Gale Warning 16, NWS Chicago, IL

328 
WHUS73 KLOT 290845
MWWLOT

URGENT - MARINE WEATHER MESSAGE
National Weather Service Chicago IL
345 AM CDT Fri Oct 29 2021

LMZ740>742-291645-
/O.CON.KLOT.SC.Y.0084.000000T0000Z-211029T1400Z/
/O.CON.KLOT.GL.W.0016.211029T1400Z-211030T0900Z/
/O.CON.KLOT.SC.Y.0085.211030T0900Z-211031T0000Z/
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
345 AM CDT Fri Oct 29 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 9 AM CDT THIS
MORNING...
...GALE WARNING REMAINS IN EFFECT FROM 9 AM THIS MORNING TO 4 AM
CDT SATURDAY...
...SMALL CRAFT ADVISORY REMAINS IN EFFECT FROM 4 AM TO 7 PM CDT
SATURDAY...

* WHAT...For the Gale Warning, north-northeast gales to 35 kt,
  significant waves up to 12 ft, and occasional waves up to 15 
  ft. For the Small Craft Advisories, north-northeast winds up to 
  25 to 30 kt, significant waves up to 9 ft, and occasional waves 
  up to 12 ft.

* WHERE...Winthrop Harbor to Calumet Harbor IL.

* WHEN...For the initial Small Craft Advisory, until 9 AM CDT this
  morning. For the Gale Warning, from 9 AM this morning to 4 AM
  CDT Saturday. For the proceeding Small Craft Advisory, from 4 
  AM to 7 PM CDT Saturday.

* IMPACTS...Strong winds will cause hazardous waves which could 
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should alter plans to avoid these hazardous conditions.
Remain in port, seek safe harbor, alter course, and/or secure the
vessel for severe conditions.

&&

$$

LMZ743-744-291645-
/O.CON.KLOT.SC.Y.0084.000000T0000Z-211029T2000Z/
/O.CON.KLOT.GL.W.0016.211029T2000Z-211030T0900Z/
/O.CON.KLOT.SC.Y.0085.211030T0900Z-211031T0000Z/
Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN-
345 AM CDT Fri Oct 29 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 3 PM CDT THIS
AFTERNOON...
...GALE WARNING REMAINS IN EFFECT FROM 3 PM THIS AFTERNOON TO
4 AM CDT SATURDAY...
...SMALL CRAFT ADVISORY REMAINS IN EFFECT FROM 4 AM TO 7 PM CDT
SATURDAY...

* WHAT...For the Gale Warning, northeast gales to 35 kt, 
  significant waves up to 10 ft, and occasional waves up to 13 
  ft. For Small Craft Advisories, north-northeast winds to 25 to 
  30 kt, significant waves up to 9 ft, and occasional waves up 
  to 12 ft.

* WHERE...Calumet Harbor IL to Burns Harbor IN.

* WHEN...For the initial Small Craft Advisory, until 3 PM CDT this
  afternoon. For the Gale Warning, from 3 PM this afternoon to 4
  AM CDT Saturday. For the proceeding Small Craft Advisory, from 
  4 AM to 7 PM CDT Saturday.

* IMPACTS...Strong winds will cause hazardous waves which could 
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should alter plans to avoid these hazardous conditions.
Remain in port, seek safe harbor, alter course, and/or secure the
vessel for severe conditions.

&&

$$

LMZ745-291645-
/O.CON.KLOT.SC.Y.0084.000000T0000Z-211031T0000Z/
Burns Harbor to Michigan City IN-
345 AM CDT Fri Oct 29 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 7 PM CDT
SATURDAY...

* WHAT...North northeast winds to 25 to 30 kt with gusts to 35 
  kt gales possible, significant waves up to 9 ft, and 
  occasional waves up to 12 ft.

* WHERE...Burns Harbor to Michigan City IN.

* WHEN...Until 7 PM CDT Saturday.

* IMPACTS...Conditions will be hazardous to small craft.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Inexperienced mariners, especially those operating smaller
vessels, should avoid navigating in hazardous conditions.

