467
FXUS63 KDVN 251715
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1215 PM CDT Wed Jun 25 2025

.KEY MESSAGES...

- An upper level front will keep the heat and humidity across
  the area the remainder of the week along with a daily risk of
  showers and thunderstorms. Some relief may be seen next week.

- Brief funnel clouds will be possible this afternoon as diurnal
  convection develops along the many boundaries across the area.
  An isolated severe storm cannot be ruled out.

- With a wet pattern across the area and the potential for more
  heavy rainfall, area rivers are expected to see rises. Refer
  to the hydrology section for more information.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 249 AM CDT Wed Jun 25 2025

Similar to yesterday, lift provided by a weak low level jet
developed an area of rain with embedded thunderstorms. This area of
rain will persist through sunrise but areal coverage will slowly
shrink as the low level jet weakens.

The combination of an upper level front and weak boundaries across
the area points to another day of isolated to scattered (20-30%)
diurnal convection developing across the area.

The situation also looks ripe for brief funnel clouds to develop
this afternoon as the convection develops along the northward moving
surface warm front. The NST parameter at the moment is favoring
areas along/south of I-80. However, a brief funnel will be possible
just about anywhere diurnal convection develops.

Tonight as the low level jet again strengthens, nocturnal convection
will fire between the surface and upper level fronts. The better
coverage of showers and thunderstorms looks to be the IA/MN border
into southern Wisconsin that could grab the highway 20 corridor.
Outflow boundaries from the convection may allow isolated to
scattered convection to develop as far south as the I-80 corridor.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 249 AM CDT Wed Jun 25 2025

Thursday/Thursday night
Assessment...high (>80%) confidence of heat and humidity
continuing with medium to high (60-80%) confidence of storms

Thursday morning may or may not see some lingering convection from
the previous night. However, there will be cold front that sweeps
through the area late Thursday afternoon and night.

Daytime heating ahead of the front will push afternoon heat indices
into the 95 to 100 range. The potential energy that builds during
the day will then go into feeding storm development in the afternoon.

New storms look to initiate in central Iowa during the afternoon
that will grow upscale into a line that marches east and arrives in
eastern Iowa just before sunset. Ahead of this line scattered storms
are possible in eastern Iowa along a pre-frontal trof that will
dissipate with sunset. The model consensus has converged on this
scenario with the highest pops west of the Mississippi late Thursday
afternoon and night.

Right now SPC has a marginal risk (level 1 out of 5) for severe
storms for the area. The primary risk looks to be damaging winds and
heavy rainfall. If severe storms were to develop, prime time looks
to be 5 to 11 PM.

Friday through Sunday night
Assessment...high (>80%) confidence of heat and humidity continuing.
Medium (40-60%) confidence of a daily risk of rain.

The heat and humidity will continue through the weekend before a
pattern change shifts the upper flow to the west northwest.

Weak disturbances running around the edge of the heat dome are
expected to result in mainly diurnal convection developing during
the afternoon and evening. Areal coverage on this will be 20-40%.
The models are suggesting a better chance of rain Sunday/Sunday
night when a slightly stronger system and front moves through the
area.

That being said, there will be many hours of dry weather over the
weekend.

Monday through Tuesday
Assessment...medium to high (60-80%) confidence on temperatures
near normal with a continued risk of rain.

The heat dome will be pushed southward as a pattern change bring
west northwest flow into the area early next week.

A weak disturbance moving along in the flow aloft will bring a low
risk (20%) of diurnal showers and thunderstorms Monday/Monday night
to the area. Again, there will be many hours of dry weather on
Monday.

High pressure building into the area on Tuesday looks to bring the
first chance of a dry day across the area.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1210 PM CDT Wed Jun 25 2025

Mainly anticipate VFR to prevail today into tonight with low
chances (10-30%) for an isolated shower or storm to impact the
terminals. Slightly higher chances (20-40%) near DBQ tonight so
have included a PROB30 for thunder there. Brief MVFR/IFR is
possible in the vicinity of any showers/storms that develop.

&&

.HYDROLOGY...
Issued at 1138 AM CDT Tue Jun 24 2025

     RIVER FLOOD WATCHES HAVE BEEN ISSUED FOR THE CEDAR RIVER AND
PORTIONS OF THE IOWA RIVER...

Heavy rainfall of 1 to 3 inches fell across portions of central and
eastern Iowa Monday evening, June 21. The combination of heavy rain
this past week, and potentially heavy rains across Iowa and southern
Minnesota in the next 3 days has brought the potential for
significant river flooding on the Cedar River and Iowa River. As
this rainfall materializes the next few days, forecasts for rivers
will become more confident, and flood warnings may be required.

HEFS guidance continues to show a wide spread at the upper end
of forecasts for many Iowa tributary rivers, especially the
Cedar River, including Cedar Rapids. There is a 10-25% chance of
exceeding major flood stage on the Cedar River at Cedar Rapids
early next week. Other points along the Cedar River have similar
potential in the 5-10% range of exceeding major FS. The Iowa
River also continues to see a forecast for potential flooding,
with 10-25% chance for exceeding moderate levels of flooding at
Marengo.

All of this information is 4+ days away from reaching flood
stage, and models are not greatly skilled at determining the
exact latitude/location of heavy rainfall events. However, due
to the potential significant impact of forecast rainfall on
rivers, the RFC is using a 72 hour forecast rainfall amount,
rather than the normal 24 hour amount (QPF). As this rainfall
verifies, or falls into another basin rather than the
Iowa/Cedar, these forecasts are subject to considerable change.

&&

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

&&

$$

SHORT TERM...08
LONG TERM...08
AVIATION...Uttech
HYDROLOGY...Ervin