Alert archive / Illinois / Winter Storm Watches in 2021

Winter Storm Watch 2, NWS Chicago, IL

January 29, 202118 counties in Illinois; 5 counties in Indiana

NWS Chicago, IL issued this winter storm watch at Jan 29, 2021, 3:23 AM CST for 18 counties in Illinois; 5 counties in Indiana. It took effect at Jan 30, 2021, 3:00 PM CST. It was in force for .

The area

The counties it named.

The facts

Issued
Jan 29, 2021, 3:23 AM CST (09:23 UTC)
In effect from
Jan 30, 2021, 3:00 PM CST
Expired
Jan 30, 2021, 3:27 AM CST
In force
Issued by
NWS Chicago, IL
All 23 counties

Boone County, IL, Cook County, IL, DeKalb County, IL, DuPage County, IL, Ford County, IL, Grundy County, IL, Iroquois County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Lake County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, McHenry County, IL, Ogle County, IL, Will County, IL, Winnebago County, IL, Benton County, IN, Jasper County, IN, Lake County, IN, Newton County, IN, Porter County, IN

The radar

The Chicago radar (KLOT), 12 km from the middle of the area, began a volume at 09:25 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 9.4 hours before the alert went out and 158 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Lincoln, IL at 00:00Z on 2021-01-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lincoln, IL at 00:00Z on 2021-01-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -21 square meters per square second.1939587897117136Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1418 m above ground
0-6 km bulk shear
74 kt
0-1 km storm-relative helicity
-21 m²/s²
0-3 km storm-relative helicity
140 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

662 
WWUS43 KLOT 290923
WSWLOT

URGENT - WINTER WEATHER MESSAGE
National Weather Service Chicago IL
323 AM CST Fri Jan 29 2021

...Heavy Wet Snow and Wind Likely Saturday PM into Early Sunday...

ILZ003-004-008-010>012-019>021-023-032-033-039-105>108-INZ001-002-
010-011-019-291730-
/O.NEW.KLOT.WS.A.0002.210130T2100Z-210131T1800Z/
Winnebago-Boone-Ogle-Lee-De Kalb-Kane-La Salle-Kendall-Grundy-
Kankakee-Livingston-Iroquois-Ford-Southern Cook-Northern Will-
Southern Will-Eastern Will-Lake IN-Porter-Newton-Jasper-Benton-
Including the cities of Rockford, Belvidere, Rochelle, Oregon, 
Byron, Dixon, DeKalb, Sycamore, Aurora, Elgin, Ottawa, Streator, 
La Salle, Mendota, Marseilles, Oswego, Yorkville, Plano, Morris, 
Coal City, Minooka, Kankakee, Bourbonnais, Bradley, Pontiac, 
Dwight, Fairbury, Watseka, Gilman, Paxton, Gibson City, 
Calumet City, Oak Forest, Lemont, Orland Park, Park Forest, 
Joliet, Bolingbrook, Plainfield, Mokena, Channahon, Manhattan, 
Wilmington, Crete, Peotone, Beecher, Gary, Hammond, Merrillville,
Portage, Valparaiso, Chesterton, Roselawn, Kentland, Morocco, 
Rensselaer, DeMotte, Fowler, and Oxford
323 AM CST Fri Jan 29 2021 /423 AM EST Fri Jan 29 2021/

...WINTER STORM WATCH IN EFFECT FROM SATURDAY AFTERNOON THROUGH
SUNDAY MORNING...

* WHAT...Heavy wet snow likely along with easterly winds gusting
  up to 30 mph. Total snow accumulations of 5 to 9 inches and
  locally higher possible.

* WHERE...Portions of northwest Indiana and central, east 
  central, north central and northeast Illinois.

* WHEN...From Saturday afternoon through Sunday morning, with the
  most significant impacts late Saturday afternoon through
  Saturday evening when much of the snow is forecast to occur.

* IMPACTS...Travel could be dangerous due to the heavy wet snow
  and strong winds causing very low visibility and snow packed
  roads. Power outages possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation. 

