394
FXUS63 KDVN 111943
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
243 PM CDT Thu Jul 11 2024

.KEY MESSAGES...

-  Isolated to scattered showers and thunderstorms continuing
   this evening, with slow movement producing locally heavy
   rain and possible flooding.

- Becoming very warm and humid this weekend and into next week,
  with heat indices in the upper 90s and low 100s. Heat
  headlines may eventually be needed Sunday and Monday.

- Ring of fire pattern early next week may bring strong/severe
  thunderstorms close to the forecast area and temporary relief
  from the heat.

- Moderate to major river flooding continues on the Mississippi
  River with most sites crested or cresting in the coming days.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 232 PM CDT Thu Jul 11 2024

Tonight...Upper level trof axis seen on water vapor(WV) imagery
edging along and east of the local area still driving isolated to
wdly sctrd showers and a few thunderstorms acrs the area until early
to mid evening with low shear but buoyancy of 1000-2000 J/kg
MUCAPEs. Locally heavy rain and ponding water possible out of these
slow movers, and along lingering boundaries may still have to watch
for funnels. Otherwise, clearing skies and light easterly sfc wind
regime with moist sfc layer may foster at least some patchy fog
development late tonight and will put mention in the grids. The
southern CWA will look to be more favorable for fog but will place
it area-wide. A cooler night with plenty of low temps in the lower
60s, and even some upper 50s possible acrs NW IL.

Friday...Looking like a typical mid July day with some sunshine,
although retreating elevated smoke layers from the southwest may
filter the insolation some. Looks dry with no POPs warranted through
00z Sat. Friday night, more signals coming in for a convergent 10-20
KT southwesterly LLJ to produce sctrd elevated convection acrs the
area later Friday night. Early signs of storm layer shear and
thermodynamics suggest at least small hail may be possible with this
activity, and possibly larger. With ongoing LLVL return flow, a milder
overnight period as well with lows in the mid 60s to around 70.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 232 PM CDT Thu Jul 11 2024

Saturday and Sunday...While heat dome ridge continues to align up
the western plains, steering west-northwesterlies aloft angle from
the northern plains to the southwestern GRT LKS and northeastern OH
RVR Valley. At the sfc locally, the main warm front continues to
look to retreat northward acrs the local area Saturday, with ambient
temps warming into the upper 80s to near 90. Some EML/capping may
try to keep a lid for a mainly dry day, but still can`t rule out an
isolated shower or storm. A better chance may come Sat night, either
in the form of an upstream MCS dropping acrs the area out of the
northern plains feed on thermal gradient of incoming high THTA-E
pool. Another scenario is that a southwesterly LLJ may converge and
blow up convection overhead and then bleed eastward into Sunday
morning. Or the EML is firmly in grip acrs the local area and the
warm front is far enough north to keep the storm clusters/systems
off to the north acrs MN and WI. Depending on what occurs Sat night
and rate of decay of resultant convective debris, Sunday is still
shaping up to be a full tilt warm sector day with ambient temps in
the low to mid 90s and low to mid 70 sfc DPTs for Heat Index`s
worthy of heat headlines. Sunday night will continue to be the same
story, if we are on the edge of the "Ring of Fire" and suspect to
storms in or near the area, or very warm and breezy with the storm
track shunted further to the north. With the extent of available
CAPEs these storm complexes will have to utilize, damaging winds and
heavy rainfall will be primary threats into early next week.

Monday and Tuesday...Looking at the latest suite of ensembles
continue to partial ring of fire pattern along and north of the CWA
early next week, so a combo of heat in between the storm chances,
with Monday looking like another possible Heat Advisory day if
convective debris and storm outflow boundaries don`t get in the way
for a long enough duration. Tuesday a low confidence day with the
potential for a southward shunt

Wednesday and next Thursday...Longer range jet stream patterns and
synoptic scale feature flux trends suggest a western upper ridge
retrograde, enough so for higher amplitude northwesterly flow
aloft(to near meridional into the NW GRT LKS) to allow for Canadian
anti-cyclone dumps into the upper Midwest mid to late next week. It
may mean more showers/storms in the transition on Wednesday, but
then the flood gates look to open for cooler and less humid Canadian
air to infiltrate the region from the north. So a much needed
pattern change and weather regime may be in store for later next
week.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1240 PM CDT Thu Jul 11 2024

Mainly VFR CIGs/cloud levels this afternoon with light east to
southeast sfc winds. There is a chance for isolated showers and
thunderstorms this afternoon and into the evening, but coverage
is expected to be too sparse to mention in the TAFs. With the
light wind regime continuing into Friday morning, there could be
more fog development after Midnight into the dawn hours at most
of the TAF sites, and for now will go with MVFR levels before
12z. Southeasterly sfc winds will increase a bit on Friday to
4-8 KTs, with VFR conditions into Friday evening.

&&

.HYDROLOGY...
Issued at 232 PM CDT Thu Jul 11 2024

The Mississippi River continues a broad crest or just starting
to fall from crest at major levels from upstream of Camanche,
IA, and through Illinois City. The crest may take 1 to as much
as 3 days to pass. From south of IL City to Burlington, the
respective crests will commence within the next 1 to 2 days.

Keokuk is now forecast to crest within Moderate Flood category
Friday night into Sat. Gregory Landing is forecast to remain
near 19.5 feet through the week.

Tributary Rivers:

On the Cedar River at Conesville, minor flooding will continue.
It is starting to fall from it`s recent crest early this
morning.

The Wapsipinicon River at Dewitt is forecast to remain in
moderate flooding category through late Friday.

The Iowa River at Oakville continues to experience high water
levels due to backwater affects from the Mississippi River. It
is forecast to rise to near 12.1 feet into Friday.

&&

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

&&

$$

SHORT TERM...12
LONG TERM...12
AVIATION...12
HYDROLOGY...12