(updated ADS-B data with 10s interval data. A note on that: not every interval provides a full complement of the data. The only reliable indicator that data is fresh is if it has changed from the last timestamp. Keep that in mind when inferring conclusions from this.)
Here's some data for the last ~20 minutes of this flight. Background is false colour infrared satellite image with blue color indicating cloud top temperatures -40C consistent with a significant frontal system in the area. YWLM METAR (see screenshot) would indicate they were in VMC the entire time, and gusts to 29kts were reported on the ground.
Significant ground speed variations of up to 30kts magnitude, as well as altitude excursions of several hundred feet between the 30 second data intervals and prior to the apparent onset of a problem would indicate turbulent conditions. This GSP variability increased to 60kts just prior to the rapid descent. There's a distinct turn towards Williamstown about 4 minutes before the descent, that might suggest something happened that prompted intent to divert. As seen in the ADS-B data:
UTC Time +/- 10s: 2019-09-06 08:14:17: TRK: 48.0 GSP: 127.0 ALT: 1450.0 V/S: -9024.0
UTC Time +/- 10s: 2019-09-06 08:14:07: TRK: 48.0 GSP: 127.0 ALT: 1450.0 V/S: -9024.0
UTC Time +/- 10s: 2019-09-06 08:13:57: TRK: 48.0 GSP: 127.0 ALT: 1450.0 V/S: -9024.0
UTC Time +/- 10s: 2019-09-06 08:13:47: TRK: 48.0 GSP: 127.0 ALT: 1450.0 V/S: -9024.0
UTC Time +/- 10s: 2019-09-06 08:13:37: TRK: 121.0 GSP: 152.0 ALT: 2200.0 V/S: -8768.0
UTC Time +/- 10s: 2019-09-06 08:13:27: TRK: 121.0 GSP: 152.0 ALT: 2200.0 V/S: -8768.0
UTC Time +/- 10s: 2019-09-06 08:13:17: TRK: 121.0 GSP: 152.0 ALT: 2200.0 V/S: -8768.0
UTC Time +/- 10s: 2019-09-06 08:13:07: TRK: 192.0 GSP: 120.0 ALT: 3250.0 V/S: -320.0
UTC Time +/- 10s: 2019-09-06 08:12:57: TRK: 192.0 GSP: 120.0 ALT: 3250.0 V/S: -320.0
UTC Time +/- 10s: 2019-09-06 08:12:47: TRK: 211.0 GSP: 76.0 ALT: 3525.0 V/S: -384.0
UTC Time +/- 10s: 2019-09-06 08:12:37: TRK: 211.0 GSP: 76.0 ALT: 3525.0 V/S: -384.0
UTC Time +/- 10s: 2019-09-06 08:12:27: TRK: 210.0 GSP: 95.0 ALT: 3300.0 V/S: 1216.0
UTC Time +/- 10s: 2019-09-06 08:12:17: TRK: 210.0 GSP: 95.0 ALT: 3300.0 V/S: 1216.0
UTC Time +/- 10s: 2019-09-06 08:12:07: TRK: 223.0 GSP: 94.0 ALT: 3050.0 V/S: 320.0
