081
FXUS63 KDVN 151923
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
223 PM CDT Sun Sep 15 2024

.KEY MESSAGES...

- Low (15-20 percent) chances for rain both Sunday and Monday
  afternoon

- Temperatures 5-10 degrees above normal through next weekend
  with mainly dry conditions.

- Confidence on rain late this week and weekend continues to
  lower with a potential blocking pattern developing over the
  eastern CONUS.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 221 PM CDT Sun Sep 15 2024

Isolated showers/sprinkles or even a thunderstorm are expected to
develop during peak heating this afternoon and dissipate with
sunset. Satellite shows developing cumulus mainly west of the
Mississippi and roughly concentrated in the I380/highway 218
corridors. Trends with the RAP have been pointing to this area for
possible diurnal convection late this afternoon.

Areal coverage of any convection that develops this afternoon looks
to be lower than yesterday so a majority of the area will remain dry
but somewhat humid.

After sunset quiet but somewhat humid conditions will be seen across
the area.

Another warm and somewhat humid day will be in store for Monday.
Although the signal is quite weak, another round of isolated showers
and possibly a thunderstorm may occur west of the Mississippi during
peak heating Monday afternoon.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 221 PM CDT Sun Sep 15 2024

Monday night through Thursday
Assessment...high confidence on above normal temperatures

If diurnal convection develops Monday afternoon it will quickly
dissipate with sunset leaving the area dry overnight. Otherwise the
upper level high retrogrades into the area which will keep the area
dry for much of the work week. IF a rogue SHRA/TSRA would develop
during peak heating during the afternoon hours, coverage would be 5
percent or less of the area.

Thursday night through Sunday
Assessment...high confidence on above normal temperatures. Low
confidence on rain chances

NHC probability guidance indicates Helene will have likely developed
earlier in the week and be a remnant low over the southeast CONUS by
late week. The system will help create a blocking pattern over the
eastern CONUS while a deep trof develops over the western CONUS.

The net result will be near meridional flow over the central CONUS
which will cause systems ejecting from the western trof to move more
north than east. This then raises the question regarding rain
chances from Thursday night into next weekend.

The trends with the QPF from the models and more of the ensemble
members has been to back off on the potential rainfall. Pops have
continued the trend of dropping but not as much as yesterday. Thus
the confidence on seeing any rainfall late this week and next
weekend is low.

Thus the model consensus does have 20-40 percent pops west of a
Freeport, IL to Quincy, IL from Thursday night through Saturday with
the better chances west of the Mississippi. However, with a
potential blocking pattern setting up I would not be surprised to
see the rain chances gradually lower during the week.

As for Saturday night and Sunday the model consensus has 20-35
percent pops for the entire area with the higher pops west of the
Mississippi. These pops continue the overall trend of going lower
compared to yesterday. Additionally, the predicted rainfall is also
lower as well which raises questions regarding the potential for
rain next weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1227 PM CDT Sun Sep 15 2024

Diurnal convection is again expected through 01z/16 across
mainly eastern and southeast Iowa. No SHRA/TSRA were included in
the 18z TAFs as the probability of a TAF site being impacted is
5 percent at best. Another round of even more isolated SHRA/TSRA
is expected after 18z/16 in southeast Iowa. Otherwise VFR
conditions will continue.

&&

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

&&

$$

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