&&

$$

541 
WHUS73 KLOT 291505
MWWLOT

URGENT - MARINE WEATHER MESSAGE
National Weather Service Chicago IL
1005 AM CDT Fri Oct 29 2021

LMZ743-744-292315-
/O.CON.KLOT.SC.Y.0084.000000T0000Z-211029T2000Z/
/O.CON.KLOT.GL.W.0016.211029T2000Z-211030T0900Z/
/O.CON.KLOT.SC.Y.0085.211030T0900Z-211031T0000Z/
Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN-
1005 AM CDT Fri Oct 29 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 3 PM CDT THIS
AFTERNOON...

...GALE WARNING REMAINS IN EFFECT FROM 3 PM THIS AFTERNOON TO
4 AM CDT SATURDAY...

...SMALL CRAFT ADVISORY REMAINS IN EFFECT FROM 4 AM TO 7 PM CDT
SATURDAY...

* WHAT...For the Gale Warning, north-northeast gales to 35 kt, 
  significant waves up to 10 ft, and occasional waves up to 13 
  ft. For Small Craft Advisories, north-northeast winds to 25 to 
  30 kt, significant waves up to 9 ft, and occasional waves up 
  to 12 ft.

* WHERE...Calumet Harbor IL to Burns Harbor IN.

* WHEN...For the initial Small Craft Advisory, until 3 PM CDT 
  this afternoon. For the Gale Warning, from 3 PM this afternoon 
  to 4 AM CDT Saturday. For the proceeding Small Craft Advisory, 
  from 4 AM to 7 PM CDT Saturday.

* IMPACTS...Strong winds will cause hazardous waves which could 
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should alter plans to avoid these hazardous conditions.
Remain in port, seek safe harbor, alter course, and/or secure the
vessel for severe conditions.

&&

$$

LMZ740>742-292315-
/O.CON.KLOT.GL.W.0016.000000T0000Z-211030T0900Z/
/O.CON.KLOT.SC.Y.0085.211030T0900Z-211031T0000Z/
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
1005 AM CDT Fri Oct 29 2021

...GALE WARNING REMAINS IN EFFECT UNTIL 4 AM CDT SATURDAY...

...SMALL CRAFT ADVISORY REMAINS IN EFFECT FROM 4 AM TO 7 PM CDT
SATURDAY...

* WHAT...For the Gale Warning, north-northeast gales to 35 kt, 
  significant waves up to 12 ft, and occasional waves up to 15 
  ft. For the Small Craft Advisories, north-northeast winds up 
  to 25 to 30 kt, significant waves up to 9 ft, and occasional 
  waves up to 12 ft.

* WHERE...Winthrop Harbor to Calumet Harbor IL.

* WHEN...For the initial Small Craft Advisory, until 9 AM CDT 
  this morning. For the Gale Warning, from 9 AM this morning to 
  4 AM CDT Saturday. For the proceeding Small Craft Advisory, 
  from 4 AM to 7 PM CDT Saturday.

* IMPACTS...Strong winds will cause hazardous waves which could 
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should alter plans to avoid these hazardous conditions.
Remain in port, seek safe harbor, alter course, and/or secure the
vessel for severe conditions.

&&

$$

LMZ745-292315-
/O.CON.KLOT.SC.Y.0084.000000T0000Z-211031T0000Z/
Burns Harbor to Michigan City IN-
1005 AM CDT Fri Oct 29 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 7 PM CDT
SATURDAY...

* WHAT...North northeast winds to 25 to 30 kt with gusts to 35 
  kt gales possible, significant waves up to 9 ft, and 
  occasional waves up to 12 ft.

* WHERE...Burns Harbor to Michigan City IN.

* WHEN...Until 7 PM CDT Saturday.

* IMPACTS...Conditions will be hazardous to small craft.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Inexperienced mariners, especially those operating smaller
vessels, should avoid navigating in hazardous conditions.

