950
FXUS63 KDVN 271557
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1057 AM CDT Fri Jun 27 2025

...Hydrology Section Marengo FS Arrival Time Correction...

.KEY MESSAGES...

- Hot and humid weather will be in place this weekend.

- After a day`s break, an unsettled pattern returns Sunday into
  Monday.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 252 AM CDT Fri Jun 27 2025

Warm and humid conditions remain over the CWA early this morning, as
a weak cold frontal slowly approaches eastern Iowa. While this front
will eventually push through today, the rainfall from last evening
and overnight is likely to create a significant stratus cloud deck
toward morning. Showers and thunderstorms in our south, and very
isolated in the north as of 2 AM will continue to move east and by 6
AM, we expect most activity to be dissipated or moving out, except
for the far southeast CWA which may see rain/embedded thunder
through 9 AM.

While the warm air mass is still around, the combination of low
clouds and later day dry advection will keep heat stress much lower
than yesterday.  Highs in the low to mid 80s north to mid to upper
80s south are forecast by NBM today, and that seems a good fit for
the lack of morning sunshine.

Tonight, we should see clear skies, at least initially, along with
light winds.  All in all, this will be a very pleasant evening!
Overnight, with some areas still quite moist from the past 24 hours
rainfall, we may see some shallow fog formation. I`m not putting in
the forecast grids yet, but this seems to be a night with a synoptic
setup for patchy to areas of fog.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 252 AM CDT Fri Jun 27 2025

Saturday and Sunday the heat returns to area, though the latest data
suggests this will be a little less than the recent bouts of 100+
Heat index.  For now, highs in the upper 80s/lower 90s are forecast,
with dew points in the upper 60s to lower 70s.

Saturday continue to appear dry, with the main threat for storms
well north of the CWA into central and northern MN. This continues
to be the case through Saturday night and Sunday morning, but Sunday
afternoon and night look to be potentially very active again with
storms. A hot and humid day is forecast, and with that instability
is expected to be rather high, hear and over the entire Midwest
ahead of the approaching weak cold front. Zonal flow aloft is
forecast, with a short wave passing through the Midwest and
triggering storms as early as mid morning over MN Sunday. The flow
should take these storms east initially through the afternoon,
before building southeastward in the late afternoon and evening. I
could see a seasonal threat for damaging winds and heavy rain in
this scenario. SPC has placed our area into a Day 3 marginal (Level
1 of 5) risk for severe weather, and that more or less fits this
thinking I have.

The blended model output lingers some chances for storms into
Monday, but this is likely to be a single larger event, followed by
some scattered activity with cooler air aloft rotating through
Monday afternoon.  Northwest flow will bring a drier air mass into
the region Monday afternoon, with dew points falling the lower 60s
for Tuesday and Wednesday.

While Tuesday remains dry in our forecast, the rest of the period
seems have some threat for showers and storms in northwest flow
aloft. These will be driven by weak disturbances, and are hard to
pin down event timing/location. As most seasoned Midwest
meteorologists know, summer northwest flow is not necessarily quiet
weather!

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 530 AM CDT Fri Jun 27 2025

Light rains are exiting the area as of 11Z, and will continue to
move away from the region as a cold front slowly moves through
eastern Iowa. Today will be a dry period Saturday. Stratus will
continue to slowly move east over the sites early this morning,
reaching both MLI and BRL around 13Z.  Cigs as low as 500 ft
are possible, but most sites will see 1500 to 2500 stratus cigs
through the morning. The front does not have much of strong push
of air to it, as west to northwest winds only reach 6-10kts
during the day. VFR weather is expected by noon in all areas
though as the strong summer sun increases mixing through the
drier air aloft.

&&

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

Forecast crests along portions of the Cedar River have continued to
be trended a bit lower 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 the watch continuance 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...12