UTC Time +/- 10s: 2019-09-06 08:11:57: TRK: 223.0 GSP: 94.0 ALT: 3050.0 V/S: 320.0
UTC Time +/- 10s: 2019-09-06 08:11:47: TRK: 283.0 GSP: 65.0 ALT: 3050.0 V/S: -128.0
UTC Time +/- 10s: 2019-09-06 08:11:37: TRK: 283.0 GSP: 65.0 ALT: 3050.0 V/S: -128.0
UTC Time +/- 10s: 2019-09-06 08:11:27: TRK: 283.0 GSP: 65.0 ALT: 3050.0 V/S: -128.0
UTC Time +/- 10s: 2019-09-06 08:11:17: TRK: 287.0 GSP: 70.0 ALT: 3100.0 V/S: -320.0
UTC Time +/- 10s: 2019-09-06 08:11:07: TRK: 287.0 GSP: 70.0 ALT: 3100.0 V/S: -320.0
UTC Time +/- 10s: 2019-09-06 08:10:57: TRK: 282.0 GSP: 71.0 ALT: 3275.0 V/S: 64.0
UTC Time +/- 10s: 2019-09-06 08:10:47: TRK: 282.0 GSP: 71.0 ALT: 3275.0 V/S: 64.0
UTC Time +/- 10s: 2019-09-06 08:10:37: TRK: 271.0 GSP: 67.0 ALT: 3350.0 V/S: -128.0
UTC Time +/- 10s: 2019-09-06 08:10:27: TRK: 271.0 GSP: 67.0 ALT: 3350.0 V/S: -128.0
UTC Time +/- 10s: 2019-09-06 08:10:17: TRK: 289.0 GSP: 64.0 ALT: 3475.0 V/S: -192.0
UTC Time +/- 10s: 2019-09-06 08:10:07: TRK: 289.0 GSP: 64.0 ALT: 3475.0 V/S: -192.0
UTC Time +/- 10s: 2019-09-06 08:09:57: TRK: 282.0 GSP: 61.0 ALT: 3400.0 V/S: 1920.0
UTC Time +/- 10s: 2019-09-06 08:09:47: TRK: 282.0 GSP: 61.0 ALT: 3400.0 V/S: 1920.0
UTC Time +/- 10s: 2019-09-06 08:09:37: TRK: 272.0 GSP: 76.0 ALT: 3025.0 V/S: 512.0
UTC Time +/- 10s: 2019-09-06 08:09:27: TRK: 272.0 GSP: 76.0 ALT: 3025.0 V/S: 512.0
UTC Time +/- 10s: 2019-09-06 08:09:17: TRK: 272.0 GSP: 76.0 ALT: 3025.0 V/S: 512.0
UTC Time +/- 10s: 2019-09-06 08:09:07: TRK: 238.0 GSP: 86.0 ALT: 3100.0 V/S: -896.0
UTC Time +/- 10s: 2019-09-06 08:08:57: TRK: 238.0 GSP: 86.0 ALT: 3100.0 V/S: -896.0
UTC Time +/- 10s: 2019-09-06 08:08:47: TRK: 238.0 GSP: 91.0 ALT: 3325.0 V/S: -192.0
UTC Time +/- 10s: 2019-09-06 08:08:37: TRK: 238.0 GSP: 91.0 ALT: 3325.0 V/S: -192.0
UTC Time +/- 10s: 2019-09-06 08:08:27: TRK: 252.0 GSP: 87.0 ALT: 3325.0 V/S: 512.0
UTC Time +/- 10s: 2019-09-06 08:08:17: TRK: 252.0 GSP: 87.0 ALT: 3325.0 V/S: 512.0
UTC Time +/- 10s: 2019-09-06 08:08:07: TRK: 234.0 GSP: 100.0 ALT: 3250.0 V/S: -192.0
UTC Time +/- 10s: 2019-09-06 08:07:57: TRK: 234.0 GSP: 100.0 ALT: 3250.0 V/S: -192.0
UTC Time +/- 10s: 2019-09-06 08:07:47: TRK: 231.0 GSP: 103.0 ALT: 3300.0 V/S: -384.0
UTC Time +/- 10s: 2019-09-06 08:07:37: TRK: 231.0 GSP: 103.0 ALT: 3300.0 V/S: -384.0