&&

$$

197 
WHUS73 KLOT 292035
MWWLOT

URGENT - MARINE WEATHER MESSAGE
National Weather Service Chicago IL
335 PM CDT Fri Oct 29 2021

LMZ740>742-300445-
/O.CON.KLOT.GL.W.0016.000000T0000Z-211030T0900Z/
/O.CON.KLOT.SC.Y.0085.211030T0900Z-211031T0000Z/
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
335 PM CDT Fri Oct 29 2021

...GALE WARNING REMAINS IN EFFECT UNTIL 4 AM CDT SATURDAY...

...SMALL CRAFT ADVISORY REMAINS IN EFFECT FROM 4 AM TO 7 PM CDT
SATURDAY...

* WHAT...For the Gale Warning, north to northeast gales to 35 kt,
  significant waves to 12 ft, and occasional waves to 15 ft. For
  the Small Craft Advisory, north to northeast winds to 30 kt,
  significant waves up to 10 ft, and occasional waves to 13 ft.

* WHERE...Winthrop Harbor to Calumet Harbor IL.

* WHEN...For the Gale Warning, until 4 AM CDT Saturday. For the 
  Small Craft Advisory, from 4 AM to 7 PM CDT Saturday.

* IMPACTS...Strong winds will cause hazardous waves which could 
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should alter plans to avoid these hazardous conditions.
Remain in port, seek safe harbor, alter course, and/or secure the
vessel for severe conditions.

&&

$$

LMZ743-744-300445-
/O.CON.KLOT.GL.W.0016.000000T0000Z-211030T0900Z/
/O.CON.KLOT.SC.Y.0085.211030T0900Z-211031T0000Z/
Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN-
335 PM CDT Fri Oct 29 2021

...GALE WARNING REMAINS IN EFFECT UNTIL 4 AM CDT SATURDAY...

...SMALL CRAFT ADVISORY REMAINS IN EFFECT FROM 4 AM TO 7 PM CDT
SATURDAY...

* WHAT...For the Gale Warning, north to northeast gales to 35 kt,
  significant waves up to 10 ft, and occasional waves to 13 ft.
  For Small Craft Advisory, north to northeast winds to 30 kt,
  significant waves up to 9 ft, and occasional waves to 12 ft.

* WHERE...Calumet Harbor IL to Burns Harbor IN.

* WHEN...For the Gale Warning, until 4 AM CDT Saturday. For the 
  Small Craft Advisory, from 4 AM to 7 PM CDT Saturday.

* IMPACTS...Strong winds will cause hazardous waves which could 
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should alter plans to avoid these hazardous conditions.
Remain in port, seek safe harbor, alter course, and/or secure the
vessel for severe conditions.

&&

$$

LMZ745-300445-
/O.CON.KLOT.SC.Y.0084.000000T0000Z-211031T0000Z/
Burns Harbor to Michigan City IN-
335 PM CDT Fri Oct 29 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 7 PM CDT
SATURDAY...

* WHAT...North to northeast winds to 30 kt with occasional gale
  force gusts to 35 kt gales possible, significant waves to 10 ft,
  and occasional waves to 13 ft.

* WHERE...Burns Harbor to Michigan City IN.

* WHEN...Until 7 PM CDT Saturday.

* IMPACTS...Conditions will be hazardous to small craft.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Inexperienced mariners, especially those operating smaller
vessels, should avoid navigating in hazardous conditions.

&&

$$

275 
WHUS73 KLOT 300203
MWWLOT

URGENT - MARINE WEATHER MESSAGE
National Weather Service Chicago IL
903 PM CDT Fri Oct 29 2021

LMZ745-301015-
/O.UPG.KLOT.SC.Y.0084.000000T0000Z-211031T0000Z/
/O.EXA.KLOT.GL.W.0016.000000T0000Z-211030T0900Z/
/O.EXA.KLOT.SC.Y.0085.211030T0900Z-211031T0000Z/
Burns Harbor to Michigan City IN-
903 PM CDT Fri Oct 29 2021

...GALE WARNING IN EFFECT UNTIL 4 AM CDT SATURDAY...
...SMALL CRAFT ADVISORY IN EFFECT FROM 4 AM TO 7 PM CDT
SATURDAY...

