Crystal Lake, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

181
FXUS63 KDVN 302302
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
602 PM CDT Sun Mar 30 2025

...Updated for 00z Aviation...

.KEY MESSAGES...

- Another strong storm system will impact the Midwest Tuesday
  night into Wednesday. Severe storms are possible, especially
  east of the Mississippi on Wednesday.

- Outside of Wednesday, temperatures look to be near or slightly
  below normal for early April.

- The active weather pattern will continue the second half of
  the week with two additional but weaker systems moving through
  the Midwest.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 221 PM CDT Sun Mar 30 2025

Windy conditions along with scattered showers will be seen across
the area for the remainder of the afternoon. As colder air continues
to move into the area late this afternoon and evening, a rain/snow
mix is expected to develop in the Highway 20 corridor that may
briefly change over to all snow. Given the very warm ground and
roads, any snow will melt on contact.

Quiet, windy and much cooler conditions will be seen across the area
on Monday.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
Issued at 221 PM CDT Sun Mar 30 2025

Monday night
Assessment...high (>80%) confidence

Canadian high pressure will bring a quiet night and cooler than
normal temperatures to the area. Attention then turns to the next
system.


Tuesday through Wednesday night
Assessment...high (>80%) confidence on a storm system. Low to
medium (20-40%) confidence on potential impacts.

After a quiet Tuesday morning the next strong storm system will move
east from the Plains and impact the area mainly Tuesday night into
Wednesday. The model consensus has the highest pops (60-90%)
confined to late Tuesday night and Wednesday morning.

The models vary regarding timing and track; the ECMWF is faster and
further east, the CMC global and ICON models are slower and further
west and the GFS is in between and further north.

Regardless of the model solution, the overall evolution of the
system is similar. A wave of moisture and forcing will move across
the area Tuesday night into Wednesday morning bringing showers and
thunderstorms to the area. Timing and track of the system will
dictate if there is a nocturnal severe risk. At this stage (3.5 to 4
days out), storms would be elevated across the area with the warm
front still in Missouri. Thus the potential severe risk would be
mainly hail but a rogue severe wind gust cannot be ruled out.

Wednesday will be dependent upon what occurs Tuesday night.

In a careful examination of the models, one can infer a weak low
along the warm front helping to form a triple point that would move
through the area. Here is where the timing and track of the main
system becomes important. The overall large synoptic scale is
favorable for severe storms. However, it will be mesocale processes
(likely on the Beta and Gamma scales) that will dictate the when and
where strong to severe storms develop Wednesday afternoon/early
evening.

The better severe signal is to the east and south of the area (Ohio
Valley into southern Illinois) based on the overall synoptic picture
and CSU probabilistic machine learning data. HOWEVER, the inferred
triple point and associated weak low would be a favored area for
severe development as far west as the Mississippi River. Again, this
is dependent upon the timing and track of the main system. Thus the
current SPC slight risk looks reasonable this far out.

Diurnal storms that initiate on Wednesday will clear the far east
and southeast areas early Wednesday evening. Once storms exit the
area, the remainder of Wednesday night will be dry.

Thursday through Saturday night
Assessment...low to medium (20-40%) confidence on rain chances

The model consensus has two weak systems that move through the
Midwest; the first one Thursday into Thursday evening and the second
Friday night into Saturday morning.

The better moisture and forcing are well removed from the area so
the areal coverage for rain is low (20-30%).

Sunday
Assessment...medium to high (60-80%) confidence on dry conditions

The model consensus has dry conditions for Sunday as cold Canadian
high pressure builds in behind the departing second system.
Temperatures should be slightly cooler than normal.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 555 PM CDT Sun Mar 30 2025

Predominantly MVFR conditions (mainly for CIGs) expected for
much of tonight. Wrap-around precipitation will shift across
areas along and especially north of I-80, and is likely (60-80%
chance) at CID and DBQ between 01z and 07z. Initially it will be
rain, but it is expected to mix or change to snow for a time
with conditions dropping into lower MVFR to IFR. Some minor
accumulation is possible on elevated surfaces during the higher
precipitation rates, but pavement should be mostly wet with
temperatures above freezing. After 09z through 15z, decreasing
clouds and a return to VFR conditions is expected from west to
east in the wake of the system. Winds will remain gusty from the
W/NW at 10-20+ kt for much of the period.

&&

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

&&

$$

SHORT TERM...08
LONG TERM...08
AVIATION...McClure