Buffalo Grove, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

317
FXUS63 KLOT 241155
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
555 AM CST Sun Nov 24 2024

.KEY MESSAGES...

- Above normal temperatures today and Monday with highs in the 50s.

- Cold front to bring a period of rain showers and drizzle
  tonight through Monday.

- Potential for travel impacts in the region from accumulating
  snow in the Tuesday night to Thanksgiving Day period appears
  to be increasing.

- Below normal temperatures will prevail Monday night through
  Thursday, followed by much below normal (true mid-winter cold)
  Friday-Saturday and beyond.

&&

.DISCUSSION...
Issued at 333 AM CST Sun Nov 24 2024

Through Monday Night:

Another gloomy morning is ahead as pesky low-level moisture
remains trapped beneath a subtle ridge overhead. While there has
been signs that the low stratus is gradually advancing
eastward, a deck of mid-level clouds has moved in aloft and
looks to persist through this afternoon. So expect at least
mostly cloudy skies today but a few pockets of sunshine may be
briefly seen especially across our far south and southwestern
counties where some scattering may occur. Despite the cloud
cover, temperatures this afternoon are still expected to reach
into the above normal category for late November with highs in
the low to mid-50s.

Heading into tonight, the subtle shortwave trough over the
Sierras is expected to be ejecting into the central Plains and
lead to the development of a weak surface low as it does so.
This surface low is then forecast to lift through northern IL
late tonight into Monday morning resulting in a period of
showers and drizzle. Since temperatures overnight should remain
nearly stationary in the mid to upper 40s, the showers and
drizzle will remain in a liquid state and thus should pose no
significant threat aside from minor visibility reductions. As
the low lifts into Lower MI Monday afternoon it will drag a cold
front across the area resulting in a period of true showers
especially across far northeast IL and northwest IN.

Showers will quickly taper behind the front late Monday
afternoon and evening as colder and drier air filters in.
However, winds will quickly increase with northwest gusts in the
20-25 mph range likely Monday afternoon and overnight.
Temperatures will also be cooling behind the front resulting in
lows in the mid to upper 20s by Tuesday morning. Though, the dry
air will finally break us out of the clouds heading into the
day on Tuesday.

Yack


Tuesday through Saturday:

Focus in the extended period remains the potential for snow-
related impacts during the busy Thanksgiving holiday travel
period with true mid-winter cold also arriving over the
extended holiday weekend.

After what has been a fairly prolonged cloudy stretch, the sun
may manage to make a brief appearance Tuesday morning, with
fairly decent ensemble agreement in a drop in cloud coverage
before increasing again later in the day. Continued cold air
advection into the area in the wake of Monday`s cold front will
still likely hinder temperatures from warming out of the 30s.

Heading into Tuesday night, there remains a signal for a
preceding warm advective and frontogenetically forced band of
snow overnight (mainly after midnight) into Wednesday morning.
The GFS and NAM are also beginning to pick up on this signal,
which the ECMWF has shown the past few model runs. The exact
placement of this feature remains somewhat in flux, but felt
comfortable maintaining 20-30% chances for snow during this
period.

Over the past 24-hours there has been a gradual increase in
confidence toward winter-related travel impacts occurring due to
accumulating snow somewhere in the region Wednesday into
Thursday. However, models continue to struggle with how
amplified the upper jet becomes during this period (related to
the handling of potential phasing of waves over the Central
Plains) which has significant implications for the system track
and intensity and accordingly whether additional snowfall
related impacts occur here locally. It does appear that the
percentage of ensembles keeping the area dry has decreased
(those with a less amplified pattern and further south storm
track). Additionally a cluster of ensemble members continues to
depict a potentially higher end outcome (shifting the ensemble
mean above the 50th percentile). With all that said, confidence
in the details for this system remains low and it bears
watching over the next couple of days as models hopefully begin
to converge on a solution.

Thursday night through the upcoming weekend continues to look
like a favorable lake effect snow set-up oriented into northwest
Indiana/western Lower Michigan as much colder air advects over
a still relatively warm lake (currently in the upper 40s).
Speaking of the cold, forecast highs over the upcoming weekend
are only in the 20s with wind chills in the teens and single
digits! Something to keep in mind for the those returning from
Thanksgiving travels!

Petr

&&

.AVIATION /12Z TAFS THROUGH 18Z MONDAY/...
Issued at 555 AM CST Sun Nov 24 2024

Key Messages:

- Brief period of IFR/LIFR cigs this morning

- Rain and drizzle chances begin late this evening through
  Monday morning with associated vis/cig reductions

- IFR cigs/vis possible early Monday during greatest DZ
  coverage

IFR stratus from overnight is beginning to lift out of the
terminals early this morning. However, in the wake of this
clearing a narrow axis of patchy LIFR stratus has developed,
including at RFD. There remain concerns that this could occur at
Chicago area terminals as well, though confidence is not high
enough to add to the TAFs. For now, have accounted for this with
TEMPOs for 500-600 ft cigs through 14Z and some minor 4-6 SM
vis reductions in BR.

Once any lingering stratus ultimately scatters out and lifts out
of the area later this morning, VFR conditions are forecast
through early evening with light southeast winds.

Heading into the evening our next system will bring increasing
rain and drizzle chances overnight into Monday. Ceilings
steadily lower during this period with the lowest cigs and vis
expected to occur early Monday morning with low-end MVFR
conditions in drizzle currently forecast. It is possible this
will need to trend even lower with later updates.

Winds turn northwesterly toward the end of the 30-hr TAF period
late Monday morning behind a cold front.

Petr

&&

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

&&

$$

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