231
FXUS63 KDVN 261053
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
553 AM CDT Sat Sep 26 2026

.KEY MESSAGES...

- Light rain will be seen in areas west of the Mississippi River
  through Saturday night, with mostly dry conditions moving in
  Sunday through Monday.

- Another active weather pattern will set up in the middle of
  the upcoming work week, bringing the potential for rounds of
  heavy rainfall and thunderstorms to the area.

- Temperatures will remain near to slightly above seasonal norms
  through the next week.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 124 AM CDT Sat Sep 26 2026

Upper ridge remains situated over the Mississippi River Valley
through today, with it starting to break down Sunday through
Monday. A ridge-riding wave will dig into our area from the west
today, which will start to break down this ridge. Best moisture
transport will be off to our west, with drier east to
southeasterly flow kicking into our east, leaving the
Mississippi River as the rough delineation line for rain
chances. Best chances for rainfall (50-80% PoPs) will be west of
the Mississippi River in parts of eastern Iowa this morning
into early afternoon. We are not expecting widespread heavy
rainfall. Rather, we should see spotty light showers passing
through, with dry time between. Dry air east of the river should
keep much of the rainfall chances <20%. With that said, there
will still be some battle with dry air west of the river. Thus,
rainfall should remain light. Later this afternoon and into the
evening, rainfall chances will decrease, prior to increasing
once again overnight tonight into Sunday AM (20-40% PoPs).
Similar locations will be in line for more light rainfall. When
all is said and done, rainfall accumulations through Sunday AM
will be low, generally <0.10-0.20" for eastern Iowa and
locations east of the Mississippi River that manage to see light
rain will see <0.10". Compared to the previous forecast
package, the trend has been decreasing and a little more west
with the rainfall. Overall, we are still looking at another
dreary day for some through Saturday, with cool temperatures in
the 60s and a light southeasterly breeze. Areas east of the
Mississippi River will have the best chance to see temperatures
warm near 70 with more potential breaks in the clouds,
especially through early afternoon.

Upper ridge will continue to slowly break down through Sunday,
with surface high pressure strengthening over the Great Lakes
Region. We will start to see this build westward a bit, which
will help usher drier air into the area. Thus, precipitation
chances will largely deplete through the day Sunday into the new
work week. Although, we will continue to see mostly cloudy
skies through the remainder of the day. Temperatures will remain
in the 60s with light easterly winds through the afternoon.
Overnight temperatures will be in the 50s throughout.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 124 AM CDT Sat Sep 26 2026

Going into Monday, we will continue to see influence from the
building high pressure over the Great Lakes Region. A greater push
of dry air will work into the area, allowing for the potential for
more breaks in the clouds. This will be a welcome sight for those
that have been socked in clouds and light precipitation this
weekend. Overall, we are expecting to remain dry through Monday,
with temperatures warming to near 70 throughout.

This period of dryness will come to an end mid-week as a larger
system builds in sometime around Tuesday/Wednesday. A longer wave
trough, with models showing a strong tropical connection to the
systems from the eastern Pacific and the Gulf, should translate
through the area, although the exact onset/ending time of associated
precipitation remains uncertain. This is pretty clearly shown from
the LREF ensemble cluster analysis, which shows various depictions
of the longer wave trough aloft. Some show a large progressive
trough sweeping across the central CONUS, while some show a slower
cut-off low with multiple rounds of rain mid to late week. However,
there remains a strong signal for abundant moisture with this system
given the tropical connection, with Pwat values progged around 1.6
to 2 inches, which is quite high for late September. In fact, these
values would be in excess of the 99th percentile for Pwats per the
NAEFS climatological percentiles. NBM exceedance probabilities for
one inch or more of rain for Tuesday night and Wednesday are around
40-60%, which is actually a pretty decent signal given we`re talking
several days out. Despite the uncertainty on the exact duration and
magnitude of rainfall amounts, this signal appears supportive of
heavy rainfall and perhaps a flash flooding threat, given wet
antecedent conditions. So, this mid-week system bears watching. With
this, WPC has much of our area in a Day 5 Slight Risk (level 2 of 4)
in their latest excessive rainfall outlooks.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 551 AM CDT Sat Sep 26 2026

VFR conditions will continue through the period, though the
morning hours will feature a band of high based rain showers
moving east/northeast from central Iowa and Missouri. These
showers will be encountering much drier air as they move into
eastern Iowa, which should cause them to diminish this morning
as they arrive. A few spotty light showers remain possible into
this evening, but with coverage low and expectations of VFR
weather, we will not include in the TAF on this issuance.

&&

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

&&

$$

SHORT TERM...Gunkel
LONG TERM...Gunkel
AVIATION...Ervin