* WHAT...For the Gale Warning, northeast gales to 35 kt.
  Significant waves to 10 ft. Occasional waves to 13 ft. For the
  Small Craft Advisory, north winds to 30 kt. Significant waves to
  9 ft. Occasional waves to 12 ft.

* WHERE...Burns Harbor to Michigan City IN.

* WHEN...For the Gale Warning, until 4 AM CDT Saturday. For the 
  Small Craft Advisory, from 4 AM to 7 PM CDT Saturday.

* IMPACTS...Strong winds will cause hazardous waves which could
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should alter plans to avoid these hazardous conditions.
Remain in port, seek safe harbor, alter course, and/or secure the
vessel for severe conditions.

&&

$$

LMZ740>742-301015-
/O.CON.KLOT.GL.W.0016.000000T0000Z-211030T0900Z/
/O.CON.KLOT.SC.Y.0085.211030T0900Z-211031T0000Z/
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
903 PM CDT Fri Oct 29 2021

...GALE WARNING REMAINS IN EFFECT UNTIL 4 AM CDT SATURDAY...
...SMALL CRAFT ADVISORY REMAINS IN EFFECT FROM 4 AM TO 7 PM CDT
SATURDAY...

* WHAT...For the Gale Warning, north gales to 35 kt. Significant
  waves to 12 ft. Occasional waves to 16 ft. For the Small Craft
  Advisory, north winds to 30 kt. Significant waves to 10 ft.
  Occasional waves to 13 ft.

* WHERE...Northerly Island to Calumet Harbor IL, Winthrop Harbor 
  to Wilmette Harbor IL and Wilmette Harbor to Northerly Island 
  IL.

* WHEN...For the Gale Warning, until 4 AM CDT Saturday. For the 
  Small Craft Advisory, from 4 AM to 7 PM CDT Saturday.

* IMPACTS...Strong winds will cause hazardous waves which could 
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should alter plans to avoid these hazardous conditions.
Remain in port, seek safe harbor, alter course, and/or secure the
vessel for severe conditions.

&&

$$

LMZ743-744-301015-
/O.CON.KLOT.GL.W.0016.000000T0000Z-211030T0900Z/
/O.CON.KLOT.SC.Y.0085.211030T0900Z-211031T0000Z/
Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN-
903 PM CDT Fri Oct 29 2021

...GALE WARNING REMAINS IN EFFECT UNTIL 4 AM CDT SATURDAY...
...SMALL CRAFT ADVISORY REMAINS IN EFFECT FROM 4 AM TO 7 PM CDT
SATURDAY...

* WHAT...For the Gale Warning, northeast gales to 35 kt.
  Significant waves to 10 ft. Occasional waves to 13 ft. For the
  Small Craft Advisory, north winds to 30 kt. Significant waves to
  9 ft. Occasional waves to 12 ft.

* WHERE...Gary to Burns Harbor IN and Calumet Harbor IL to Gary 
  IN.

* WHEN...For the Gale Warning, until 4 AM CDT Saturday. For the 
  Small Craft Advisory, from 4 AM to 7 PM CDT Saturday.

* IMPACTS...Strong winds will cause hazardous waves which could 
  capsize or damage vessels and reduce visibility.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Mariners should alter plans to avoid these hazardous conditions.
Remain in port, seek safe harbor, alter course, and/or secure the
vessel for severe conditions.

&&

$$

945 
WHUS73 KLOT 300746
MWWLOT

URGENT - MARINE WEATHER MESSAGE
National Weather Service Chicago IL
246 AM CDT Sat Oct 30 2021

LMZ740>742-301600-
/O.CAN.KLOT.GL.W.0016.000000T0000Z-211030T0900Z/
/O.EXT.KLOT.SC.Y.0085.211030T0746Z-211031T0000Z/
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
246 AM CDT Sat Oct 30 2021

...SMALL CRAFT ADVISORY NOW IN EFFECT UNTIL 7 PM CDT THIS
EVENING...
...GALE WARNING IS CANCELLED...

