073
FXUS63 KDVN 270827
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
327 AM CDT Thu Jun 27 2024

.KEY MESSAGES...


- Less humid and pleasant today

- Showers overnight mainly west of the MS River, with showers
  and thunderstorms possible areawide Friday and Friday night.
  The Slight Risk area for severe thunderstorms shifted westward
  and is now along our western tier of counties, roughly west of
  a line from Vinton IA southward to Memphis MO.

- Active weather returns from Monday through Wednesday

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 325 AM CDT Thu Jun 27 2024

High pressure will gradually slide east of the area today. Skies
will start out sunny with an increase in clouds this afternoon.
Highs will be in the upper 70s and lower 80s. Tonight, light ESE
winds will usher upper 40 and lower 50 dew points into the
eastern CWA from Lake Michigan. Meanwhile, an upper level wave
will be trying to spread showers into the western CWA. Backed
off on POPS in the east due to the drier dew points, but
maintained chance POPs (30-50%) working into areas west of the
MS River. This appears to be mainly showers, with the thunder
potential remaining in cental IA. Lows will be in the 60s.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 325 AM CDT Thu Jun 27 2024

Friday and Friday night, showers and thunderstorms will be
moving across the area first as a warm front lifts through and
then as a cold front slowly moves across IA. The cold frontal
passage has slowed and now the storm energy remains more to our
west than prior model runs showed. The SPC has shifted the
Slight Risk (level 2 of 5) roughly 80 miles westward. It now
encompasses our far western counties roughly along and west of a
line from Vinton IA to Memphis MO. A Marginal Risk area (level
1 of 5) overspreads the rest of the area. The main severe risks
are damaging winds and hail. Dew points do climb into the upper
60s to lower 70s and models continue to show PWATs of 2 to 2.25,
so heavy rain-producing showers and storms seem likely into
early Saturday. This will need to be monitored due to the
ongoing river flooding concerns across the area.

A dry Canadian high will build into the area over the weekend
scouring out the humidity once again. Skies will be clearing
Saturday, with sunny conditions Sunday. Highs will be in the 80s
Saturday with a hint of humidity, but on Sunday highs will be
in the low 70s north to upper 70s south with dew points in the
50s.

Active weather is expected Monday through Wednesday, with
several rounds of rain, possibly heavy, as PWATs over 2 inches
build back into the region. It remains too early to determine
the severe potentail.

Those with river flooding concerns should follow the forecast
more closely.


&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1200 AM CDT Thu Jun 27 2024

VFR will continue through the forecast period with light NNE
winds becoming ESE by mid morning.

&&

.HYDROLOGY...
Issued at 1207 PM CDT Wed Jun 26 2024

Changes...

Flood warnings have been issued for the Mississippi River from
Keokuk, IA down through Gregory Landing, MO. The flood warning
for Gladstone, IL (L/D 18) has been raised to the major
category.

Flood warnings have been issued for the Cedar River for Cedar
Bluff and Conesville, IA.

Flood warnings have been issued for the Iowa River from Wapello
to Oakville, IA.

Discussion...

The Mississippi continues to rise with multiple locations
expected to reach flood stage by Friday. The flood crest is still
north of La Crosse, WI so much of the Mississippi will likely
remain above flood stage through the middle of July. Crests on
the Mississippi north of L/D 15 look to occur around the Forth
of July. South of L/D 15 crests will occur after the Forth of
July.

There is a high to very high probability that the Mississippi
will reach major flood stage before cresting from L/D 15 down
through L/D 17 in the July 3-10 time frame.

On the Cedar River the Crest is currently located in the Cedar
Falls area with crests occurring in Vinton, Palo and Cedar
Rapids areas in the Friday to Saturday time frame.

Water from the Cedar River will bring the lower Iowa River above
flood stage downstream from the confluence with the Cedar River.
Right now the Iowa River at Columbus Junction is not forecast to
reach flood stage. That may change depending upon where and how
much rainfall occurs late Thursday night into Friday night.

More rainfall is expected Thursday night through Saturday which
will have the potential to be heavy. This rainfall is not
included in the current river forecasts. As such, one should
expect changes to the crest forecasts based on the forecast QPF.

Outlook...

The overall weather pattern looks to remain quite active through
the Forth of July and potentially into the middle of July. The
MJO which has been weak to non-existent for much of June is
forecast to strengthen over the next 10 days and is forecast to
move from phase 2 to phase 4 over the next two weeks. Phase 3
and 4 of the MJO climatologically correlates to above normal
rainfall for the upper Midwest and Mid-Mississippi Valley.
Indeed the Climate Prediction Center has a 40-50 percent
probability of above normal precipitation July 3-9.

&&

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

&&

$$

SHORT TERM...14
LONG TERM...14
AVIATION...14
HYDROLOGY...Gibbs/08