afternoon.

Air is already near saturation in most places especially after
evening rainfall, however extensive cloud cover aloft is likely
to prevent more widespread fog formation. However, areas which
see breaks in the clouds will have a good chance of seeing some
fog by morning. The greatest chance is at DBQ where an easterly
wind is rising over the bluffs and condensing near the surface.

There will again be a corridor of instability Saturday afternoon
mainly across central to southeast Iowa. There is no clear
forcing mechanism to trigger widespread convection, but a storm
or two could develop in this region. Most likely terminals
impacted are CID or BRL, though confidence is too low to include
in the TAF at this time.

&&

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

&&

$$

SHORT TERM...Kimble
LONG TERM...Kimble
AVIATION...Kimble