Small Craft Advisory 9, NWS Chicago, IL

700 
WHUS73 KLOT 260926 CCA
MWWLOT

URGENT - MARINE WEATHER MESSAGE...CORRECTED
National Weather Service Chicago IL
326 AM CST Tue Jan 26 2021

LMZ740>743-261715-
/O.EXP.KLOT.GL.W.0003.000000T0000Z-210126T0900Z/
/O.COR.KLOT.SC.Y.0009.210126T0925Z-210128T0900Z/
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
Calumet Harbor IL to Gary IN-
326 AM CST Tue Jan 26 2021

...SMALL CRAFT ADVISORY IN EFFECT UNTIL 3 AM CST THURSDAY...
...GALE WARNING HAS EXPIRED...

* WHAT...North winds to 30 kt and waves to 12 ft and occasionally
  to 16 ft.

* WHERE...Illinois nearshore and Calumet Harbor IL to Gary IN.

* WHEN...Until 3 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

LMZ744-745-261715-
/O.COR.KLOT.SC.Y.0008.000000T0000Z-210128T1500Z/
Gary to Burns Harbor IN-Burns Harbor to Michigan City IN-
326 AM CST Tue Jan 26 2021

...SMALL CRAFT ADVISORY NOW IN EFFECT UNTIL 9 AM CST THURSDAY...

* WHAT...North winds to 30 kt and waves to 8 ft and occasionally 
  to 11 ft.

* WHERE...Gary to Michigan City IN.

* WHEN...Until 9 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

233 
WHUS73 KLOT 261558
MWWLOT

URGENT - MARINE WEATHER MESSAGE
National Weather Service Chicago IL
958 AM CST Tue Jan 26 2021

LMZ744-745-270000-
/O.CON.KLOT.SC.Y.0008.000000T0000Z-210128T1500Z/
Gary to Burns Harbor IN-Burns Harbor to Michigan City IN-
958 AM CST Tue Jan 26 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 9 AM CST
THURSDAY...

* WHAT...Northeast winds to 30 kt and waves to 8 ft and 
  occasionally to 11 ft.

* WHERE...Gary to Michigan City IN.

* WHEN...Until 9 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

LMZ740>743-270000-
/O.CON.KLOT.SC.Y.0009.000000T0000Z-210128T0900Z/
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
Calumet Harbor IL to Gary IN-
958 AM CST Tue Jan 26 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 3 AM CST
THURSDAY...

* WHAT...Northeast winds to 30 kt and waves to 12 ft and 
  occasionally to 16 ft.

* WHERE...Illinois nearshore and Calumet Harbor IL to Gary IN.

* WHEN...Until 3 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

817 
WHUS73 KLOT 262133
MWWLOT

URGENT - MARINE WEATHER MESSAGE
National Weather Service Chicago IL
333 PM CST Tue Jan 26 2021

LMZ744-745-270545-
/O.CON.KLOT.SC.Y.0008.000000T0000Z-210128T1500Z/
Gary to Burns Harbor IN-Burns Harbor to Michigan City IN-
333 PM CST Tue Jan 26 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 9 AM CST
THURSDAY...

* WHAT...Northeast winds to 25 kt and waves to 9 ft and 
  occasionally to 12 ft.

* WHERE...Gary to Michigan City IN.

* WHEN...Until 9 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

LMZ740>743-270545-
/O.CON.KLOT.SC.Y.0009.000000T0000Z-210128T0900Z/
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
Calumet Harbor IL to Gary IN-
333 PM CST Tue Jan 26 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 3 AM CST
THURSDAY...

* WHAT...Northeast winds to 30 kt and waves to 9 ft and
  occasionally to 12 ft.

* WHERE...Illinois nearshore and Calumet Harbor IL to Gary IN.

* WHEN...Until 3 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

392 
WHUS73 KLOT 270342
MWWLOT

URGENT - MARINE WEATHER MESSAGE
National Weather Service Chicago IL
942 PM CST Tue Jan 26 2021

LMZ744-745-271145-
/O.CON.KLOT.SC.Y.0008.000000T0000Z-210128T1500Z/
Gary to Burns Harbor IN-Burns Harbor to Michigan City IN-
942 PM CST Tue Jan 26 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 9 AM CST
THURSDAY...