&&

$$

ILZ005-006-013-103-104-291730-
/O.NEW.KLOT.WS.A.0002.210130T2100Z-210201T0000Z/
McHenry-Lake IL-DuPage-Northern Cook-Central Cook-
Including the cities of Crystal Lake, Algonquin, McHenry, 
Woodstock, Waukegan, Buffalo Grove, Mundelein, Gurnee, 
Naperville, Wheaton, Downers Grove, Lombard, Carol Stream, 
Evanston, Des Plaines, Schaumburg, Palatine, Northbrook, Chicago,
Cicero, Oak Lawn, Oak Park, and La Grange
323 AM CST Fri Jan 29 2021

...WINTER STORM WATCH IN EFFECT FROM SATURDAY AFTERNOON THROUGH
SUNDAY AFTERNOON...

* WHAT...Heavy wet snow likely along with easterly winds gusting
  up to 35 mph. Total snow accumulations of 6 to 9 inches and
  locally higher possible. 

* WHERE...McHenry, Lake IL, DuPage, Northern Cook and Central 
  Cook Counties.

* WHEN...From Saturday afternoon through Sunday afternoon, with
  the most significant impacts Saturday evening through early
  Sunday when much of the snow is forecast to occur.

* IMPACTS...Travel could be dangerous due to the heavy wet snow
  and strong winds causing very low visibility and snow packed
  roads. Power outages possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation. 

&&

$$

Castro/MTF
4 follow-up statements
466 
WWUS43 KLOT 291714
WSWLOT

URGENT - WINTER WEATHER MESSAGE
National Weather Service Chicago IL
1114 AM CST Fri Jan 29 2021

...Heavy Wet Snow and Wind Likely Saturday PM into Early Sunday...

ILZ003-004-008-010>012-019>021-023-032-033-039-105>108-INZ001-002-
010-011-019-300115-
/O.CON.KLOT.WS.A.0002.210130T2100Z-210131T1800Z/
Winnebago-Boone-Ogle-Lee-De Kalb-Kane-La Salle-Kendall-Grundy-
Kankakee-Livingston-Iroquois-Ford-Southern Cook-Northern Will-
Southern Will-Eastern Will-Lake IN-Porter-Newton-Jasper-Benton-
Including the cities of Rockford, Belvidere, Rochelle, Oregon, 
Byron, Dixon, DeKalb, Sycamore, Aurora, Elgin, Ottawa, Streator, 
La Salle, Mendota, Marseilles, Oswego, Yorkville, Plano, Morris, 
Coal City, Minooka, Kankakee, Bourbonnais, Bradley, Pontiac, 
Dwight, Fairbury, Watseka, Gilman, Paxton, Gibson City, 
Calumet City, Oak Forest, Lemont, Orland Park, Park Forest, 
Joliet, Bolingbrook, Plainfield, Mokena, Channahon, Manhattan, 
Wilmington, Crete, Peotone, Beecher, Gary, Hammond, Merrillville,
Portage, Valparaiso, Chesterton, Roselawn, Kentland, Morocco, 
Rensselaer, DeMotte, Fowler, and Oxford
1114 AM CST Fri Jan 29 2021 /1214 PM EST Fri Jan 29 2021/

...WINTER STORM WATCH REMAINS IN EFFECT FROM SATURDAY AFTERNOON
THROUGH SUNDAY MORNING...

* WHAT...Heavy wet snow likely along with easterly winds gusting 
  up to 30 mph. Total snow accumulations of 5 to 9 inches and 
  locally higher possible.

* WHERE...Portions of northwest Indiana and central, east 
  central, north central and northeast Illinois.

* WHEN...From Saturday afternoon through Sunday morning, with 
  the most significant impacts late Saturday afternoon through 
  Saturday evening when much of the snow is forecast to occur.

* IMPACTS...Travel could be dangerous due to the heavy wet snow 
  and strong winds causing very low visibility and snow packed 
  roads. Power outages possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$

ILZ005-006-013-103-104-300115-
/O.CON.KLOT.WS.A.0002.210130T2100Z-210201T0000Z/
McHenry-Lake IL-DuPage-Northern Cook-Central Cook-
Including the cities of Crystal Lake, Algonquin, McHenry, 
Woodstock, Waukegan, Buffalo Grove, Mundelein, Gurnee, 
Naperville, Wheaton, Downers Grove, Lombard, Carol Stream, 
Evanston, Des Plaines, Schaumburg, Palatine, Northbrook, Chicago,
Cicero, Oak Lawn, Oak Park, and La Grange
1114 AM CST Fri Jan 29 2021

...WINTER STORM WATCH REMAINS IN EFFECT FROM SATURDAY AFTERNOON
THROUGH SUNDAY AFTERNOON...

