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135
FXUS63 KDVN 200726
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
226 AM CDT Fri Sep 20 2024

.KEY MESSAGES...

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- Above normal temperatures through Saturday then at or slightly
  below normal temperatures next week.

- The weather pattern will remain active over the weekend and
  into early next week with several chances for rain.
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&&

.SHORT TERM /THROUGH TONIGHT/...
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Issued at 225 AM CDT Fri Sep 20 2024

Weak frontal boundary with isolated to scattered convection will
push east of the Mississippi by sunrise and clear the area by mid-
morning. Most areas are expected to remain dry through sunrise.

Otherwise expect another day of well above normal temperatures for
Friday with somewhat humid conditions. Peak afternoon heat indices
will be in the mid to upper 80s.

Tonight will be mainly dry for the area as return flow brings
moisture back into the area ahead of an approaching weak storm
system. Far northeast Missouri and parts of southeast Iowa may see
isolated to scattered convection (20-30 percent) moving into the
area a few hours prior to sunrise Saturday.
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&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
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Issued at 225 AM CDT Fri Sep 20 2024

Saturday through Monday night
Assessment...medium confidence on rain chances

The global models shows the upper low over the western CONUS
ejecting into the Plains over the weekend with at least two weak
storm systems moving through the area.

While there are some timing differences between the models, both the
deterministic and ensemble runs paint some QPF across the area in
the Saturday through Monday night time frame.

Now this will not be a washout. There will be many hours of dry
weather. However, the timing differences suggest continuous pops
from Saturday through Monday night.

The model consensus does appear to be targeting two different time
frames as the most likely for rain; late Saturday night into Sunday
morning and late Sunday afternoon/night. Here the model consensus
has 70-90 percent rain chances (Saturday night/Sunday AM) and 50-70
percent rain chances (Sunday afternoon/night).

Outside of the suggested prime times for rain, the model consensus
generally has 30-40 percent rain chances (Saturday and Monday/Monday
night).

Tuesday through Thursday
Assessment...low to medium confidence on dry conditions. Medium to
high confidence on temperatures at or slightly below normal.

The model consensus has dry conditions across the area with at or
slightly below normal temperatures.

The global models generally agree that an upper low will develop
across the eastern CONUS but disagree on where it will form.

The ECMWF develops the upper low over the Great Lakes and keeps it
there into the following weekend. The CMC develops it in the central
Plains and slowly moves it into the Midwest. The GFS develops it
over the upper Midwest and drops it southeast into the Ohio Valley.

The ECMWF solution would be more supportive of mainly dry conditions
across the area. THe CMC/GFS solutions would suggest periods of dry
conditions but with the potential for diurnal cycles of showers and
possibly a few thunderstorms. IF the CMC/GFS solutions end up being
correct then low pops (20-30 percent) would be appropriate during
the afternoon and early evening hours of Tuesday through Thursday.

The overall theme of at or slightly below normal temperatures is
reasonable given the proximity of the upper low to the area.
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&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1228 AM CDT Fri Sep 20 2024

Weak frontal boundary with SHRA/TSRA associated with it will
move through eastern Iowa and northern Illinois through 18z/20.
Brief MVFR/IFR with SHRA/TSRA through 12z/20 but otherwise VFR
conditions will be seen through 06z/21.

&&

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

&&

$$

SHORT TERM...08
LONG TERM...08
AVIATION...08