* WHAT...North winds to 30 kt and waves to 9 ft and occasionally 
  to 12 ft.

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

* WHEN...Until 9 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

LMZ740>743-271145-
/O.CON.KLOT.SC.Y.0009.000000T0000Z-210128T0900Z/
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
Calumet Harbor IL to Gary IN-
942 PM CST Tue Jan 26 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 3 AM CST
THURSDAY...

* WHAT...North winds to 30 kt and waves to 9 ft and occasionally 
  to 12 ft.

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

* WHEN...Until 3 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

532 
WHUS73 KLOT 270913
MWWLOT

URGENT - MARINE WEATHER MESSAGE
National Weather Service Chicago IL
313 AM CST Wed Jan 27 2021

LMZ743-271715-
/O.EXT.KLOT.SC.Y.0009.000000T0000Z-210128T1500Z/
Calumet Harbor IL to Gary IN-
313 AM CST Wed Jan 27 2021

...SMALL CRAFT ADVISORY NOW IN EFFECT UNTIL 9 AM CST THURSDAY...

* WHAT...Northeast winds to 25 kt and waves to 7 ft and 
  occasionally to 9 ft.

* WHERE...Indiana nearshore.

* WHEN...Until 9 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

LMZ744-745-271715-
/O.CON.KLOT.SC.Y.0008.000000T0000Z-210128T1500Z/
Gary to Burns Harbor IN-Burns Harbor to Michigan City IN-
313 AM CST Wed Jan 27 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 9 AM CST
THURSDAY...

* WHAT...Northeast winds to 25 kt and waves to 7 ft and 
  occasionally to 9 ft.

* WHERE...Indiana nearshore.

* WHEN...Until 9 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

LMZ740>742-271715-
/O.CON.KLOT.SC.Y.0009.000000T0000Z-210128T0900Z/
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
313 AM CST Wed Jan 27 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 3 AM CST
THURSDAY...

* WHAT...North winds to 25 kt and waves to 7 ft and occasionally
  to 9 ft.

* WHERE...Illinois nearshore.

* WHEN...Until 3 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

Carlaw

217 
WHUS73 KLOT 271521
MWWLOT

URGENT - MARINE WEATHER MESSAGE
National Weather Service Chicago IL
921 AM CST Wed Jan 27 2021

LMZ744-745-272330-
/O.CON.KLOT.SC.Y.0008.000000T0000Z-210128T1500Z/
Gary to Burns Harbor IN-Burns Harbor to Michigan City IN-
921 AM CST Wed Jan 27 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 9 AM CST
THURSDAY...

* WHAT...Northeast winds to 25 kt and waves to 7 ft and 
  occasionally to 9 ft.

* WHERE...Indiana nearshore.

* WHEN...Until 9 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

LMZ743-272330-
/O.CON.KLOT.SC.Y.0009.000000T0000Z-210128T1500Z/
Calumet Harbor IL to Gary IN-
921 AM CST Wed Jan 27 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 9 AM CST
THURSDAY...

* WHAT...Northeast winds to 25 kt and waves to 7 ft and 
  occasionally to 9 ft.

* WHERE...Indiana nearshore.

* WHEN...Until 9 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

LMZ740>742-272330-
/O.CON.KLOT.SC.Y.0009.000000T0000Z-210128T0900Z/
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
921 AM CST Wed Jan 27 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 3 AM CST
THURSDAY...

* WHAT...North winds to 25 kt and waves to 7 ft and occasionally 
  to 9 ft.

* WHERE...Illinois nearshore.

* WHEN...Until 3 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

340 
WHUS73 KLOT 272124
MWWLOT

URGENT - MARINE WEATHER MESSAGE
National Weather Service Chicago IL
324 PM CST Wed Jan 27 2021

LMZ744-745-280530-
/O.CON.KLOT.SC.Y.0008.000000T0000Z-210128T1500Z/
Gary to Burns Harbor IN-Burns Harbor to Michigan City IN-
324 PM CST Wed Jan 27 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 9 AM CST
THURSDAY...

* WHAT...North to northeast winds to 20 kt and waves to 7 ft and 
  occasionally to 9 ft.

* WHERE...Indiana nearshore.

* WHEN...Until 9 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

LMZ743-280530-
/O.CON.KLOT.SC.Y.0009.000000T0000Z-210128T1500Z/
Calumet Harbor IL to Gary IN-
324 PM CST Wed Jan 27 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 9 AM CST
THURSDAY...