* WHAT...Heavy wet snow likely along with easterly winds gusting 
  up to 35 mph. Total snow accumulations of 6 to 9 inches and 
  locally higher possible.

* WHERE...McHenry, Lake IL, DuPage, Northern Cook and Central 
  Cook Counties.

* WHEN...From Saturday afternoon through Sunday afternoon, with 
  the most significant impacts Saturday evening through early 
  Sunday when much of the snow is forecast to occur.

* IMPACTS...Travel could be dangerous due to the heavy wet snow 
  and strong winds causing very low visibility and snow packed 
  roads. Power outages possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$
626 
WWUS43 KLOT 292038
WSWLOT

URGENT - WINTER WEATHER MESSAGE
National Weather Service Chicago IL
238 PM CST Fri Jan 29 2021

...Heavy Wet Snow and Wind Likely Saturday PM into Early Sunday...

ILZ003-008-010-019-300445-
/O.UPG.KLOT.WS.A.0002.210130T2100Z-210131T1800Z/
/O.NEW.KLOT.WS.W.0002.210130T1800Z-210201T0000Z/
Winnebago-Ogle-Lee-La Salle-
Including the cities of Rockford, Rochelle, Oregon, Byron, Dixon,
Ottawa, Streator, La Salle, Mendota, and Marseilles
238 PM CST Fri Jan 29 2021

...WINTER STORM WARNING IN EFFECT FROM NOON SATURDAY TO 6 PM CST
SUNDAY...

* WHAT...Heavy wet snow likely along with easterly winds gusting
  up to 30 mph. The snow could begin as a short period of rain or
  freezing rain Saturday afternoon. Total snow accumulations of 5
  to 9 inches and locally higher possible.

* WHERE...Winnebago, Ogle, Lee and La Salle Counties.

* WHEN...From noon Saturday to 6 PM CST Sunday.

* IMPACTS...Travel could be very difficult due to very low
  visibilities and snow packed roads. Power outages are also
  possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in
your vehicle in case of an emergency. 

The latest road conditions for Illinois can be obtained on the
internet at www.gettingaroundillinois.com.

&&

$$

ILZ005-006-013-103-104-300445-
/O.UPG.KLOT.WS.A.0002.210130T2100Z-210201T0000Z/
/O.NEW.KLOT.WS.W.0002.210130T2100Z-210201T0000Z/
McHenry-Lake IL-DuPage-Northern Cook-Central Cook-
Including the cities of Crystal Lake, Algonquin, McHenry, 
Woodstock, Waukegan, Buffalo Grove, Mundelein, Gurnee, 
Naperville, Wheaton, Downers Grove, Lombard, Carol Stream, 
Evanston, Des Plaines, Schaumburg, Palatine, Northbrook, Chicago,
Cicero, Oak Lawn, Oak Park, and La Grange
238 PM CST Fri Jan 29 2021

...WINTER STORM WARNING IN EFFECT FROM 3 PM SATURDAY TO 6 PM CST
SUNDAY...

* WHAT...Heavy wet snow expected. Total snow accumulations of 5 
  to 9 inches. Winds gusting as high as 35 mph.

* WHERE...McHenry, Lake IL, DuPage, Northern Cook and Central 
  Cook Counties.

* WHEN...From 3 PM Saturday to 6 PM CST Sunday.

* IMPACTS...Travel could be very difficult due to very low
  visibilities and snow packed roads. Power outages are also
  possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in
your vehicle in case of an emergency. 

The latest road conditions for Illinois can be obtained on the
internet at www.gettingaroundillinois.com.

&&

$$

ILZ004-011-012-020-021-023-105>108-INZ001-002-300445-
/O.UPG.KLOT.WS.A.0002.210130T2100Z-210131T1800Z/
/O.NEW.KLOT.WS.W.0002.210130T2100Z-210201T0000Z/
Boone-De Kalb-Kane-Kendall-Grundy-Kankakee-Southern Cook-
Northern Will-Southern Will-Eastern Will-Lake IN-Porter-
Including the cities of Belvidere, DeKalb, Sycamore, Aurora, 
Elgin, Oswego, Yorkville, Plano, Morris, Coal City, Minooka, 
Kankakee, Bourbonnais, Bradley, Calumet City, Oak Forest, Lemont,
Orland Park, Park Forest, Joliet, Bolingbrook, Plainfield, 
Mokena, Channahon, Manhattan, Wilmington, Crete, Peotone, 
Beecher, Gary, Hammond, Merrillville, Portage, Valparaiso, 
and Chesterton
238 PM CST Fri Jan 29 2021

...WINTER STORM WARNING IN EFFECT FROM 3 PM SATURDAY TO 6 PM CST
SUNDAY...

