The track was dry as qualifying began but rain was falling to make conditions extra sketchy.
Bourdais started the ball rolling with 1m11.979s, before being beaten by Filipe Albuquerque’s Wayne Taylor Racing Acura, who produced 1m11.481s, then 1m10.751s and finally 1m10.661s.
But Bourdais wouldn’t be denied, unleashing a 1m10.439s to take his third pole of the season, beating Albuquerque by 0.222s.
Oliver Jarvis took third for Meyer Shank Racing, producing a final lap of 1m10.791s in his Acura ARX-05. Alex Lynn will start fourth in the second CGR car, ahead of the remaining Cadillac drivers, Tristan Nunez (Action Express) and Tristan Vautier (JDC-Miller).
Patrick Kelly took LMP2 pole for PR1 Mathiasen Motorsports on 1m14.340s, ahead of the sister team car of Steven Thomas, who escaped a wild early spin.
Jarett Andretti took LMP3 pole for Andretti Autosport, ahead of Josh Sarchet (MLT Motorsports) and Dan Goldburg (Performance Tech).
#1 Paul Miller Racing BMW M4 GT3: Bryan Sellers, Madison Snow
Photo by: Jake Galstad / Motorsport Images
Snow takes GTD pole for BMW
In GTD, where there is no Pro class this weekend, the track was damp at the start but dried out quickly.
Paul Miller Racing’s BMW M4 of Madison Snow led the way when it mattered on 1m20.525s, two tenths clear of Stevan McAleer (Korthoff Mercedes), Roman De Angelis (Heart of Racing Aston Martin) and early pacesetter Robby Foley (Turner BMW).
Russell Ward (Winward Mercedes) will start fifth, ahead of the Lexuses of Frankie Montecalvo and Richard Heistand, the latter escaping the gravel after an early spin.