747
FXUS63 KDVN 171943
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
243 PM CDT Fri Oct 17 2025

.KEY MESSAGES...

- Periodic chances for showers and thunderstorms from late this
  evening through Sunday morning.

- Heaviest rainfall will fall east of the area, with Illinois
  counties seeing totals half an inch up to one inch of rain.

- Seasonable mid to late October weather is forecast for much
  of next week with no significant precipitation expected.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 243 PM CDT Fri Oct 17 2025

Complex upper level pattern a series of waves approach the area
in the short term. The first one moves through the area today
dragging a cold front across Iowa. This front will stall up as
another stronger shortwave moves NE into the area while a deeper
wave to our NW moves in. These two waves phase over the area
around 00z Sunday, leading to intense height falls and
subsequent rising motion. The majority of this will occur
outside of the short term period. The first wave will be
discussed below.

Overall forcing for the first wave is weak. Currently to our
west, good returns are seen on radar corresponding to a sfc
boundary with this wave. This boundary is expected to become
more diffuse as the wave moves east. The main forcing for ascent
will become the wave resulting scattered showers and even a
rumble of thunder tonight into the AM. Low-level moisture is
forecast to be low and thus likely impeding to actually rainfall
until early morning across the area. The best chance for rain
will be likely around 12z and after and along and east of the
Mississippi River. The storms tonight could have some small hail
with them, but severe weather is not expected.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Issued at 243 PM CDT Fri Oct 17 2025

Turning to Saturday evening into Sunday morning. Strong
dynamics, a sign of the change in seasons, overspreads the area.
140 to 150 meter 12 hour height falls at H5 will lead to
intense vertical motion. The height falls will move east the
area by 18z on Sunday. Looking to moisture, latest GFS has
slowed down on the front leaving the area. The deep moisture
looks to hang up along the Mississippi River in the afternoon
before moving east by 06z. This will give us a good 6 hour
window of deep moisture and ascent. CAMs are trending towards
convection, probably switching to largescale stratiform rain as
the front moves east.

Again, looking at the cold front being slower as cyclogensis
takes hold over our area during the evening on Sunday, there
remains a window where deep layer shear, and instability
overlap. CAMs are starting to show better chances for more
convection, especially along and east of the Mississippi River.
Looking at soundings, there is very good directional shear in
the llvls with not much speed shear. At the top of the profile
there is good speed shear. There is also around 140-160 J/kg of
0-3 CAPE. This means that ingredients are in place for updraft
organization. I still think we will be watching convection
during this time and would bet against severe weather, but can`t
rule it out.

Another deep upper trough is forecast to dig into the Midwest
and Great Lakes early next week with an attendant surface low
tracking north of the local area across the Great Lakes. After a
brief warm up ahead of the trough on Monday, cooler more
seasonable temperatures are expected for the rest of the week.
We`ll stay on the drier southwest flank of the early week
system, so rain chances will be on the low side for Monday
night into Tuesday. High pressure then returns for mid to late
in the week. We`ll have to watch for frost potential along/north
of Highway 30 Tuesday night, which will depend on how quickly a
surface ridge builds in behind the departing low. Latest NBM
has mid 30s for lows north of I-80, but again confidence is low
this far out.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1241 PM CDT Fri Oct 17 2025

VFR conditions are expected for the majority of the period as
MVFR vsbys are possible in showers overnight and towards
daybreak. Between now and then, gusty winds are the main threat
to aviation. Thunder was left out of the TAF due to low
confidence in timing/coverage. This could be added later.

&&

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

&&

$$

SHORT TERM...Gibbs
LONG TERM...Gibbs/Uttech
AVIATION...Gibbs