809
FXUS63 KDVN 191110
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
610 AM CDT Sat Sep 19 2026

...Updated for 12z Aviation...

.KEY MESSAGES...

- Heavy rain and thunderstorms are likely for portions of the
  area this morning and again this evening into the overnight.
  Localized flash flooding is the primary concern. Rapid rises
  on small creeks and streams and the flooding of low-lying
  areas are possible.

- The ongoing Flood Watch has been expanded southward a few
  counties across east-central Iowa and far northwestern
  Illinois, and all of it extended through Sunday morning.
  Rainfall totals of 1-3 inches are still likely (60-80%) in
  these areas with the potential for localized areas/swaths of
  3+ inches.

- The Marginal Risk for isolated severe storms has been removed
  for much of the area except far southeast Iowa and northeast
  Missouri.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 305 AM CDT Sat Sep 19 2026

Looking at the latest water vapor and upper analysis, notice a short
wave trof acrs western into central IA, and another one lurking
further upstream acrs north central NM. Messy sfc wave with multiple
trofs and boundaries pushing east acrs the MO RVR Valley ATTM, and
as the feature ridge-rides east-northeast acrs IA today it will try
to pull up a warm front through the local CWA at the day progresses,
how far north it gets is still a question...I-80 may be it by late
afternoon. This will make high temps today a challenge with
areas north of the front in clouds and held in the 70s, while
areas in the south may get into the low to mid 80s with cloud
breaks. Very unseasonable airmass already in place with high sfc
DPTs and 2+ inch PWATs(3-4 sigma) in convergent flow currently
along and north of the CWA. The ongoing showers and storms ahead
of the nearby wave will continue to either seep down from the
north or move in from the west with bouts of heavy rain mainly
along and north of the Hwy 30 corridor through mid morning. Then
maybe a bit of a precip lull during the late morning and early
afternoon, but with boundaries and sfc waves on the move acrs
the area there will probably be isolated to sctrd precip
perculating all day.

Agree with SPC pulling most of the Marginal Risk out of the local
area for day 1, although an isolated severe precip loaded downburst
or gravity wave enhanced downward wind thrust is still possible
today and tonight. Heavy rain and localized flooding remain the
primary concern. The advertised 1-3 with localized 4+ inch rainfall
amounts by Sunday morning still look on target where repeated
showers/storms occur with this kind of PWAT feed.

Tonight...the above mentioned NM wave or some vort max/MCV will look
to roll up out of the southwestern plains and ridge-ride it`s way
acrs IA and northern MO through Sunday morning. Pre-system
southwesterly 25+ KT LLJ will again feed and converge high THTA-E
air up acrs the region fueling more west-to-east oriented convective
bands. LLVL boundaries aligned the same way will be the focus, and
it`s tough to say exactly where they will lay out but the latest CAM
type ensembles suggest maybe along the I-80 corridor. Heavy rain and
flash flooding will continue to be a concern along any storm
training axis and with some uncertainty on placement and all these
convective rounds adding up, have gone ahead and both extended the
ongoing flood watch through 12z Sunday, as well as added some more
counties to the south of the original headline to include the Cedar
Rapids and Quad Cities metro areas for urban flooding potential. The
next shift during the day will have to assess the need to expand
further west and south depending on focal boundary placement and
trends. Some transient fog may occur in precip lull windows this
morning and then again late tonight. Low temps an after-thought but
most of the area to get down in the 60s.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 305 AM CDT Sat Sep 19 2026

Sunday...A cooler cloudy and post-frontal day with ongoing lift up
and over the LLVL baroclinicity which should be settling off to the
south of the DVN CWA. Increasing north to northeasterly boundary
layer(BL) winds with some spotty rain will make for not a very nice
day with a lot of the area held down in the 60s to low 70s. With the
upper wave still moving acrs the area, suppose some isolated
thunderstorms possible as well as nuisance funnels.

Monday through Friday...Quick look at the longer range suggests that
the large upper low/wave currently centered over southern ID will
roll eastward acrs the northern plains and toward the upper MS RVR
Valley through Tuesday. This may keep cloudy, cooler weather going
acrs the area as well as sctrd showers for the early next week
period. As this upper wave fills and pulls off to the east, there
may be a mid week precip lull until medium range ensemble indicated
next passing trof brings the next precip chances by Thu night or
next Friday. Cooler temp regime still looks to last much of the
week.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 559 AM CDT Sat Sep 19 2026

Rounds of showers and storms are expected throughout the period.
BRL may be predominantly VFR with transient bouts of MVFR/IFR
in showers/storms at times. Elsewhere, predominantly MVFR to
IFR conditions are expected in lower clouds and periodic
showers and storms. Timing of the precipitation remains the
greatest challenge. Winds will also be challenging. Initially
with the passage of an outflow enhanced boundary they will
start out from the NE to E around 10 kt with higher gusts.
Then, a low pressure system ripples in from the west during the
afternoon causing this boundary to return north winds will
increase from a southerly direction. Winds then go variable by
evening with the wave passing through. There may also be some
transient bouts of MVFR/IFR fog mixed in tonight with any precip
lull in the weaker wind regime. Late in the TAF winds may increase
from the NW to N at CID and DBQ.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Flood Watch through Sunday morning for IAZ040>042-052>054-
     065>068.
IL...Flood Watch through Sunday morning for ILZ001-002-007-009-015.
MO...None.

&&

$$

SHORT TERM...12
LONG TERM...12
AVIATION...McClure