677
FXUS63 KDVN 010511
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1211 AM CDT Wed May 1 2024

...Updated for 06z Aviation...

.KEY MESSAGES...

- The forecast will remain active through the period with
  almost daily chances of showers and thunderstorms.

- Heavy rain is possible over the next 7 days with 1 to 3+
  inches of rain in the forecast from WPC.

- Temperatures are forecast to remain near to slightly above
  normal through the period.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 210 PM CDT Tue Apr 30 2024

A weakening area of showers and storms continues to lift east
northeastward this afternoon across central Iowa north of a
warm front that is forecast to continue lifting across the
remainder of the area. Winds have shifted to the south behind
this warm front with gusts up to 25 mph. At 2 PM, temperatures
range from 69 degrees at Dubuque to 79 degrees at Washington
with dewpoints largely in the lower to mid 50s.

The dry air continues to impact the area of showers in central
Iowa and think that this will continue to dissipate over the
next couple of hours with light rain possible across Benton,
Buchanan, Delaware, and Linn Counties.

CAMs continue to show the development of a line of storms to our
west this afternoon that moves east southeastward through this
evening and has it moving across eastern Iowa, northwest
Illinois and far northeast Missouri between 00 and 06 UTC. HREF
2 to 5 km updraft helicity swaths show the convection moving
into our area west of a Fairfield to Cedar Rapids line before
gradually weakening as it moves eastward. Continue to think
that hail and damaging wind gusts are the main threat. SPC has
our western two rows of counties in a slight or level 2 out of 5
risk of severe storms and the reminder of the area in a
Marginal or level 1 out of 5 risk for severe storms. CAMs are in
good overall agreement in the evolution of these storms and have
been hinting at potentially stronger storms across area south of
I-80. Several runs of the HRRR as well as the 12 UTC NAm Nest
show the development of strong winds behind the convection
across the area mainly along and north of Interstate 80. We will
continue to monitor the situation to see if this does occur.

The cold front will move across the area from west to east
overnight with high pressure quickly building into the area at
the surface and aloft. Skies will quickly clear from the west.
High temperatures on Wednesday are forecast to be in the lower
to mid 70s. Model soundings show some mixing behind the cold
front with gusts west winds developing Wednesday morning with
gusts up to 25 MPH through the day.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Issued at 210 PM CDT Tue Apr 30 2024

A more active pattern will remain in place across the Upper
Midwest Wednesday night through Monday night. There is a storm
system roughly every 24 hours or so. A potent wave digging into
the Rockies Wednesday night into Friday is forecast to deepen
as it moves into the Plains. We will see a few leading impulses
ahead of this wave pass through the area, leading to persistent
showers/storms for the remainder of the week. The first of these
will arrive Wednesday night. This will be a wet period, with
the potential to see quite a bit of rain. With recent rains and
more forecast, some rises along area rivers are possible. The
parent wave developing is the one that has our attention though.
There is plenty of uncertainty with this system, as well as
major timing differences amongst guidance. Although, all long
term guidance does show this system. If this wave deepens
enough and we get that negative tilt upon arrival, this will
bring the potential for strong to severe storms late in the
week. Although, it is too soon to say for sure. WPC is
highlighting our area in the risk for Excessive Rainfall from
midweek through the end of the week, as they are currently
forecasting between 1-3+ inches of rain by the week`s end for
some. Thus, flash flooding will be possible, as well as rises
along area rivers. So, just be mindful and stay up to date with
the latest forecasts!

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1158 PM CDT Tue Apr 30 2024

Last of the shower and storm activity is moving well east of the
MLI and BRL terminals. Overnight expect decreasing cloudiness
with predominantly VFR conditions persisting through much if not
all of the daylight hours on Wednesday. If winds can decouple
there is the potential for patchy fog through 13z with pooling
low level moisture, but confidence is too low for mention at
this time. Late this afternoon and evening, elevated warm
advection will lead to an increase in showers with a few storms
also possible. Expect predominantly VFR with this precipitation
with pockets of MVFR (visibility) possible in the heavier
showers or with any storms. Winds will remain gusty at times
at around 10-20 kts while veering from southerly to westerly
through Wednesday. Late afternoon through evening, winds will
diminish to around 10 kt or less and shift from the east/northeast.

&&

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

&&

$$

SHORT TERM...Cousins
LONG TERM...Cousins/McClure
AVIATION...McClure