773
FXUS63 KDVN 120030
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
Issued by National Weather Service Duluth MN
730 PM CDT Fri Jul 11 2025

.KEY MESSAGES...

- Flash Flooding will continue across much of eastern Iowa and
  into northwest Illinois tonight.

- An Enhanced Risk (Level 3 of 5) of severe weather is expected
  this evening. Damaging winds are the primary hazard. A few
  tornadoes and large hail can not be ruled out.

- Quieter weather arrives this weekend with only isolated
  thunderstorms. Temperatures begin to increase next week ahead
  of our next weather system by the middle of the week.
  Increasing thunderstorm chances are expected with this next
  system.

&&

.UPDATE...
Issued at 722 PM CDT Fri Jul 11 2025

Very heavy rainfall and flash flooding will continue this evening as
thunderstorms train along a very slow moving frontal boundary. With
strong moisture advection converging into this boundary with the low
level jet, precipitable water values around 2.00 inches, and very
slow Corfidi vectors indicative of backbuilding, training
convection, all ingredients are in place for a continued and
potentially worsening flash flood threat across eastern Iowa and
northwest Illinois this evening. The zone of greatest concern is
from the Memphis, Keokuk, Macomb, Fairfield and Mount Pleasant
areas, northeast through the Quad Cities, Geneso and Morrison
areas. An additional two to three inches of rainfall are
expected for these locations, with locally higher amounts. The
dangers of flash flooding at night will also become a concern
when it is harder to see. NEVER DRIVE INTO WATER COVERED ROADS
OR GO NEAR FAST MOVING WATER.

Did expand the Flood Watch to the remaining southern tier of
counties from Memphis, Missouri east through Macomb, Illinois.
The southern portion of the Watch will be in effect until 400am
CDT Saturday.

Regarding the severe threat, the primary hazard will be damaging
winds from established cold pools and water loading, with the
secondary threat being tornadoes from the QLCS with
mesovorticies.


&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 126 PM CDT Fri Jul 11 2025

Several locations across the area received 2 to 4 inches of rainfall
over the last 24 hours. This will contribute greatly to the expected
hazards through tonight. In the meantime, a decaying area of showers
and thunderstorms continues to lift northeastward out of our region.
A positively-tilted shortwave trough is situated over the central
Great Plains and is expected to progress eastward through this
afternoon and evening. Late this morning and early this afternoon,
pockets of sunshine allow for rapid daytime heating and
destabilization. Temperatures reach the middle to upper 80s along
and south of Interstate 80, with upper 70s and lower 80s to the
north where clouds linger. This sets the stage for a very active
afternoon and evening.

With the approaching trough and afternoon destabilization,
thunderstorm development is expected near convective outflow from
morning thunderstorms across our north and ahead of the approaching
trough to our west. These thunderstorms are forecast to develop in a
favorable environment for severe weather and flash flooding. As
such, the Storm Prediction Center has upgraded to an Enhanced Risk
(Level 3 of 5) over the area. Convectively-enhanced low-level winds
support curved hodographs that favor supercell development
initially. These supercells will pose an all hazards threat, with
damaging winds, marginally large hail, and even a few tornadoes
possible. Flash flooding will be another hazard. Low-level winds
favor continuous moisture transport from the southwest into our
area, alongside an already deep-saturated airmass. Given weak and
backed upper-level winds, high-precipation rates are expected. 2 to
4 inch per hour rainfall rates are probable. As the afternoon and
evening progresses, additional thunderstorm development and gradual
upscale growth into lines of thunderstorms is anticipated. This
upscale growth will transition the hazards to a primary threat of
damaging winds and flash flooding as cold pools congeal. With that
said, a couple tornadoes can not be ruled out. Slow movement and
training of thunderstorms appears likely. Weaker upper-level winds
and shear vectors generally in the same direction as thunderstorm
orientation supports prolonged heavy rainfall. With this
expectation, widespread additional rainfall of 1 to 3 inches is
forecast with locally higher amounts possible. A Flood Watch is in
effect for much of the area as a result due to this threat of flash
flooding and river flooding.

Late tonight and into early Saturday morning, thunderstorms
gradually shift eastward, along with the trough and precipitation
tapers off by midnight with any lingering showers and thunderstorms
dissipating after midnight. Patchy fog may develop behind this
rainfall with plentiful moisture and cooler temperatures filling in
behind this activity. Temperatures cool into the upper 60s by
Saturday morning as remnant clouds continue to linger.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 126 PM CDT Fri Jul 11 2025

With widespread cloud cover and rain-cooled air lingering Saturday
morning, comparatively quieter weather is anticipated for Saturday.
With that said, at least a few afternoon thunderstorms can be
expected during the mid-afternoon before everything clears to the
east by evening. Temperatures reach the middle 80s across the area
on Saturday. Cooler temperatures continue on Sunday, with morning
temperatures down into the lower 60s and afternoon temperatues
reaching the middle 80s once again. Mostly sunny skies offer up
beautiful weather to end the weekend. Temperatures climb back into
the upper 80s and lower 90s to start the week under mostly sunny
skies and ahead of our next system. Heading towards the middle of
the week, our next weather system brings increasing thunderstorm
chances and cooling temperatures. A cold front could bring upper 70s
and lower 80s to the area late in the week.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 722 PM CDT Fri Jul 11 2025

Widespread thunderstorms this evening across eastern Iowa and
western Illinois with MVFR to IFR visibilities and wind gusts of 30
to 50kts with the strongest storms. Thunderstorms will decrease in
coverage from west to east between the 05Z and 08Z timeframe. Low
level stratus and fog is expected to expand across the area tonight
into Saturday morning with MVFR/IFR conditions. Ceilings will slowly
lift to MVFR by late morning on Saturday. Isolated to scattered rain
showers and thunderstorms are forecast with daytime heating on
Saturday.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Flood Watch until 1 AM CDT Saturday for IAZ040>042-051>054-
     063>068-076>078.
     Flood Watch until 4 AM CDT Saturday for IAZ087>089-098-099.
IL...Flood Watch until 1 AM CDT Saturday for ILZ001-002-007-009-
     015>018-024.
     Flood Watch until 4 AM CDT Saturday for ILZ025-026-034-035.
MO...Flood Watch until 4 AM CDT Saturday for MOZ009-010.

&&

$$