DeKalb, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

759
FXUS63 KLOT 111131
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
631 AM CDT Fri Apr 11 2025

.KEY MESSAGES...

- Quiet conditions are expected through at least Saturday before
  some lower end chances (20-30%) for precipitation are
  forecasted late Saturday night through Monday.

&&

.DISCUSSION...
Issued at 336 AM CDT Fri Apr 11 2025

Through Saturday:

A deep trough with several embedded waves continues to drift
eastward across the Great Lakes region, with plenty of
associated cloud cover arcing from eastern Minnesota to the
eastern Great Lakes. Mid-level suppression from a ridge building
toward the Upper Mississippi River Valley behind the departing
trough as well as deep N/NE flow will erode and advect much of
this cloud cover to the S/SW today. However, some diurnal
cumulus can be expected well inland this afternoon. Otherwise,
expect a seasonably cool day with temps ranging from the 40s
near the lake to mid 50s well inland.

Mostly clear skies will prevail tonight into Saturday morning
as a surface ridge drifts across the forecast area. Upper-level
clouds will then increase and thicken from the northwest through
the afternoon as WAA on increasing SSW winds pushes temps to
the low 60s inland (50s near the lake) during the afternoon.

Kluber


Saturday Night through Thursday:

On Sunday, surface low pressure developing over the central
Plains will help strengthen a low-level jet positioned along the
southeastern flank of the surface low. This southwesterly low-
level jet will end up pointing towards the lower Great Lakes and
will help facilitate the advection of a warmer, more moisture-
laden air mass into the region. It`s possible that at least some
spotty showers may end up developing within the impinging warm
air advection wing late Saturday night into Sunday, though
deterministic and ensemble model guidance remains at odds
regarding the quality of low- to mid-level moisture that will
ultimately be realized. Have largely kept the lower-end PoPs
output by the NBM as is for now given the existing uncertainties,
and will see if these PoPs need adjustment as some of the
shorter range hi-res models start to give their first takes on
what moisture profiles might look like during this time frame.

Otherwise, in spite of the increased cloud cover, Sunday should
be a mild day with breezy southerly to southwesterly low-level
flow pushing a low-level thermal ridge into the area. High
temperatures appear poised to reach the mid-upper 60s across
most of the area and could potentially end up eclipsing the 70
degree mark, particularly in our southwestern counties. One
exception to this might be locations along the far northeast
Illinois lakeshore, where winds may carry a slight onshore
component through most or all of the day, resulting in
temperatures that would potentially be several degrees cooler
than just a few miles farther inland.

Sunday night into Monday, an upper-level trough will swing into
the Great Lakes, spurring the development of a new surface low
near Lake Superior that should overtake the central Plains low
as the dominant low pressure area in the region. An associated
cold front will track eastward across our forecast area early in
the day on Monday. The early timing of this frontal passage
(which may potentially even occur before sunrise) should keep
any threat of diurnally-driven surface-based convection well to
our east, though the large-scale forcing brought in by the
upper-level trough coupled with sufficient column moisture in
the vicinity of the front could still support some showers and
perhaps an isolated thunderstorm or two in our forecast area
before the front has passed well to our east. The highest
chances for this to occur will be across southeastern portions
of our CWA, where the latest NBM output some lower-end chance
PoPs (25-30%).

Monday should otherwise be another breezy day, this time
featuring winds from the west in the wake of the cold front. The
main push of colder air behind the front should lag the front
itself by a good bit, which should allow for high temperatures
in the low-mid 60s to be realized across most of our forecast
area again (with our northwestern counties potentially being an
exception). Depending on how far south the core of the
aforementioned upper-level trough tracks, couldn`t rule out
some light precipitation occurring here Monday night into early
Tuesday as its backside shuffles across the region, though this
possibility doesn`t have enough ensemble support at this time to
warrant carrying mentionable PoPs during this time frame.

Drier and slightly cooler (though still seasonable) conditions
are then expected on Tuesday into Wednesday as high pressure
briefly builds back into the region. Another upper-level trough
will dive southeastward into the Great Lakes on Thursday and
bring us our next opportunity for precipitation during the
latter half of next week.

Ogorek

&&

.AVIATION /12Z TAFS THROUGH 18Z SATURDAY/...
Issued at 631 AM CDT Fri Apr 11 2025

There are no significant aviation forecast concerns for the
current TAF period.

Northerly winds this morning will turn more north-northeasterly
by late morning and increase to around 10-15 kts going into the
afternoon. Winds will then become light/calm tonight into
Saturday morning as surface high pressure settles into the
region.

While one or two patches of VFR stratocumulus will move across
the Chicago metro this morning, skies should trend clearer
thereafter and remain clear/mostly clear through the remainder
of the current TAF period.

Ogorek

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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