* WHAT...Heavy wet snow expected. Total snow accumulations of 5 to
  9 inches.

* WHERE...Portions of northwest Indiana and north central and 
  northeast Illinois.

* WHEN...From 3 PM Saturday to 6 PM CST Sunday.

* IMPACTS...Travel could be very difficult due to very low 
  visibilities and snow packed roads. Power outages are also 
  possible.



PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in
your vehicle in case of an emergency. 

In Illinois, the latest road conditions for Illinois can be
obtained on the internet at www.gettingaroundillinois.com. In
Indiana, the latest road conditions for Indiana are available by
calling 1-800-261-7623.

&&

$$

ILZ032-033-039-INZ010-011-019-300445-
/O.CON.KLOT.WS.A.0002.210130T2100Z-210131T1800Z/
Livingston-Iroquois-Ford-Newton-Jasper-Benton-
Including the cities of Pontiac, Dwight, Fairbury, Watseka, 
Gilman, Paxton, Gibson City, Roselawn, Kentland, Morocco, 
Rensselaer, DeMotte, Fowler, and Oxford
238 PM CST Fri Jan 29 2021 /338 PM EST Fri Jan 29 2021/

...WINTER STORM WATCH REMAINS IN EFFECT FROM SATURDAY AFTERNOON
THROUGH SUNDAY MORNING...

* WHAT...Period of heavy wet snow likely along with easterly 
  winds gusting up to 30 mph. Total snow accumulations of 3 to 7 
  inches and locally higher possible.

* WHERE...Portions of northwest Indiana and central, east 
  central, north central and northeast Illinois.

* WHEN...From Saturday afternoon through Sunday morning, with 
  the most significant impacts late Saturday afternoon through 
  Saturday evening when much of the snow is forecast to occur.

* IMPACTS...Travel could be dangerous due to the heavy wet snow 
  and strong winds causing very low visibility and snow packed 
  roads. Power outages possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$
232 
WWUS43 KLOT 300310
WSWLOT

URGENT - WINTER WEATHER MESSAGE
National Weather Service Chicago IL
910 PM CST Fri Jan 29 2021

...Heavy Wet Snow and Wind Likely Saturday PM into Early Sunday...

ILZ003-008-010-019-301115-
/O.CON.KLOT.WS.W.0002.210130T1800Z-210201T0000Z/
Winnebago-Ogle-Lee-La Salle-
Including the cities of Rockford, Rochelle, Oregon, Byron, Dixon,
Ottawa, Streator, La Salle, Mendota, and Marseilles
910 PM CST Fri Jan 29 2021

...WINTER STORM WARNING REMAINS IN EFFECT FROM NOON SATURDAY TO
6 PM CST SUNDAY...

* WHAT...Heavy wet snow likely along with easterly winds gusting  
  to 30 mph. The snow could begin as a short period of rain or 
  freezing rain Saturday afternoon. Total snow accumulations of 5 
  to 9 inches and locally higher possible.

* WHERE...Winnebago, Ogle, Lee and La Salle Counties.

* WHEN...From noon Saturday to 6 PM CST Sunday.

* IMPACTS...Travel could be very difficult due to very low 
  visibilities and snow packed roads. Power outages are also 
  possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in
your vehicle in case of an emergency. 

The latest road conditions for Illinois can be obtained on the
internet at www.gettingaroundillinois.com.

