Clinton, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

939
FXUS63 KDVN 201747
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1247 PM CDT Sun Jul 20 2025

.KEY MESSAGES...

- Daily storm chances through the coming week will bring chances
  for strong to severe storms and flash flooding.

- Temperatures increase after Monday with highs in the 90s for
  most of the week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 228 AM CDT Sun Jul 20 2025

GOES satellite imagery this morning shows a swath of convection
across west-central to southern Iowa with IR satellite
especially vibrant with a line of towering storms. Heavy rain
and frequent lightning are being observed within this line with
progression expected towards the southeast within the latest CAM
guidance. The Flood Watch active until 1pm this afternoon favors
the southern 3/4ths of the CWA as this line will likely be the
primary driver behind any flooding potential, especially if the
linear shape continues as it moves through which would result in
prolonged periods of heavy rain from training thunderstorms. Per
the SPC Mesoanalysis, PWAT values remain above 2.0 in southern
to southeastern Iowa and northeastern Missouri with the most
efficient moisture transport also favoring this region. The
`tropical` airmass and nocturnal timing have largely kept severe
weather from occurring tonight as heavy rain and lightning will
remain the primary outcomes of the storms as they continue this
morning.

After this line of storms pushes through the region by late
morning to early afternoon, overall area rain chances dwindle
with sprinkles possible underneath a continuous deck of
stratocumulus clouds which look to persist through the afternoon
and evening. A few models try producing another round of storms
favoring northern Missouri by the late evening with forecast
soundings showing a healthy 2000+ J/KG MLCAPE alongside 30-35kts
of deep layer shear and a favorable hodograph as a warm front
moves northwards from west-central Missouri. This boundary will
be the key thing to monitor within guidance throughout the day
as it will serve as the locus for severe weather potential, with
additional warm core rain possible north of the boundary as
well.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 228 AM CDT Sun Jul 20 2025

The longer term period will be marked by a warmup starting
Tuesday and lasting through the remainder of the week, with high
temperatures in the low 90s likely beginning Wednesday and
continuing towards the weekend. In addition, diurnal shower and
storm chances will be present with weak ridging present to the
north amidst weak zonal flow above 500mb as the lower level
winds will advect warm and moisture rich air into the region
beginning Tuesday and lasting throughout the week, alluding the
previously mentioned Ring of Fire pattern. Ensemble guidance
shows sporadic QPF across the entire period with the GEFS
showing the sole mostly dry period being Thursday, as shower and
storm chances show up frequently amidst the membership
otherwise. In terms of heavier rain, aside from a direct hit
from a storm it appears that the best chance will be later in
the week favoring next weekend with a more powerful upper level
shortwave appearing within the deterministic global guidance.
Until there is a better handle on the synoptic forcing, the
timing and intensity will change throughout the week until we
get a bit closer.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1232 PM CDT Sun Jul 20 2025

Nocturnal convection has pushed the effective boundary to near
the IA/MO border. Any diurnal convection is expected to be
isolated through 00z/21 with the probability of a TAF site being
impacted at 10 or less. After 00z/21 a new round of nocturnal
convection will develop in northern Missouri and move east. Main
impact to eastern Iowa and northern Illinois is the development
of fairly widespread MVFR conditions that would last through
15z/21 before slowly lifting.

&&

.HYDROLOGY...
Issued at 1232 PM CDT Sun Jul 20 2025

What has changed...

New flood warnings have been issued for the English River at
Kalona and for the North Skunk River near Sigourney.

Discussion...

As expected additional bands of 1-3 inches of rainfall with
locally higher amounts fell across parts of eastern Iowa and
Illinois. These bands were generally a bit south of the previous
days heavy rain bands.

Both the Iowa River at Marengo and English River at Kalona will
be going into minor flood. The North Skunk River near Sigourney
will minimally go into minor flood but has roughly a 1 in 3
chance of hitting moderate flood stage. It will take about
another 1-1.5 days to get a better accounting of the runoff in
the North Skunk River basin as to whether or not a low end
moderate flood will be realized near Sigourney.

Precipitation over the next 24 hours will be isolated to
scattered and much further south than the previous two rounds of
heavy rainfall. The tropical connection to the Gulf is still
present but much weaker than 24 hours ago. Thus any heavy
rainfall will be much more localized than the previous two
days.

After tonight and Monday the heat dome will build into the area
which will result in little if any rain Monday night through
Thursday. This time period should allow most rivers to crest and
then be on the downward trend for late this week and into the
weekend. Area river levels are expected to remain above to much
above normal through the end of July.

&&

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

&&

$$

SHORT TERM...NWS
LONG TERM...NWS
AVIATION...08
HYDROLOGY...08