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574
FXUS63 KDVN 231735
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1235 PM CDT Mon Sep 23 2024

.KEY MESSAGES...

- Cool weather is expected today with highs only in the upper
  60s to low 70s and a bit of rain possible in the south.

- Low confidence in the forecast regarding late this week into next
  weekend as an upper low interacts with the tropics in a
  blocking pattern.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 202 AM CDT Mon Sep 23 2024

While the cold front is moved through the entire CWA, the dry air is
still only in the northwest 2/3rds of the CWA early this morning.
While showers have moved out, the southeast counties continue to see
dewpoints in the upper 50s to low 60s, while the northwest is seeing
lower to mid 40s!  Low clouds continue in the southeast counties as
well, holding up temperatures into the low 60s at 2 AM, while the
northwest is falling into the mid 40s to around 50 at this time.

The moisture in the south looks to help light rain chances again
today, as another wave moves through Missouri. While significant
rains will be well south of us, there is enough forcing from that
wave to bring light rain chances as far north as Highway 34 today,
mainly in the afternoon. Tonight, this wave is forecast to allow a
closed low pressure from the surface to 850mb, and that should bring
stratiform rains in our southeast 1/2 of the CWA tonight into early
Tuesday.  There are several CAMS, as well as the GFS, that bring
moderate rainfall up as far north as the Quad Cities tonight, and
all of those models show a stronger 850mb low moving from northeast
Missouri through Chicago.  This is quite a bit farther north than
earlier runs, and is most favored if convection doesn`t form to our
south tonight, and that seems unlikely.  Still, a potential wet
night is in store in our southeast 1/2 with amounts of 0.05 to 0.30
possible. For now, were not going with high pop/low qpf yet, but
this could be the favored mode for tonight.

The cloud cover in the south today will keep locations coolest
south, warmest north, but with temperatures ranging from the upper
60s to low 70s, it`ll be a pleasant airmass in all locations.
Tonight, with greater cloud cover, lows mainly in the 50s are
forecast.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 202 AM CDT Mon Sep 23 2024

Some sprinkles may be possible Tuesday as an upper low moves over
the region, but any activity would be very light. This low is more
likely to bring cloud cover and hold temperatures down a bit. For
now, we`re going with upper 60s to low 70s again.

Wednesday into Thursday morning, we`re confident on dry,
pleasant weather, as ridging north of the southern closed upper
low is positioned over the area.

This upper low is expected to phase with a tropical low
Thursday night and Friday. While confidence on that phasing, as
well as any Fujiwara interaction will be low until that storm
actually takes shape, the broad long range forecast shows at
least some persistent rain chances Thursday night through the
weekend, along with temperatures in the 70s. The NBM mean
continues to show rather light QPF in this interaction, as do
most members of the GEFS output. However, there continue to be
some that show potential for a widespread rainfall event. Time
will tell on how these systems interact, and locking into any
one model on a interaction like this would be way too early give
this model spread.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
-- Changed Discussion --
Issued at 1220 PM CDT Mon Sep 23 2024

A tale of two aviation forecasts exists today. The first will
be the easy ones, focusing on CID and DBQ. These locations will
see a mix of clouds and sun today, but cloud cover should remain
above 3000 ft, with light easterly winds between 5-10 KTs.
Overnight, we will see a slight uptick in clouds, with winds
becoming light and variable. VFR conditions should prevail
through much, if not all of the TAF period for these locations.

MLI and BRL will pose some problems through today and tonight.
Currently at BRL, we are already observing an overcast MVFR
deck, hovering around 2000-2500 ft. This will continue through
the evening, with cigs dropping further (1000-1500 ft) as rain
starts to move into the area. Better chances for rain will begin
around 03z in our south, possibly reaching as far north as MLI
around 06z. Confidence is low on the northern extent of the
rain, but confidence is higher on at least observing MVFR cigs
at MLI similar to BRL. These cigs will continue through the
night, with winds also becoming light and variable at these
terminals. By 12-15z, we will see the rain chances start to
decrease as the surface low moves out, scattering the cigs. From
there, winds will be light and out of the north throughout the
forecast area.
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&&

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

&&

$$

SHORT TERM...Ervin
LONG TERM...Ervin
AVIATION...Gunkel