368
FXUS63 KDVN 272007
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
307 PM CDT Thu Jun 27 2024

.KEY MESSAGES...

- Showers will develop west of the Mississippi River after
  midnight and expand east of river after 7 AM. There is a
  Slight Risk of severe storms west of a Cedar Rapids to Kahoka
  Missouri line with a Marginal Risk to the east mainly Friday
  night. There is also the risk of heavy rainfall Friday

- Pleasant weather this weekend.

- Active weather returns early next week Monday through
  Wednesday.

- Moderate to Major flooding is expected on several area river.

 &&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 202 PM CDT Thu Jun 27 2024

Surface high pressure is centered over the area early this
afternoon. Dewpoints are comfortable in the upper 50s to lower
60s across the area at this time. Air temperatures at 2 PM
range from 75 degrees at Dubuque to 81 degrees at Keokuk. There
are currently scattered to broken stratocumulus deck across the
area. Light precipitation is present on radar west of Interstate
35 but KFOD, KIFA, and KPRO are reporting light rain in central
Iowa.

Surface high pressure is forecast to move into the eastern
Great Lakes tonight as winds at the surface turn to the south
with slow moisture advection through the period. Models are
showing dry air in the mid levels tonight making the timing of
precipitation later despite returns on radar.

A 20 to 30 knot low level jet develops this evening across
western Iowa and then veers into eastern Iowa between 06 to 12
UTC and then along and east of the river after 12 UTC. CAMS and
synoptic models show limited amounts of CAPE resulting in
diminishing thunderstorms and showers. These continue through
the morning before dissipating during the afternoon.

Another, stronger disturbance will move across the area on
Friday evening and night with some instability building across
the area in the wake of a warm front that lifts into Wisconsin.
Models show CAPE of 1000 to 1500 J/KG and 0 to 6 km shear of 30
to 40 knots. This is sufficient for severe thunderstorms to
developing during the evening. Think that hail and damaging wind
gusts will be the primary threat. Models also show 2.00 to 2.25
inches of precipitable water so heavy rain is also a threat.
The Storm Prediction Center has a Slight or level 2 out of 5
Risk for severe storms along west of a line from Cedar Rapids to
to Kahoka Missouri with a Marginal or level 1 out of 5 risk of
severe storms to the east.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 202 PM CDT Thu Jun 27 2024

A progressive zonal flow is forecast to remain in place across
the region through the long term. A storm system moving through
the flow will bring chances of precipitation Monday through
Thursday. Ridging will build northward in the wake of this storm
system early next week and allow warm temperatures so surge
northward for the middle of next week.

Showers and storms will linger across far southeast Iowa, west
central Illinois and northeast Missouri as cool front sinks
across the remainder of the area during the morning hours on
Saturday. High temperatures on Saturday in the 80s.

High pressure is forecast slowly build into the region Saturday
into Sunday at the surface and aloft. The weather will be
pleasant with slowly falling dewpoints into Sunday. Low
temperatures on Sunday morning will range from the upper 50s to
lower 60s. High temperatures on Sunday will be below normal and
in the 70s.

Another storm system will approach the area later in the day on
Monday and bring increasing chances of showers and storms
through Wednesday. Current model runs show better instability
and precipitable water values of 2.00 to 2.25 building into the
area. Heavy rain will be the main threat. It is to early to
determine the severe potential.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1234 PM CDT Thu Jun 27 2024

High pressure is forecast to shift to the east tonight and allow
easterly winds to become more southerly and increase to around
10 knots tonight. A developing low level jet tonight is forecast
to lead to the development of showers after 08 UTC at KCID, and
KDBQ and then after 12 UTC at KMLI and KDBQ. Periods of MVFR
ceilings and visibilities are possible with these showers.
Widespread MVFR conditions are possible after 12 UTC as showers
become more widespread. Southerly winds with gusts up to 20
knots are forecast to develop after 12 UTC on Friday.

&&

.HYDROLOGY...
Issued at 202 PM CDT Thu Jun 27 2024

Change:

The Mississippi River at Rock Island: A flood warning for MAJOR
flood category is in effect until further notice. The river is
expected to continue to rise to 18.0 ft on July 4th. However,
additional rises thereafter are likely.

Rainfall potential: Several storm systems may bring heavy rainfall
to the Midwest, which may aggravate the flooding or delay any crests.
There is additional showers and thunderstorms this Friday and Friday
night, again early next week, and another system towards the end of
next week. Stay tuned!

Outlook...

The overall weather pattern looks to remain quite active through
Independence Day and potentially into the middle of July. The Madden-
Julian Oscillation (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 rainfall July 4-10.


&&

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

&&

$$

SHORT TERM...Cousins
LONG TERM...Cousins
AVIATION...Cousins
HYDROLOGY...Haase/08