813
FXUS63 KDVN 081025
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
525 AM CDT Mon Jul 8 2024

...Updated for 12z Aviation...

.KEY MESSAGES...

- Near daily shower and storm chances this week, but these
  chances will be low for most days and thus many dry hours
  expected.

- Post tropical Beryl will bear watching for rain chances
  across portions of WC/NW Illinois Tuesday night.

- Seasonable temperatures into late week, but then heat and
  humidity look to increase next weekend.

- Moderate to major river flooding continues on the Mississippi
  River with most sites cresting or starting to fall this week,
  while flooding continues on parts of the Iowa, Cedar and
  Wapsipinicon Rivers.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 330 AM CDT Mon Jul 8 2024

A linear MCS with trailing stratiform rain was moving into portions
of eastern Iowa early this morning, but is encountering a much
less favorable kinematic and thermodynamic environment and
subsequently weakening. That being said, weak elevated
warm/moist advection atop the cool pool and convergence along
outflows and with the MCV will continue to foster at least
scattered showers and a few storms across portions of the area
this morning. This afternoon, forcing is a bit nebulous but any
residual outflow or differential heating boundaries could serve
as foci for redevelopment of showers and storms. Coverage is
anticipated to be fairly low (20-40%) and may favor areas east
and south of the Quad Cities. Overall, the better forcing and
subsequent greater coverage is suggested to be further north and
east of the service area. Outside of the precipitation chances,
look for seasonable temperatures and humid conditions.

Tonight, not currently seeing much in the way of a trigger or
focus for storms and as such anticipate a quieter night with
weak west/northwest low level flow on the front flank of a
Missouri Valley ridge axis. Will have to monitor for at least
some patchy radiational fog, especially in the river valleys and
areas that have received rain recently given lows in the 60s
forecast near to a bit below crossover temperatures.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 330 AM CDT Mon Jul 8 2024

Early on in the period we`ll be keeping an eye on the remnants
of post tropical Beryl. The latest NHC guidance and ensemble
model guidance are in reasonable agreement on taking the center
from south of St Louis to near Indianapolis to northwest Ohio from
06z Wednesday to 06z Thursday. Along and just northwest of the
track will be a focus for heavy rain given the anomalously deep
moisture and strong upward vertical motions aided by phasing or
merging of the post tropical system with a synoptic upper trough,
but the good news for area rivers this threat looks to remain well
south of the area. In fact based on the GEFS and ECS ensemble
mean QPF probabilities we either "beryly" get brushed by rain Tuesday
night across the far southeast service area, or completely missed
as there`s likely to be a sharp cut-off to the rain shield on the
northwest side. Still we have to keep an eye for any adjustments to
the track of this system given complexity/extent of the phasing,
but it would appear as though the only impacts would be whether it
rains or not... i.e. PoPs.

In the wake of the departing post tropical Beryl through the
Mid Mississippi and Ohio Valleys, a remnant and persistent
broad upper trough will linger over the Upper Midwest and continue
at least low near daily chances for showers and storms mid
to late week.

Heading into next weekend, the ensemble guidance supports ridging
across the Intermountain West and Mid-Atlantic with weak troughing
from the western Great Lakes to the Lower Mississippi Valley.
This will keep some chances for precipitation around. There is
also signs though that the western ridge /heat dome/ may also try
to build toward the region leading to greater summer heat potential.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 525 AM CDT Mon Jul 8 2024

We`ll continue to see chances for showers and storms today into
early evening with a weak frontal boundary and various outflow
boundaries draped across the region. Trying to time these out
and determine the most favored TAF sites will be an exercise in
nowcasting. In the near term it looks like the river sites will
have the best chances for any shra/tsra. This will be handled
with VCSH or prevailing shower mention for a time this morning.
Additional shra/tsra development is possible this afternoon
into evening, but currently looking like the better chances will
be east and north of the terminals right now. Conditions in any
stronger shra and tsra will drop to MVFR to IFR. Otherwise,
predominantly VFR conditions expected although with heating and
abundant low level moisture we could see periodic MVFR ceilings
develop by mid morning through midday before lifting to VFR.
Meanwhile, later tonight with light winds there is the
possibility of patchy fog. However, with a light west/northwest
wind and likely some higher level cloudiness around confidence
is too low for mention at this time.

&&

.HYDROLOGY...
Issued at 1225 PM CDT Sun Jul 7 2024

The Mississippi River is currently cresting at and upstream of
Camanche, IA. The crest may take 1 to as much as 3 days to pass.
From Le Claire to Burlington, the respective crests will commence
within the next 1 to 2 days.

Keokuk is now forecast to crest within Moderate Flood category
beginning Friday.  The crest at Gregory Landing is forecast late
Friday into Saturday.

Tributary Rivers:

Heavier rainfall overnight of near an inch upstream of Cedar Rapids
has resulted in a slightly higher forecast for the Cedar River at
Cedar Rapids. The Watch has been upgraded to a Warning for minor
flooding with a forecast crest near 12.2 feet Monday evening.

On the Wapsipinicon River at Dewitt, it is near crest around 11.8
feet.  It is forecast to remain in moderate flooding category
through late on Friday.

On the Cedar River at Conesville, minor flooding will continue. It
will see a secondary crest near 14.6 feet Wednesday night into
Thursday.

The Iowa River at Oakville is seeing high water levels due to
backwater affects from the Mississippi River. It is forecast to
remain near 11.7 or 11.8 feet through midweek and then rise to near
12.1 feet late Thursday into Friday.

&&

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

&&

$$

SHORT TERM...McClure
LONG TERM...McClure
AVIATION...McClure
HYDROLOGY...14