Crystal Lake, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

383
FXUS63 KDVN 250837
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
337 AM CDT Fri Apr 25 2025

.KEY MESSAGES...

- Scattered showers and isolated storms are expected today.
  Severe storms are not anticipated.

- Seasonable weekend weather is expected with highs in the 60s
  and cool overnight lows in the 30s and 40s.

- Severe thunderstorms are possible early next week as a strong
  storm system moves through the Midwest. While confidence on
  the details remains low this far out, it looks like the main
  period to watch for eastern Iowa and northwest Illinois is
  Monday evening and Monday night.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 315 AM CDT Fri Apr 25 2025

As of 3 AM, GOES WV imagery showed a messy mid-level pattern
across the Midwest with zonal flow and several separate areas of
convection. The SPC mesoanalysis displayed a few embedded mid-
level impulses or vorticity maxima within the 500mb westerly
flow. Weak forcing associated with these disturbances combined
with a relatively moist atmosphere and low instability (MUCAPE
<500 J/kg) has led to scattered showers and isolated storms
developing across E Iowa and NW Illinois. With that said, the
areal coverage has remained low so far. The main impulse (500mb
lobe of vorticity) is set to sweep across the region into the
early to mid morning hours, bringing with it a better chance for
more widespread showers and isolated storms, especially to the
west and north of Quad Cities, where rain chances peak between
60-80%. Low instability and weak effective shear under 30 kts
will preclude a severe weather threat.

A surface low is forecast to slowly shift into central Illinois
through the day, causing surface winds to increase out of the
N/NW which will advect in a cooler and drier air mass. Some
shower activity may linger into the afternoon, but with low
coverage (20-40%). Low overcast and breezy north winds will
make it feel quite a bit cooler than yesterday. A chilly night
is in store as high pressure builds in, with lows in the
upper 30s north of Highway 30 to low/mid 40s south.

Saturday: A beautiful spring day is expected with plenty of
sunshine and highs in the low to mid 60s! Patchy frost is
possible at night to the northeast of the Quad Cities as light
winds and a dry air mass allow temperatures to bottom out in the
mid to upper 30s.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Issued at 315 AM CDT Fri Apr 25 2025

On Sunday as we get on the other side of the progressing ridge
axis, elevated return flow may spawn more showers and storms
trying to spread in from the west. But the lingering ridge
effects and dry air may erode incoming activity from the west
until there`s better support later Sunday night. It may also
shunt the better precip chances to the north and northwest, but
we may still have to deal with decay debris/clouds in some
portions of the local area. Still a warmer day Sunday with highs
in the upper 60s to low 70s.

Monday through Wednesday...Medium range ensembles continue to show a
large piece of the upstream long wave acrs the western Rockies
ejecting out acrs the plains and upper Midwest Monday into Tuesday.
Plenty of conceptual synoptic scale features suggest this system may
be a severe weather maker, but some of the trends such as positive
tilt to the main upper wave and pre-system deep southwesterly
uniform flow maybe not so tornadic looking at this time. Also like
the previous shift stated, at this far out still plenty of phasing
and timing issues to better define in the coming days, with the
energy center still well off the west coast. Monday looks to be full
blown warm sector with gusty south winds and strong WAA, pumping
temps into the 80s and sfc DPTs in the 60s. So CAPEs will be there
for the kinematics, again it`s timing and placement. This scenario
will bleed into Tuesday with the frontal timing. Current ensembles
that strike our area with Monday evening and overnight storms, then
progress the front through eastward enough for Tuesday convective
redevelopment east and southeast of the DVN CWA. System wake ridging
following the cyclone would bring about dry cooler weather into the
mid week period.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1254 AM CDT Fri Apr 25 2025

An area of low pressure passing across northern MO into central
IL will bring occasional scattered showers and isolated storms
to the area overnight into Friday. The highest chances for some
measurable rain are at CID and DBQ from late tonight into
Friday AM. Ceilings will deteriorate area-wide late tonight into
Friday morning with periods of MVFR/IFR anticipated to last into
the afternoon/evening.

&&

.HYDROLOGY...
Issued at 1022 AM CDT Thu Apr 24 2025

With recent bouts of heavy rainfall, and possibly more tonight with
increased run-off especially in the upper basins of the Iowa, Wapsi,
and Cedar Rivers, these rivers will likley experience significant in-
bank rises. Some points and stretches of these rivers may also
surpass action stage and even the flood stage into the weekend. But
there is still some uncertainty with respect to tonight`s
placement of additional heavy rainfall amounts, as well as
associated extent of run-off. Since there is still some time to
assess these factors before the potential crests occur, have
issued river flood watches for the Wapsi at De Witt, and the
Iowa River at Marengo.

&&

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

&&

$$

SHORT TERM...Uttech
LONG TERM...12/Uttech
AVIATION...Uttech
HYDROLOGY...12