412
FXUS63 KDVN 120012
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
712 PM CDT Sun Aug 11 2024

.KEY MESSAGES...

- Active stretch of weather ahead of us, with near daily chances
  for precipitation somewhere in our area. Best chances for more
  widespread showers/storms will be midweek and beyond.

- Temperatures trending near normal by midweek, with most in the
  low-mid 80s.

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 131 PM CDT Sun Aug 11 2024

High pressure remains planted over the region through today, where
it will slowly start to slide east this evening and through tonight,
as a new wave emerges over the region. Currently, satellite data
suggests this wave is over the Central Plains, with the attendant
surface low developing. This will progress east tonight, with a push
of moisture working it`s way into our south. Some guidance suggests
the onset of precipitation quite early tonight, but given some
dry air to work through, I wouldn`t be shocked if we don`t start
to see measurable precipitation until after midnight. This is
highlighted well in the HREF as well, bringing the precipitation
in between 3-6am. The best moisture will be situated south of
Interstate 80, where the best PoPs have been placed. Areas
south of I-80 have the best chance to see upwards to a
0.25-0.50"+ rainfall, with those south of Highway 34 potentially
seeing between 0.50-1.00". The increasing moisture and
resultant cloud cover will allow temperatures to be more mild
tonight, with much of the area near or above 60, with the
exception of our northeast.

Tomorrow, the wave is expected to move out, with LLVL easterly flow
aloft helping to diminish the rain chances through the day, with dry
air moving in. A brief period of high pressure fills in behind
the low, bringing a break in precipitation before the next wave
approaches the area. With the presence of clouds through much of
the day and showers in our south, temperatures are not expected
to increase much tomorrow. Much of the area should remain in
the low-mid 70.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 131 PM CDT Sun Aug 11 2024

Upper ridge continues to build over the Central US Tuesday,
slowly pushing east into Wednesday. Weak waves will continue to
pass through the flow, which may bring low-end chances for
precipitation. The best wave will start its approach to the
region Wednesday/Thursday, bringing the better chances for
widespread rainfall, which can be heavy. This timeframe has been
highlighted by the WPC, bringing in the most precipitation for
the week. Current timing seems to start Wednesday afternoon,
with increasing coverage through the night and Thursday. The
best moisture arrives on Thursday, which is resolved well
amongst guidance, hinting at upwards to 2.00" PWATs or higher.
Given our past heavy rainfall events this summer, I am not quite
sure that we will go much higher than that 2.00" PWAT, as we
have underperformed compared to guidance prior. In either case,
PWATs between 1.50-2.00" are near or greater than the 90th
percentile in climatology, indicating that we can expect heavy
rain in any thunderstorm. While I don`t plan on discussing
deterministic QPF values, the ECMWF ensemble suite seems to
favor at least 0.50-1.00" of rain, with 50-90% favorability.
While this is the wettest of the solutions, it has been quite
consistent and increasing. As was mentioned in the previous
discussion, there is a non-zero severe risk during this
timeframe as well. Although, it is a ways out and much can
change, especially with the timing and track of the system,
which are important ingredients in the recipe. So, stay tuned,
but be prepared for a rainy mid-late week!

Temperatures will be near normal through the week, with some
trending slightly above normal. Temperatures heading into the
weekend may be up for discussion though, as temperatures may not be
as warm as advertised. The GFS and EURO both cut the upper low
off over the Great Lakes region, with our area under the western
flank of the system. Thus, we would fall under largely
northerly to northwesterly flow Friday and through the weekend.
This would put us under cold advection and keep the chance for
possible wrap-around precipitation into the weekend. Thus, the
weekend might trend a bit cooler than normal and remain gloomy.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 655 PM CDT Sun Aug 11 2024

VFR will continue into tonight with increasing high and mid
clouds. Showers are possible by early Monday morning mostly at
BRL, which could last into the afternoon. The precipitation will
be accompanied by MVFR ceilings between 1500-3000ft AGL.
Further to the north at CID and MLI, anticipate ceilings to
lower to 3000-5000 ft AGL later Monday AM into the
afternoon.

&&

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

&&

$$

SHORT TERM...Gunkel
LONG TERM...Gunkel
AVIATION...Uttech