Air carrier flight crew reported an encounter with severe turbulence.

Attributes
ACN	1573217
Time
Date	201808
Local Time Of Day	1801-2400
Place
Locale Reference	MDW.Airport
State Reference	IL
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Make Model Name	Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 342
Person 2
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Instrument Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Track / Heading All Types Inflight Event / Encounter Weather / Turbulence

Narrative:

Aircraft encountered severe turbulence over pnt VOR while in the turn to jot VOR. The aircraft banked 45 degrees due to turbulence; bank angle warning sounded and autopilot disengaged. The aircraft lost 200 feet to 500 feet of altitude; and heading was 30 degrees off course to avoid additional turbulence. ATC was notified of event and further instructions were to fly direct cadon when able. [The] rest of [the] flight was uneventful.I could see the frontal system ahead of us on radar and it appeared we would stay clear of weather over pnt. Ten miles prior; I queried the first officer to ask for 20 degrees right. The first officer was unable to get a clearance due to heavy radio congestion. We stayed on vector and subsequently encountered the turbulence. I should have used my emergency authority to begin the turn prior to ATC clearance but due to compressed vectors in and out of weather; I wasn't quick enough to react to the situation.

Original NASA ASRS Text

Title: Air carrier flight crew reported an encounter with severe turbulence.

Narrative: Aircraft encountered severe turbulence over PNT VOR while in the turn to JOT VOR. The aircraft banked 45 degrees due to turbulence; Bank Angle Warning sounded and autopilot disengaged. The aircraft lost 200 feet to 500 feet of altitude; and heading was 30 degrees off course to avoid additional turbulence. ATC was notified of event and further instructions were to fly direct CADON when able. [The] rest of [the] flight was uneventful.I could see the frontal system ahead of us on radar and it appeared we would stay clear of weather over PNT. Ten miles prior; I queried the First Officer to ask for 20 degrees right. The First Officer was unable to get a clearance due to heavy radio congestion. We stayed on vector and subsequently encountered the turbulence. I should have used my emergency authority to begin the turn prior to ATC clearance but due to compressed vectors in and out of weather; I wasn't quick enough to react to the situation.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.