Elmhurst, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

608
FXUS63 KLOT 230853
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
253 AM CST Sat Nov 23 2024

.KEY MESSAGES...

- Seasonable today with above normal temperatures for late
  November expected Sunday.

- A pair of systems could bring rain and snow to the broader
  region Wednesday-Thanksgiving. Confidence in degree of local
  impacts remains low.

- Temperatures turn much colder late next week and beyond.

&&

.DISCUSSION...
Issued at 253 AM CST Sat Nov 23 2024

Through Sunday:

Modest upper-level ridging has started to build overhead this
morning and will continue to do so through the weekend. While
this would typically mean a return to sunny skies, a plume of
low-level moisture has become trapped beneath the ridge and
unfortunately looks to persist through Sunday as well resulting
in continued mostly to completely cloudy skies. However, there
is a chance that as winds just off the surface become
southwesterly this afternoon that the clouds could begin to
clear out. Given that these southwest winds will also generate
increasing warm advection (forcing for ascent within the
atmosphere) there is also the potential for the back edge of the
clouds (currently in eastern MO) to actually fill in and allow
the gloomy conditions to prevail. Since there is a good deal of
uncertainty as to which of these scenarios will play out have
decided to maintain mostly to completely cloudy skies in the
forecast through this afternoon, but did show some improvement
to a 60-70% cloud coverage tonight into Sunday in case some
clearing can occur. Obviously we will keep a close eye on trends
today and make adjustments to the forecast as conditions
warrant.

Regardless of how the clouds pan out, dry conditions are
expected to prevail through Sunday afternoon. Though, there is a
small chance (around 10%) that a mid-level shortwave
disturbance (currently over the Dakotas) could lead to some
spotty drizzle from daybreak through early afternoon today.
While there are some radar returns noted with the wave at this
time, surface observations are not showing any precipitation
reaching the ground. Couple this fact with the expectation for
the wave`s forcing to be focused above the aforementioned low-
level cloud deck, it appears the moisture will be insufficient
to generate much of anything other than mid-level clouds. For
now have decided to forego a formal drizzle mention in the
forecast but did expand the silent 10% POPs across northern IL
and northwest IN (mainly north of I-80) as a precaution.

Finally, temperatures today will likely be a few degrees cooler
than originally forecast due to persistent cloud cover but
still seasonable in the mid-40s nonetheless. Though the
increasing warm advection tonight and through the day on Sunday
should result in notably warmer temperatures regardless of cloud
coverage, expect highs to top out in the low to mid-50s to
close out the weekend.

Yack


Sunday Night through Friday:

Continued southerly flow Sunday night will result in one final
unseasonably warm night before a cold front sweeps through the
region on Monday. This will usher in a cooler and potentially
more active weather pattern through midweek with even colder
conditions in store toward the end of the week.

The aforementioned cold front will also bring the potential for
a few light showers early Monday along with breezy northwest
winds. Renewed shower development will then be possible later in
the day with the arrival of a trailing mid-level wave. While
the magnitude of cooling will ultimately be determined by how
quickly cloud cover manages to exit to the east in the wake of
the Monday system, temperatures are currently forecast to drop
into the 20s by early Tuesday morning with slightly below normal
temperatures (for late November) expected to continue through
Thanksgiving day with highs generally in the 30s to around 40.

This cooler pattern will also be accompanied by wintry
precipitation chances due to a pair of systems expected to
traverse the broader region Wednesday through Thursday night and
could lead to impacts to the busy Thanksgiving holiday travel
period. Unfortunately confidence in the degree of impacts here
locally remains low due to continued variability in storm track
and intensity, particularly when comparing ensemble clusters.
Given this uncertainty, broad brushed 20-40% chances for
rain/snow WED-THU seem appropriate at this distance. Stay tuned!

In the wake of the Thanksgiving system, much colder air will
begin to surge into the region with a continued strong signal
for well below normal temperatures heading into the long holiday
weekend.

Petr

&&

.AVIATION /06Z TAFS THROUGH 12Z SUNDAY/...
Issued at 1103 PM CST Fri Nov 22 2024

Key messages:

- MVFR cigs tonight. Increased chances to build down to IFR at
  RFD and DPA into Saturday morning.

- Highly uncertain cig and vsby trends late Saturday afternoon
  and evening.

MVFR cigs continued to slowly build downwards this evening.
Expecting prevailing low-MVFR cigs at ORD, MDW, and GYY
tonight, with higher chances for IFR at RFD and DPA.

Uncertainty regarding cig and vsby trends increases markedly
late Saturday afternoon and evening. A sharp edge to the stratus
layer is evident across central Iowa and eastern Missouri, and
as the low-level flow turns southwesterly, this should slosh
towards the area. Most guidance suggests a rapid clearing trend
occurring late in the afternoon, while some of the more
aggressive guidance maintains IFR to LIFR conditions through
much of Saturday night. Given the sharpness of the western edge
of the stratus deck, along with the general multi-model
consensus, will continue to show a gradual improving trend
after 00z Sunday. However, much lower cig/vsbys than advertised
remain on the table, and do have some concern that low cigs will
stay entrenched and/or re-develop through the evening.

Carlaw

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 4 AM CST early this morning for
     Winthrop Harbor IL to Gary IN.

     Small Craft Advisory until 10 AM CST this morning for Gary to
     Burns Harbor IN-Burns Harbor to Michigan City IN.

&&

$$

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