* WHAT...North winds to 25 kt and waves to 7 ft and occasionally 
  to 9 ft.

* WHERE...Indiana nearshore.

* WHEN...Until 9 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

LMZ740>742-280530-
/O.CON.KLOT.SC.Y.0009.000000T0000Z-210128T0900Z/
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
324 PM CST Wed Jan 27 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 3 AM CST
THURSDAY...

* WHAT...North winds to 25 kt and waves to 7 ft and occasionally 
  to 9 ft.

* WHERE...Illinois nearshore.

* WHEN...Until 3 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

688 
WHUS73 KLOT 280342
MWWLOT

URGENT - MARINE WEATHER MESSAGE
National Weather Service Chicago IL
942 PM CST Wed Jan 27 2021

LMZ744-745-281145-
/O.CON.KLOT.SC.Y.0008.000000T0000Z-210128T1500Z/
Gary to Burns Harbor IN-Burns Harbor to Michigan City IN-
942 PM CST Wed Jan 27 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 9 AM CST
THURSDAY...

* WHAT...Northwest winds to 25 kt. Significant waves to 6 ft.
  Occasional waves to 8 ft.

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

* WHEN...Until 9 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

LMZ743-281145-
/O.CON.KLOT.SC.Y.0009.000000T0000Z-210128T1500Z/
Calumet Harbor IL to Gary IN-
942 PM CST Wed Jan 27 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 9 AM CST
THURSDAY...

* WHAT...Northwest winds to 25 kt. Significant waves to 6 ft.
  Occasional waves to 8 ft.

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

* WHEN...Until 9 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

LMZ740>742-280900-
/O.CON.KLOT.SC.Y.0009.000000T0000Z-210128T0900Z/
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
942 PM CST Wed Jan 27 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 3 AM CST
THURSDAY...

* WHAT...Northwest winds to 25 kt. Significant waves to 6 ft.
  Occasional waves to 8 ft.

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

* WHEN...Until 3 AM CST Thursday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

277 
WHUS73 KLOT 280838
MWWLOT

URGENT - MARINE WEATHER MESSAGE
National Weather Service Chicago IL
238 AM CST Thu Jan 28 2021

LMZ740>742-280945-
/O.EXP.KLOT.SC.Y.0009.000000T0000Z-210128T0900Z/
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
238 AM CST Thu Jan 28 2021

...SMALL CRAFT ADVISORY WILL EXPIRE AT 3 AM CST EARLY THIS
MORNING...

Waves have subsided to under 4 feet early this morning and will
continue to gradually subside today.

$$

LMZ744-745-281500-
/O.CON.KLOT.SC.Y.0008.000000T0000Z-210128T1500Z/
Gary to Burns Harbor IN-Burns Harbor to Michigan City IN-
238 AM CST Thu Jan 28 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 9 AM CST THIS
MORNING...

* WHAT...Northwest winds to 20 kt. Significant waves to 6 ft. 
  Occasional waves to 8 ft.

* WHERE...Gary to Michigan City IN.

* WHEN...Until 9 AM CST this morning.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

LMZ743-281500-
/O.CON.KLOT.SC.Y.0009.000000T0000Z-210128T1500Z/
Calumet Harbor IL to Gary IN-
238 AM CST Thu Jan 28 2021

...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 9 AM CST THIS
MORNING...

* WHAT...Northwest winds to 20 kt. Significant waves to 6 ft.

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

* WHEN...Until 9 AM CST this morning.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

385 
WHUS73 KLOT 281459
MWWLOT

URGENT - MARINE WEATHER MESSAGE
National Weather Service Chicago IL
859 AM CST Thu Jan 28 2021

LMZ744-745-281600-
/O.EXP.KLOT.SC.Y.0008.000000T0000Z-210128T1500Z/
Gary to Burns Harbor IN-Burns Harbor to Michigan City IN-
859 AM CST Thu Jan 28 2021

...SMALL CRAFT ADVISORY WILL EXPIRE AT 9 AM CST THIS MORNING...