* WHAT...North winds to 30 kt in the morning and 25 kt in the
  afternoon. Significant waves to 10 ft occasionally to 13 ft in 
  the morning

* WHERE...Winthrop Harbor to Calumet Harbor IL.

* WHEN...Until 7 PM CDT this evening.

* IMPACTS...Conditions will be hazardous to small craft.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Inexperienced mariners, especially those operating smaller
vessels, should avoid navigating in hazardous conditions.

&&

$$

LMZ743>745-301600-
/O.CAN.KLOT.GL.W.0016.000000T0000Z-211030T0900Z/
/O.EXT.KLOT.SC.Y.0085.211030T0746Z-211031T0000Z/
Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN-
Burns Harbor to Michigan City IN-
246 AM CDT Sat Oct 30 2021

...SMALL CRAFT ADVISORY NOW IN EFFECT UNTIL 7 PM CDT THIS
EVENING...
...GALE WARNING IS CANCELLED...

* WHAT...North winds to 30 kt in the morning and 25 kt in the
  afternoon. Significant waves to 9 ft occasionally to 12 ft in 
  the morning.

* WHERE...Calumet Harbor IL to Michigan City IN.

* WHEN...Until 7 PM CDT this evening.

* IMPACTS...Conditions will be hazardous to small craft.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Inexperienced mariners, especially those operating smaller
vessels, should avoid navigating in hazardous conditions.

&&

$$

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
935 PM CDT Thu Oct 28 2021

.UPDATE...
930 PM CDT

The main update to the forecast message was the issuance of a
Lakeshore Flood Advisory for the Illinois and Lake County Indiana
shore. Forecast lake level rise (storm surge) for Calumet Harbor
from FVCOM is nearing 1 foot, which makes sense given lengthy
duration of favorable north-northeasterly fetch. Winds are
forecast to peak from the mid to late afternoon through the
evening when frequent gusts of 35-40 mph are expected. Considering
the surge forecast and peak wave heights near/over 10 feet, felt
confident enough in lakeshore flooding impacts to especially most
vulnerable portions of the Chicago bike path to issue the
advisory. Confidence is a bit lower for Lake County IL (more shore
parallel flow of strongest winds) and Lake County IN (later onset
of higher waves and slightly lower peak), though felt it's close
enough to warrant including them in the advisory.

Aside from the likelihood of renewed beach erosion closely on the
heels of the previous event, the main message as typical is to
avoid the immediate lakeshore due to life-threatening conditions
in the lake. Stay away to avoid getting swept away.

Otherwise, no big changes to the forecast thinking, with tweaks
made to hourly PoPs through the morning and refinement of
afternoon PoPs. There has been a relative lull with southward
extent this evening, which is expected to fill in some. Overall
focus later tonight through the evening on Friday for steadiest
rain is near the lake due to lake enhancement (including the heart
of the Chicago metro). Had earlier sent a graphic to hit the
wind-driven rain aspect of both commutes.

Castro

&&

.SHORT TERM...
315 PM CDT

Through Friday night...

A 992 mb surface low centered over southern Missouri continues
its slow movement towards the east-northeast, with light to
moderate rain rotating around it, especially towards its northeast
where dynamic support is stronger (upper level jet support and
diffluence). Although surface winds are from the east, winds
become more southeasterly with height, and that is helping move
rain over the area. Rain amounts have mainly been light so far,
and upstream too, though a couple reports around one half inch in
eastern Illinois. Showers will continue late this afternoon into
this evening. There may be some diminishing and light fog in the
far south later tonight as the low shifts into the Lower Ohio
River Valley, but otherwise rain showers are likely to prevail.
This looks to be even a steady rain over parts of northeast
Illinois later tonight and continuing into Friday morning, where
lake enhancement will be a factor due to onshore flow and
relatively warm lake temperatures inducing lake-effect
instability. This could result in some widespread slower
conditions during the Friday morning commute due to the widespread
rain.

