193
FXUS63 KLOT 070736
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
136 AM CST Thu Nov 7 2024

.KEY MESSAGES...

- Patchy fog possible tonight into Friday morning, mainly south
  of about I-80.

- A period of showers likely Saturday evening, then next good
  chance of rain Tuesday night-Wednesday.

&&

.DISCUSSION...
Issued at 136 AM CST Thu Nov 7 2024

Through Friday:

The western extent of an expansive region of stratus has been
gradually eroding and making slow inroads into the region. This
trend should continue, with scattering/clearing from northwest to
southeast today. A combination of cloud cover downwind of the lake
and diurnal mixing into a shallow moist layer around 2 kft may
slow the clearing trends east of about I-55 until mid to late
afternoon, however. Highs today look to top out in the mid to
upper 50s.

Tonight, the low-level gradient will tighten up as as an elongated
area of high pressure presses southward. This will drive an
increase in the low-level/near-surface flow and even with some
decoupling, looks to result in at least a few knots of surface
westerlies through the overnight. While the environment will
otherwise be supportive of fog development (near-surface
hydrolapse, relatively clear skies, etc.), this increase in
boundary layer flow should temper the dense fog threat north of
about I-80, although visibilities falling into the 4 to 6 mile
range seem plausible. Farther to the south, winds will be a bit
lighter, although may still remain a bit too elevated to
facilitate widespread dense fog development with more of a
patchy dense scenario looking more likely.

High pressure builds back north across the region through Friday
with tranquil and pleasant conditions expected to close out the
workweek.

Carlaw


Friday Night through Wednesday:

No significant changes for the extended period. A storm system
will develop in the Plains Friday and lift northeast reaching
the western Great Lakes on Sunday. Best precip chances will be
tied to the warm front lifting north across the area Saturday
afternoon into Saturday evening. The precipitation continues to
look fairly progressive, possibly ending early Sunday morning
with a small chance for a few lingering showers across far
northern IL Sunday morning. Thunder chances remain fairly low
and currently no thunder in the forecast. West/southwest winds
may become breezy Sunday with gusts into the 30 mph range
possible.

While mainly dry weather is expected Sunday afternoon through
Tuesday, there is a similar set up Monday to last night,
Wednesday evening, where a few showers or patchy drizzle may be
possible. Confidence is too low for any mention from this
distance but the pattern looks similar.

Still some timing differences with the next system for Wednesday
but this has more or less been a consistent feature for the past
several days, which is a cold front moving across the region.
Blended likely pops seem fine for now along with a chance for
thunder, though similar to this weekend`s system, precip chances
will likely be confined to a short time window.

Southerly winds will likely increase Tuesday night into
Wednesday morning ahead of this front and then shift westerly
behind the front Wednesday afternoon/evening. Still plenty of
uncertainty for how strong these winds may become, but wind
gusts into the 30-35 mph are possible based on current trends.
cms

&&

.AVIATION /06Z TAFS THROUGH 12Z FRIDAY/...
Issued at 1055 PM CST Wed Nov 6 2024

Aviation Forecast Concerns for 06Z TAFs:

- MVFR ceilings lingering into Thursday morning, fairly low
  confidence in exact timing of improvement to VFR.

- Some potential for fog or low stratus development later
  Thursday night.

Extensive MVFR ceilings persist across parts of the western
Great Lakes region late this evening, though some slow erosion
has been noted over parts of central WI. Would expected some
scattering/lifting into northern IL toward morning, though some
redevelopment is possible for a time after sunrise before
skies really clear out midday/early afternoon.

North-northwest surface winds of 10 kts or less will gradually
back more northwest Thursday morning, then west-southwest later
in the day and evening. Some potential for fog or low stratus
development will exist later Thursday night, though confidence
is low at this distance.

Ratzer

&&

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

&&

$$

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