Winds and waves will continue to subside today, with conditions
falling below small craft advisory criteria. Therefore the
advisory has been allowed to expire.

$$

LMZ743-281600-
/O.EXP.KLOT.SC.Y.0009.000000T0000Z-210128T1500Z/
Calumet Harbor IL to Gary IN-
859 AM CST Thu Jan 28 2021

...SMALL CRAFT ADVISORY WILL EXPIRE AT 9 AM CST THIS MORNING...

Winds and waves will continue to subside today, with conditions
falling below small craft advisory criteria. Therefore the
advisory has been allowed to expire.

$$

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
225 AM CST Tue Jan 26 2021

.UPDATE...
1015 PM CST

There have been no changes made to the going Winter Storm Warnings
and Winter Weather Advisories. However, based off conditions in
the pre-dawn hours, the midnight shift may give consideration to
converting some of the warnings over to a Winter Weather Advisory.
This is because snowfall rates aside from lake enhancement near
Lake Michigan are expected to be mainly light and occasionally
moderate on Tuesday. The main message tonight remains hazardous
travel due to a variety of winter hazards, snow covered roads,
reduced visibility and at least patchy blowing snow in the north
due to 30-40 mph northeast wind gusts, and freezing rain and
drizzle south. Have overall lowered storm total snowfall a bit to
only locally to 6+" inland and highest amounts near Lake Michigan
in Illinois at 6-8", maybe a few spots coming in just above 8"+.
These changes were reflected in the updated WSW text product.

The evolution of our winter system is quite different from just a
few days ago, as double or triple barreled weaker low pressure is
analyzed from southwest MO to western KY, instead of a stronger
low lifting northeast of the Ohio River. Forcing is being driven
by weakening, but still certainly sufficient large scale forcing
from 500 mb short-wave, along with mesoscale f-gen (thermal
gradient) driven forcing at the lower and mid-levels, plus also
augmented by convective processes by very steep lapse rates aloft.

Trends have been a challenge this evening, as we've been fighting
pockets of dry air aloft. Most notably, dry air centered around
850 mb was driven into far northern Illinois and southern
Wisconsin earlier, which guidance did a fairly poor job of
capturing. That dry air finally lost out as snow banding finally
pushed north. There's been some good f-gen driven banding amidst
the dry air issues, so reports of nearing 2" have trickled in
centered near I-88 and just south. More convective elements have
been streaming northward out of central Illinois thanks to
aforementioned very steep mid and upper lapse rates sampled by
DVN RAOB. The dry air at 500 mb and above is allowing for
convection to help fill in some of the dry pockets where snow has
been more prevalent and this should be the case north of I-80 for
a decent chunk of the overnight.

850 mb warm nose appears it made inroads into our far southern CWA
near and south of US-24, while to the north of that varied precip
types have been from pockets of saturation amidst some 700 mb
drying and above described convection that has brought reports of
snow and sleet. This dry layer at 700 mb will shift northward
overnight, causing a loss of cloud ice in the DGZ and introducing
a concern for some freezing drizzle from I-80 and south into
Tuesday morning. It appears that for areas to the north of that up
to around I-88 corridor, saturation depth will be to just cold
enough at -9 to -11C to keep snow as primary p-type. Steady
generally light to moderate snow rates with briefly heavier snow
will occur until about 3 or 4 AM, and then expecting the lake
enhancement to take hold along the Illinois shore. On Tuesday, the
500 mb and 700 mb circulations will slowly translate across the
area, keeping lighter snow going and resulting in light additional
accumulations of 1-2/1-3", but higher near lake in IL at up to
2-5". The midnight shift will assess transition to lake effect
snow Tuesday night, which should last into Wednesday and add
additional accumulations for affected areas.

Castro

&&

.SHORT TERM...
235 PM CST

Through Tuesday night...

...DIFFICULT DRIVING CONDITIONS TO DEVELOP THIS EVENING ACROSS MUCH
OF NORTHERN ILLINOIS...

The main forecast points are as follows:

- Steady snow will develop across the entire area this evening and
  last through Tuesday evening. Travel will be difficult due to
  the combined effects of steady snow rates and patchy blowing
  snow

- Snow rates will be heaviest from sunset to 3 AM CST tonight-
  Tuesday, with the heaviest (0.75-1"/hr) along the Lake Michigan
  shore

- Snow "weight" will be wet and heavy overnight. Tuesday, it will
  become lighter and fluffier

- Snow will taper from west to east Tuesday evening, but persist
  along the lakeshore through Wednesday.

