229
FXUS63 KDVN 261924
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
224 PM CDT Sat Apr 26 2025

.KEY MESSAGES...

- Seasonably warm conditions will continue tonight through
  Sunday, with highs back in the middle to upper 60s for most
  locations

- A significant severe weather outbreak is possible Monday
  across portions of the Midwest, with the most likely period
  of severe weather in our region being Monday evening and
  night, with lower confidence on storm coverage Monday
  afternoon

- Another round of widespread rainfall is forecast Wednesday
  night and Thursday

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 221 PM CDT Sat Apr 26 2025

Our quiet weekend continues tonight and Sunday, as an area of high
pressure over the Upper Midwest translates eastward over the central
Great Lakes region by Sunday morning. Mostly clear skies this
evening into the early overnight hours will lead to some cooler
temps tonight, with lows in the upper 30s northeast to the middle
40s southwest. Some locations, especially in low-lying areas over
far northwestern IL, could see some patchy frost tonight.

Sunday should see a bit more cloud cover compared to today, but dry
conditions are still expected for most, if not all, locations.
Southeasterly return flow on the western side of the high pressure
system will help conditions warm to the middle to upper 60s for most
locations, so a seasonably warm day on tap.

We could see some increasing chances of showers late Sunday night as
a weak mid-level impulse approaches the region ahead of a
strengthening nocturnal low-level jet, which should remain just to
the west of our region. Thanks to the associated cloud cover and
continued warm air advection, Sunday night lows will cool only to
the lower to middle 50s across the area.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 221 PM CDT Sat Apr 26 2025

The main focus for this forecast package continues to be on the
potential for a severe weather outbreak across the Upper Midwest for
Monday into early Tuesday. An upper-level longwave trough, which is
just beginning to come on-shore over the western CONUS this
afternoon, will continue to translate eastward this weekend. An
attendant surface low will undergo lee cyclogenesis over eastern
Colorado by Sunday afternoon and lift northeastward towards
northeast Minnesota by 7 PM Monday. Increasing theta-e in the warm
sector of the low will settle across our CWA Monday, resulting in
very warm and humid conditions. High temperatures Monday should warm
to the upper 70s to lower/middle 80s for most locations, with dew
points in the lower to middle 60s. This should result in ample
instability, with the GEFS ensemble indicating a 40 to 60 percent
chance of CAPE at or greater than 2000 J/kg. Strong southwesterly
flow throughout the column should also provide ample deep-layer
shear, as well, along with some veering winds in the lower levels
which will support some clockwise curvature in the low-level
hodographs. Other AI/ML fields also suggest a higher end severe
weather threat, so the forecast remains on track for a severe
weather outbreak across the Upper Midwest region.

There are a few things that remain uncertain with this severe
weather event:

1) Both the GFS and NAM model soundings suggest a capping inversion
near the 750-800 mb layer, with differing degrees of cooling of
strength to the cap. If the cap holds, this could result in more
limited severe weather coverage for us.

2) Timing of the cold front that will be the focal point of severe
weather. Later convection could have more difficulty becoming severe
due to less instability and/or more convective inhibition.

This is still a very potent system, so definitely bears watching.
With that said, SPC continues to keep areas along and northwest of a
line from Galena, IL to Sigourney, IA in a Moderate Risk (level 4 of
5) of severe weather, with an Enhanced Risk (level 3 of 5) for most
other locations in our CWA to the southeast. All hazards are
possible with this system, including tornadoes, so make sure to
you`re prepared for this severe weather threat!

Eventually, the cold front will move through our region sometime
late Monday night into Tuesday morning, bringing any lingering
severe weather risk to an end for us Tuesday morning. For Tuesday
afternoon onward, the pattern remains on the active side, but no
additional severe weather threat is expected at this time. Another
upper-level trough approaches the local region by mid-week, which
will bring more chances (50-70%) for Wednesday night into Thursday
morning.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1234 PM CDT Sat Apr 26 2025

VFR conditions are expected throughout the TAF period. Winds
will slowly turn more easterly this afternoon through tonight
as an area of high pressure moves to the east over the western
Great Lakes. Winds will eventually become southeasterly by
sunrise Sunday. Some high clouds will move through the area at
times.

&&

.HYDROLOGY...
Issued at 1244 PM CDT Fri Apr 25 2025

With recent bouts of heavy rainfall, and possibly more late in
the weekend and the start of next week, we are seeing some
rises along the upper basins of the Iowa, Wapsi, and Cedar
Rivers. These rivers will likley experience significant within-
bank rises. Some points and stretches of these rivers may also
surpass action stage into flood stage at the start of next week,
but uncertainty remains. Over the last 24 hours, the
precipitation observed was less than initially anticipated,
which resulted in decreases in the forecast rises on the rivers.
Although, there will be some chances for precipitation Saturday
night into Sunday, especially northwest of the area, along with
widespread rainfall potential on Monday-Tuesday. Thus, we may
continue to see these rises, with possibly more rivers to watch
out for when the time comes. At the moment, only two rivers
continue to show a forecast going into Minor Flood Stage. Thus,
we will continue the River Flood Watches for the Wapsi at De
Witt and the Iowa River at Marengo until confidence increases on
the flood potential.

&&

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

&&

$$

SHORT TERM...Schultz
LONG TERM...Schultz
AVIATION...Schultz
HYDROLOGY...Gunkel