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415
FXUS63 KDVN 230819
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
319 AM CDT Sun Jun 23 2024

.KEY MESSAGES...

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- Much calmer conditions are expected for Sunday, with partly to
  mostly sunny skies and dry conditions

- A somewhat active weather pattern remains for the long-term,
  with periodic chances of showers and storms, especially for
  Tuesday and Tuesday night

- Hot and humid conditions return for Tuesday
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&&

.SHORT TERM /THROUGH MONDAY/...
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Issued at 317 AM CDT Sun Jun 23 2024

A much calmer day is on tap for today, as the cold front that moved
through our area last evening has moved off to the southeast. Early
this morning, we are seeing an expanding post-frontal layer of
clouds building in from the north, which will result in partly to
mostly cloudy skies early this morning. However, subsidence from an
approaching area of high pressure and dry air filtering in will
gradually taper off these clouds, so expect more sunshine later in
the day. Additionally, cold air advection and cooling 850 mb
temperatures, with values around 14 to 17 degrees C per the GEFS
ensembles should also support more seasonal temperatures, with highs
in the lower to middle 80s. If you have outdoor plans, today will be
a great day for them!

As we head into tonight, quiet conditions prevail despite a mid-
level trough diving southward across the western Great Lakes. The
high pressure system remains with us, which should suppress any
precipitation from developing ahead of the trough, so we will
maintain a dry forecast through tonight. Temperatures will be
relatively cool compared to the last several night, with lows in the
60s. Should be a great night to open your windows!
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&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
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Issued at 317 AM CDT Sun Jun 23 2024

The long-term forecast period will be a mixed bag, overall, with
some dry days and some days with showers and storms. Monday will
start us off on a dry note, as the area of high pressure gradually
moves eastward. Southerly return flow will help increase theta-e in
our region once again, with temperatures warming to the upper 80s to
lower 90s and dew points largely in the middle 60s. It won`t feel as
muggy as it did Saturday, but it will be warmer and more humid than
today.

Then, a more active pattern develops for late Monday night through
Tuesday night, as a mid-level impulse ejects from the Intermountain
West region towards the central Plains, as well as an intensifying
upper-level jet along the US/Canadian border, which will result in a
deepening trough. Global models are in fairly good agreement with a
larger MCS-type system developing over Minnesota and diving
southeast along the instability gradient. It is uncertain just how
much of our area will be clipped by this system, but if it does, it
should result at least some isolated strong wind gusts and small
hail in the strongest convection. As we go into the day Tuesday, the
aforementioned mid-level impulse moves through in the wake of the
MCS, and a surface cold front will sweep through the area from the
north. A strongly unstable air mass will be in place ahead of the
front, with the GEFS ensemble probabilities of CAPE 3000 J/kg or
larger around 50 to 80 percent for our region, owing to hot and
humid conditions expected. How strong the overall shear profile will
be is a bit more uncertain, given a pretty wide range of 0-6 km
shear magnitudes. However, PWAT values will once again be quite
high, with both the GEFS and ECMWF ensembles indicating between a 40
to 70 percent chance of PWATs in excess of 1.5 inches. Corfidi
forward propagation vectors oriented more west to east parallel to
the boundary indicates possible training convection, so heavy
rainfall/flash flooding will be possible once again. This
thunderstorm activity actually doesn`t appear to end until after
sunrise Wednesday morning. In terms of severe weather potential, the
CSU ML severe probs continue to paint equivalent of Slight Risk for
wind and hail in our area, and as such, SPC has just issued a Slight
Risk, or level 2 of 5, for severe weather for us Tuesday, while WPC
has a Slight Risk for excessive rainfall, so make sure to stay tuned
to the forecast as more details roll out.

For Tuesday`s heat and humidity, we are expecting very similar
conditions to Saturday, with high temperatures in the lower to
middle 90s and dew points in the upper 60s to lower 70s, so it will
feel pretty muggy once again. Heat indices between 95 to around 100
degrees will be possible.

As we go into the day Wednesday, any lingering showers or storms
early Wednesday morning should diminish from increased subsidence
from an area of high pressure moving into the area. This high
pressure system will remain in control through the day Thursday,
resulting in more seasonal temperatures for both Wednesday and
Thursday, with highs in the lower to middle 80s. Friday and Saturday
could be active, with more chances of showers and storms.
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&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1240 AM CDT Sun Jun 23 2024

The cold front that brought widespread showers and storms to the
area has now just about cleared the forecast area, so showers
and storms are done for the local TAF terminals. Attention will
then turn to low ceilings filtering in post-frontal, which can
be seen expanding across our northern areas in the GOES-East
nighttime micro satellite imagery. The expectation is that these
MVFR and IFR ceilings will continue to expand southward with
time. There is some uncertainty just how low the ceilings will
go, especially for DBQ, CID, and MLI, but they should generally
be around the cusp of MVFR to IFR. Breezy northwest winds will
be with us, as well. Ceilings should improve to VFR by late
morning.

&&

.HYDROLOGY...
Issued at 959 PM CDT Sat Jun 22 2024

In the Cedar River basin, the most recent rain event
underperformed significantly, particularly around the Shell Rock
River. This coupled with more soil absorption than expected led
to a decrease in flows on the Shell Rock River by as much as
5000 cubic feet per second. When this translated to the Cedar
River, many forecasts became lower. Included in this is the
Cedar River at Cedar Rapids forecast, which is still likely to
reach Moderate flood stage. Some precipitation is still expected
before the Cedar River crests towards the middle to end of this
week, so we will continue to monitor and update.

The Mississippi River is expected to reach flood stage at
multiple locations, including the Rock Island gage, by the
middle of this week. Long term we expect the Mississippi to
reach Moderate and/or Major flood stages the week of the Fourth
of July, with the crest at the Rock Island gage possibly
reaching just over 18 feet early on the Fourth of July.
However, a larger margin of error should be taken into
consideration when forecasting precipitation amounts and
locations in the 7-10 day timescale. Watches are currently out
for most of the Mississippi River and warnings will follow in
the next few as a clearer picture is drawn on what
precipitation and routed water we have coming downstream.

&&

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

&&

$$

SHORT TERM...Schultz
LONG TERM...Schultz
AVIATION...Schultz
HYDROLOGY...Wilson