UTC Time +/- 10s: 2019-09-06 08:07:27: TRK: 230.0 GSP: 105.0 ALT: 3500.0 V/S: -640.0
UTC Time +/- 10s: 2019-09-06 08:07:17: TRK: 230.0 GSP: 105.0 ALT: 3500.0 V/S: -640.0
UTC Time +/- 10s: 2019-09-06 08:07:08: TRK: 232.0 GSP: 99.0 ALT: 3475.0 V/S: 576.0
UTC Time +/- 10s: 2019-09-06 08:06:58: TRK: 232.0 GSP: 99.0 ALT: 3475.0 V/S: 576.0
UTC Time +/- 10s: 2019-09-06 08:06:48: TRK: 225.0 GSP: 112.0 ALT: 3400.0 V/S: 192.0
UTC Time +/- 10s: 2019-09-06 08:06:38: TRK: 225.0 GSP: 112.0 ALT: 3400.0 V/S: 192.0
UTC Time +/- 10s: 2019-09-06 08:06:28: TRK: 225.0 GSP: 113.0 ALT: 3400.0 V/S: 64.0
UTC Time +/- 10s: 2019-09-06 08:06:18: TRK: 220.0 GSP: 102.0 ALT: 3275.0 V/S: 1216.0
UTC Time +/- 10s: 2019-09-06 08:06:08: TRK: 220.0 GSP: 102.0 ALT: 3275.0 V/S: 1216.0
UTC Time +/- 10s: 2019-09-06 08:05:58: TRK: 218.0 GSP: 104.0 ALT: 3200.0 V/S: 64.0
UTC Time +/- 10s: 2019-09-06 08:05:48: TRK: 218.0 GSP: 104.0 ALT: 3200.0 V/S: 64.0
UTC Time +/- 10s: 2019-09-06 08:05:38: TRK: 221.0 GSP: 107.0 ALT: 3250.0 V/S: 128.0
UTC Time +/- 10s: 2019-09-06 08:05:28: TRK: 221.0 GSP: 107.0 ALT: 3250.0 V/S: 128.0
UTC Time +/- 10s: 2019-09-06 08:05:18: TRK: 218.0 GSP: 108.0 ALT: 3275.0 V/S: -320.0
UTC Time +/- 10s: 2019-09-06 08:05:08: TRK: 218.0 GSP: 108.0 ALT: 3275.0 V/S: -320.0
UTC Time +/- 10s: 2019-09-06 08:04:58: TRK: 190.0 GSP: 136.0 ALT: 3425.0 V/S: -512.0
UTC Time +/- 10s: 2019-09-06 08:04:48: TRK: 190.0 GSP: 136.0 ALT: 3425.0 V/S: -512.0
UTC Time +/- 10s: 2019-09-06 08:04:38: TRK: 205.0 GSP: 120.0 ALT: 3525.0 V/S: -256.0
UTC Time +/- 10s: 2019-09-06 08:04:28: TRK: 205.0 GSP: 120.0 ALT: 3525.0 V/S: -256.0
UTC Time +/- 10s: 2019-09-06 08:04:18: TRK: 205.0 GSP: 120.0 ALT: 3525.0 V/S: -256.0
UTC Time +/- 10s: 2019-09-06 08:04:08: TRK: 206.0 GSP: 120.0 ALT: 3525.0 V/S: -320.0
UTC Time +/- 10s: 2019-09-06 08:03:58: TRK: 206.0 GSP: 120.0 ALT: 3525.0 V/S: -320.0
UTC Time +/- 10s: 2019-09-06 08:03:48: TRK: 213.0 GSP: 113.0 ALT: 3525.0 V/S: 0.0
UTC Time +/- 10s: 2019-09-06 08:03:38: TRK: 213.0 GSP: 113.0 ALT: 3525.0 V/S: 0.0
UTC Time +/- 10s: 2019-09-06 08:03:28: TRK: 206.0 GSP: 115.0 ALT: 3400.0 V/S: 256.0
UTC Time +/- 10s: 2019-09-06 08:03:18: TRK: 206.0 GSP: 115.0 ALT: 3400.0 V/S: 256.0
UTC Time +/- 10s: 2019-09-06 08:03:08: TRK: 206.0 GSP: 115.0 ALT: 3400.0 V/S: 256.0
