695
FXUS63 KDVN 181916
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
216 PM CDT Mon Aug 18 2025

.KEY MESSAGES...

-  The watch is on for the development of more thunderstorms
   this afternoon and evening, with some possibly strong to
   severe. Localized torrential rainfall leading to flash
   flooding is also possible.

- Mostly dry and more seasonal conditions are expected from
  later Tuesday and especially Wednesday through the upcoming
  weekend.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 210 PM CDT Mon Aug 18 2025

Tonight...In watching for the latest storm development this
afternoon and evening, the prime axis appear along a 3000+ J/kg
MLCAPE area from the STL area up through the central WI/IL border,
including the far eastern portion of the DVN CWA. A secondary area
may be along a MLCAPE gradient in the vicinity of a MCV from east of
DSM and acrs the northern 1/2 or so of the DVN CWA. This secondary
area along and north of I-80 is where several of the latest CAMs
light up convection over the next few hours. Will have to have POPs
to cover both areas and scenarios. With the high CAPEs and low
LCL`s, damaging wind gusts and a tornado are the prime concerns.
Near two inch PWAT`s in place support localized torrential rainfall
at high rates again, and thus a slow moving storm may be able to
flood. But effective shear is marginal at 20-30 KTs, and deeper
layer lapse rates are weak, so some things against a higher severe
threat. After mid evening, expect the convective activity to wane and
slip east/south into the overnight hours along with the migration of
the main frontal system. Light north winds should be CWA-wide by
dawn. But there are some signs of at least patchy fog development in
the north around dawn as well, but it may be more widespread toward
the MN/IA border region. Low temps in the lower 70s to upper 60s.

Tuesday...A day with increasing post-frontal influence and deepening
northerly fetch acrs the area. A low chance for an isolated shower
or storm in the heating of the day, but there may be a large field
of post-frontal clouds putting the clamps down on instability build
up and a high temp potential buster. A secondary short wave dropping
down in steepening northwesterlies may try to kick up isolated
showers acrs MN and WI Tue evening, with a low chance for some of
that activity try try and make it down into our north. Otherwise
clearing and continued with the cool advection for widespread low
temps down in the mid to upper 60s.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 210 PM CDT Mon Aug 18 2025

Largely dry conditions are expected for Wednesday through the
upcoming weekend, with perhaps our next chances of precipitation
coming Friday night as another front approaches the region.


&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1225 PM CDT Mon Aug 18 2025

Generally a VFR to MVFR mix of clouds along a boundary slipping
through the area. Sfc winds generally south to southwest, with
variable fluctuations along a couple of sfc boundaries hanging
around the area. There will be the chance for more isolated to
sctrd thunderstorms popping up this afternoon especially along
and north of the I-80 corridor into northwest IL. Some of these
storms may be strong to severe with damaging wind gusts and
sharply reduce VSBYs from locally heavy downpours. After the
late afternoon into evening storm risk, we should be VFR with
the sfc winds becoming north at 5-10 KTs into Wed morning. A low
chance for some MVFR fog at a few sites just before dawn.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Heat Advisory until 7 PM CDT this evening for IAZ067-068-
     076>078-087>089-098-099.
IL...Heat Advisory until 7 PM CDT this evening for ILZ009-015>018-
     024>026-034-035.
MO...Heat Advisory until 7 PM CDT this evening for MOZ009-010.

&&

$$

SHORT TERM...12
LONG TERM...Schultz
AVIATION...12