697
FXUS63 KLOT 092336
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
536 PM CST Sat Nov 9 2024

.KEY MESSAGES...

- Period of showers and drizzle tonight into Sunday morning.

- Breezy winds areawide Sunday afternoon along with a chance
  for scattered showers for areas north of I-88.

- Another storm system looks to bring another chance for
  rain towards the middle of next week.

&&

.DISCUSSION...
Issued at 319 PM CST Sat Nov 9 2024

Through Sunday Night:

Through Sunday night:

A vertically stacked low pressure system continues to lift into
the Upper Midwest this afternoon with an occluding frontal
boundary stretching from southern MN southward across the
Mississippi River Valley. Along this frontal boundary an area of
broken showers continues to gradually move across central IL
towards our area. While there has been a couple of radar echoes
developing ahead of the main shower axis, these echoes have
struggled to produce much more than sprinkles due to the large
quantity of low-level dry air. However, the aforementioned
showers are expected to move into northern IL and northwest IN
this evening and persist through the overnight hours as the
front traverses the area. The progressive nature of the front
should allow showers to exit the area prior to daybreak Sunday
morning, however; patchy drizzle is forecast to develop behind
the showers as lingering low-level moisture interacts with the
broad forcing beneath the systems dry slot. Therefore, expect
dreary weather, including reduced visibilities, to linger into
Sunday morning before conditions improve towards midday. Despite
the drizzle, rainfall totals are still expected to remain
generally below a tenth of an inch, but pockets of quarter inch
amounts may materialize especially southeast of I-57.

As conditions improve on Sunday, winds will increase through
the afternoon resulting in 25-30 mph gusts for the afternoon
hours. Otherwise, expect gradually clearing skies through the
day on Sunday with highs in the upper 50s and lower 60s giving
way to lows in the 40s Sunday night. However, there is still the
chance (20-40%) for scattered showers to develop Sunday
afternoon mainly for areas north of I-88 as the low passes to
our north. Regardless, expect dry conditions to return Sunday
evening.


Monday through Saturday:

The main forecast concern for the upcoming week will be another
storm system that looks to bring additional chances for rain
towards midweek. Until then, expect high pressure to remain the
dominant weather feature overhead resulting in dry and
seasonably mild conditions. Though, a cold front is expected to
move through the area on Monday which does look to generate
another period of breezy northwest winds gusting 20-25 mph
Monday afternoon. Furthermore, highs on Tuesday will also be a
bit cooler than Monday with readings in the lower 50s.

While our area benefits from a surface high overhead, another
deepening trough is expected to move into the western CONUS on
Tuesday. This trough is then expected to drift across the
central Plains and eventually into the Great Lakes late
Wednesday into the day on Thursday. Guidance remains in decent
agreement that the surface low is expected to traverse across
northern MN and southern Canada which means our area will have
to deal with the trailing cold front and its associated showers.
Despite the good agreement on evolution, there is still some
uncertainty in timing and coverage of showers along the front.
So while the current forecast has maintained the 40-50% POPs
offered by the NBM, subtle changes may occur as we get closer.
Nevertheless, another period of tranquil weather looks to
materialize behind the midweek storm system resulting in more
mild temperatures to close out the upcoming work week.

Yack

&&

.AVIATION /00Z TAFS THROUGH 06Z SUNDAY/...
Issued at 536 PM CST Sat Nov 9 2024

Aviation Forecast Concerns for the 00Z TAFs:

- SHRA continue to overspread terminals this evening, eventually
  tapering to drizzle late tonight.

- MVFR conditions develop later this evening as rain persists,
  with IFR/LIFR likely late tonight into Sunday morning in
  drizzle/fog. Improvement expected behind mid-late morning
  cold front Sunday.

- SSE winds become breeze WSW behind front on Sunday with gusts
  25-30 kt in the afternoon.

Surface low pressure over central NE will lift slowly
northeast to the U.P. of MI through late Sunday. Southerly low-
level winds will pull Gulf moisture into the system, resulting
in increasing SHRA this evening. Ceilings and visibilities are
expected to gradually deteriorate to MVFR by late
evening/midnight as rain persists, with further degradation to
IFR/LIFR late tonight into Sunday morning as SHRA tapers to
drizzle within moist low level air mass ahead of a cold front
trailing the aforementioned low. Already seeing extensive
IFR/LIFR conditions developing upstream across IA/MO, adding
confidence to model forecasts of IFR/LIFR conditions developing
across the terminals later tonight.

Cold front is progged to move across the area mid-morning
Sunday, with winds shifting to west-southwest and becoming
gusty 25-30 kt behind it (strongest gusts in the afternoon).
A quick improvement to high-end MVFR/VFR conditions is expected
behind the front, though there may be a period of additional
scattered SHRA with MVFR cigs into early afternoon beneath the
upper level trough axis. Winds should gradually ease into Sunday
evening, beneath a lingering VFR deck.

Ratzer

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 3 AM CST Sunday for the IL
     nearshore waters.

&&

$$

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