UTC Time +/- 10s: 2019-09-06 08:02:58: TRK: 208.0 GSP: 106.0 ALT: 3275.0 V/S: 576.0
UTC Time +/- 10s: 2019-09-06 08:02:48: TRK: 208.0 GSP: 106.0 ALT: 3275.0 V/S: 576.0
UTC Time +/- 10s: 2019-09-06 08:02:38: TRK: 203.0 GSP: 114.0 ALT: 2925.0 V/S: 320.0
UTC Time +/- 10s: 2019-09-06 08:02:28: TRK: 203.0 GSP: 114.0 ALT: 2925.0 V/S: 320.0
UTC Time +/- 10s: 2019-09-06 08:02:18: TRK: 218.0 GSP: 103.0 ALT: 2900.0 V/S: 256.0
UTC Time +/- 10s: 2019-09-06 08:02:08: TRK: 218.0 GSP: 103.0 ALT: 2900.0 V/S: 256.0
UTC Time +/- 10s: 2019-09-06 08:01:58: TRK: 222.0 GSP: 105.0 ALT: 2925.0 V/S: -1408.0
UTC Time +/- 10s: 2019-09-06 08:01:48: TRK: 222.0 GSP: 105.0 ALT: 2925.0 V/S: -1408.0
UTC Time +/- 10s: 2019-09-06 08:01:38: TRK: 227.0 GSP: 99.0 ALT: 3325.0 V/S: -1216.0
UTC Time +/- 10s: 2019-09-06 08:01:28: TRK: 227.0 GSP: 99.0 ALT: 3325.0 V/S: -1216.0
UTC Time +/- 10s: 2019-09-06 08:01:18: TRK: 234.0 GSP: 96.0 ALT: 3625.0 V/S: -896.0
UTC Time +/- 10s: 2019-09-06 08:01:08: TRK: 234.0 GSP: 96.0 ALT: 3625.0 V/S: -896.0
UTC Time +/- 10s: 2019-09-06 08:00:58: TRK: 234.0 GSP: 96.0 ALT: 3625.0 V/S: -896.0
UTC Time +/- 10s: 2019-09-06 08:00:48: TRK: 226.0 GSP: 106.0 ALT: 3725.0 V/S: -704.0
UTC Time +/- 10s: 2019-09-06 08:00:38: TRK: 226.0 GSP: 106.0 ALT: 3725.0 V/S: -704.0
UTC Time +/- 10s: 2019-09-06 08:00:28: TRK: 229.0 GSP: 100.0 ALT: 3725.0 V/S: 192.0
UTC Time +/- 10s: 2019-09-06 08:00:18: TRK: 229.0 GSP: 100.0 ALT: 3725.0 V/S: 192.0
UTC Time +/- 10s: 2019-09-06 07:58:58: TRK: 228.0 GSP: 102.0 ALT: 2525.0 V/S: -128.0
UTC Time +/- 10s: 2019-09-06 07:58:48: TRK: 228.0 GSP: 102.0 ALT: 2525.0 V/S: -128.0
UTC Time +/- 10s: 2019-09-06 07:58:38: TRK: 228.0 GSP: 102.0 ALT: 2525.0 V/S: -128.0
UTC Time +/- 10s: 2019-09-06 07:58:28: TRK: 228.0 GSP: 102.0 ALT: 2525.0 V/S: -128.0
UTC Time +/- 10s: 2019-09-06 07:58:18: TRK: 223.0 GSP: 109.0 ALT: 2575.0 V/S: 0.0
UTC Time +/- 10s: 2019-09-06 07:58:08: TRK: 223.0 GSP: 109.0 ALT: 2575.0 V/S: 0.0
UTC Time +/- 10s: 2019-09-06 07:57:58: TRK: 226.0 GSP: 100.0 ALT: 2400.0 V/S: 448.0
UTC Time +/- 10s: 2019-09-06 07:57:48: TRK: 226.0 GSP: 100.0 ALT: 2400.0 V/S: 448.0
UTC Time +/- 10s: 2019-09-06 07:55:28: TRK: 229.0 GSP: 111.0 ALT: 2775.0 V/S: -1536.0
UTC Time +/- 10s: 2019-09-06 07:55:18: TRK: 229.0 GSP: 111.0 ALT: 2775.0 V/S: -1536.0
UTC Time +/- 10s: 2019-09-06 07:55:08: TRK: 229.0 GSP: 111.0 ALT: 2775.0 V/S: -1536.0
