Tornado Watch Issued for Most of Illinois, Including Chicagoland

NWS Storm Prediction Center Tornado Second Outlook Map for Monday afternoon, October 11, 2021 (SOURCE: NWS Storm Prediction Center)
NWS Storm Prediction Center Tornado Second Outlook Map for Monday afternoon, October 11, 2021 (SOURCE: NWS Storm Prediction Center)

A final arc of thunderstorms (a “Second Wave”), currently developing just northeast of the surface low over west central Illinois, will shift northeastward across northeastern IL and northwestern Indiana into early evening Monday, October 11, 2021, according to the National Weather Service. The evolution of this line of storms will be of great interest for northeast Illinois after 5:00 p.m., with it potentially producing the best threat of severe storms for the area into early evening. Recently this line of storms produced a tornado in Greene county IL.

A Tornado Watch was activated by the National Weather Service at 3:10 p.m. for the following Illinois counties …

BOONE, BUREAU, CARROLL
CASS, CHAMPAIGN, CHRISTIAN
CLARK, COLES, COOK
CUMBERLAND, DE KALB, DE WITT
DOUGLA, DUPAGE, EDGAR
EFFINGHAM, FORD, FULTON
GRUNDY, HENRY, IROQUOIS
KANE, KANKAKEE, KENDALL
KNOX, LAKE, LA SALLE
LEE, LIVINGSTON, LOGAN
MACON, MARSHALL, MASON
MCHENRY, MCLEAN, MENARD
MORGAN, MOULTRIE, OGLE
PEORIA, PIATT, PUTNAM
SANGAMON, SHELBY, STARK
TAZEWELL, VERMILION, WHITESIDE
WILL, WINNEBAGO, WOODFORD

Several Tornado Warnings have been issued in Morgan County and Sangamon County just west and southwest of Springfield, Illinois.

According to the National Weather Service Chicago, showers and storms are expanding in coverage this afternoon. There have been indications of mini-supercell structures embedded in the showers at times which could result in funnel clouds or even brief tornadoes. Another round is expected later this afternoon into the evening. These have the potential to become severe with all severe hazards possible, including strong winds, tornadoes, and large hail.

General storm motion is north-northeast at 50 MPH.

Severe weather is forecast to be exiting northeast Illinois including the Lake Michigan shoreline by about 9:00 p.m. or 10:00 p.m. after a second round of storms passes through Chicagoland from 4:00 p.m. to 8:00 p.m.

Atmosphere “Struggling” to Be Severe

Early Monday afternoon, the National Weather Service described a weakened atmosphere. In the wake of the initial arc of showers and storms, visible satellite imagery showed a dry intrusion with some clearing. However, earlier Monday afternoon, the National Weather Service stated that the atmosphere could recover in the wake of the first wave with the subsequent storms over central and western Illinois expected to move into our CWA later this afternoon. Should the atmosphere recover sufficiently — and apparently the atmosphere has recovered for severe weather conditions with the issuance of a Tornado Watch — then this activity could pose a risk of damaging winds and perhaps tornadoes as well, the National Weather Service said.

Before the Tornado Watch was issued, the National Weather Service described Radar signatures over north central Illinois that starting to resemble some low topped mini-supercells. This is fairly typical with strong sheared/strongly forced environments with limited instability.

“Continued strengthening low level shear along with very gradual destabilization this afternoon suggests we could see additional mini-supercells this afternoon. The potential severe hazards with mini-supercells tend to be only brief tornadoes, with typically little straight line wind or hail threat. Tornadic mini-supercells often do not exhibit as strong of rotational velocities as radar as larger, more classic supercells, so will continue to closely monitor radar trends this afternoon.”

— NWS Chicago

The first wave of “storms” early Monday afternoon produced little if any lightning and thunder in Arlington Heights.

Weather Radar) shows are large area of thunderstorms in northeast Illinois moving from south-southwest to north-northeast at 3:20 p.m.

See also Arlingtoncardinal.com/clouds

 O’HARE FORECAST … 

Columbus Day: Periods of showers and possibly a thunderstorm. Some storms could be severe, with large hail and damaging winds. Steady temperature around 73. Breezy, with a south wind around 20 mph, with gusts as high as 35 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Tonight: Periods of showers and thunderstorms before 1am, then a chance of showers. Some storms could be severe, with large hail and damaging winds. Low around 60. South southwest wind around 15 mph, with gusts as high as 30 mph. Chance of precipitation is 90%. New rainfall amounts between a half and three quarters of an inch possible.

Tuesday: Mostly cloudy, with a high near 71. Southwest wind 10 to 15 mph, with gusts as high as 25 mph.

Tuesday Night: Partly cloudy, with a low around 56. West southwest wind 5 to 10 mph.

Wednesday: A chance of showers, with thunderstorms also possible after 4pm. Mostly cloudy, with a high near 73. South wind 5 to 10 mph increasing to 10 to 15 mph in the afternoon. Winds could gust as high as 20 mph. Chance of precipitation is 40%.

Wednesday Night: Showers likely and possibly a thunderstorm before 1am, then a chance of showers and thunderstorms between 1am and 4am, then a chance of showers after 4am. Mostly cloudy, with a low around 61. Chance of precipitation is 60%.

Thursday: A 20 percent chance of showers. Partly sunny, with a high near 72.

Thursday Night: A slight chance of showers after 1am. Partly cloudy, with a low around 53.

Friday: A chance of showers. Partly sunny, with a high near 66.

Friday Night: A chance of showers. Mostly cloudy, with a low around 48.

Saturday: A slight chance of showers. Mostly sunny, with a high near 60.

Saturday Night: Mostly clear, with a low around 46.

Sunday: Sunny, with a high near 63.

 LAKE TEMPS … 

SOUTHERN LAKE MICHIGAN WATER TEMPERATURES
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
913 AM CDT Mon Oct 11 2021

LAKE MICHIGAN WATER TEMPERATURES…

CHICAGO SHORE……….67.

CHICAGO CRIB……….66.

CHICAGO BUOY……….67.

WILMETTE BUOY……….66.

WAUKEGAN BUOY……….M.

WINTHROP HARBOR BUOY……….65.

MICHIGAN CITY……….65.

MICHIGAN CITY BUOY………M.

SOUTH MID LAKE BUOY……….66.

NORTH MID LAKE BUOY……….64.

&&

M IS FOR MISSING DATA THAT IS NORMALLY AVAILABLE.

THE MICHIGAN CITY WATER TEMPERATURE SENSOR IS LOCATED AT A WATER
INTAKE ONE MILE OFFSHORE AND 60 FEET BELOW WATER SURFACE. IT IS READ
EVERY DAY OF THE YEAR.

october.chicagoweatherstation.com

Arlingtoncardinal.com/radar

Chicago Weather Forecast for your MAC/PC/TABLET includes surrounding suburbs.

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