Crystal Lake, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

236
FXUS63 KDVN 232312
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
512 PM CST Mon Dec 23 2024

.KEY MESSAGES...

- After a brief setback closer to normal for highs Tuesday, a
  warmup will ensue for Christmas into next weekend leading to
  above normal temperatures.

- A gray Christmas is in store this year.

- A more active pattern sets up after Christmas leading to
  several chances for rain late week through next weekend.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 220 PM CST Mon Dec 23 2024

A cold front continues to push through late this afternoon.
This will bring a little setback on temperatures Tuesday with
highs closer to normal and mainly in the 30s. This cooling may
be accentuated coming of a day in which highs today topped out
into the 40s to near 50 for many south of Hwy 30!

Satellite shows areas of stratus upstream across portions of
WI/MN/N IA, and this cloud cover looks to be drawn down into the
area tonight as surface ridging builds in. Areas that are
mainly clear this evening/tonight ahead of the stratus will have
the potential to see some fog development with the low dew
point depressions and radiational cooling. Timing of stratus
will be critical for extent/magnitude of any fog. Low
temperatures will also be another challenge, as I would expect
to see a good drop this evening/tonight in the areas that are
void of any stratus before leveling off once the low clouds
arrive. Areas that stay mainly clear the longest will likely
drop into the 20s (favored south), while areas that see the
clouds sooner will likely only drop into the 30s.

&&

.LONG TERM /TUESDAY THROUGH MONDAY/...
Issued at 220 PM CST Mon Dec 23 2024

The pattern remains active through the long term period, as a
longwave trough moves across the western U.S. with a series
of compact and vigorous shortwaves lifting across the central
CONUS. These systems will bring warmer and more moist air into
the region. Through the Christmas holiday we`ll see gray days,
with the potential for some dreariness with patchy drizzle and
spotty light rain late by Christmas Eve through Thursday as
moisture is trapped and deepens beneath a developing broad
upper level trough.

With the active pattern expect the specifics to change with
each run of the guidance. What is clear is that the thermal
profiles across our area support rain from any of these systems.
Our overall rainfall totals through the weekend are likely to
be under an inch. In fact, much of the rain looks to be
stratiform and predominantly light. If one of these systems
slows down and pulls further west, then we may find ourselves
more in a warm sector and could see convective showers which
could increase rainfall amounts.

As we get into next week heading toward 2025 and then beyond
into mid January, there is a general consensus from the
ensembles of turning colder which we`ve noted this potential
in recent Climate sections of the AFD in line with the Week 3-4
temperature outlook (Jan 4-17) from CPC issued on Dec 20th of
favoring below normal temperatures. With the pattern looking to
stay active we`ll most certainly have opportunities for snow!

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 508 PM CST Mon Dec 23 2024

An extensive stratus deck covers all of northern Iowa, northern
Illinois, Minnesota, and Wisconsin. This stratus is slowly
moving south, and will be over the entire area through the next
24 hours and maybe much longer. Cigs around 1000 to 1500 ft will
lower to 800 to 1000 ft overnight, then raise back to the 1000
to 1500 ft height again after mid morning Tuesday. Fog would be
possible with any clearing, but with stratus, we are siding
towards good visibility, but low cigs. There is a short term fog
bank that`s moving towards CID early this evening, and I`ve put
a temporary condition in there as upstream sites from them have
visibility of 2-3 miles in fog.


&&

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

&&

$$

SHORT TERM...McClure
LONG TERM...Gibbs
AVIATION...Ervin