&&

$$

ILZ004>006-011>013-020-021-023-103>108-INZ001-002-301115-
/O.CON.KLOT.WS.W.0002.210130T2100Z-210201T0000Z/
Boone-McHenry-Lake IL-De Kalb-Kane-DuPage-Kendall-Grundy-Kankakee-
Northern Cook-Central Cook-Southern Cook-Northern Will-
Southern Will-Eastern Will-Lake IN-Porter-
Including the cities of Belvidere, Crystal Lake, Algonquin, 
McHenry, Woodstock, Waukegan, Buffalo Grove, Mundelein, Gurnee, 
DeKalb, Sycamore, Aurora, Elgin, Naperville, Wheaton, 
Downers Grove, Lombard, Carol Stream, Oswego, Yorkville, Plano, 
Morris, Coal City, Minooka, Kankakee, Bourbonnais, Bradley, 
Evanston, Des Plaines, Schaumburg, Palatine, Northbrook, Chicago,
Cicero, Oak Lawn, Oak Park, La Grange, Calumet City, Oak Forest, 
Lemont, Orland Park, Park Forest, Joliet, Bolingbrook, 
Plainfield, Mokena, Channahon, Manhattan, Wilmington, Crete, 
Peotone, Beecher, Gary, Hammond, Merrillville, Portage, 
Valparaiso, and Chesterton
910 PM CST Fri Jan 29 2021

...WINTER STORM WARNING REMAINS IN EFFECT FROM 3 PM SATURDAY TO
6 PM CST SUNDAY...

* WHAT...Heavy wet snow expected. Total snow accumulations of 5 
  to 9 inches. Winds gusting as high as 35 mph.

* WHERE...Portions of northwest Indiana and north central and
  northeast Illinois, including the Chicago Metro area.

* WHEN...From 3 PM Saturday to 6 PM CST Sunday.

* IMPACTS...Travel could be very difficult due to very low 
  visibilities and snow packed roads. Power outages are also 
  possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in
your vehicle in case of an emergency. 

In Illinois, the latest road conditions for Illinois can be
obtained on the internet at www.gettingaroundillinois.com. In
Indiana, the latest road conditions for Indiana are available by
calling 1-800-261-7623.

&&

$$

ILZ032-033-039-INZ010-011-019-301115-
/O.CON.KLOT.WS.A.0002.210130T2100Z-210131T1800Z/
Livingston-Iroquois-Ford-Newton-Jasper-Benton-
Including the cities of Pontiac, Dwight, Fairbury, Watseka, 
Gilman, Paxton, Gibson City, Roselawn, Kentland, Morocco, 
Rensselaer, DeMotte, Fowler, and Oxford
910 PM CST Fri Jan 29 2021 /1010 PM EST Fri Jan 29 2021/

...WINTER STORM WATCH REMAINS IN EFFECT FROM SATURDAY AFTERNOON
THROUGH SUNDAY MORNING...

* WHAT...Period of heavy wet snow likely along with easterly winds
  gusting to 30 mph. Total snow accumulations of 3 to 7 inches 
  and locally higher possible.

* WHERE...Newton, Jasper and Benton Counties in northwest Indiana
  and Livingston, Ford and Iroquois Counties in central Illinois.

* WHEN...Saturday afternoon through Sunday morning, with the most
  significant impacts late Saturday afternoon through Saturday 
  evening when much of the snow is forecast to occur.

* IMPACTS...Travel could be dangerous due to the heavy wet snow 
  and strong winds causing very low visibility and snow packed 
  roads. Power outages possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation. 

&&

$$
193 
WWUS43 KLOT 300927
WSWLOT

URGENT - WINTER WEATHER MESSAGE
National Weather Service Chicago IL
327 AM CST Sat Jan 30 2021

...Heavy Wet Snow and Wind Developing This Afternoon into 
Tonight...

ILZ033-INZ010-011-019-301730-
/O.UPG.KLOT.WS.A.0002.210130T2100Z-210131T1800Z/
/O.EXA.KLOT.WS.W.0002.210130T2100Z-210201T0000Z/
Iroquois-Newton-Jasper-Benton-
Including the cities of Watseka, Gilman, Roselawn, Kentland, 
Morocco, Rensselaer, DeMotte, Fowler, and Oxford
327 AM CST Sat Jan 30 2021 /427 AM EST Sat Jan 30 2021/

...WINTER STORM WARNING IN EFFECT FROM 3 PM CST /4 PM EST/ THIS
AFTERNOON TO 6 PM CST /7 PM EST/ SUNDAY...

* WHAT...Heavy wet snow along with easterly winds gusting to 30
  mph. The snow could begin as a short period of rain or freezing
  rain this afternoon. Total snow accumulations of 4 to 8 inches
  and locally higher possible, with highest values north.

