Crystal Lake, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

496
FXUS63 KDVN 040456
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1056 PM CST Tue Dec 3 2024

...06z Aviation Update...

.KEY MESSAGES...

- Warner temperatures are forecast on Wednesday before a strong
  cold front moves across the area. Strong gusts winds are
  possible Wednesday afternoon into the evening with some gusts
  up to 40 MPH.

- There is a slight chance of showers on Wednesday afternoon.

- Thursday is forecast to be noticeably colder with high
  temperatures in the lower 20s.

- A warming trend Friday through Sunday with the warmest
  temperatures on Sunday.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 203 PM CST Tue Dec 3 2024

Another clipper like system will clip the area on Wednesday and
bring a strong cold front across the area during the day. Ahead
of this storm system, warm advection will occur with south
winds across the area tonight. There may be period of wind gusts
up to 20 MPH tonight as a low level jet develops across the
area.

Wind will begin to increase late tomorrow afternoon as the front
moves through. There is a wide spread in possible wind gusts between
the models behind the front Wednesday afternoon with almost 30 MPH
difference in wind gust speeds ranging from 15 MPH to almost 40 MPH.
A look at model soundings show around 40 to 44 knots at the top of
the mixed layer during the late afternoon and into the evening
hours. Mixing those wind speeds to the surface results in gusts of
35 to 40 MPH. For this reason we have decided to hold off on a wind
advisory at this time to allow the overnight shift time to look at
the data due to model differences.

Temperatures ahead of the front are expected to be in the mid 30s in
Buchanan County to the mid 40s in far northeast Missouri. There is a
weak signal for precipitation behind the front in both synoptic and
CAMS but more likely across northeast third of our CWA with snow
showers the main concern. Little if any accumulation is expected at
this time.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Issued at 203 PM CST Tue Dec 3 2024

Arctic high pressure is forecast to build into the area on Thursday
in the wake of Thursday`s clipper system. This will spread cold
air into the area Wednesday through Thursday. Low temperatures
on Thursday morning will be largely be in the single digits
above zero. Winds will be decreasing Thursday morning as the
pressure gradient relaxes but wind chill values in the single
digits below zero with the exception of the highway 20 corridor
where wind chill values will be as low as twelve below zero.
High temperatures on Thursday will be in the lower 20s.

A warming trend will begin on Friday and continue into the weekend
as the persistent eastern trough moves eastward and 500 mb
ridge builds into the Plains. High temperatures on Saturday will
be in the 40s with lower 50s possible on Sunday southwest of a
Iowa City to Moline to Galesburg line.

Another trough is forecast to approaching the area early next week
with model cluster analysis is showing differences in timing and
placement between the models. The current forecast has increasing
chances of precipitation on Monday. The current forecast has rain
across the area at this time with temperatures in the 40s.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1050 PM CST Tue Dec 3 2024

Increasing south to southwesterly LLVL pressure gradient will
continue to tighten up overnight, producing sfc winds of 10-15
KTs with a few gusts at times. With LLVL jet flow at 1500 to
2000 FT AGL ramping up overnight, have maintained LLVL wind
shear in most the TAF sites into Wed morning. Otherwise, VFR
skies until a low VFR to MVFR cloud deck advects down acrs the
area late Wed morning and into the afternoon with a strong cold
frontal passage. Sfc winds will veer to the northwest and become
strong, possibly gusting over 35 KTs at times by mid to late Wed
afternoon, lasting into the evening. Some embedded snow or
rain-snow shower mix will rotate down acrs the area as well Wed
afternoon, mainly along and north of the Interstate 80
corridor. Thus there may be passing bouts of lower MVFR or even
IFR VSBYs in these showers when combined with the brisk gradient
winds, or even enhanced higher wind gusts up to 45 KTs in the
showers themselves.

&&

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

&&

$$

SHORT TERM...Cousins
LONG TERM...Cousins
AVIATION...12