UTC Time +/- 10s: 2019-09-06 07:54:59: TRK: 229.0 GSP: 111.0 ALT: 2775.0 V/S: -1536.0
UTC Time +/- 10s: 2019-09-06 07:54:19: TRK: 236.0 GSP: 104.0 ALT: 3950.0 V/S: -1728.0
UTC Time +/- 10s: 2019-09-06 07:54:09: TRK: 235.0 GSP: 103.0 ALT: 3950.0 V/S: 0.0
UTC Time +/- 10s: 2019-09-06 07:53:59: TRK: 235.0 GSP: 103.0 ALT: 3950.0 V/S: 0.0
UTC Time +/- 10s: 2019-09-06 07:53:49: TRK: 235.0 GSP: 103.0 ALT: 3950.0 V/S: 0.0
UTC Time +/- 10s: 2019-09-06 07:53:39: TRK: 235.0 GSP: 103.0 ALT: 3950.0 V/S: 0.0
UTC Time +/- 10s: 2019-09-06 07:53:29: TRK: 235.0 GSP: 103.0 ALT: 3950.0 V/S: 0.0
UTC Time +/- 10s: 2019-09-06 07:53:19: TRK: 232.0 GSP: 100.0 ALT: 3925.0 V/S: 192.0
UTC Time +/- 10s: 2019-09-06 07:53:09: TRK: 232.0 GSP: 100.0 ALT: 3925.0 V/S: 192.0
UTC Time +/- 10s: 2019-09-06 07:52:59: TRK: 225.0 GSP: 109.0 ALT: 3925.0 V/S: 64.0
UTC Time +/- 10s: 2019-09-06 07:52:49: TRK: 225.0 GSP: 109.0 ALT: 3925.0 V/S: 64.0
UTC Time +/- 10s: 2019-09-06 07:52:39: TRK: 217.0 GSP: 116.0 ALT: 3900.0 V/S: -64.0
UTC Time +/- 10s: 2019-09-06 07:52:29: TRK: 217.0 GSP: 116.0 ALT: 3900.0 V/S: -64.0
UTC Time +/- 10s: 2019-09-06 07:52:19: TRK: 215.0 GSP: 120.0 ALT: 3975.0 V/S: -64.0
UTC Time +/- 10s: 2019-09-06 07:52:09: TRK: 215.0 GSP: 120.0 ALT: 3975.0 V/S: -64.0
UTC Time +/- 10s: 2019-09-06 07:51:59: TRK: 214.0 GSP: 120.0 ALT: 3975.0 V/S: 0.0
UTC Time +/- 10s: 2019-09-06 07:51:49: TRK: 212.0 GSP: 116.0 ALT: 3950.0 V/S: 512.0
UTC Time +/- 10s: 2019-09-06 07:51:39: TRK: 212.0 GSP: 116.0 ALT: 3950.0 V/S: 512.0
UTC Time +/- 10s: 2019-09-06 07:51:29: TRK: 205.0 GSP: 122.0 ALT: 3800.0 V/S: 64.0
UTC Time +/- 10s: 2019-09-06 07:51:19: TRK: 205.0 GSP: 122.0 ALT: 3800.0 V/S: 64.0
UTC Time +/- 10s: 2019-09-06 07:51:09: TRK: 203.0 GSP: 121.0 ALT: 3800.0 V/S: 128.0
UTC Time +/- 10s: 2019-09-06 07:50:59: TRK: 203.0 GSP: 121.0 ALT: 3800.0 V/S: 128.0
UTC Time +/- 10s: 2019-09-06 07:50:49: TRK: 197.0 GSP: 129.0 ALT: 3675.0 V/S: 192.0
UTC Time +/- 10s: 2019-09-06 07:50:39: TRK: 197.0 GSP: 129.0 ALT: 3675.0 V/S: 192.0
UTC Time +/- 10s: 2019-09-06 07:50:29: TRK: 188.0 GSP: 142.0 ALT: 3625.0 V/S: 0.0
UTC Time +/- 10s: 2019-09-06 07:50:19: TRK: 188.0 GSP: 142.0 ALT: 3625.0 V/S: 0.0
UTC Time +/- 10s: 2019-09-06 07:50:09: TRK: 188.0 GSP: 142.0 ALT: 3625.0 V/S: 0.0