Crystal Lake, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

101
FXUS63 KDVN 070910
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
410 AM CDT Sat Jun 7 2025

.KEY MESSAGES...

- Chances of mainly showers remain in the picture for this
  afternoon south of Interstate 80, with another chance
  (30-60%) of showers and even a few thunderstorms Sunday
  afternoon.

- A Slight Risk (level 2 of 5) for severe weather has been
  introduced for locations south of the Quad Cities, with a
  Marginal Risk (level 1 of 5) for most other locations. The
  main hazards are damaging winds and large hail.

- Generally seasonal temperatures will continue before warming
  up by mid-week next week.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 403 AM CDT Sat Jun 7 2025

An active weekend is on tap as periodic chances of showers and
storms are expected, mainly during the afternoon and early evening
hours today and Sunday. Synoptically, a longwave trough
continues to loiter over the northern CONUS early this morning,
with an embedded mid-level shortwave expected to sweep through
the area this afternoon into the early evening hours. Overall,
instability appears to be lacking, with most of the
deterministic guidance and HREF ensemble mean suggesting only a
few hundred J/kg of MUCAPE. There doesn`t appear to be a strong
signal for thunderstorms today, so this activity will mainly be
showery in nature. Higher dew point air is expected south of
Interstate 80, which is where we expect the bulk of the rainfall
today. Farther north, it`s possible some locations could remain
dry, especially for locations along the Highway 20 corridor. An
area of lower confidence is for our far northwest IL region
around Stephenson county where the HRRR model suggests showers
and even a storm possible there, seemingly along a lake breeze
boundary from Lake Michigan. Other CAM guidance doesn`t seem to
have this, hence the lower confidence. High temperatures today
should remain seasonal, warming to the middle to upper 70s -
coolest to the south where showers are more likely.

A brief respite from showers is expected tonight into Sunday morning
before the next system quickly moves in for Sunday afternoon. A
broad upper-level trough is expected to approach our region,
with a cut-off upper low over Manitoba Canada moving over far
northern MN by the afternoon. A PVA maxima and attendant cold
front is expected to dive through our region by the afternoon,
which will provide the large scale forcing for increased chances
(30-60%) of showers and storms. While instability appears to be
more modest, with SBCAPE around 500 to 1500 J/kg per most
ensemble and deterministic guidance, strong kinematics appear to
accompany the approaching wave. 500 mb level flow per the
07.00z HREF indicates 50 to 70+ knot magnitudes, which are near
95 percent of the ECMWF ensemble climatology, so some pretty
strong flow for this time of the year. Enhanced deep-layer
shear of 35 to 45 knots should support organized convective
updrafts, with damaging winds as the main threats. Large hail is
also possible, although appears to be a secondary threat due to
more limited mid-level lapse rates (~6 C/km). Given the
potential for a damaging wind threat, SPC has introduced a
Slight Risk (level 2 of 5) of severe weather for locations south
of the Quad Cities, with a Marginal Risk (level 1 of 5) for
locations along and south of a line from Sigourney, IA to
Galena, IL. Uncertainty remains on the expected timing of the
strong to severe convection, but it looks most likely in the
afternoon into the early evening.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 403 AM CDT Sat Jun 7 2025

Any lingering showers and storms ongoing early Sunday evening will
eventually wane as the aforementioned cold front and PVA maxima exit
the region, making for a dry night Sunday night. However, the upper-
level trough will continue to linger over the western Great Lakes
region, keeping cyclonic flow over the region. This should keep
periodic chances of showers and perhaps a few storms for Monday.
Strong to severe weather isn`t expected.

For Tuesday and Wednesday, a period of dry conditions is
expected, thanks to surface high pressure developing in the wake
of the cold front. The main story for this time frame is a
noticeable warm up, with high temperatures on Tuesday in the
upper 70s to the middle to upper 80s on Wednesday and Thursday.

For Thursday and Friday, there is a signal for a more active period
as a southern stream shortwave lifts northeastward towards our
region, but there remains uncertainty on the onset timing and
coverage due to larger differences among the guidance.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1246 AM CDT Sat Jun 7 2025

VFR conditions were seen as of TAF issuance, under mostly clear
skies. An approaching mid-level shortwave will support
increasing chances of showers and isolated thunderstorms this
afternoon, largely focused south of Interstate 80. Confidence is
highest for MVFR ceilings at BRL, with lower confidence for our
other TAF terminals. Generally light winds (less than 10 knots)
will continue through Saturday, mainly from the southeast.

&&

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

&&

$$

SHORT TERM...Schultz
LONG TERM...Schultz
AVIATION...Schultz