Crystal Lake, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

826
FXUS63 KDVN 180456
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1056 PM CST Fri Jan 17 2025

.KEY MESSAGES...

- Coldest air of the season so far expected this weekend through
  early next week.

- A Cold Weather Advisory has been issued for parts of eastern
  Iowa late Saturday night through Sunday morning. This is the
  first in this developing cold spell, which is likely to
  feature additional cold weather headlines as the cold air
  peaks Sunday into Monday.

&&

.UPDATE...
Issued at 919 PM CST Fri Jan 17 2025

Based on evening upper air data and trends with radar, observations
and very short range models, the rain/snow chances across the
far southeast and east have been removed. for the evening hours.

Observation trends show the cold advection is pushing more south
than southeast which helped push the storm track a bit further
south. Thus outside of some flurries late tonight, the remainder
of the evening hours will be dry across the area.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 251 PM CST Fri Jan 17 2025

Full sunshine and dry ground fostering deep mixing and owing to
gusty southwest winds to 30-35+ mph. This and potentially some
assistance of pre-frontal compressional heating ahead of an
approaching cold front, has propelled temps well above normal and
into the upper 40s to mid 50s this afternoon. The cold front is
currently making inroads and will sweep across the entire area
through mid evening. The brunt of the cold air however, lags behind
the front and does not arrive until late evening through the
overnight. As it does we`ll see temps plunge and winds turn gusty
from the northwest up to 30 to 40 mph. Can`t totally rule out
advisory criteria briefly being met, but overall winds at 35-40 kt
atop the mixed layer and lack of a very strong isallobaric push
albeit still modest will likely keep any threat fairly isolated.
Will continue with some low chances for rain this evening far
south/east, being on the north side of the phasing energy over
the Mid/Lower Mississippi Valley, but overall mainly dry. Late
this evening/overnight there may be a few flurries with a shallow
moisture layer atop steepening near surface lapse rates. The NAM
soundings are more moist and would indicate some potential for even
freezing drizzle with loss of in-cloud ice, but the model has been
verifying too moist and therefore have no mention and just kept
with flurries potentially for a few hour period with the onset of
the strong cold advection late evening into overnight.

&&

.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 251 PM CST Fri Jan 17 2025

The forecast remains unchanged over the weekend through early next
week, with bitterly cold air settling into the region. This
will come in waves, with the first surge Saturday night into
Sunday. This will result in single digits above/below zero for
lows with wind chills in the negative teens and 20s as a
lingering pressure gradient keeps winds up at 10-20+ mph.
Confidence is highest on reaching Cold Weather Advisory criteria
of -20F north of I-80 on the Iowa side where the gradient will
be a little more stout, and as a result we`ve issued the
advisory for those areas late Saturday night through Sunday
morning. The main core of the arctic air arrives Sunday night
through Monday night on the backside of low pressure near Hudson
Bay. This will dislodge a chunk of arctic air with 850 hPa
temperatures progged as cold as -25 to -30C over the region. If
these values verify, they will fall in the top 10 coldest 850 mb
temps in the SPC sounding climatology for DVN (period of record
goes back to 1995). Despite the lack of snow cover and even
with some moderation it`s still going to be bitterly
cold/frigid. Lows Sunday night through Monday night will be in
the single digits and teens below zero, with minimum wind chills
of -15 to -30 degrees. This will necessitate additional cold
weather headlines.

The forecast remains dry through early week, but can`t rule out some
waves embedded in the N/NW flow. Given the low amplitude nature of
these, they are hard to resolve in the models at this juncture, and
as such the NBM offers no measurable PoPs. But, something to keep an
eye on as the arctic air will be very efficient at producing some
flakage.

Mid-late week, we`re still on track to see a pattern change
toward more semi-zonal flow aloft. This will lead to a moderation on
temperatures, and can`t rule out some additional precipitation
chances with any embedded waves but not a strong signal at this
time.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1050 PM CST Fri Jan 17 2025

Observation trends shows an extensive area of MVFR CIG across
northwest Iowa and southern Minnesota behind the arctic front.
HREF cloud categories indicate MVFR CIGS moving into eastern
Iowa by 12z/18 along with some flurries. Some transient wind
gusts up to 35 knots will also be possible. HREF cloud
categories show a rapid breaking up of the MVFR CIGS 15-18z/18
across eastern Iowa and eventually into northern Illinois. Wind
gusts above 20 knots will persist past 00z/19.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Cold Weather Advisory from 3 AM to noon CST Sunday for
     IAZ040>042-051>054-063>066.
IL...None.
MO...None.

&&

$$

UPDATE...08
SHORT TERM...McClure
LONG TERM...McClure/Schultz
AVIATION...08