* WHERE...In Indiana, Newton, Jasper and Benton Counties. In 
  Illinois, Iroquois County.

* WHEN...From 3 PM CST /4 PM EST/ this afternoon to 6 PM CST /7 PM
  EST/ Sunday, with the highest impacts this evening.

* IMPACTS...Travel could be dangerous due to the heavy wet snow
  and strong winds causing very low visibility and snow packed
  roads. Patchy blowing snow is possible this evening and
  overnight. Power outages are also possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in
your vehicle in case of an emergency. 

In Illinois, the latest road conditions for Illinois can be
obtained on the internet at www.gettingaroundillinois.com. In
Indiana, the latest road conditions for Indiana are available by
calling 1-800-261-7623.

Use plenty of extra caution when shoveling heavy snow. Stay
hydrated and take frequent breaks.

&&

$$

ILZ003-008-010-019-301730-
/O.CON.KLOT.WS.W.0002.210130T1800Z-210201T0000Z/
Winnebago-Ogle-Lee-La Salle-
Including the cities of Rockford, Rochelle, Oregon, Byron, Dixon,
Ottawa, Streator, La Salle, Mendota, and Marseilles
327 AM CST Sat Jan 30 2021

...WINTER STORM WARNING REMAINS IN EFFECT FROM NOON TODAY TO 6 PM
CST SUNDAY...

* WHAT...Heavy wet snow along with easterly winds gusting to 30
  mph. The snow will likely begin as a short period of a mix with
  rain or freezing rain this afternoon. Total snow accumulations
  of 4 to 8 inches and locally higher possible. Ice accumulations
  up to one tenth of an inch near and west of Interstate 39.

* WHERE...Winnebago, Ogle, Lee and La Salle Counties.

* WHEN...From early afternoon today to 6 PM CST Sunday, with the
  highest impacts late this afternoon through this evening.

* IMPACTS...Travel could be very difficult due to very low
  visibilities and snow packed roads. Patchy blowing snow is
  possible this evening and overnight. Power outages are also 
  possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in
your vehicle in case of an emergency.

The latest road conditions for Illinois can be obtained on the
internet at www.gettingaroundillinois.com.

Use plenty of extra caution when shoveling heavy snow. Stay
hydrated and take frequent breaks.

&&

$$

ILZ004>006-011>013-020-021-023-103>108-INZ001-002-301730-
/O.CON.KLOT.WS.W.0002.210130T2100Z-210201T0000Z/
Boone-McHenry-Lake IL-De Kalb-Kane-DuPage-Kendall-Grundy-Kankakee-
Northern Cook-Central Cook-Southern Cook-Northern Will-
Southern Will-Eastern Will-Lake IN-Porter-
Including the cities of Belvidere, Crystal Lake, Algonquin, 
McHenry, Woodstock, Waukegan, Buffalo Grove, Mundelein, Gurnee, 
DeKalb, Sycamore, Aurora, Elgin, Naperville, Wheaton, 
Downers Grove, Lombard, Carol Stream, Oswego, Yorkville, Plano, 
Morris, Coal City, Minooka, Kankakee, Bourbonnais, Bradley, 
Evanston, Des Plaines, Schaumburg, Palatine, Northbrook, Chicago,
Cicero, Oak Lawn, Oak Park, La Grange, Calumet City, Oak Forest, 
Lemont, Orland Park, Park Forest, Joliet, Bolingbrook, 
Plainfield, Mokena, Channahon, Manhattan, Wilmington, Crete, 
Peotone, Beecher, Gary, Hammond, Merrillville, Portage, 
Valparaiso, and Chesterton
327 AM CST Sat Jan 30 2021

...WINTER STORM WARNING REMAINS IN EFFECT FROM 3 PM THIS
AFTERNOON TO 6 PM CST SUNDAY...

* WHAT...Heavy wet snow along with easterly winds gusting to 30 to
  35 mph. Total snow accumulations of 5 to 9 inches and locally
  higher possible. 

* WHERE...Portions of northwest Indiana and north central and 
  northeast Illinois, including the Chicago Metro area.

* WHEN...From 3 PM this afternoon to 6 PM CST Sunday, with the
  highest impacts this evening.

* IMPACTS...Travel could be very difficult due to very low
  visibilities and snow packed roads. Patchy blowing snow is
  possible this evening into Sunday morning. Power outages are 
  also possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in
your vehicle in case of an emergency.

