134
FXUS63 KDVN 281008
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
508 AM CDT Sat Jun 28 2025

.KEY MESSAGES...

- Hot and humid weather returns today and continues Sunday.

- Storms to our northwest will need to be watched this morning, as
  they move towards our area.

- Another threat for storms is expected Sunday / Sunday evening,
  with possible strong/severe storms.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 218 AM CDT Sat Jun 28 2025

Clear skies have been over our area through 2 AM, and with a
drier air mass than past days, we have seen good radiational
cooling, and temperatures have fallen to the mid 60s in much of
the northern 2/3rds of the CWA. In the south, lower level
moisture levels remain higher, and with that, temperatures
continue to be near 70. Fog thus far has been limited to a few
low lying area sites, like Monticello IA.

While the air over our area area is stable and dry, just to the
west, warm advection over the Plains and Missouri Valley is
forcing two areas of strong overnight storms, one in the main
zone in eastern ND/western MN, and the other near Sioux Falls
SD. The southern cluster is moving east, and so far remains
connected to it`s moisture transport on the LLJ, but may outrun
this in the next few hours. If that happens, a dry forecast will
be in place for out area today. However, it`s close enough to
require us to introduce a period of <20% pops in our northwest
counties through mid morning today. We`ll be watching radar and
will update as necessary this morning.

This warm advection pattern will bring the moisture back to lower
levels during the day today, and with crops getting much larger in
fields, transpiration should be a factor as well. In any case,
dew points rising back to the upper 60s to lower 70s are
forecast today, with highs reaching the upper 80s to low 90s.
Heat index readings in the mid to upper 90s will be around this
afternoon and evening. No headline is expected for this, but an
afternoon SPS may be needed, as well as HWO mentioning. Sunday
looks to be very similar with heat index values of 95 to 100 in
the afternoon and early evening.

Sunday, the morning hours may see some isolated to scattered higher
based showers that back build into the LLJ axis, but nothing
organized. By late morning to mid afternoon, a dry period should be
in place as we wait for the incoming front from the northwest. This
front is likely to bring a organized line of storms to our north
during the day, but will arrive in our area with less certainty.
Many CAMs show convection dropping more south/southwest into central
Iowa during the afternoon and evening into the primary
instability axis, with our area seeing less activity. Pops
remain in the 50-70 % range Sunday afternoon through Sunday
night, but the WPC QPF guidance now has shifted most of the
heavy rain west of our CWA. That said, the air mass in place
will have PWATS over 1.75" and heavy rain amounts remain
possible. Should severe weather take place, damaging winds seem
the main threat with a mature linear mode expected to arrive in
the northwest by mid to late afternoon. SPC has a Level 2,
slight risk in our northwestern counties, with a level 1,
marginal risk farther southeast over the remaining CWA
Sunday/Sunday night.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 218 AM CDT Sat Jun 28 2025

Monday is a transition day, with cooler air arriving in the
afternoon, and passing energy aloft with the upper trof near our
area. Some addition showers and thunderstorms remain possible
through the day, mainly in the eastern counties. Highs will be a
notch cooler, with mid to upper 80s forecast.

Tuesday through Wednesday continues to be a dry period within our
forecast, as high pressure moves through the region in the wake of
the upper trof Monday. However, beyond that period, Thursday through
Friday may see some activity as warm air at lower levels builds
back into the region, with northwest flow aloft. This will
certainly offer a potential for showers and storms later in the
week, but little certainty in timing or placement at this point.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 506 AM CDT Sat Jun 28 2025

High clouds from distant storms, or clear skies and light winds
will continue through the period with VFR conditions. Variable
winds will be light, then become predominantly southeast later
this morning. There is a very very small chance, under 10% that
storms in Minnesota may approach eastern Iowa late this morning,
but nearly all models suggest this is not going to occur. It`s
worth keeping an eye on, that`s all for now.


&&

.HYDROLOGY...
Issued at 1055 AM CDT Fri Jun 27 2025

Forecast crests along portions of the Cedar River have continued
trend a bit lower into next week after assessing recent run-
off and a dry forecast over at least the next 24 hours. However,
additional rounds of heavy rainfall are possible on Sunday and
into early next week may result in changes to the timing and
magnitude of the forecast crests. The latest river level
forecasts are only accounting for forecast rainfall (QPF) over
the next 24 hours, again which is mainly dry. With run-off
uncertainty, flow attenuation, and the dry forecast through
Saturday, will maintain the River Flood Watches for now for the
Cedar River at Cedar Rapids and Conesville, and the Iowa River
at Marengo. Of the three sites, it appears Marengo has the
highest potential to rise above the flood stage Saturday night,
but how much higher than FS still at question. Thus, we will
continue the watches for now, but a warning may have to be
issued this evening or Sat morning if the projected upward
trends are close to what the forecast is. The Cedar River at
Cedar Rapids has been trended down and now has just one point
hitting flood stage during Tuesday evening July 1st, and
depending on rainfall on that basin Sunday into Monday, may fall
short of that 12 FT level.

&&

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

&&

$$

SHORT TERM...Ervin
LONG TERM...Ervin
AVIATION...Ervin
HYDROLOGY...Gibbs/12