Canton, Iowa Weather Forecast Discussion

819
FXUS63 KDVN 211925
AFDDVN
Area Forecast Discussion
National Weather Service Quad Cities IA IL
225 PM CDT Sun Sep 21 2025
.KEY MESSAGES...
- Off and on chances for showers and storms through the middle
  of the week. Strong to severe storms are possible later in the
  day on Monday mainly across the northern CWA.
- Models are converging on a solution for midweek with the
  heaviest precipitation south of the area.
- Quieter weather pattern expected late in the period.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 224 PM CDT Sun Sep 21 2025
A complex upper level flow pattern continues through the short
term as two waves pass through our longitude, The first one
will be north of the area into N MN, the other will be just
south of the area in MO. We are squeezed between these two
system as overall ascent across the are has led to partly to
mostly cloudy skies across the area. At the same time, low level
flow has turned to the SW at H85, helping to advect in more
moisture into the area later tonight and into Monday.
The southern wave will drive most of the weather tonight and
into tomorrow morning. With it being a much more progressive
wave it will move quickly through the area. As mentioned by
earlier shifts, the better thermodynamic environment is ahead of
the wave, so by the time the shear is in place, we will have
little to no instability, severe weather looks to be very low
this evening.
The northern wave, which is more closed in nature will drag a
diffuse cold front into the area tomorrow. This boundary along
with the moisture return will serve as the foci for thunderstorm
development late in the period and into Monday evening. Overall,
shear looks to be weak with this setup however CAPE will be
larger than the last few days. The majority of this setup will
occur in the beginning of the long term and will be addressed
below.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 224 PM CDT Sun Sep 21 2025
Pattern remains messy through most of the long term
before weak zonal flow/ridging overtakes the area leading to
quiet weather for the weekend. While there looks to be
differences in the overall flow, the differences are just what
flavor of quiet weather we will get. Cooler and drier or warmer
with maybe some more humidity. Regardless, quiet weather to end
the week.
Monday while the overall cold front looks to be diffuse from a T
and wind shift stand point, there does appear to be a decent
gradient and boundary in the dewpoint field. This with the H85
flow will serve as the initiation point north and west of the
CWA in northern IA. SBCAPE in the GFS of 2000 - 2500 J/kg is
forecast just north of the CWA will help create the threat of
strong to severe weather. There is weak 0-3km shear of 20kts.
With the cooler environment this may actually help to lead to
some sort of cold pool generation and some longevity of the
storms, which could increase the severe wind threat. That said,
most CAMs keep cellular convection in close proximity of each
other. So this would likely limit any severe hail production.
The best chance for our area to see these strong to severe
storms is going to be between 00z and 06z, probably in some sort
of weakening state as they move in.
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.
&&
.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1253 PM CDT Sun Sep 21 2025
Clouds have been slow to clear out today leading to MVFR vsbys
and decks through 18z today. These decks should scatter out
before nightfall. Some MVFR fog is possible again tonight
especially at DBQ and CID. Light showers could move across the
area and affected BRL overnight. Otherwise mainly a VFR/MVFR
through the period with light winds.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
SHORT TERM...Gibbs
LONG TERM...Gibbs/Schultz
AVIATION...Gibbs

NWS DVN Office Area Forecast Discussion