- Total snow accumulations through Tuesday evening of 3 to 7
  inches are expected north of I-80 with 5-8" (locally higher)
  east of I-355. South of I-80, snow totals of 1-4 inches and ice
  totals of 0.1-0.2" are expected.

Discussion:

Overall, the thinking and messaging with this storm has not changed.
The upper-level wave responsible for the blossoming area of snow
across Nebraska, Iowa, and northern Missouri will become "sheared
out" as it propagates eastward. Such will lead to an increasingly
elongated zone of wintry precipitation, initially all snow, from
this evening through Tuesday. As a mid-level dry slot works
northward into Illinois this evening, the snowflake growth zone
will dry out generally along and south of I-80 but possibly as
far north as I-88. Within the dry slot, there'll be a narrow zone
where in-cloud temperatures are still favorable for very low snow-
ratio snow grains, altogether leading to a gradual transition
from snow along I-88 to snow grains along I-80 to freezing drizzle
south of I-80. Meanwhile, a plume of steep mid- level lapse rates
will advect generally south of I-80 leading to pockets of
convective/splotchy snow in otherwise widespread freezing drizzle
and mist. As such, we'll probably have a hodgepodge of
precipitation types including periods of accumulating ice (and
even at times no precipitation) south of I-80 through much of the
night. North of I-88, all snow is expected.

Snow rates will be heaviest from roughly sunset through
early Tuesday morning (0.75-1"/hr), especially along the Lake
Michigan shore where lake enhancement is probable. Snow "weight"
tonight will be wet and heavy with a ratio near 10:1, except near
the IL/WI border where strong lift through the snowflake growth
layer will promote ratios closer to 15:1. Toward daybreak Tuesday,
snow rates will become less heavy as snow ratios become
"fluffier." An uptick in intensity (and changeover to all snow
areawide) is expected during the Tuesday afternoon hours as the
parent upper- level waves slides through northern Illinois. Snow
will thus taper from west to east Tuesday evening. Low-level
confluence of winds along the Lake Michigan shore will allow for
steady light snow to continue generally east of I-355 into
Wednesday, and eventually northwest Indiana by Wednesday evening.

As the low-level pressure gradient tightens tonight, northeasterly
winds will increase and gust 30-40 mph, highest along the Lake
Michigan shoreline. Such will set the stage for patches of
blowing snow especially along the lakeshore (more exposed to the
wind) and near the Wisconsin state line (where snow ratios will be
higher). Blowing snow may become more widespread Tuesday
especially as the snow ratios altogether become higher and a fresh
snowpack becomes established.

Taken altogether, all of northern Illinois and northwest Indiana
will experience wintry weather and difficult travel conditions over
the next 24-36 hours. The highest snow totals of 5-8" (locally
higher) are expected across the Chicago metropolitan area east of
I-355 due to lake enhancement. North of I-80, 3-7" of snow is
expected. South of I-80, 1-4" of snow and 0.1-0.2" of ice
accumulations are expected. Localized power outages remain
possible due to the weight of the heavy/wet snow and/or ice and
gusty winds (e.g. tree branches may fall on power lines).

Borchardt

&&

.LONG TERM...
224 AM CST

Wednesday through Monday...

LES parameters become somewhat favorable Wednesday morning as CAA
increases lake-EL values to around 5kft with 850hPa-lake delta Ts
of ~14C. While these values do not suggest significant LES,
enhanced dynamics from a low-level convergent axis and a passing
mid-level trough should help overcome deficiencies in the thermal
profile. Concern still exists for a dominant LES band to affect
Cook and Lake(IN) counties during the morning and into the
afternoon. Evolution of single band LES can be difficult to
forecast even 24 hours out, but at this time the band should have
enough motion to prevent an extensive residence time over any
given location. For that reason, the current forecast is for 1-2"
Wednesday from far northeast Cook County through Chicago and into
northwest Lake(IN). With all that said, if conditions begin to
look more favorable for a stronger band to sit over an area for
several hours Wednesday morning, a Winter Weather Advisory for 3"+
in a narrow corridor may be needed, especially given the
potential impacts for the morning commute.

A couple cold nights look likely Wednesday and Thursday night
with high pressure drifting across the region. Sub-zero readings
are appearing more likely for at least north-central IL Wednesday
night as high pressure edges in from the west toward daybreak.

