263
FXUS63 KDVN 101759
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1259 PM CDT Sun Aug 10 2025

.KEY MESSAGES...

- Several rounds of thunderstorms are forecast through Tuesday.
  Heavy rain is expected with storms now through Monday night.

- Flash flooding is the main concern through the next several
  days with a 25% for excessive rainfall. The strongest storms
  could produce torrential rainfall rates between 1-3" per hour
  and locally damaging winds.

- Widespread 2 to 4 inches of rain are possible through Monday
  with some areas receiving higher amounts.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 220 AM CDT Sun Aug 10 2025

Current radar shows some scattered showers forming across IA as
a warm front extends across the region early this morning.
Farther west there is a larger complex of storms along the NE
and MO border that are being driven east by a compact shortwave.
We may see some additional development within the warm sector
of the aforementioned warm front as our atmosphere remains quite
moist and surface dew points still hitting in the 70s. The main
show however will likely be associated with the thunderstorm
complex out west. A strengthening low level jet will further
aide in propelling this into our forecast area. While CAMs are
struggling with the current set up the HiResW-ARW seems to be
initializing the best and brings the storms into our western
borders after 5AM. The environment remains quite moist with
PWATs of around 2" which is around the 90th percentile of
climatology for this time of year. Sounding profiles showcase a
deep column of saturation with a warm cloud depth of over 12,000
ft which will lead to the efficient production of large
raindrops and higher rainfall rates. The latest HREF PMM
precipitation totals continue to favor areas west of the
Mississippi with totals ranging from 3-7." Unfortunately the
CAMs have a lot of descrepancies for initiation time leading to
a larger spread in solutions with an average spread of 2-3"
between the 25th and the 75th percentile. With this system
looking slightly more progressive then previous forecasted the
higher rain totals may be overly optimistic. Overall, the
atmosphere is primed for heavy rain. WPC has a 25% chance of
exceeding flash flood guidance draped through areas west of the
Mississippi.

The initial convective environment boasts higher instability
courtesy of our high dew points. But we are lacking in overall
bulk shear. Any storms firing off of the warm frontal boundary
will have a hard time getting any tilt for sustainability. Shear
profiles do start to improve as the shortwave and storms out
west approach in the morning. This would be the most likely time
for any severe storms to develop. Primary hazards would be
damaging winds and large hail.

While the main activity is largely expected to move off to the
east by the afternoon we maintain some higher PoPs through the
day. The environment remains very moist and capable of producing
scattered showers. Additionally, another potent shortwave is
projected to slide in from the west in the late afternoon and
evening hours. This will lead to another round of storms and
heavy rainfall. Depending on how much rain we receive from this
first set of storms the soils may be primed for quick runoffs.
For now, we will continue to maintain our Flash Flood Watch
through Monday morning. Severe weather threat will also still be
present with adequate shear and buoyancy to work with. The
primary threat will most likely be damaging winds from heavy
precipitation loading storms.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 220 AM CDT Sun Aug 10 2025

There remains some disagreement among the 00Z suite of
deterministic guidance for the overall departure of rain
chances. The NAM is the most progressive with having rain
chances tapering off completely on Monday as a cold front starts
to move in from the NW. However, this seems to be the outlier
with the other models showing a much slower progression in the
pattern. For the time being we will maintain PoPs of 30-50%.

Once this front moves through we will have a stretch of quieter
and cooler weather over the region. Highs will be in the low
80s on Tuesday and begin to gradually warm through the week.
Towards the end of the week southerly flow returns over the
region and high temperatures will begin to climb back into the
90s. The southerly flow will also promote an increase in
humidity with our heat index soaring back into the triple digits
by Friday.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1257 PM CDT Sun Aug 10 2025

Winds are shifting to the S to SSW this afternoon as morning storms
have moved out. A few showers in the early afternoon are possible at
southeastern sites. Models suggest a line or two of showers and
storms developing this afternoon, more likely in the southeast near
KMLI/KBRL. Heavy rain from today may contribute to fog formation
overnight, but fog will be limited in areas of broader low cloud
coverage. Rain is unlikely overnight through tomorrow morning and
winds remain 5 kts or less, leaving MVFR cigs the primary concern
mid to late morning, especially in the southeast.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Flood Watch until 7 PM CDT this evening for IAZ040>042-051>054-
     063>068-076>078-087>089-098-099.
IL...Flood Watch until 7 PM CDT this evening for ILZ001-002-007-009-
     015-016-024>026-034.
MO...Flood Watch until 7 PM CDT this evening for MOZ009-010.

&&

$$

SHORT TERM...Britt
LONG TERM...Britt
AVIATION...NWS PAH