Clinton, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

345
FXUS63 KDVN 260521
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1221 AM CDT Sat Jul 26 2025

...Updated for 06z Aviation...

.KEY MESSAGES...

- Chance of showers and storms today mainly south of Hwy 20,
  increasing coverage tonight into Saturday AM with heavy
  rainfall and localized flooding potential particularly in
  counties along and south of I-80. Gusty winds are also
  possible with a Marginal Risk or level 1 of 5 for severe
  weather for parts of the area.

- Heat builds back in Sunday through Tuesday, potentially
  dangerous, but there will also be episodes of storms making
  for a challenging temperature forecast and low confidence on
  the spatial extent and magnitude of the heat (day to day
  evaluation needed).

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 145 PM CDT Fri Jul 25 2025

GOES visible satellite imagery showed several compact cyclonic
circulations (MCVs) in a corridor stretching from southeast
Iowa into northern Kansas. These low/mid-level impulses were
positioned atop a weak quasi-stationary front as analyzed by
WPC, extending from the Lower Great Lakes back to the southwest
into the Central Plains.

Not a big air mass difference on either side of the boundary
with very humid conditions over the region (dewpoints in the
low/mid 70s). SPC mesoanalysis does show a rather tight north
to south gradient in PWATs from ~1.25" across the north to 2.25"
in the central to southern forecast area. This enhanced
corridor of deep moisture is forecast to gradually shift
northward through tonight into Saturday AM, ahead of the
approaching MCVs. With the anomalously moist air mass -- near
the 98-99th percentile per the NAEFS climatology -- and
expectation for slow storm motions around 10-20 mph at times per
MBE vectors, some locally very heavy rainfall is possible over
the next ~24 hours. Additionally, high freezing levels of 15-16
kft will promote efficient warm rain processes with potential
for peak hourly rain rates around 2-2.5" in the strongest
storms.

Forecasting the most likely placement of the heaviest rain is a
bit tricky, but based on a CAM model consensus counties along
and especially south of I-80 appear to have the highest chances.
The latest HREF LPMM QPF does show potential for localized
bullseyes of 3-4" with 0.5 - 1.5" amounts being more common, and
then a rapid drop off in amounts along/north of Highway 30.
Decided to issue a Flood Watch for counties along/south of I-80
due to the potential for localized flash flooding with 3 hr FFG
values in the 1.5 to 2.5" range. Of course the thick
vegetation/mature crops can handle a lot of water this time of
year, so areas most susceptible will be urban locations and
other low-lying flood prone areas.

For timing, scattered convection is anticipated to develop with
the lead MCV this afternoon and evening, likely to track
through the central portion of the outlook area. More widespread
slow moving showers and storms are then expected tonight, again
with the highest chances south of Highway 30. This activity
will likely linger into Saturday AM and it`s possible scattered
storms redevelop during the afternoon. SPC has continued with
the Marginal Risk (level 1 of 5) for severe storms, mainly for
locally damaging winds. And WPC has a Slight Risk (level 2 of 4)
for flash flooding.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 320 AM CDT Fri Jul 25 2025

Saturday night and Sunday models support some amplification of the
upper ridge overhead. The building heights aloft and lack of
any appreciable forcing may limit storm coverage and support
more diurnally induced widely scattered activity. This upper
ridge and increasing heights aloft will also bring a return of the
heat. With corn sweat in prime-time, we`ll see some very humid
to oppressive conditions with dew points likely in the mid/upper
70s and possibly 80 in spots. This will bring the potential for
dangerous heat index readings exceeding 100 to around 105 degrees
across much of the area, provided convection and cloud cover stay
limited to allow highs to top out in the upper 80s to around 90.

Monday through Wednesday, the pattern looks to become quite
conducive for periodic storm complexes with an attendant heavy rain
and severe weather threat, as the ridge is suppressed further
to the south allowing our region to reside in the action zone or
`ring of fire` with main belt of westerlies strengthening and
shifting southward through the Northern Plains and Upper Midwest.
This timeframe will also hold the potential for a continuation
of dangerous heat and humidity, but this will likely be a day to
day evaluation because of the uncertainty with temperatures given
the active pattern and potential for rounds of convection.

Beyond mid-week though there are signs pointing to a cooler and
somewhat drier pattern for late next week, as we see a bout
of northwest flow attendant to an eastern Canada low.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1205 AM CDT Sat Jul 26 2025

The forecast in general is expected to be predominantly VFR
through 09z, then after 09z becoming predominantly MVFR to IFR
with increasing precipitation chances through 17z, then
gradually returning to VFR after 17z through 21z.

We appear to be in a bit of a lull in-between waves and as such,
the next few hours will likely predominantly VFR with low
chances for a brief shower along with some patchy MVFR possible
particularly at DBQ and CID. After 09z, much of the guidance is
pessimistic with developing lower CIGs particularly at DBQ and
CID with low MVFR to IFR and even the potential for pockets of
LIFR, along with some fog. Some concerns with this due to the
amount of cloudiness, but with the abundant moisture and light
wind any breaks should allow for some lower conditions to
develop. Also, expecting a burgeoning of showers and storms
toward dawn and through late morning (11z-17z) ahead of the
next wave lifting up from NE Kansas. Highest precipitation
probabilities during this time appear to be at MLI and BRL, and
have gone with prevailing mention while also hitting
visibilities harder with low end IFR due to expected high
rainfall rates. Probabilities are lower at CID, but still high
enough certainty to warrant TEMPO mention. Meanwhile at DBQ,
confidence is lower to warrant just PROB30 mention for
precipitation. Sat afternoon is expected to trend back to mainly
VFR, with an isolated storm possible but confidence too low for
any mention at this time.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Flood Watch through this evening for IAZ063>068-076>078-
     087>089-098-099.
IL...Flood Watch through this evening for ILZ009-015>018-024>026-
     034-035.
MO...Flood Watch through this evening for MOZ009-010.

&&

$$

SHORT TERM...Uttech
LONG TERM...McClure
AVIATION...McClure