In Illinois, the latest road conditions for Illinois can be
obtained on the internet at www.gettingaroundillinois.com. In
Indiana, the latest road conditions for Indiana are available by
calling 1-800-261-7623.

Use plenty of extra caution when shoveling heavy snow. Stay
hydrated and take frequent breaks.

&&

$$

ILZ032-039-301730-
/O.UPG.KLOT.WS.A.0002.210130T2100Z-210131T1800Z/
/O.NEW.KLOT.WW.Y.0003.210130T2100Z-210131T2100Z/
Livingston-Ford-
Including the cities of Pontiac, Dwight, Fairbury, Paxton, 
and Gibson City
327 AM CST Sat Jan 30 2021

...WINTER WEATHER ADVISORY IN EFFECT FROM 3 PM THIS AFTERNOON TO
3 PM CST SUNDAY...

* WHAT...Wet snow expected, likely heavy at times late this
  afternoon and evening. The snow is expected to begin as a mix 
  with rain or freezing rain this afternoon. Total snow 
  accumulations of 3 to 7 inches with highest values north. Ice 
  accumulations of a glaze possible.

* WHERE...Livingston and Ford Counties.

* WHEN...From 3 PM this afternoon to 3 PM CST Sunday, with the
  highest impacts late this afternoon through this evening.

* IMPACTS...Plan on hazardous, snow covered and slippery road
  conditions. Patchy blowing snow is possible this evening,
  especially for northern sections.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. 

The latest road conditions for Illinois can be obtained on the
internet at www.gettingaroundillinois.com.

Use plenty of extra caution when shoveling heavy snow. Stay
hydrated and take frequent breaks.

&&

$$

Castro/MTF

What forecasters said that day

The local office's own words before this winter storm watch went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Chicago, IL wrote its last area forecast discussion before this winter storm watch went out at Jan 29, 2:10 AM CST, 1 hour 13 minutes earlier.

Area forecast discussion, Jan 29, 2:10 AM CST, 1 hour 13 minutes before
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
210 AM CST Fri Jan 29 2021

.SHORT TERM...
301 PM CST

Through Friday night...

Seasonably cold but dry weather will persist through Friday night.

Afternoon surface analysis depicts a north-south oriented surface
high pressure ridge across Wisconsin and Illinois. The surface
ridge will continue to drift slowly east tonight, eventually
shifting east of the forecast area Friday morning. The combination
of light/calm winds within the ridge axis, a cold/dry low level
modified arctic air mass, and the potential for periods of clear to
partly cloudy skies will likely set up another chilly night across
the region. Mid-level warm advection just upstream of the area was
producing patch7 mid and high level clouds this afternoon however,
and this scattered cloud cover will spill across the forecast area at
times overnight and may keep temps a little milder overall than last
night. Even so, lows in the single digits (above zero) are likely
across northern IL portions of the cwa where snow cover exists. A
few sub-zero readings can't be ruled out if skies clear for an
appreciable amount of time. Have trended toward the cooler MAV
guidance where snow cover is more prevalent. Temps are expected to
moderate a bit more into the upper 20s/low 30s Friday, as the
surface ridge moves off to the east of the area, and warm advection
increases aloft.

Cloud cover will thicken up Friday night, in advance of a
disturbance tracking toward the region across the Plains. Along with
a modest but persistent southeast wind, this will help keep temps
mainly in the 20s through the night.

Ratzer

&&

.LONG TERM...
205 AM CST

Monday through Thursday...

Beyond this weekend's system of interest, the pattern favors
continued progressive and fairly deep long waves over North
America, aided too by teleconnections. For next week, attention
in time may turn to the Thursday-Friday time frame. Despite days
7-8 in the forecast, there is higher than normal confidence in a
deep and anomalous system in the Midwest based on consistency in
guidance, as well as global ensembles showing higher probabilities
in key mass fields.

For Monday, lingering clouds from the weekend system's influence
are likely, especially lake effect clouds and possibly flurries.
This looks like a setup where at least some of the CWA if not most
of it may clear during the day going into a 1026+ mb high over
fresh snow cover. Have blended a cooler National Blend of Models
(NBM) solution into the forecast for highs Monday and lows Monday
night with this regime. This does not look like any type of
substantial cold for the first day of February by any means, with
850 mb only around -5C (near normal). More sun looks favored
Tuesday and possibly into Wednesday as amplifying upper riding is
predicted to move over. This ridging is ahead of a deepening
western trough which is the aforementioned late week system.