As the low moves closer, winds will pick up due to the tightening
surface gradient. Gusts up to 35 to 40 mph will be possible
starting mid morning and into Friday evening, especially near the
lake front. This strong northeasterly flow will create high waves
along the Lake Michigan shore of Illinois especially, with regular
wave heights on Friday as high as 10-11 ft tonight. This is less
than the waves with the storm earlier this week, however still may
end up resulting in spotty issues of minor flooding or spray from
the lake.

Rain continues throughout Friday and into Friday night but likely
focuses more in the eastern CWA. With still continued lake
enhancement, it is expected that far northeast Illinois, including
the Chicago metro, will see the most rain with this event. We
have inched up our forecast rainfall amounts with some locations
receiving over 1.25 inches looking more likely. Cannot rule out 2
or even a little over, considering the 12Z HREF probability
matched mean (PMM) guidance indicates that for an event total in
northeast Illinois. This is likely not to be enough for flooding,
but may present some ponding issues during the morning commute.

Cloud cover will keep temperatures fairly steady over the next 36
hours or so, with temperatures remaining in the low to mid 50s,
including lows Friday morning. Winds will become more northerly by
Saturday morning, so although we'll still have widespread cloud
cover, temperatures will be a bit cooler Saturday morning, with
lows in the upper 40s/near 50.

BKL/MTF

&&

.LONG TERM...
315 PM CDT

Saturday through Wednesday...

The key messages in the extended period include 1. pleasant
weekend weather in store for Halloween and 2. consensus that we
are entering a cooler than normal pattern bringing more widespread
sub-freezing temps to the area and possibly our first snowflakes
of the season.

The closed upper low responsible for our late week rain showers
will be well on its way east of the area by Saturday. North
northeast winds will persist on the back side of the low, however,
which could bring some lingering lake effect showers through the
morning hours across northeast Illinois near the lake then
trending east into northwest Indiana over the afternoon. A cold
front does push through the area sometime Sunday morning which
will bring some breezy northwest winds and limit warming only
into the mid-upper 50s in the afternoon. Dry conditions are still
on tap on Sunday which should make for a pleasant Halloween.
Temperatures do begin to cool down after sunset with mid-upper 40s
in the city and the lower 40s in the suburbs expected in the
evening for Trick-or-Treat time.

Beyond the weekend, cold air from Canada continues to dive
southward across the Upper Midwest. This will bring below normal
temperatures across the area for the remainder of the work week
with high temperatures only in the 40s. In turn, temperatures
overnight will begin to dip into the lower 30s with more
widespread sub-freezing temps becoming increasingly likely,
especially across more rural areas outside of the metro later in
the week. As to be expected when temperatures dip below freezing,
we could very well see our first snowflakes of the season. At
this time there remains some variability and thus uncertainty with
the timing and placement of various mid-level shortwaves rounding
the base of the upper trough, so for now will simply maintain
slight chances for light rain/snow off and on during the Monday
through Thursday period.

Petr

&&

.AVIATION...
For the 00Z TAFs...

Aviation Forecast Concerns:

* IFR ceilings through the period, with some potential for LIFR
  300-400 foot later tonight/early Friday morning. Visibility high
  end IFR to MVFR in showers/drizzle/fog much of the period as
  well.

* Northeast winds gradually back north-northeast and increase and
  become gusty near 30 kts Friday.

Surface low pressure was located near the confluence of the Ohio
and Mississippi rivers early this evening. This disturbance will
continue to track slowly to the east-northeast across the Ohio
Valley through Friday. Cyclonic (counter-clockwise) flow around
the northern periphery of the low will continue to pull moisture
across the forecast area through the period, resulting in fairly
persistent showers/drizzle (and resulting low clouds/vis) for the
terminals through much of the TAF period. Extensive MVFR ceilings
were already in place across northern IL/IN early this evening,
with pockets of IFR and visibility 3-4SM in spots in rain and
light fog. Expectation is for IFR ceilings to expand early this
evening, and gradually lower overnight. Some guidance continues to
indicate the potential for a period of patchy 300-400' LIFR
ceilings across the Chicago terminals after midnight.

