914
FXUS63 KDVN 211834
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
134 PM CDT Mon Sep 21 2026

.KEY MESSAGES...

- An upper low over the northern plains will continue to roll through
  the area through Tuesday morning, with mostly light amounts
  of rain and drizzle. Then expected a precip break for
  Wednesday thru Friday.

- Pleasant early fall weather is expected for Wednesday through
  Friday.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 132 PM CDT Mon Sep 21 2026

Though we remain cut off from significant moisture transport
under a small upper low over the Midwest, our area is in a
convergent low level flow near the Mississippi River to
convergent flow just aloft a bit northwest around northeast
Iowa. The upper low aloft is bringing lift to the northeast
Iowa area, and will combine with both mechanisms over eastern
Iowa and far western Illinois tonight into early Tuesday. The
result, wet weather continues!

I have increased pops to 80+ percent over eastern Iowa this
afternoon and tonight, mainly north of Highway 34, as the efficient
process of lifting the saturated low level air mass continues. So
far today, this is resulting in a hundredth or two per hour in this
band, but over northeast Iowa, the deeper moisture has allowed slow
moving showers to bring 0.36" to Waterloo this morning.  I fully
expect there to be some spotty county sized spots that receive 0.25
to 0.50 tonight, and up to an inch is possible in a worse case
scenario, which is concerning, but we`d be unlucky to have the one
or two small areas like that line up over a metro area.  We`ll just
have to keep an eye on it, and also know the rate per hour is not
expected to exceed 0.20 per hour. An isolated brief flash of
lightning remains possible within the heaviest showers tonight.

Tuesday, the upper low is expected to weaken and move east, with
drier air aloft gradually mixing in from the north.  I expect clouds
to linger (along with some rain/drizzle) through mid morning,
followed by clouds and eventually some breaks by afternoon in the
north.  The dry hours in the afternoon should be able to allow for
temperatures to rise to the mid 60s central and south, but the north
should remain cool near 60.

The dry air will continue to arrive Tuesday night, with lows in the
mid 40s northwest to low 50s southeast, under clearing skies. For
now, fog may be held off by north winds at 5 to 10 mph, but that
will need to be watched in this forecast.

Wednesday stands out as a very pleasant day, with highs in the mid
60s north to upper 60s central and south, as a brief period of
upper ridging moves through the region. skies appear mostly
sunny much of the day.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Issued at 132 PM CDT Mon Sep 21 2026

Thursday through Friday...Ensemble and upper jet trends suggest
that the local area to benefit from becoming under the influence of
some of the ridging of the blocked pattern aloft, which would
lead to some fine fair weather fall days with highs in the 60s
to near 70 and overnight lows in the 50s and 40s. Will have to
watch for some upper trof energy to try and undercut the ridging
and shuttle some showers or way Thu or into Friday, but the
latest ensembles suggest an omega ridge to get pumped up along
the MS RVR Valley from subsidence off developing east coast deep
cyclone and erode precip as it tries to near the area from the
west Thursday and especially on Friday.

Saturday and Sunday...Getting into a more uncertain period, but the
same ensembles suggest another ridge-undercutting trof may finally
bring in some shower chances to the area Sat into early Sunday.
Currently temps look seasonable for the weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1216 PM CDT Mon Sep 21 2026

Low clouds remain widespread over the area late this morning,
and will continue to remain in these clouds through the period
as northeast low level flow combines with a weak upper low over
the area to bring widespread cigs around 800 to 1500 ft,
drizzle, and rain. Tonight, a thunderstorm is possible, but that
threat is low, compared to rain, which may be widespread over
the entire area tonight and overnight as the upper low moves
overhead. Current indications suggest this low aloft will move
east of the area between 12Z and 15Z Tuesday. Behind the low,
the moist atmosphere will slowly see improvement through the day
Tuesday, but the morning is expected to be MVFR with high
confidence.

&&

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

&&

$$

SHORT TERM...Ervin
LONG TERM...Ervin/12
AVIATION...Ervin