Romeoville, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

533
FXUS63 KDVN 070118 AAA
AFDDVN

Area Forecast Discussion...UPDATED
National Weather Service Quad Cities IA IL
718 PM CST Fri Mar 6 2026

.KEY MESSAGES...

- Organized storms late this evening into early overnight; a
  level 2 of 5 risk for severe with primary hazards damaging
  winds, with some potential for a localized all hazards risk
  primarily west of the Mississippi River.

- Dry and cool conditions Saturday, with another warming trend
  returning Sunday and Monday.

&&

.UPDATE...
Issued at 715 PM CST Fri Mar 6 2026

The primary forecast thoughts from earlier still continue with
the main severe timing being late evening into early overnight.
The CWA is entirely in the warm sector with a very mild early
March evening unfolding. Somewhat shallow near-surface moisture
as seen on our 00Z RAOB and surface observations will climb
back into the lower 60s ahead of the incoming system. With
increased forcing for ascent overriding the warm sector in
central/southern Iowa and northwest Missouri, the storm coverage
in that area should continue to increase the next couple hours
as it propagates toward our area, likely to arrive 8:30-9 PM in
the far west-southwest CWA.

We would expect the convective mode to be semi-disecrete to
clusters/small scale bows as storms arrive in our area given
deep layer shear orientation and magnitude as well as support
from CAM solutions. Some supercell structures are probable in
south central Iowa based on the environment and recent radar
trends, and if so could propagate into our CWA too. A hail
threat would be present with these. We will have to regularly
evaluate whether they are elevated or surface-based, as right
now they currently look elevated. Being in the north end of the
warm sector, we do have the "looping" hodograph environment, so
a few tornadoes are possible due to supercells or any
mesovortices in well defined clusters/lines. While not the
likely scenario, if a supercell were to maintain itself for a
while it could briefly have significant all hazards threat given
the environmental helicity and low-level shear. Otherwise,
damaging winds should be the primary threat, and any sustained
larger surges with preicpitation-loading would be capable of
70+ mph. Again, due to low confidence in convective mode, it
lowers certainty in specific hazard evolution too.

Localized heavy rainfall will be a given. After the soaking from
this morning, minor flooding could result but probably tied to
low-lying locations or metros. Propagation should generally limit
true flash flood threats.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 156 PM CST Fri Mar 6 2026

Much of the area received beneficial rain this morning, with
totals generally between 0.30" and 1.50". The last time we saw
rain amounts this high was back on Jan 9th! A Spring-like feel
to the air was seen today, as a warm front lifted north. As of
Noon, surface observations have a surface low near Estherville,
IA, with a warm frontal zone extending southeast towards
Marshalltown and then along the Hwy 30 corridor into Illinois. A
strong cold front was observed from the surface low near KEST
southwest towards KOMA. Radar mosaics show a few thunderstorms
over northwest IL developing along a MUCAPE and 700mb moisture
gradient with more isolated storms forming just east of Des
Moines.

An active 18-24 hours is in store for the region, as the
aforementioned surface low tracks northeast into northern WI by
09z Saturday. Differential heating due to breaks in the clouds
late this morning has allowed some areas to warm quicker than
forecast today. This has resulted in a very low risk of strong
storms developing this afternoon and early evening roughly along
and south of a line from Ottumwa, to the Quad Cities, to
Sterling. Storm coverage will be quite isolated if any more
develop with the lack of an apparent trigger until late evening.
Our 18z DVN sounding had a capping inversion around 940mb which
may keep any surface based and subsequent tornadic threat near
zero this afternoon.

Attention then turns to the progression of the strong cold front
that is progged to move through late this evening. Very strong
kinematics and a very moist environment (deep layer shear over
55kts, steep lapse rates, and PWs around 1.3") will be in place
ahead of the front. The question mark remains is how much
instability will still be available as the storms near the CWA
late in the evening. At this time, latest CAMs show scattered
discrete storms developing over central IA after 4pm growing
upscale into one or two dominant segments or lines. The primary
hazards will be strong wind gusts of 60+ mph, isolated large
hail, and possibly a few spin up tornadoes associated with any
northeastward surging segments. After midnight, the convection
should quickly become less organized with the severe threat
quickly diminishing. Heavy rain and sub-severe winds will
remain through the rest of the overnight hours as the cold front
pushes east.

&&

.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 156 PM CST Fri Mar 6 2026

This Weekend...the aforementioned cold front will be just east
of MS RVR at 12z Saturday, with breezy northwest winds ushering
in cooler temperatures. Some wrap-around clouds may linger into
the late morning/early afternoon keeping temps noticeably
cooler and reminding us that it is still early March. Calendar
day highs will occur before sunrise, with afternoon temps only
reaching the mid to upper 40s. Return flow commences Sunday,
with highs reaching the 60s with plentiful sunshine. Deep mixing
and a strong pressure gradient develops in the afternoon to
support breezy southwest winds gusting over 30 mph at times. We
may have to watch for some fire wx concerns as afternoon min RH
values drop below 35%.

Next Week...roller coaster temperatures are expected once again with
well above normal temps close to record highs Monday/Tuesday and
then falling temps closer to more seasonable values behind a cold
front Tuesday night. This front will offer our next chance of precip
but doesn`t look to bring widespread QPF, with the NBM only showing
50-70% probs of greater than 0.25" south of a Rockford, IL to
Fairfield, IA line ending 12z Wed.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 519 PM CST Fri Mar 6 2026

Downward motion in the atmosphere has created a lull in
convection across eastern Iowa and most of northern Illinois.
Final round of convection, in the form of a line, will be
associate with a cold front sweeping through 03z-12z/07.
Potential is still there for gusts up to 40 knots with TSRA
ahead of the front. Post-frontal MVFR/IFR conditions with wind
gusts up to 25 knots. After 18z/07 a slow improvement to MVFR
with winds still gusting up to 25 knots.

&&

.CLIMATE...
Issued at 715 PM CST Fri Mar 6 2026

Record High Temperatures:

March 9:
KBRL: 74 in 1986
KCID: 68 in 2021
KDBQ: 65 in 1977
KMLI: 71 in 2021

&&

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

&&

$$

UPDATE...Friedlein
SHORT TERM...Gross
LONG TERM...Gross
AVIATION...08
CLIMATE...Gross