Romeoville, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

582
FXUS63 KDVN 191619
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1119 AM CDT Sat Jul 19 2025

.KEY MESSAGES...

- Flood watch remains in effect through 1 PM Sunday for parts of
  the area. Repeated rounds of heavy rain through Sunday may
  lead to flash flooding.

- Active pattern is underway across area with warmer and more
  moist air in place.

- Ring of fire pattern across the area is forecast to bring
  daily chances for thunderstorms. Some of which could be strong
  to severe with heavy rain and flash flooding.

- The heat returns in earnest by the middle of next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 244 AM CDT Sat Jul 19 2025

Temperatures are much warmer this morning with most locations
in eastern Iowa, northwest Illinois and far northeast Missouri
in the lower to mid 70s and dewpoints in the upper 60s to lower
70s. A surface low sits in southeast South Dakota, northeast
Nebraska, and far northwest Iowa with a warm front draped
southeastward into east south central Iowa early this morning.
An MCS is developing this morning across southern Minnesota into
northern Iowa and is forecast to move into eastern Iowa in the
7 to 10 AM timeframe and move southeastward across the area
through the early afternoon. Recent CAM runs have slowed
slightly but still move the MCS across the area this morning
into the early afternoon. Heavy rain is possible this morning
with this line of storms with HREF probability match mean
rainfall rates of 1 to 2 inches per 3 hours. CAMs have also
consistently showed a gusty wind threat from these storms. We
will still continue to monitor these storms for any wind threat
early this morning. Some showers and thunderstorms may linger
across the area through the afternoon especially in the vicinity
of the front this afternoon. A marginal risk for severe storms
remains in place through 7 AM with a slight risk for severe
storms today through tonight with the main threat being damaging
winds.

Zonal flow is in place across the CONUS through the period with
subtle shortwave moving through the flow and bringing chances
for showers and storms to the area. The previously mentioned
front is forecast to surge northeastward and into Wisconsin and
illinois this morning with a a cold front moving across eastern
Iowa and far northwest Illinois by 00 UTC Sunday. This front
will then stall across southern Iowa and northwest Illinois
Saturday night. Due to lingering clouds from this morning
convection have lowered high temperatures slightly for today
with high temperatures in the 80s. Higher dewpoints will still
lead to heat indices today in the lower to mid 90s along and
south of Interstate 80. With a warm and humid airmass in place
and precipitable water values of 2.00 to near 2.25 inches have
kept the flash flood watch in effect across the area through
Sunday afternoon. We decided to add Scotland and Clark Counties
to the watch.

Another MCS is possible Saturday night and will be focused to near
the stalled frontal boundary across the area which is roughly
along a line from Fairfield to Galesburg. 0 to 6 KM shear
vectors and both the upwind and backbuilding corfidi vectors
show that precipitation will move along the front in repeated
rounds Saturday night into Sunday morning. These repeated
rounds of heavy rainfall may lead to flash flooding in parts of
eastern Iowa, northwest Illinois, and far northeast Missouri.
These storms are forecast to continue into Sunday morning.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 244 AM CDT Sat Jul 19 2025

The pattern looks to be very favorable late in the weekend
through early next week for several storm complexes to
traverse in/near the area, as we`ll reside just north of
the upper ridge/heat dome within the `ring of fire` and
barrage of ridge riders on the southern periphery of the
stronger mid level flow traversing the International border.
This will bring about perhaps greater concerns for a more
widespread severe weather threat due to the likelihood of
MCS`s, along with torrential rain and flooding particularly
as soils are likely to be quite saturated and rivers running
high in those areas that receive noteworthy rainfall in the
days prior.

By Wednesday, there is fairly good agreement that the upper
ridge will build into the region shunting the main storm
track to our north. This will bring about the threat for
dangerous heat Wednesday with highs well into the 90s and
dew points in the mid/upper 70s (possibly 80+F in some areas
due to evapotranspiration from maturing corn crops) owing to
heat index readings of 100-110+. This dangerous heat could
extend into Thursday, particularly across our south/east ahead
of a cold front. This front will also bring a return of storm
chances over the latter portion of next week and possibly through
next weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 631 AM CDT Sat Jul 19 2025

A line of thunderstorms is moving east southeastward and will
impact eastern Iowa TAF sites through 19 UTC. Expect periods of
IFR to possibly LIFR ceilings and visibilities with the
strongest storms with gusts up to around 40 knots. Gusts up to
50 knots are possible but confidence is low on the timing and
location. MVFR ceilings may linger into the afternoon before
they lift to VFR. Another round of storms is possible this
evening and overnight with the better chances at KCID, KBRL, and
KMLI have put a prob30 at all TAF sites to account for this but
confidence is low in the timing but possibly in the window from
3 to 12 UTC. MVFR to IFR ceilings and visibilities will be
possible in the strongest storms.

&&

.HYDROLOGY...
Issued at 1053 AM CDT Sat Jul 19 2025

What has changed...

A flood warning has been issued for the Iowa River at Marengo,
IA.

A flood watch has been issued for the North Skunk River near
Sigourney, IA.

Discussion...

Overnight bands of 1 to 3 inches of rain fell across parts of
eastern Iowa and west central Illinois. Within those bands were
localized pockets of 3+ inches.

Another round of heavy rainfall is expected tonight into Sunday
morning. This round of rain is concerning as the Weather
Prediction Center has much of the area outlooked in an upper end
slight risk for excessive rainfall. The risk of excessive
rainfall will continue into Monday night.

As mentioned yesterday atmospheric moisture levels will be
near 2 inches tonight which is greater than the 90th percentile
for July. With a tropical moisture connection developing with
the Gulf, warm rain processes have a high probability of
dominating which will lead to very efficient rainfall production.
There is a high probability of rainfall rates of 1 to 2+ inches
per hour.

Data so far this morning from weather models is pointing to the
general area of along or south of I-80 as being the focus for
the heavy rainfall tonight into Sunday morning. There will
likely be more bands of 1 to 3 inches of rain with locally
higher amounts. If storms repeat over the same areas (there is a
50-60% probability of this occurring) then rainfall rates of 2+
inches per hour would lead to rapid runoff and resultant flash
flooding. This additional round of heavy rainfall will produce
general rises on area rivers with the potential for river
flooding.

The following tributary rivers will need to be watched carefully
through the end of July since they already have above to much
above normal streamflows; Cedar, English, Iowa, North Skunk,
Skunk and Wapsipinicon.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Flood Watch through Sunday afternoon for IAZ051>053-063>068-
     076>078-087>089-098-099.
IL...Flood Watch through Sunday afternoon for ILZ015-016-024>026-
     034-035.
MO...Flood Watch through Sunday afternoon for MOZ009-010.

&&

$$

SHORT TERM...Cousins
LONG TERM...Gibbs
AVIATION...Cousins
HYDROLOGY...08