475
FXUS63 KDVN 111134
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
634 AM 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 /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 620 AM CDT Fri Jul 11 2025

As expected, what came out of central Iowa is in a decaying
phase this morning, with showers and the occasional rumble of
thunder expected through about 15z. After that, a wavy boundary
will be splayed out across eastern Iowa and it`s just a
question of when, not if the next round of thunderstorms and
heavy rain gets going. We didn`t change the timing much from the
going TAFs, with just some minor delays in TS arrival, nudging
TS timing closer to the HRRR. None of our terminals will miss
this round of thunderstorms. Confidence drops off considerably
for what will happen behind the storms Friday night. RAP
soundings certainly show a nearly saturated boundary layer,
which will spell the threat for fog/stratus. About 2/3rds of the
HREF members show sub 3k foot cigs developing by the end of the
period, so did start adding in some IFR conditions late Friday
night, though it`s still uncertain just how widespread these
lower conditions will be.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Flood Watch through late tonight for IAZ040>042-051>054-
     063>068-076>078.
     Flood Watch through late tonight for IAZ087>089-098-099.
IL...Flood Watch through late tonight for ILZ001-002-007-009-
     015>018-024.
     Flood Watch through late tonight for ILZ025-026.
MO...None.

&&

$$

SHORT TERM...Schultz
LONG TERM...Schultz/NWS
AVIATION...NWS