Guidance continues to advertise a strong system across the region
this weekend, with a consensus trend toward mostly snow for our
area. Continue to monitor the forecast as significant impacts are
possible either over or very near the CWA Saturday night into
Sunday.

Kluber

&&

.AVIATION...
For the 06Z TAFs...

Aviation forecast concerns:

* IFR conditions in light snow through Tuesday, with occasional
  LIFR visibilities in moderate snow overnight.

* Lake effect snow showers linger across ORD/MDW/GYY terminals
  into Tuesday night.

* Northeast winds gusting around 30 kt early overnight, only
  gradually easing and backing more north-northeast Tuesday.

Light to occasionally moderate snow overspread the region Monday
evening, though dry low level air on strong northeast winds has
limited extent of persistent heavier snow through the evening. Air
mass continues to saturate as impressive forcing for ascent
continues with mid-level disturbance moving across the region, so
still expecting an expansion of light to moderate snow across the
terminals overnight, though LIFR visibilities will likely be more
limited than earlier thinking. Still, light snow will persist
through much of the period as the mid-level circulation slows and
weakens over the area. Guidance suggests IFR conditions will
linger into mid-day Tuesday before some gradual improvement occurs
inland from Lake Michigan. Near the lake however, low level cold
air will be pulled in from the north-northeast, which should
result in the development of lake enhanced/effect snow which will
likely affect the Chicago area terminals into Tuesday night. Lake
effect will likely become more showery Tuesday night, lowering
confidence a bit as to impacts on individual terminals, though
ORD/MDW/GYY do appear to be in line for some snow shower activity.

Strong northeast winds, currently gusting near 30 kts, will very
gradually through the day, while also gradually backing more
northerly by later in the day/evening.

Ratzer

&&

.MARINE...
248 PM CST

Strong surface low pressure will track from the lower Missouri
Valley through the lower Ohio Valley through Tuesday. Between this
low, and an area of high pressure off to the northeast of the
Great Lakes, a strong surface pressure gradient has led to
increasing northeast surface winds across southern Lake Michigan
today. The strongest winds are expected to develop by this evening
and continue much of the night before slowly easing Tuesday.

Current indication is that there will likely be a period of at
least occasional 35 kt gale force winds this evening/overnight.
With this in mind, a gale warning remains in effect for mainly the
western shore of southern Lake Michigan, from near Gary north to
the IL/WI border for tonight. It is possible that brief gale force
gusts may edge further into the Indiana waters as well, though
small craft advisory conditions remain most likely along the
Indiana shore. Small craft advisory headlines will also be needed
after the gale headlines end early Tuesday along the IL shore,
with SCA conditions likely persisting into Wednesday night before
waves subside.

Ratzer/Kluber/Lenning

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Winter Storm Warning...ILZ006-ILZ013-ILZ103-ILZ104-ILZ105-ILZ106-
     ILZ107 until 5 PM Tuesday.

     Lakeshore Flood Advisory...ILZ006-ILZ103-ILZ104 until noon
     Tuesday.

     Winter Storm Warning...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-ILZ011-
     ILZ012-ILZ019-ILZ020-ILZ021 until noon Tuesday.

     Winter Weather Advisory...ILZ023-ILZ032-ILZ033-ILZ039-ILZ108
     until noon Tuesday.

IN...Lakeshore Flood Advisory...INZ001 until noon Tuesday.

     Winter Weather Advisory...INZ001-INZ002-INZ010-INZ011-INZ019
     until noon Tuesday.

LM...Gale Warning...Winthrop Harbor to Gary IN until 3 AM Tuesday.

     Small Craft Advisory...Gary to Michigan City IN until 6 PM Wednesday.

&&

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Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
335 PM CST Mon Jan 25 2021

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-262145-
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-
335 PM CST Mon Jan 25 2021 /435 PM EST Mon Jan 25 2021/

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

.DAY ONE...Tonight.

Weather hazards expected...

  Elevated Ice Accumulation Risk.
  Significant Snow Risk.
  Elevated Lakeshore Flood Risk.

DISCUSSION...

A winter storm will impact the area through Tuesday. Total snow
accumulations of 3 to 7 inches are expected north of I-80 with
higher amounts east of I-355. A wintry mix, including freezing
rain, is likely south of a line from Streator to Kankakee to
DeMotte. Gusty winds combined with a somewhat wetter nature to the
snow may result in sporadic power outages as well as blowing
snow.

