361
FXUS63 KDVN 171029
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
529 AM CDT Sat May 17 2025

...Updated for 12z Aviation...

.KEY MESSAGES...

- Near to mostly below normal temperatures through next week.

- Active pattern ramps up Monday into Wednesday with high rain
  chances and widespread beneficial soaking rain with the
  potential for locally heavy rainfall. Severe weather potential
  remains uncertain.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 330 AM CDT Sat May 17 2025

Upper level water vapor imagery shows a broad area of low
pressure shifting eastward from Minnesota into Wisconsin.
Cloud cover is most prominent north of Hwy 30, but we`ll
likely see it fill southward with solar insolation in the
cyclonic flow/caa regime today leading to partly sunny/
mostly cloudy skies. A few sprinkles can`t also be ruled
out north of I-80 with some glancing weak vorticity, but
most of any very light rain/sprinkles will shift across
parts of Wisconsin. Gusty winds will linger as well today,
though not quite as windy as Friday but still expect gusts
25-35+ kt. Highs will be a challenge pending cloud trends and
amount of sun peaks, but generally anticipated to range from
around 60 north to around 70 south. If clouds were to remain
entrenched most of the day north then highs would be limited
to the mid/upper 50s in some spots, while across the south
if more sunshine occurs then more lower to mid 70s would be
possible. Either way, a cooler and refreshing feel after the
past few days of summerlike warmth for many.

Tonight, as the low pushes further east through the Great
Lakes it will allow high pressure to begin building in.
This will bring a decrease in clouds and diminishing winds
setting the stage for a rather cool night with lows mainly in
the 40s. Can`t rule out some upper 30s in drainage spots in
parts of northeast Iowa.

Sunday looks like a fantastic day with lots of sunshine, light
winds and highs mainly in the 70s, as high pressure remains
in control.

Sunday night, high pressure will quickly retreat allowing for
return flow/warm advection to commence. This increase in
isentropic ascent will foster some shower and storm chances
late south of I-80. May have some small hail potential to
monitor with any storms.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 330 AM CDT Sat May 17 2025

Early to mid week the pattern continues to look wet and promising
for widespread beneficial soaking rains, as western CONUS
energy forms a closed upper low that meanders across the central
CONUS. A persistent southerly low level flow will lead to an
entrainment of Gulf moisture (PWATs ramping to near 1.5 inches,
which would be above 90th percentile for all DVN raobs for Mon
May 19th and Tue May 20th per SPC sounding climatology) and
fairly persistent bouts of low to mid level moisture convergence
resulting in periodic rounds of showers and storms. Strength
of forcing suggests at least rainfall accumulating to near the
PWAT, or roughly 1 to 2 inches widespread between 06z Monday
and 12z Wednesday, but with convection and persistent moist
conveyor and slow moving system for repetitive rounds it`s
possible to see locally higher amounts of 3-4+ inches. Latest
NBM shows probabilities of 40-60% for >2 inches of rain over
72 hour period ending 12z Wednesday for areas roughly along and
south of Cedar Rapids to Quad Cities line with the highest
probabilities focused across far SE Iowa, NE Missouri and WC
Illinois. Much of the area is in abnormal dryness to moderate
drought per the latest U.S. drought monitor and could really
use 2-3+" of rain. One thing to watch for is the likelihood of
MCS activity to our south mainly the next few nights along the
retreating warm front, and whether or not this convection will
hamper the poleward progress of the retreating warm front and
subsequently alter where the heavier rains occur. Severe
weather potential is being monitored but of low confidence due
to clouds, rain and cooler temperatures and may be mostly
elevated convection and a hail threat potentially, although
Tuesday could have some surface based threat possibly ahead of
the mid level trough and triple point. Want to stress though
that there`s plenty of uncertainty on the extent of instability
and the track/timing/strength of the trough. Stay tuned as we
continue to fine tune this potential over the next few days.

For the late week period we look to see the low shift east
with high pressure building in. This looks to bring nice
weather with moderating temperatures heading into the Memorial
Day holiday weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 525 AM CDT Sat May 17 2025

Combination of wrap-around moisture with low pressure over Wisconsin
and surface heating in cyclonic flow/CAA will support low
clouds and MVFR to VFR ceilings (1500-3500ft agl) today. This
afternoon through evening will see clouds decreasing from
southwest to northeast in dry air and building subsidence. Gusty
W/NW winds at 15-30+ kt will turn light tonight, as high pressure
begins to build in.

&&

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

&&

$$

SHORT TERM...McClure
LONG TERM...McClure
AVIATION...McClure