With this far in the forecast and active weather this coming
weekend, have not gone into detailed analysis of this Plains Low
archetype system that is forecast in guidance. It's worth noting
though that the EC ensemble (50 members worth) mean MSLP is below
999 mb for Thursday and Thursday night. It's also quicker, more
in line with the GFS and Canadian models, as opposed to the
operational ECMWF which did slow with the surface low on its 00Z
run. The system speed as it possibly moves into the Upper Midwest
or Great Lakes region will be important in that it would impact
the duration of potential rain, as well as warm sector
temperatures and dew points above freezing. These two together if
they were to align would be rain on snow melt. This does not
scream aggressive melt in current solutions, although a slower
ECMWF is a bit more concerning. Will have to keep an eye on this.

MTF

&&

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

No forecast concerns expected this period. High pressure is
centered over the area currently and will slowly shift east Friday
morning. Light/calm winds will become light east/southeast by
daybreak and slowly increase into the 8-10kt range on Friday. Wind
speeds are likely to increase further Friday night, into the
10-15kt range with some gusts possible.

Mid level cloud cover has developed and spread across the area and
mid clouds at various levels can be expected through the period.
There is an area of mvfr cigs across central IA shifting northeast
with a 3-4kft vfr deck on the leading edge. This cloud cover may
get close to rfd before sunrise, but confidence is low. cms

&&

.MARINE...
205 AM CST

A Small Craft Advisory has been issued for the weekend with the
upcoming system, but its worth noting here that there is a
potential for a period of gales in the Illinois nearshore on
Saturday evening into overnight. The winds with this system will
be southeast during Saturday gradually backing to easterly
Saturday night, providing a stiff onshore component. The magnitude
of pressure falls occurring Saturday night over the southern part
of the lake in this type of setup, especially with some
instability over the water, has supported gales before. For now
will mention occasional gales in the Illinois nearshore. Also the
waves will build significantly to over 8 ft with this type of
setup, and potentially to once again 10-12 ft that could linger
into Sunday morning.

MTF

&&

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

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Hazardous weather outlook, Jan 28, 3:50 PM CST, 11 hours 33 minutes before
Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
350 PM CST Thu Jan 28 2021

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-292200-
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-
350 PM CST Thu Jan 28 2021 /450 PM EST Thu Jan 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 Excessive Cold Risk.

DISCUSSION...

Single digit to mid-teen low Temperatures Friday morning.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Friday...
  Limited Excessive Cold Risk Friday Morning.

Saturday Late Afternoon and Night...
  Significant Snow Risk.
  Limited Ice Accumulation Risk south of I-80.
  Limited Lakeshore Flood Risk.
Sunday...
  Elevated Snow Risk.
  Limited Lakeshore Flood Risk.

DISCUSSION:

A significant weather system is likely to impact the region
late Saturday afternoon through Sunday. Moderate to heavy snow,
and significant snow accumulations are possible across at least
portions of the area with this storm system.

Gusty east to northeast winds could result in a threat for minor
lakeshore flooding, mainly Saturday night and into Sunday across
the northeast Illinois shore.

.SPOTTER INFORMATION STATEMENT...

  Spotter activation will not be necessary through tonight.

LMZ740>745-292200-
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-
350 PM CST Thu Jan 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.

  No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Friday through Wednesday...
  Hazardous conditions for small craft are likely.

BKL

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The office that day

Everything else NWS Chicago, IL issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jan 29, 3:20 AM CSTSmall Craft AdvisoryLOT5 days
Jan 29, 12:07 PM CSTRiver Flood AdvisoryLOTWinnebago21 hr
Jan 29, 2:22 PM CSTGale WarningLOT43 hr
Jan 29, 2:22 PM CSTSmall Craft AdvisoryLOT4 days
Jan 29, 2:38 PM CSTWinter Storm WarningLOTBoone, Cook, DeKalb, DuPage, Grundy, Iroquois and 10 more51 hr
Jan 29, 2:43 PM CSTLakeshore Flood AdvisoryLOTCook, Lake60 hr

Nearby

Winter Storm Watches in Illinois, 2021Winter Storm Watches in Indiana, 2021Every winter storm watch in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.