472
FXUS63 KDVN 111825
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
125 PM CDT Fri Jul 11 2025

.KEY MESSAGES...

- An active day ahead, with additional rounds of showers and
  storms, some of which could become severe as a Slight Risk
  (level 2 of 5) remains for most of the area

- There is also a risk of flash flooding due to heavy rainfall potential.
  Flash flooding will be most likely for locations that saw
  copious amounts of rainfall Thursday, especially for low-lying
  and urban areas. River flooding may also become a concern.

- Seasonal temperatures and humidity levels will continue into
  next week, with above average temperatures possible for early
  next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 354 AM CDT Fri Jul 11 2025

An active day is on tap across the area over the next 24 hours as a
few waves of heavy showers and thunderstorms move through. After an
active evening, with heavy rainfall leading to an estimated 2-4+
inches of rain, some locations are vulnerable to flash flooding
later today. The culprit for this active pattern are a few distinct
mid-level shortwaves moving through the area. The first is currently
moving through east-central into northeastern Iowa this morning,
with a second, more pronounced shortwave moving through the area
this afternoon and evening. This morning, a warm frontal zone is
evident in both the surface temperatures and wind field, which will
act as an area of convective development for this morning. The
southerly flow has helped result in PWAT values around 2 inches per
the 11.00z DVN RAOB. Let`s break down the hazardous weather threats
below:

* FLASH FLOOD THREAT

As the afternoon/evening shortwave moves through, an attendant cold
front looks to accompany the shortwave, which should help pool
moisture along the boundary. Latest guidance suggests surface dew
points likely to increase to around the lower to middle 70s, so it
will be quite muggy outside. Additionally, the 11.00z HREF ensemble
and GFS/NAM global models all suggest PWAT values this PM between
1.8 to 2.2" (perhaps even higher if the NAM is correct). These
values would be near the daily maximum for PWATs per the SPC
sounding climatology! Obviously, copious moisture for the storms to
tap into. With several inches of rainfall already fallen last night,
the signal in the latest HREF is very concerning as the 24-hour QPF
PMM values from 12z this morning to 12z Saturday suggests widespread
rainfall totals of 2-4", with the LPMM suggesting even higher
isolated values than that possible (5-7 inches of additional
rainfall not out of the question for isolated areas, although this
is on the higher end of the model spectrum). Additionally, another
concerning aspect of today`s rainfall is the orientation of the
Corfidi forward-propagation vectors parallel to the boundary as the
CAMs depict a more linear convective mode this afternoon, which
should support training convection. Thus, we will continue the Flood
Watch over most of the area through 1 AM tonight when the bulk of
the rainfall should be done with. We did expand the watch slightly
to include the reminder of southeastern Iowa into west-central
Illinois. Keep a very close eye on the location of storms today, and
if they impact similar areas that saw copious rainfall yesterday,
there will likely be more flash flooding issues, especially for low-
lying areas and urban areas, which could eventually result in river
flooding.

* SEVERE WEATHER THREAT

SPC has maintained a Slight Risk (level 2 of 5) of severe weather
across most of the area today. The convective parameter space
continues to show ample instability, with values progged around 2000
to 3000 J/kg south of the warm frontal zone. Unlike the last few
severe weather days prior to yesterday, today will have more dynamic
support, thanks to deep-layer shear around 30 to 40 knots and
stronger 700 mb flow from the southwest today. Steep low-level lapse
rates in this environment could be supportive of damaging winds in
the form of wet microbursts. One additional concern for severe
storms today is the fact that the 0-3 km bulk shear orientation and
magnitudes would be supportive of QLCS mesovort tornadoes, if any
surges or bows extend to the northwest to allow for more line-normal
orientation of the shear (magnitudes around 30-40 knots possible per
the RAP). With this said, we can`t rule out a few embedded tornadoes
within the linear convection.

As we get into the late evening and overnight hours tonight, the
shortwave should move off to the east of the region, resulting in a
gradual decrease in storm coverage. Can`t rule out some lingering
showers and storms, but the severe threat should gradually come to
an end.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 354 AM CDT Fri Jul 11 2025

With the main trough expected to push east of the area by Saturday
afternoon, only isolated to widely scattered thunderstorms are
forecast over our southeast. Temperatures will otherwise remain
seasonal. Sunday will likely remain dry with overall beautiful July
weather for the region. Temperatures heat up into the 90s Monday and
Tuesday ahead of our next weather system that should bring the
return of rain chances by the middle of next week. Temperatures will
return to near normal before a potential cold front later in the
week brings cooler temperatures to the area. Below normal
temperatures in the upper 70s may be possible towards the end of the
week.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1212 PM CDT Fri Jul 11 2025

VFR conditions and southeast winds are expected during the early
afternoon. A few showers and thunderstorms have developed near and
north of CID and DBQ. Brief aviation impacts and VCTS are possible
through early afternoon. As the afternoon progresses, thunderstorm
development is expected near western terminals initially. Scattered
thunderstorms may proceed a stronger line of thunderstorms that
moves east across the region this afternoon and evening. Gusty and
variable winds are expected with these thunderstorms. MVFR
visibility and ceilings are likely with thunderstorms with
reductions to IFR ceilings and visibility possible at times. Behind
these thunderstorms late this evening, rain may linger along
with MVFR ceilings. Fog is expected to develop across the area
once rain ends with MVFR visibility with MVFR or IFR ceilings
after midnight. Eventual clearing will arrive towards the end
of the TAF period.

&&

.HYDROLOGY...
Issued at 107 PM CDT Fri Jul 11 2025

What is NEW...

Flood watches have been issued for the Wapsipinicon River near
DeWitt and for the Mississippi River from Gladstone, IL (L/D 18) to
Burlington, IA.

Discussion...

Bands of heavy rain fell across eastern Iowa and northwest and
west central Illinois. Rainfall ranged from 1 to 4 inches with
3-4+ inches in the bands of heavier rainfall. The urban areas of
Dubuque and the Quad Cities were hit hard with heavy rainfall
last night and are especially at risk for flooding.

Most of the area is abnormally dry or in moderate drought and
transpiration from agricultural fields is near maximum.

As of right now river gages are showing little to no increases
suggesting a good chunk of last nights rainfall appears to have
soaked into the ground. However, another round of heavy rainfall
is expected late this afternoon through sunrise Saturday. Early
estimates suggest another 1 to 3 inches of rain occurring with
pockets of 3+ inches possible due to PWATs above the 90th
percentile.

If the heavier bands of rain occur in roughly the same areas as
last night, then considerable runoff will occur due to soils
being near saturation. If the heavier rain occurs in areas that
received less rainfall last night, then a good portion of the
rain may soak into the ground.

Regardless of which scenario occurs, baseline ground water flow
will increase and eventually reach area waterways. As a result,
area rivers are forecast to see general within bank rises over
next next 5-7 days. If the upcoming round of heavy rain occurs
in areas that have saturated soils, then portions of some rivers
may reach flood stage.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Flood Watch until 1 AM CDT Saturday for IAZ040>042-051>054-
     063>068-076>078-087>089-098-099.
IL...Flood Watch until 1 AM CDT Saturday for ILZ001-002-007-009-
     015>018-024>026.
MO...None.

&&

$$

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