Bluff Park, Iowa Weather Forecast Discussion

137
FXUS63 KDVN 211107
AFDDVN
Area Forecast Discussion
National Weather Service Quad Cities IA IL
607 AM CDT Sun Sep 21 2025
.KEY MESSAGES...
- On and off periods of showers and thunderstorms are expected through
  the first half of the week. Some storms could become strong
  to severe on late Monday.
- A Marginal Risk of strong to severe storms for Monday has been
  introduced, mainly for our northwestern areas.
- Lower confidence in forecast midweek as models differ dramatically
  on solutions.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 325 AM CDT Sun Sep 21 2025
Largely dry conditions were seen on local radar early this morning,
with the exception for some isolated showers over southeastern Iowa
into west-central Illinois ahead of a weak trough traversing the
IA/MO border. Skies have cleared a bit behind the trough, and
visibilities of 1/4 mile due to fog were reported under the
clearing. We will have to watch local observations near this
area closely as we go through the early morning hours to see if
similar visibility reductions occur locally. If visibilities
fall to around 1/4 mile, we would consider a Dense Fog
Advisory.
Mostly dry conditions are expected through the afternoon as subtle
mid-level ridging should keep forcing for showers/storms out of the
area. This is very short-lived, however, as another shortwave moves
through the area by the evening hours, which can be seen on the
latest GOES-East mid-level water vapor satellite imagery moving into
western Nebraska. Ahead of the wave, mid-level flow looks to
strengthen slightly, which should result in more favorable deep-
layer shear for storms. With this said, the 21.00z HREF joint
probabilities of instability and shear suggest the more favorable
environment is slightly displaced ahead of the wave, so the
potential for strong to severe storms for our area remains lower.
SPC actually has our region largely out of any severe weather
risk, but with two Marginal Risks (level 1 of 5) just outside of
our CWA to the east, and another over northwestern Iowa near
the base of another trough. If this wave speeds up at all, we
can`t rule out any severe weather in our region capable of
locally strong winds and hail.
Precipitation associated with the wave appears to cross our southern
areas by this evening, along with the northern wave approaching our
northwest, so chances (20-50%) of showers and an isolated storm will
increase this evening through tonight, with the higher chances
confined to southeastern Iowa into west-central Illinois.
Precipitation amounts through tonight don`t appear to be too
noteworthy in these areas, with the HREF PMM QPF values
indicating most locations receiving less than a tenth of an
inch, with isolated amounts closer to a quarter inch.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 325 AM CDT Sun Sep 21 2025
The extended forecast period will continue to remain unsettled, with
daily chances (20-40%) of showers and isolated storms Monday through
at least Wednesday. A large-scale pattern change appears possible by
Friday into next weekend.
First, let`s focus on Monday. We continue to remain under an upper-
level longwave trough, with an embedded mid-level shortwave progged
to dive southward towards our area late in the day. An attendant
cold front will also sweep through the area from the north, which
will provide a general focus for showers and isolated storms. The
front generally looks diffuse, and the convective parameter space
shows modest values of deep-layer shear, instability, and mid-
level lapse rates. Still, there is the potential for some
stronger convection along the boundary, and SPC has introduced a
Marginal Risk (level 1 of 5) of severe weather to locations
along and north of a line from Millersburg, IA to Freeport, IL.
Again, locally strong winds and hail are the main threats.
Tuesday and Wednesday will continue to have low to medium chances
(20-40%) of showers and isolated storms as the aforementioned cold
front slowly moves southward. The upper-level trough is expected to
become quite elongated to the west, with a cut-off upper low
developing over the upper Midwest. Potential for strong to severe
storms during this period looks quite low, given very meager values
of shear and instability, and the various machine learning severe
probability tools agree with this assessment.
Thursday through Saturday: a much quieter weather pattern
develops, as the upper-level trough is kicked out by large
upper-level ridging over the Intermountain West region. It`s
still unclear when the ridging will take control, given
differences among the global models and ensembles, but
confidence remains decently high for a drier pattern by weeks-
end.
&&
.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 606 AM CDT Sun Sep 21 2025
A mix of MVFR to LIFR conditions due to fog and low stratus were
observed for portions of the area as of TAF issuance, particularly
for locations along and south of Interstate 80. Confidence on
how these conditions will change over time remains quite low
with highly variable flight conditions in terms of coverage.
By this afternoon, conditions should improve back to VFR, with
a period of dry conditions expected. Another round of showers
could move across our south this evening into the overnight
hours, which could support MVFR visbys under light rain.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Dense Fog Advisory until 9 AM CDT this morning for IAZ098-099.
IL...None.
MO...Dense Fog Advisory until 9 AM CDT this morning for MOZ009-010.
&&
$$
SHORT TERM...Schultz
LONG TERM...Schultz
AVIATION...Schultz

NWS DVN Office Area Forecast Discussion