384
FXUS63 KDVN 091049
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
549 AM CDT Wed Jul 9 2025

...12z Aviation Update...

.KEY MESSAGES...

- There is a daily risk of isolated to scattered showers and
  thunderstorms(20-40%) that will be most favorable in the
  afternoon and early evening. Thunderstorms later Thursday and
  Thursday night will have the potential to be stronger as a
  lead shortwave moves into the area. Strong storms with heavy
  rain again possible on Friday and Friday night.

- Seasonal temperatures and humidity levels will continue through
  the weekend and into early next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 315 AM CDT Wed Jul 9 2025

Today...Will continue to watch fog trends through dawn and issue a
headline if needed, otherwise will let the fog SPS ride or expand
that if warranted. Then the rest of the day looks to be a typical
mid July day with temps in the mid to upper 80s, some ambient CU,
and isolated pop-up showers and thunderstorms, buoyancy bubbles in
the afternoon heating. As yesterday, slow storm movement in a low
shear/light low to mid level vertical wind profile may allow for
very localized heavy rainfall and flooding.

Tonight...Any lingering isolated showers or storms will wane early,
then much of the night to be a lull period before the watch will be
on for for elevated return flow(convergent southwesterly 20 KT H85
MB winds) induced spotty showers and storms late toward dawn. Low
coverage and confidence in this sctrd linear line of precip
developing however...20 POPs. Some patchy fog possible again in
spots and low temps generally in the upper 60s.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 315 AM CDT Wed Jul 9 2025

Thursday...Ongoing high CAPE airmass of 2000-3000+ J/kg will look to
be acted upon by an approaching shortwave in broad west-
northwesterlies acrs the mid CONUS. Thus expect an uptick in sctrd
storm development as the day progresses, and storm layer effective
shear of 20-30 KTs will help the cause for strong to severe storms
if convective temps in the upper 80s can be reached. Damaging wind
gusts the primary threat, and PWAT`s of 1.5 to 1.8 inches again will
fuel locally heavy rainfall and localized ponding water or flooding.
The storm threat will continue into Thu night, with ensembles
showing a nice plume of 25+ KT southwesterly H85 MB LLJ flow acrs
the region with ample THTA-E advection.

Friday...Assessing the latest suite of medium range model solutions
and ensembles, there is more uncertainty now regarding storm
strength and coverage this day. The models have generally slow with
the incoming seasonably impressive short wave, possibly keeping the
potential for more organized storm systems off to the west of the
local area. Closer to home we may have to just deal with sporadic
storm development on the remnants of boundaries and discrepancy
gradients lingering out of Thu night, if the slower wave progression
verifies. Will have to keep solid chance POPs going however, but the
target time may be switching to late Friday night and especially
Saturday. There may be the scenario of an MCS developing upstream
off to the west and then propagating eastward into the area later
Friday night into early Sat morning. Then that effects the Sat
potential.

Saturday through Tuesday...Depending on the progressive nature of
the Friday wave as mentioned above, Saturday may be an organized
storm day if the models are on track with the slowed progression of
the main upper trof. Strong to severe storms look possible if we get
the CAPE build-up(no debris or MCS out of Friday night) to go along
with stronger shear profiles of 35-45+ KTs. Timing will be
everything and will continue to monitor the Friday into Saturday
period. Besides the severe threat, ensemble indicated PWAT feed of 2
to 2.3 inches either for Friday and/or Saturday make for flash
flooding concerns with the potential rainfall rates that the wind
shear and juiced air mass will produce(1-2" an hour). Current timing
thinking suggests Sunday into Monday to be a quieter and seasonable
period after whatever Fri-Sat system can make it through the
region.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 545 AM CDT Wed Jul 9 2025

Some fog of at least MVFR VSBY`s may still creep into the VCNTY
of some of the TAF sites through 8 AM CDT, otherwise a VFR TAF
cycle through the period with light sfc winds under a passing
ridge of weak high pressure. Will also keep with the idea that
while most the area will stay dry today, it will be another day
with the chance for an isolated shower or thunderstorm to pop up
in the heating of the day. Late tonight toward dawn, will have
to watch for more patchy fog especially on the IL side, and the
chance for a band of sctrd to isolated elevated showers or even
a thunderstorm to develop on the convergent nose of a
southwesterly LLJ.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...Dense Fog Advisory until 8 AM CDT this morning for ILZ001-002-
     007-009-016>018.
MO...None.

&&

$$

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