061
FXUS63 KDVN 150459
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1159 PM CDT Sat Sep 14 2024

...Updated for 06z Aviation...

.KEY MESSAGES...

- Continued above normal temperatures with with potential for
  above normal temperatures into the first third of October.

- The best chances for any measurable rain look to be next
  weekend when a cold front moves through the Midwest. The
  timing of that front may depend upon when and if Helene forms.

- There is a signal suggesting the potential for below normal
  precipitation into the first third of October.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 225 PM CDT Sat Sep 14 2024

Isolated showers/sprinkles or even a thunderstorm may develop during
peak heating this afternoon that will dissipate with sunset.
Satellite does show developing cumulus mainly south of I-80 and
concentrated around the Mississippi River. Trends with the HRRR/RAP
have been pointing to this area for possible diurnal convection late
this afternoon.

Areal coverage of any convection that develops this afternoon would
be around 10 percent so a majority of the area will remain dry but
somewhat humid.

Sprinkles or isolated showers may develop late tonight west of the
Mississippi in an area of weak convergence over the western third of
the area. Again, coverage on any precipitation would be 10 percent
at best.

On Sunday another warm and somewhat humid day will be in store for
the area. Some sprinkles or isolated showers may or may not occur
west of the Mississippi during the morning. Another round of
sprinkles or isolated showers are expected to develop during peak
heating for areas mainly west of the Mississippi in the afternoon. A
rogue thunderstorm cannot be ruled out.

&&

.LONG TERM /SUNDAY THROUGH SATURDAY/...
Issued at 225 PM CDT Sat Sep 14 2024

Sunday night through Thursday
Assessment...medium to high confidence on continued dry conditions.
High confidence on above normal temperatures.

The model consensus has dry conditions across the area as a strong
surface high remains over New England and southern Canada with an
upper level high in the eastern Great Lakes. If Helene does develop
off the southeast coast, that would result in a rex block over the
eastern CONUS and slow or stall systems ejecting from the trof over
the western CONUS.

The net result is temperatures well above normal with little if any
rain.

Thursday night through Friday night
Assessment...low to medium confidence on rain chances. High
confidence on above normal temperatures.

The overall trend of the model consensus has been to slowly back off
on the rain chances Thursday night through Friday night. As
mentioned earlier if Helene does develop by early next week it would
help develop a blocking pattern and slow down or stall any systems
coming out of the trof over the western CONUS.

Given the NHC probability of Helene developing is now at 40% (next
48 hours) and 50% (next 7 days) it would be reasonable to expect the
rain chances for Thursday night through Friday night will continue
to slowly decrease as next week progresses.

Saturday
Assessment...medium confidence on rain occurring. High confidence
on above normal temperatures.

The model consensus has 20 to 30 percent chances for rain with the
higher chances west of the Mississippi. Again, the trend of the
model consensus has been to slowly lower the rain chances.

The deterministic runs of the CMC/ECMWF keep the area dry through
Saturday night while the GFS has some rain west of the Mississippi.
The CMCE/EPS/GEFS have several members that are more robust with
rainfall and thus are contributing to the increased but trending
down of pops for Saturday.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1155 PM CDT Sat Sep 14 2024

Light winds, thinning clouds and abundant low level moisture aided
by recent rainfall in some areas may foster some patchy IFR/MVFR
fog potential through daybreak. Confidence on development at the
terminals however is too low for mention, but will continue to
monitor trends and update if needed. Otherwise, additional widely
scattered convection (15-30%) is once again possible Sunday later
afternoon through early evening. This too is of lower confidence
on occurrence at terminals and thus precludes mention at this time.
Brief MVFR and gusty winds will be possible in/near any convection.

&&

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

&&

$$

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