389
FXUS63 KDVN 301956
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
256 PM CDT Wed Jul 30 2025

.KEY MESSAGES...

- Scattered showers and thunderstorms remain possible this
  afternoon and evening (30-70% chance). Lightning and locally
  heavy rainfall are the primary concerns with this activity.

- River rises will continue across the area from previous heavy
  rainfall. Additional rainfall amounts of a 0.50 to 1.0 inch
  are possible through tonight, mainly east of the Mississippi
  River.

- Very high confidence on less humid and cooler conditions late
  this week and over the weekend.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 230 PM CDT Wed Jul 30 2025

Current Conditions and Synoptic Pattern: Water vapor and upper
air analysis continues to show the upper level ridge beginning
to shift south into the southern plains. A mesoscale convective
vortex (MCV) from this morning`s cluster of storms was now
moving into the western CWA and will likely be the focus for
afternoon and evening redevelopment of showers and perhaps a
thunderstorm. Instability, however, was quite low with only
100-250 J/kg of ML CAPE with the exception of the far south CWA
where values had increased to around 1000 J/kg. The higher PW
values were also beginning to shift east of the area, but
1.6-1.8 inches was still prevalent across the region. While
some breaks in the clouds have occurred, temps were generally in
the middle to upper 70s.

This Afternoon through Tonight: Expectations are for an overall
increase in scattered showers through the afternoon and evening
as the MCV moves through. Given low instability levels, a few
thunderstorms could occur, but no severe weather is expected.
The highest pops will be centered east of the Mississippi River
through tonight per latest HREF guidance. Overall additional
rainfall amounts have come down from previous updates. However,
a few pockets of 0.5 to 1 inch could still occur given slow
storm motions. While river flooding remains, we think that any
additional flooding will be localized, and we have cancelled
the Flood Watch early. Behind the MCV and associated frontal
boundary, northerly winds and low clouds will develop tonight.

Thursday: An area of smoke currently across the Great Lakes
(where vis is 3-5 miles) may move down into the area during the
day. This can be seen in the HRRR near-surface smoke tool.
Concentrations look low at this time and have just gone with
hazy skies, but this will likely be refined with future
updates. Otherwise, HREF cloud cover probs suggest that partly
cloudy conditions and northeast winds will prevail, which will
likely keep highs in the 70s with lower dewpoints.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Issued at 230 PM CDT Wed Jul 30 2025

Friday through the weekend: Ensembles continue to be in strong
agreement that a pattern change will occur with the upper level
high getting shunted farther southwest, with northwest flow
aloft developing over our area. This will allow for a much
cooler and drier air mass to continue to move into the area
Friday into the weekend. NBM high temp spreads are quite small
(2-4 deg) for the weekend. The ECMWF Shift of Tails tool is
showing a signal for anomalously cool highs/lows which leads to
high confidence in highs in the 70s and lows in the 50s. This
is 10 degrees below average for late July. There are actually a
few climate sites that are within three degrees from record low
temps Friday night into Saturday morning! This will be a welcome
change from the previous hot and humid conditions experienced
the last week.

Early next week: Ensemble cluster analysis does show some signs
of a weak precip signal as some energy could approach from the
northwest. However, pops thus far remain below 30 percent
Monday and Tuesday. A slight warming trend should occur as mid
level heights and thicknesses begin to rise.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1240 PM CDT Wed Jul 30 2025

Best chance for additional thunder this afternoon will be across
SE Iowa, so have opted to include a TEMPO at BRL. Latest hi-
res models guidance has trended down with prospects of thunder
at CID/MLI/DBQ, though isolated storms remain possible. Cigs
trend MVFR through the afternoon, with most sites dipping to low
MVFR/IFR later this evening/overnight. SE departure of a
stationary boundary will allow for improvements to VFR starting
with CID/DBQ and ending with MLI/BRL heading into Thursday
morning.

&&

.HYDROLOGY...
Issued at 1142 AM CDT Wed Jul 30 2025

An additional 1-3 inches of rain has fallen in the headwaters and
within several river basins across the hydrologic service area (HSA)
over the past 24 hours. This rain combined with previous day`s
rainfall totals has resulted in more rises on most tributary rivers.
The morning forecasts from the North Central River Forecast
Center has prompted new river flood warnings and flood watches
for several points along the Cedar, Iowa, Skunk, Wapsipinicon,
and the mainstem Mississippi downstream of Keithsburg. Since the
Cedar River at Vinton has not responded yet to recent rainfall,
have decided to hold off on issuing a river flood watch for now
but will need to monitor through the evening for any updates.

The height and timing of the crests on the rivers will be largely
dependent on how quickly and how much runoff goes into the rivers.
In addition, another 0.5-1.5" of QPF is forecast in the next 24 hrs
which if verifies, could bring faster rises and higher crests to the
tribs.

&&

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

&&

$$

SHORT TERM...Burchfield
LONG TERM...Burchfield
AVIATION...NWS
HYDROLOGY...Gross