Gusty northeast winds combined with elevated lake levels will
cause minor to moderate lakeshore flooding impacts late this
afternoon and especially tonight.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Tuesday...
  Elevated Ice Accumulation Risk.
  Elevated Snow Risk.
  Elevated Lakeshore Flood Risk.
Wednesday...
  Limited Ice Accumulation Risk.
  Limited Snow Risk, mainly along the Lake Michigan shore.
Saturday...
  Limited Snow Risk.

DISCUSSION:

Steady snow will continue through the day Tuesday. The snow will
mix with or change to freezing drizzle along and south of I-80
through mid-morning. Snow will end from west to east Tuesday
evening, with lake effect snow showers persisting along the Lake
Michigan shore into Wednesday.

Gusty northeast winds combined with elevated lake levels will
continue to cause minor to possibly moderate lakeshore flooding
impacts through Tuesday morning.

.SPOTTER INFORMATION STATEMENT...

  Spotter activation will not be necessary through tonight.
  However, any snowfall reports would be greatly appreciated.

LMZ740>745-262145-
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-
335 PM CST Mon Jan 25 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...

  Gale force winds and very hazardous waves.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Tuesday...
  Gale force winds and very hazardous waves are likely.
Wednesday...
  Hazardous conditions for small craft are likely.
  Limited Freezing Spray Risk.
Thursday through Sunday...
  Hazardous conditions for small craft are likely.

Borchardt

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1026 PM CST MON JAN 25 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1000 PM     SNOW             OAK LAWN                41.72N 87.75W
01/25/2021  M1.5 INCH        COOK               IL   PUBLIC

&&

LCARLAW

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1027 PM CST MON JAN 25 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0845 PM     SNOW             SOMONAUK                41.63N 88.68W
01/25/2021  M1.6 INCH        DE KALB            IL   PUBLIC

&&

LCARLAW

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1029 PM CST MON JAN 25 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0930 PM     SNOW             4 NNW PLAINFIELD        41.67N 88.23W
01/25/2021  M1.3 INCH        WILL               IL   NWS EMPLOYEE

            0.12 INCH LIQUID EQUIVALENT.

&&

LCARLAW

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1241 AM CST TUE JAN 26 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1200 AM     SNOW             OHARE AIRPORT           41.98N 87.90W
01/26/2021  M0.7 INCH        COOK               IL   OFFICIAL NWS OBS

            TOTAL BETWEEN 6PM AND 12AM.

1200 AM     SNOW             ROCKFORD AIRPORT        42.20N 89.10W
01/26/2021  M1.0 INCH        WINNEBAGO          IL   OFFICIAL NWS OBS

            SNOW TOTAL BETWEEN 6PM AND 12AM.

1200 AM     SNOW             3 SW MIDWAY AIRPORT     41.75N 87.79W
01/26/2021  M1.5 INCH        COOK               IL   CO-OP OBSERVER

            EVENT TOTAL SO FAR. 1.4 INCHES BETWEEN 6PM AND 12AM. 0.10
            INCHES LIQUID EQUIVALENT FOR THE DAY.

1200 AM     SNOW             ROMEOVILLE              41.65N 88.09W
01/26/2021  M1.2 INCH        WILL               IL   OFFICIAL NWS OBS

            EVENT TOTAL SO FAR AT NWS CHICAGO. 1.1 INCHES BETWEEN 6PM
            AND 12AM. 0.19 INCHES LIQUID EQUIVALENT FOR THE DAY.

&&

RC

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1255 AM CST TUE JAN 26 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1230 AM     SNOW             N CAPRON                42.40N 88.74W
01/26/2021  M2.0 INCH        BOONE              IL   COCORAHS

            EVENT TOTAL SINCE 7PM MONDAY.

&&

RC

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
120 AM CST TUE JAN 26 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1245 AM     SNOW             PALATINE                42.11N 88.04W
01/26/2021  M2.5 INCH        COOK               IL   NWS EMPLOYEE

0100 AM     SNOW             1 N ROSELLE             41.99N 88.08W
01/26/2021  M3.0 INCH        COOK               IL   COCORAHS

&&

KLUBER