IFR conditions, showers and light fog are expected to persist
through the day and into the evening Friday for the Chicago
terminals, while conditions likely improve a bit farther to the
west at KRFD by later afternoon. Otherwise, east-northeast winds
will back to northeast overnight and to north-northeast Friday as
the low passes to the south of the area. Tightening of the
pressure gradient and cooler air aloft supporting better low level
mixing over Lake Michigan will result in winds increasing near 20
kts with gusts near 30 kts especially later in the
afternoon/evening.

Ratzer

&&

.MARINE...
315 PM CDT

Another strong low pressure system will move eastward across the
middle of the country over the next 36 hours, though this one
further south than the earlier week one. The pressure gradient
and lower atmospheric winds will be less over the area with this.
With instability still over the lake, the potential for some 35 kt
gales on Friday is there, namely into the Illinois nearshore.
Confidence is high that if a gale ends up occurring, it would not
exceed a mid 30 kt gale.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Lakeshore Flood Advisory...ILZ006-ILZ103-ILZ104...9 AM Friday to
     7 AM Saturday.

IN...Lakeshore Flood Advisory...INZ001...9 AM Friday to 7 AM Saturday.

LM...Gale Warning...LMZ740-LMZ741-LMZ742...9 AM Friday to 4 AM
     Saturday.

     Small Craft Advisory...IL nearshore waters until 9 AM Friday.

     Small Craft Advisory...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744...4 AM
     Saturday to 7 PM Saturday.

     Gale Warning...LMZ743-LMZ744...3 PM Friday to 4 AM Saturday.

     Small Craft Advisory...LMZ743-LMZ744...1 AM Friday to 3 PM
     Friday.

     Small Craft Advisory...LMZ745...1 AM Friday to 7 PM Saturday.

&&

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Hazardous Weather Outlook...UPDATED
National Weather Service Chicago/Romeoville IL
924 PM CDT Thu Oct 28 2021

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-300230-
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-
La Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford-
Northern Cook-Central Cook-Southern Cook-Northern Will-
Southern Will-Eastern Will-Lake IN-Porter-Newton-Jasper-Benton-
924 PM CDT Thu Oct 28 2021 /1024 PM EDT Thu Oct 28 2021/

This Hazardous Weather Outlook is for portions of North Central
Illinois...Northeast Illinois and Northwest Indiana.

.DAY ONE...Tonight.

Weather hazards expected...

  Limited Fog Risk near and south of US-24.

DISCUSSION...

Areas of fog near and south of US-24 could result in patchy
visibility reductions below one mile.

.DAYS TWO THROUGH SEVEN...Friday through Tuesday.

Friday...
  Elevated Lakeshore Flood Risk.
  Limited Non Thunderstorm Wind Risk, especially near the lakeshore.
  Limited Fog Risk near and south of US-24 in the morning.
Sunday night through Wednesday...
  Elevated to Significant Freeze Risk.

DISCUSSION:

North-northeast winds regularly gusting to 35 to near 40 mph
along the Lake Michigan shore of Illinois and Lake County Indiana
throughout Friday will build waves to 8 to 11 ft. Minor lakeshore
flooding is likely along portions of the Illinois and Lake County
Indiana shore.

Sunday night through Wednesday will feature periods of subfreezing
temperatures for outlying northern Illinois.

.SPOTTER INFORMATION STATEMENT...

  Spotter activation will not be necessary through tonight.

LMZ740>745-300230-
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN-
Burns Harbor to Michigan City IN-
924 PM CDT Thu Oct 28 2021

This Hazardous Weather Outlook is for portions of the Illinois
nearshore waters of Lake Michigan and the Indiana nearshore
waters of Lake Michigan.

.DAY ONE...Tonight.

Weather hazards expected...

  Hazardous conditions for small craft.

.DAYS TWO THROUGH SEVEN...Friday through Tuesday.

Friday...
  Gale force winds and or very hazardous waves are likely.
Saturday...
  Hazardous conditions for small craft are likely.

Castro

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