Well, that lasted a long time!
Both rtl_433 and weewx were running for about 3 hours, and then it seems like they stopped talking to each other despite both still running according to ps.
I decided to grab the latest rtl_433 source and re-build it to replace the 12/18/2016 version that I was running. Now, whenever I start weewx, it does not write *anything* to the console, but logged the following in syslog:
Jan 14 20:14:57 WXpi3 weewx[1741]: manager: Starting backfill of daily summaries
Jan 14 20:14:57 WXpi3 weewx[1741]: manager: Daily summaries up to date
Jan 14 20:14:57 WXpi3 weewx[1741]: restx: StationRegistry: Registration not requested.
Jan 14 20:14:57 WXpi3 weewx[1741]: restx: Wunderground-RF: Data for station KNYMONTG4 will be posted
Jan 14 20:14:57 WXpi3 weewx[1741]: restx: PWSweather: Posting not enabled.
Jan 14 20:14:57 WXpi3 weewx[1741]: restx: CWOP: Posting not enabled.
Jan 14 20:14:57 WXpi3 weewx[1741]: restx: WOW: Posting not enabled.
Jan 14 20:14:57 WXpi3 weewx[1741]: restx: AWEKAS: Posting not enabled.
Jan 14 20:14:57 WXpi3 weewx[1741]: engine: Starting up weewx version 3.6.2
Jan 14 20:14:57 WXpi3 weewx[1741]: engine: Starting main packet loop.
Jan 14 20:15:05 WXpi3 weewx[1741]: sdr: MainThread: Acurite5n1Packet: unrecognized data: '2017-01-15 01:15:05 :#011Acurite 5n1 sensor#012'
Jan 14 20:15:05 WXpi3 weewx[1741]: sdr: MainThread: Acurite5n1Packet: unrecognized data: '2017-01-15 01:15:05 :#011Acurite 5n1 sensor#012'
Jan 14 20:15:08 WXpi3 weewx[1741]: sdr: MainThread: Acurite5n1Packet: unrecognized data: '2017-01-15 01:15:05 :#011Acurite 5n1 sensor#012'
I'm falling back to the previous rtl_433 for now, and falling back to MeteoBridge WU updates again until I figure this out.....
[edit - It appears that the output format from rtl_433 has changed significantly since last month's code. I guess that's why there were sdr.py commits this week for adding JSON to the Acu-Rite driver? Since adding a -F json to the rtl_433 command didn't work with today's sdr.py, I'm staying back with the older rtl_433 until sdr.py's JSON is ready.]